How to retro-fit skid trays, aerodynamic under trays, & stone guards to a MK7 Golf

[golfdave]

Disclaimer:- This info is for community usage. I am NOT affiliated to, or sponsored by, any company/individual to promote them or their products. Companies/individuals may NOT use my name, photos, or threads/technical guides, for financial or personal gain (fraudulent misrepresentation).

How to retro-fit skid trays, aerodynamic under trays, & stone guards to a MK7 Golf

This guide is a “How to” retro-fit skid trays, aerodynamic under trays, & stone guards to a MK7 Golf. Otherwise what is generally known as a “Rough Road Package”.

The car used for this is a UK spec MK7 Golf Estate GT (Highline), 1.4lt 140PS petrol, with a manual gearbox, front wheel drive, -15mm OEM sports suspension & the multi-link rear suspension as per the “”Alltrack”, “GTI” & “R”. All the components listed & mods done will work as described on all versions of MK7 Golf Hatch & Estate (unless otherwise stated). You will notice that various car components appear to be covered in a yellowish coating. This is the Waxoyl treatment that I had previously done myself.

There has been a lot of speculation & discussion on this subject with people posting up part numbers & saying this will fit etc.. Some of the information given is correct, some of it is wrong. I am the first to thoroughly go through the VW parts list & actually fit all the correct pieces, & figuring out which future items to watch out for

http://www.golfmk7.com/forums/showthread.php?t=6185

The main reasons for doing these mods is to provide better “rough road” protection, e.g. from stones, & debris which has fallen off other vehicles. However they also help smooth the under body airflow with the benefit of better fuel consumption! Full aerodynamic under trays are used in “eco-vehicles”, supercars, F1 racing, etc.. In fact some of these mods you will find on other “Eco” versions of VAG vehicles!

At the time of writing this guide, the Golf 1.0TSI Bluemotion, GTE, GTD, & R Hatch, 1.0TSI Bluemotion, Alltrack, GTD, & R Estate have been released here in the UK for sale. These models usually have the “extra” trim pieces fitted to them, & I have looked at Etka for these cars also. Unfortunately I cannot find any trim pieces other than those listed here, & most are not fitted at the factory to these models either for UK spec cars!

We can also look for items from the factory “P” codes:-
P1SB: Engine protection grille
P1SK: Engine underside & stonechip guard
P1SL: Underbody stonechip protection.
All these “P” codes make up previous so called “Rough Road Packages”.

The E-Golf (all electric) hatch has different under trays (parts 5Q0 825 236P, 5QE 825 902B, 5QE 825 229B, 5QE 825 218C). But it would be unwise to use them as you will get too much heat soak into the cabin from the exhaust! Basically instead of two length ways covers between the front & rear wheels with a gap for the exhaust, the E-Golf has two width ways covers which totally cover the whole area up, as it has no exhaust! There is also a bigger rear cover under the axle/boot, but of course it has no exhaust which would also be covered up!


VW states on the e-Golf:-
Air drag reduced by 10 per cent. Volkswagen was able to lower the air drag of the Golf by developing very specific measures such as reducing the volume of cooling air (via a radiator shutter and partially closed-off radiator grille), new underbody panelling, rear body modifications with a rear spoiler and C-pillar air guides, and by developing new aerodynamic wheels (essentially closing off gaps, making the wheels flush with the car's exterior). Whereas on the standard Golf (1.6 TDI with 77 kW) air drag is 0.686 m², air drag was reduced to 0.615 m² on the e-Golf, which represents a 10 per cent improvement. Correspondingly, the cD value was lowered to 0.281.

Rolling resistance reduced by 10 per cent. Volkswagen was able to achieve another positive effect on energy consumption and range by optimising the tyres (205/55 R16 91 Q). Reducing the rolling resistance coefficient from 7.2 per 1,000 (Golf BlueMotion) to 6.5 per 1,000 for the e-Golf (likewise an improvement of 10 per cent) also improves the range.
Aerodynamics and rolling resistance | Volkswagen Newsroom (volkswagen-newsroom.com)


MK7 Golf Bluemotion (1.0lt petrol) = 0.27cd??
From other sources & quoted as being “the Golf TSI BlueMotion’s Cd value has been reduced to 0.28 (from 0.29 in the standard Golf), & “10% better in aero than standard Golf” therefore making standard Golf = 0.29cd. The 0.27cd cannot be the hatch version there was no aero difference, so must be the then “new” estate version. The 0.28cd could be the hatch just rounded down??
Manual, & 195/65/R15 wheels.
Sports suspension (-15mm).
Basic MK7 Golf body, bumpers, & lower grille.
Front upper grille has blanking panel in middle.
Engine bay has full length aero under tray from diesel engine cars.
Rear window gloss black fins.

The cd figures below are from the VW Erwin “Self Study guides”.
ID.3 = 0.267cd

Mk8 Golf = 0.275cd (depending on equipment)

MK7 Golf Bluemotion (1.2lt petrol) = 0.287cd.
Manual, & 195/65/R15 wheels.
Sports suspension (-10mm or -15mm).
Basic MK7 Golf body, bumpers, & lower grille.
Front upper grille has blanking panel in middle.
Engine bay has full length aero under tray from diesel engine cars.
Hatch roof spoiler?, rear window gloss black fins.

MK7 e-Golf (total electric) = 0.29cd.
DSG, & 205/55R15 wheels.
Standard ride height suspension.
Upper front grille is a solid blanked grille.
Unique smooth front bumper.
Totally flat under body from front bumper to rear axle as no exhaust!
Hatch roof spoiler?, rear window gloss black fins.
As standard in UK it came with bigger 205/55R16 wheels!

MK7 Golf GTE (petrol/hybrid) = 0.299cd.
DSG, & 205/55R16 wheels.
Sports suspension (-15mm).
GTE has open slat grille like the basic one.
Unique semi-smooth front bumper.
The GTE has the full length diesel engine bay undertray, but with more ventilation holes/slats cut into it.
Bigger rear roof spoiler & gloss black side fins from GTD/GTI.
As standard in UK it came with 225/40R18 wheels!

MK7 Golf GTD (2.0lt diesel) = 0.316cd.
Manual, & 225/45R17 wheels
Sports suspension (-15mm).
Honey comb upper grille.
Unique front bumper with honey comb lower grille & strakes across fog lights.
Full length engine bay under tray called “noise insulation” to quieten the diesel engine.
Bigger rear roof spoiler & gloss black side fins from GTE/GTI
As standard in UK it came with 225/40R18 wheels!

MK7 Golf GTI (2.0lt petrol) = 0.318cd.
Manual, & 225/45R17 wheels
Sports suspension (-15mm).
Honey comb upper grille.
Unique front bumper with honey comb lower grille & strakes across fog lights.
The “half” length engine bay under tray.
Bigger rear roof spoiler & gloss black side fins from GTD/GTE
As standard in UK it came with 225/40R18 wheels!

These figures prove that the wider wheels, fully open honeycomb grilles & exposed fog light grille “strakes” create lots of drag!

So removing the “half under tray & fitting a “full length” diesel under tray removes 0.002cd of drag (GTi-GTD)

Removing 225/45R17 wheels & fitting 205/55R16 wheels removes almost 0.017cd of drag (GTD-GTE) (some has to be the difference in grilles/bumpers, but tyre width is the biggest factor)

There is strong possibility that the first figures has the Variant/Estate as 0.01cd less drag than the Hatch version (trim spec for trim spec), which follows basic aerodynamics.
Besides the e-Golf which has its own unique undertrays, none of the above models has the front exhaust tunnel tray, the rear exhaust tunnel tray, or the rear axle tray fitted!!

Basically fitting wider tyres, mudflaps, the Audi TT brake cooling air guides, & the rear lower wishbone stones guards, will all ADD to the drag, by increasing the frontal x-sectional area & disrupting air flow. However they are important & functional, & the adverse effects of these items is countered by the positive effects of the other aero mods!


By fitting all these items in the Guides below, I have added a minimum conservative estimate of 0.82m2 (8.8ft2) of flat under trays to my car! This has made the car quieter, more stable at high speed & whilst cornering, & will have improved fuel consumption. However because I have been doing this whilst the car is running in I cannot say exactly much the fuel consumption has improved by!

This “How-to” guide has been split into six parts, one for each different part/area.

Webpage done comparing the Mk5 Golf -vs Mk8 Golf & further improvements basically to the rear
Volkswagen Golf Aerodynamics - How to cut emissions even further (airshaper.com)


Front lower grill cover, designed for diesels to keep them warm in the winter months & only for the basic front bumper..

Winter cover VOLKSWAGEN Golf VII 2012-2016 (bottom) HEKO (e-heko.com)

 

[golfdave]

Part I

UPDATE Jan 2018
Engine skid tray/ under tray
VW supply all petrol engine cars with the thin flexi plastic "half" tray which only covers the front lower half of the engine bay. The front edge of this tray clips into the front under bumper valance (& one screw to fix), & seven screws are used to fix it around the sides to the wheel arches.

All diesel engine cars get a "full" cover version of this. This thin flexi plastic "full" cover is known as "sound absorbing" as it stops noise emitted by the diesel engine. This cover is NOT a skid tray, only an AERO tray. This tray is exactly like the half tray but for the additional length which extends to the front subframe & requires three additional bolts to secure it to the subframe.

There is in Germany & France a factory option of front skid tray. This covers the same area as the full thin aero tray above, however..it does not clip into the front bumper lower valance. Instead it requires two brackets to be bolted to the front crash bar chassis rails & the tray bolts to these brackets using two bolts per bracket (4 in total).

However, due to how low the factory sports suspension (in my view) is I feel that the “skid tray” is of more use to us for protection purposes as well as aerodynamics! VW used to make a steel “protection under tray” for the MK4 Golf, however for “eco” reasons & cost cutting the one for the MK7 Golf is G.R.P. (Glassfibre Reinforced Plastic). There are however after market companies such as ECS Tuning (ECS) & Sherriff who make aluminium & steel skid trays for the MK7. However these aluminium & steel skid trays will make more noise with stones hitting them. Also the ESC tray has a major design flaw! It only clips into the front bumpers lower valance like the thin VW one! If you hit something hard enough it will cause the ECS tray to flex upwards at the rear bend until it hits your sump! Also because there are big holes where their tray does not cover the areas where the VW one does & where the VW brackets are, you cannot easily fit the ECS tray to the VW brackets!!

I decided that after doing some research into the strength & durability of GRP, that the VW one would be strong enough for my needs, e.g. it will provide better aerodynamics & good protection from most impacts! Also the VW one has a proper NACA cooling duct, & metal reinforcing sleeves in the skid tray for the main bolt holes, which prevent crushing & stress fractures of the G.R.P. from the bolts

Thin plastic "Aero" tray NOT the Skid tray:-
There are several types depending on the number of NACA ducts you want...
5Q0 825 236Q gives you two ducts/vents near the front
3Q0 825 236 give you an additional baffle grill at the rear ....(used on GTE)
5Q0 825 236M gives you NO vents so do not get!!

Item 10, WHT 000 729 A, hexagon socket head bolt, self-locking,(M8x20mm), (x3) shorter than the skid tray rear bolts as the "Aero" tray is thinner plastic
All are full size trays & require the rear three bolts, but do NOT require the brackets or front bolts due to the light weight, they also use the existing small black screws...

To Fit as per VW at the factory:-
Parts list & approx. costs in UK £
Item No. 23:- 5Q0 825 902C, Underrun bar with one duct (Skid tray), £195.73***
Item No. 23:- 5Q0 825 902B, Underrun bar with NO ducts (Skid tray), DO NOT GET as NO air ducts
Item No. 24:- 909 747 01, Black wide head T-star screw A04B, £0.16 (x7)
Item No. 25:- 019 530 7, Flange hex head bolt (M8x25mm), £0.93 (x7)
Item No. 26:- 5Q0 825 921, Retaining bracket, £6.98
Item No. 26:- 5Q0 825 922, Retaining bracket, £6.98
Item No. 27:- 907 559 02, Spline head bolt with washer, £1.14 (x2)

For NAR (USA, Canada, Mexico, etc) Forum member "ADVNTURR" has found that the following parts are easier to order in NAR & do fit as he posts in this thread here:-Click here

Item No. 23:- 3Q0 825 902, Underrun bar (Skid tray), $282.48
3Q0 825 902 B (now) with one duct as per mine)
Item No. 27:- N 0195 307, Hex head bolt , $ (x2), (easier to fit this bolt in tight space but the one above is the correct VW one)

I have confirmed with the VW ETKA & these parts are correct for NAR MK7 Golf, & the tray is from a new Passat hence the "3Q0" start to the part number. The Passat is also an MQB platform car so will share many parts & dimensions.

For NAR (USA, Canada, Mexico, etc) Forum member "DiuSee" has found that on his 2019 "R" the following parts (907 559 02, Spline head bolt with washer,) fouled a weld when fixing the bracket on the passenger side. He instead used another of the bolts with the smaller built in flanged head (019-530-7)-..his post here:-Click here

To fit as per my way:-
Parts list & approx. costs in UK £
Item No. 23:- 5Q0 825 902C, Underrun bar with one duct (Skid tray), £195.73
Item No. 26:- 5Q0 825 921, Retaining bracket, £6.98
Item No. 26:- 5Q0 825 922, Retaining bracket, £6.98
Item No. 27:- 907 559 02, Spline head bolt with washer, £1.14 (x2)
M8 x 25mm Flanged hexagon bolts (DIN 6921), marine stainless steel (A4) (x7 quantity),
M8, 24mm dia. x 2mm thick, Flat washers (DIN 9021), marine stainless steel (A4), (x7 quantity)

I get my stainless stuff from here:-
Buy Precision Components | 500,000+ Components | Accu®

Info
This tray covers the whole underside of the engine bay area! It fits to the wheel arch liners at the sides, & the front bumper (as per the OEM half tray). However it extends to, & overlaps the metal subframe & uses three threaded inserts which already exist in the subframe! Be warned that because it is approx. 25mm (1 inch) thick, & it overlaps the main metal subframe, your ground clearance at this point is thus reduced by the same amount!! My ground clearance is now about 125mm (5 inches) as this point. It also weights 5kg. Also to remove it for servicing you have seven of the original black trim screws (as per the factory half tray), & a further seven main bolts to undo!


Optional Audi Cabriolet METAL skid tray,
This item covers the whole of the metal subframe. The Audi subframe is an "open web" design made in Aluminium alloy, so not as aero as our sheet metal "closed" design.
https://www.golfmk7.com/forums/showpost.php?p=662179&postcount=376

Parts sheet:-
https://audi.7zap.com/en/rdw/audi+a3+cabriolet/a3ca/2016-778/8/825-825000/#24

Note there are numerous versions of the tray (ie ducts)

Item No. 24:- 5Q7 825 235 A or B or C or D, skid tray
Item No. 25:- N907 371 07, Fillister head bolt with multi point socket M6x12mm (x 4) For front edge with bumper
Item No. 26:- N909 747 01, Hex socket head bolt M5x16mm (x7) for fixing the wheel arch side edges
Item No. 27:- N907 583 02, Hex socket bolt combi M8x25mm (x9) for the main nine.

I can't find brackets for this & think its a different style fit??


Fitting
Firstly it is best to be able to jack up & have the whole front end of the car in the air & supported by either axle stands, or in my case two 3ton professional trolley jacks! You could also use drive on ramps. Using a T-star (T-25 size) bit/key, undo the eight black screws holding up your existing half sized under tray (four down one side, three down the other, & one at the front). These are listed as Item No. 24, so keep & put to one side for later.

You will notice that the brackets are shaped differently, the straight one is for the passenger side UK (drivers side NAR), with the curved one for the opposite side. They can only be fitted one way around, & one side as they also have a “tab” sticking out which locates into a hole in the mounting area. Now the tricky bit! You need to reach up & with great dexterity, place the brackets on the rear face of the crash bar mounting plates & insert the bolts with built in washers (Item No. 27) from the front face, & tighten (12 point spline, 10mm size). Now leave the bolts slightly loose (you should just be able to move the brackets) to help with the alignment of the tray.

Now fit the tray by getting the front tabs behind the front lower trim & use the three rear bolts into the subframe only. Align the tray so that the metal sleeves are centred under the bolt heads. Now insert a long screwdriver through the front bolt holes into the brackets & move the brackets to align the bolts holes in the bracket up with the holes in the tray. Now remove the tray & holding the brackets still, tighten up the bracket spline bolts (20Nm) so that the brackets don’t move. I also had to “pull” the brackets forwards in my case, to get better alignment.

Now you can loosely refit the tray using the main seven bolts. Now reusing seven of the original (black wide head) screws from your OEM tray, loosely secure the sides of the tray to the wheel arch liners as per the OEM (three screws down one side & four down the other). The OEM screw at the front is not needed as the full tray only has the two tabs at the front & not the additional screw hole (as per the OEM half tray). Now once you have everything fitting & aligned, fully tighten the seven main bolts up (no torque setting given just “nip-up”, but used 1lbft max), followed by the seven black trim screws. I did also use a bit of “copper grease” on the main bolts to protect the threads in the brackets. Job done!!

Modification
Due to the winters & salt that is on the roads where I live I decided to get stainless steel versions of Item No. 25, for better corrosion resistance!. I also got stainless steel washers because I noticed that the bolts (even the OEM Item No. 25) didn’t fully cover the sleeves in the tray unless they are perfectly aligned. The DIN type washers are 2mm thick & will not collapse into the tray bolt holes when tightened up, unlike form A,B,C, or penny washers which are all thinner.

Now enjoy better protection for your sump, better aerodynamics, better fuel consumption, less road dirt sprayed into the engine bay, etc., etc.!

P.S. I have noticed the oil temp heating up quicker (better for winter), but not overheating!

 

[golfdave]

Part II
How to retro-fit the exhaust tunnel front cover.

Vehicle used in this guide
UK spec, 2014yr model, Mk7 Golf Estate (GSW), GT (Highline) trim, 1.4lt TSI (140PS) CHPA petrol engine, MQ250 6speed manual gearbox, multilink rear suspension.

Vehicles that this guide is applicable to
All VW Mk7 Golf’s. (except e-Golf)

Special thanks to
Forum member “fullyswitched” for suggesting alternative OEM VW push rivets. Also to forum member "Chillout" for confirming 100% that the long cover will not fit the GTE due to the side covers having a different shape from standard & thus the long cover will not fit between them. Also to forum member "pschwa" for confirming further that the alternative push rivets suggested by "fullyswitched" are a good fit, they are not a 100% tight fit..so the panels good be sucked off by aero.

Introduction
Ever looked under the car & thought “wow that’s a big hole with exposed parts that will cause a lot of air turbulence & needs covering/protection”? Guess what, so did VW, & they made a part for the job! In the “Before” picture one of the big side trays is removed because I was putting Waxoyl treatments on the underbody.

Research
This item (long cover) covers the exhaust tunnel area between the rear of the engine subframe & the first metal brace bar (2WD). When I enquired at the dealer’s parts dept. the VW parts programme (ETKA) showed the long cover as “relevant” to my chassis number, it also stated that my car was built correctly without the cover!

There are two covers, one of which is shown in the ETKA diagrams, but not mentioned in the listings, & the one that is given in the listings but looks nothing like the one in the ETKA diagrams! Confusing!!

The longer cover which is used in my pictures is for the 2WD Mk7 Golf’s which have a front section exhaust silencer, between the brace & the fuel tank & out of shot to the left of the picture.

Those which have a front section exhaust catalyst are supposed to use the short cover, as their catalyst is in the way as fitted between the brace & the engine subframe. This affects the 1.6lt petrol engine, GTE, & those running on natural gas. (engine codes CWVA, CUKB, & CPWA). The GTE has different side cover panels & the long cover will NOT fit between them correctly, you have to use the short cover! I suspect this is done on purpose to stop the fitment of the long cover which could cause heat issues with the exhaust for the GTE.

The 4WD cars have the cardan shaft bracket for the 4wd system exactly where the brace is shown for the 2WD cars. Both items use the same locating holes in the cars bodywork. You could fit retro-fit the 2WD brace over the cardan shaft bracket to install the rear fixing points for the long cover. You will have to check the bolt length but a few "mm" is neither here or there, or get longer bolts. The factory ones are M8x38mm. It will drop the rear of the cover down closer to the road by the thickness of the cardan brace where it bolts to the body. Also the side locating tabs may not fit perfectly behind the side covers due to the cover now bending away from the body. However those could be gently heated up & bent back up to fit properly.

EDIT JUNE 2020
The MK8 Golf & other MQB platform cars now use a pressed sheet steel cover, which although noisier if stones hit it may offer more heat resistance compared to the plastic one with the foil lining.

Parts required
Firstly, ETKA shows the shorter cover for the front catalyst in the diagrams.

VAG ETKA illustration for VW Golf Mk7/Body/No.825-000,

Parts list & approx. costs in UK £
For long cover:-
Item No.14:- 5Q0 825 229 C, Lining (cover) long length WITH heat shield material on reverse, £13.22 (x1) ***
Item No.14:- 5Q0 825 229 H or B, Lining (cover) long length WITHOUT heat shield material on reverse, £?? (x1) NOT recommended!!!
Item No.15:- N 038 549 4, Black plastic push rivet A04A, £0.18 (x4) ***(Use these ones for the most secure fit, October 2018 EDIT)

*** = Only these items required from the dealers in my project! ***

For short cover (GTE & 4WD):-
Item No.14:- 5Q0 825 230 J, Lining (cover) short length, £??.?? (x1)
Item No.15:- N 038 549 4, Black plastic push rivet A04A, £0.18 (x2) (Use these ones for the most secure fit, October 2018 EDIT)
Item No.16:- N909 747 01, Black wide head T-star screw A04B, £0.17 (x2)

VAG ETKA illustration for VW Golf Mk7/Body/No.803-005,
Parts list & approx. costs in UK £
For 4WD:-
Item No.15:- 5Q0 804 421 B, Reinforcement for tunnel (Brace), £??.?? (x1)

Fitting
The long cover:- It is advisable to jack up one side of the car & support on axle stands. However I used my two trolley jacks, one front & one rear! Firstly you have to locate the captive plastic flanged nuts which are recessed into the under trays each side of the exhaust tunnel. Now undo the four nearest the position of the new trim (two each side of the exhaust tunnel) using a 10mm socket. This allows you to flex the trim panels down & get the tabs on the new trim panel behind the existing trim (it is obvious what to do when under the car).

The cover only fits one way around, & must have the silver heat reflecting foil facing the exhaust. Hopefully the four holes in the cover will align with the holes in the metal cross bar at the rear & the two brackets at the front. If they don’t you have the cover facing the wrong way! Then place two rivets front & two rivets at the rear. Push the rivets in & then gently push the central stem in. Then using a dowel/something similar & a plastic mallet/etc. gently hammer them home/flush. Then refit the plastic nuts on the side trim panels. Job done!

The short cover:- Same as above. However as it is a shorter cover you obviously cannot use the rear two plastic rivets in the metal brace. Instead, the two tabs you placed behind the existing trim panels have a hole for a self tapping screw in each tab. These should be aligned with the two holes in the existing trim panel. Then you can screw in Item No.16 (T-25 size bit/key required) through the outer trim panel into the new one behind!

For 4WD with long cover:- Same as before. However you need to support the cardan shaft to undo the four bolts for the cardan shaft bracket, then place the 2WD brace over the bracket & then refit the bolts. These bolts are given a torque setting of 25Nm (18.4lbft). Please see the last paragraph in the research section for more info on modification to get this cover to fit.

Further considerations on fitting
Forum member “fullyswitched” suggests alternative VW push rivets for Item No.15.
8E0 825 267:- These allow you to pull the centre pin out using a right angle pick or pair or specialized pliers.
4D0 807 300:- These have a three position pin. The centre pin is more or less captive during use. The three pin positions are proud/unlocked, flush/locked, indented/unlocked. Once installed the pin pressure is released by pushing the pin further in to step over an internal notch & now the push rivet can be extracted by pulling. The pin is reset when the rivet is removed.

EDIT October 2018:- Forum member "pschwa" tried all three rivet versions & concludes that the ones I used (N 038 549 4) which are recommended ones are the best/tightest fit, otherwise it could all work loose & be "sucked" off due to aero!
https://www.golfmk7.com/forums/showpost.php?p=699829&postcount=457

Results
It is definitely quieter inside the car in this area (central console between front seats It will have reduced the amount of air drag & turbulence. It also protects that part of the car body & exhaust from road spray & thus corrosion. The car looks more “finished” now, i.e. as it should have left the factory!

Conclusions
Again with the cost cutting VW, why?? You designed the item, but chose not to fit it to save money. So you are in the dog house over the diesel emissions & a cheat device, but in your quest for money grabbing you forgot the oldest fuel saving trick in the book!! Make the underbody flat by covering it up, as this reduces the aero drag coefficient, & thus saves fuel. Idiots!!

 

[golfdave]

Part III
How to retro-fit the rear exhaust tunnel cover

Vehicle used in this guide
UK spec, 2014yr model, Mk7 Golf Estate (GSW), GT (Highline) trim, 1.4lt TSI (140PS) CHPA petrol engine, MQ250 6speed manual gearbox, multilink rear suspension.

Vehicles that this guide is applicable to
All 2WD VW Mk7 Golf’s (not e-Golf)

Special thanks to
Forum member “ColinStone” who confirmed the hard way, that the twist beam rear suspension requires a different trim panel, & for finding the correct parts!

Introduction
Ever looked under the rear of the car & thought “wow that’s a big hole with exposed parts & exhaust that will cause a lot of air turbulence & needs covering/protection”? Guess what, so did VW, & they made a part for the job!

Research
This item covers the exhaust area where it bends around between the fuel tank & the rear wheel, by joining onto the fuel tank & the big under tray for the side of the car. The part code is 5Q0 825 206C, although ETKA says the product has been superseded by version "K". The item still has "C" moulded onto it, & is stickered over with "K" on the ID sticker! ETKA describes this rear trim as "production ceased 2013, replacement part is K". So no warnings like “do not refit as dangerous”, “no replacement part”, “see technical product info” etc., etc..

There is a difference in the parts between the multilink suspension & twist beam versions. This is because the twist beam gets in the way, which also makes the fuel tank a different shape. So the trim panel is shorter with two of the mounting points in slightly different positions.

There is no trim for the 4WD Golf’s & these trim items will not fit either. The 4WD Golf’s have the “saddle” type fuel tank with the exhaust routed with the central drive shaft straight down the middle of where the fuel tank sits.

These trim parts require fixing at 4 points. The multilink suspension trim panel should come already fitted with 2 x speed washers (Item No.19) for fixing the trim to the two rear body threaded studs. The twist beam suspension panel may not have these pre-fitted. Both trim panels should also come with 1 clip/speed nut (Item No.20) fitted at the front of the trim. You will also require one additional clip/speed nut (Item No.20), & the two matching screws (Item No.22). Both of the clip/speed nuts fit at the front edge of the new trim, & have the two bolts going through the new trim & existing trim into the clip nuts, just like on your typical VW engine undertray.

There is also a "D/E" ..d is twist beam...version which is for cars with a smaller exhaust tunnel area than mine..as the "J" version is for the twist beam suspension.

Parts required

VAG ETKA illustration for VW Golf Mk7/Body/No.825-000,
Parts list & approx. costs in UK £
For multilink rear suspension:-
Item No.18:- 5Q0 825 206 C (K), Underbody trim, £13.31 (x1)*** (might also appear as "E") (PR code = 0N4 for multi-link axle)
Item No.19:- N903 350 05, Speed washer, £?.?? (x2)
Item No.20:- N909 591 01, Clip/Speed nut, £0.48 (x1) ***
Item No.22:- N909 747 01, Black wide head T-star screw A04B, £0.17 (x2) ***
*** = Only these items required from the dealers in my project! ***

For twist beam rear suspension:-
Item No.18:- 5G0 825 206 J, Underbody trim for twist beam, £??.?? (x1) (might also appear as "D") (PR code = 0N1 for twist beam axle)
Item No.19:- N903 350 05, Speed washer, £?.?? (x2)
Item No.20:- N909 591 01, Clip/Speed nut, £0.48 (x1)
Item No.21:- N 038 549 4, Black plastic push rivet A04A, £0.18 (x1)
Item No.22:- N909 747 01, Black wide head T-star screw A04B, £0.17 (x2)


Fitting
Multilink suspension:- Jack up & support one rear side of the car (passenger side UK, drivers side NAR). Locate the rear two existing threaded studs (one on fuel tank, other on bracket opposite this near the wheel arch). Align the trim so that the two metal speed washers locate over these studs, then align the front edge of the trim with the rear edge of the big side under tray. The edge on the new trim has a tab which has to clip into the rear of the existing trim, align & fit. Then using a flat head screwdriver positioned in the slots of the speed washers screw them up fully onto the studs. Then go back & insert the screws into the front holes/clip nuts, & tighten up (T-25 size bit/key required).

Twist beam rear suspension:- Same as above, except that instead of two metal speed washers you have one metal speed washer & a plastic push rivet.

Further considerations on fitting
Instead of using the metal speed washers (Item No.19) to fix the cover to the threaded studs, you could use the same plastic nuts that are used to fix the main underbody trays to the car body threaded studs! These would then “match” all the other plastic covers/trays, & will not corrode!
Item No.13:- WHT 000 713, Hex collared plastic nut Z11, £0.23 (x2)

Results
It is definitely quieter inside the car in this area (rear seats). It will have reduced the amount of air drag & turbulence. It also protects that part of the car body & exhaust from road spray & thus corrosion. The car looks more “finished” now, i.e. as it should have left the factory!

Conclusions
Again with the cost cutting VW, why?? You designed the item, but chose not to fit it to save money. So you are in the dog house over the diesel emissions & a cheat device, but in your quest for money grabbing you forgot the oldest fuel saving trick in the book!! Make the underbody flat by covering it up, as this reduces the aero drag coefficient, & thus saves fuel. Idiots!!

 

[golfdave]

Part IV

How to retro-fit the rear axle cover.

Vehicle used in this guide:-
UK spec, 2014yr model, Mk7 Golf Estate (GSW), GT (Highline) trim, 1.4lt TSI (140PS) CHPA petrol engine, MQ250 6speed manual gearbox, multilink rear suspension.

Vehicles that this guide is applicable to:-
All 2WD VW Mk7 Golf’s with the multilink rear suspension. (not e-Golf)

Special thanks to:-
Forum member “Ursus americanus” for confirming my suspicions (the hard way), that the big Passat tray does NOT fit a Mk7 Hatch unless heavily cut/modified.

Introduction:-
Ever looked under the rear of the car & thought “wow that’s a big hole with exposed parts that will cause a lot of air turbulence & needs covering/protection”? Guess what, so did VW, & they made a part for the job! But not for our cars!

Research:-
Firstly there is nothing made or shown in ETKA for any version of the Mk7 Golf! So we have to look at other VAG cars which used the same or similar components in the rear suspension setups. The Mk5 Golf was the first with similar multilink rear suspension, & a small cover for this area was made for the eco model. The current & previous VW Passat uses a very similar rear suspension setup & has a bigger tray made to cover this area.

The short cover comes from the Golf Mk5 & Mk6 (2007 -2014). The long cover from the previous generation (PQ46 platform) VW Passat (B6/7) & CC. The new Mk7 Golf MQB platform uses most of the same axle & support frame, just the support frame to car body locating arms are different! This trim has a straighter leading edge so will not interfere with the fuel tank, & covers more of the axle area.

There is also the new 3V Passat/Skoda Superb version of the long cover, Part No.3Q0 501 713. However this uses different brackets, & although it has a longer (front to rear) centre section it is shorter (front to rear) near the bracket areas. I am less certain about this one fitting the Mk7 Golf Estate!

On the hatch the exhaust will interfere with the bigger cover. The hatch has the exhaust routed in the gap between the rear wishbone to support frame pivot points. This is where the cover has a central upstand which clips onto the top part of the support frame. Although the Mk7 Golf rear sub frames look the same as the Mk6 ones, the main problem is that the Mk6 Golf trim fits up against the fuel tank, which is shaped slightly differently on the Mk7 Golf, which could make a good fit difficult, so some cutting to the short trim might be required! This trim uses one bracket as per the full trim & one of the existing threaded stubs on the support frame. This trim will not interfere with the exhaust pipe.

The 4WD Golf’s have a different rear support frame it & does not have the mounting points for the trim brackets. Also the Haldex unit & rear stub drive shafts would interfere with the trim.

Part code N 901 838 02, although Etka can show this number, the correct new version is N 901 838 03. The plastic trim piece (Item No.12) should come pre-fitted with 2 x Hex collared plastic nuts (Item No.13), & 2 x metal Clip/Speed nut (Part code N909 591 01). The two metal clip/speed nuts are not required so remove these.

EDIT JUNE 2020:-
MK8 Golf hatch has a short axel tray similar to the below listed MK5 Golf one. However there is a larger rounder end shape near where the tray meets the fuel tank/exhaust. On initial inspection it looks like it will still fit. Part number 5WA-501-713

Parts required:-

VAG ETKA illustration for VW Passat/2009/Rear Axle/No.505-000,
Parts list & approx. costs in UK £
For big cover:-
Item No.7:- 1K0 501 681, retaining bracket, left, £2.68 (x1) ***
Item No.7:- 1K0 501 682, retaining bracket, right, £2.75 (x1)***
Item No.9:- N 905 483 05, Hex collared bolt M8x20mm, £0.86 (x2) ***
Item No.10:- N 901 838 03, Hex collared nyloc nut M8, £0.67 (x2) ***
Item No.12:- 3C0 501 713 A, Plastic trim for rear axle support frame (includes Item No.13), £36.10 (x1) ***
Item No.13:- WHT 000 713, Hex collared plastic nut Z11, £0.23 (x2)
*** = Only these items required from the dealers in my project! ***

VAG ETKA illustration for VW Golf Mk5/Rear Axle/No.505-000,
Parts list & approx. costs in UK £
For small cover:-
Item No.7:- 1K0 501 682, retaining bracket, right, £2.75 (x1)
Item No.9:- N 905 483 05, Hex collared bolt M8x20mm, £0.86 (x1)
Item No.10:- N 901 838 03, Hex collared nyloc nut M8, £0.67 (x1)
Item No.12:- 1K0 501 713D, Plastic trim for rear axle support frame (includes Item No.13), £41.54 (x1)
Item No.13:- WHT 000 713, Hex collared plastic nut Z11, £0.23 (x2)

Fitting:-
Big Passat cover for Estate:- Firstly it is best to be able to jack up & have the whole rear end of the car in the air & supported by either axle stands, or in my case two 3ton professional trolley jacks! You could also use drive on ramps. Clean the areas on the support frame where the new retaining brackets will fit. I used some WD40, & I also wiped over the nuts/bolts & all mating faces.

Fit the retaining brackets (Item No.7) to the support frame, making sure they are the correct way around. You will notice that they naturally fit in a certain position which you will have to hold them in whilst you tighten the nut/bolt (13mm sockets/spanners required). I fitted the bolt/nut as per the ETKA diagram which shows the nut nearest the centre of the car. I had no torque setting from VW for the bolt/nut. So I looked in my ISO charts for the bolts (M8x20mm, 8.8 spec), & the lowest setting for "clean/lubricated" was 18Nm (13lbf ft) which I used.

Now to fit the trim (Item No.12), you have to angle the trim upwards & align the catches on the trim & “catch” the lip of metal on the support frame. Then gently hand tighten just a few turns, the plastic hex nuts (Item No.13) (10mm socket required) onto the threaded studs. Now reach up & clip the central upstand onto the top hole in the cross rail on the support frame. Then go back & do up the plastic nuts fully until the trim does not move, but do not over tighten!

Short Mk5 Golf cover for Hatch:- Start as above, but only one bracket (Item No.7) has to be fitted. This bracket is fitted on the opposite side of the frame to the existing threaded stud.

Results:-
It is definitely quieter inside the car in this area (rear seats). It will have reduced the amount of air drag & turbulence. It also protects that part of the car body & exhaust from road spray & thus corrosion. The car looks more “finished” now, i.e. as it should have left the factory!

As I had done all the other aero mods to my car a few months previously & therefore this is the last one, I would be able to tell any difference it made. I still cannot believe the immediate effect of this cover on the handling! I know a very nasty, off camber, sharp, uphill turn on a dual carriageway, in a 50mph zone off a roundabout. This is a great way to totally unsettle a car & usually my Golf Estate feels “jittery”, mainly as if the inside rear is wanting to lift, & the outside rear is not stable either! The car went around totally stable & planted, even with just half a tank of fuel & nothing in the boot. This cover directs the air flow under the rear wishbone arms, as before it was creating turbulence in the cavity above the arms & “lifting” the rear of the car!!

Conclusions:-
Considering the handling difference this cover has in regards to added safety I am surprised that VW has not considered this part for the Golf Estate! They designed & made the small one for the Mk5 & Mk6 Hatch, but nothing for any Mk7 Golf, which has the same problems with underbody aero as those previous cars do. Again with the cost cutting, & not sorting out the aero as per previous models, WHY?? Bloody idiots VW!!

 

[golfdave]

Reserved

 

[golfdave]

Part VI

Rear lower arm stone guard/aerodynamic trim for Multi-Link Rear Suspension.

http://www.partsbase.org/audi/audi-a...aud-1k0511539e

Item No. 33:- 1K0 511 539E, Stone chip guard ”Discontinued item see technical product info’ 36;2029695​

​

These items were on previous generations of Audi TT/A3, VW Golf’s, but VAG had fixing problems with them. VAG did sort the fixing problems out & amended the item. However the previous lower arm is different to the MQB arm. The above link is the only info I can find with them shown to be fitting a MK7 Golf MQB lower arm! However the MK6 Golf had manual handbrake cables which are routed differently to the electric wires for the MK7 electric handbrake (not NAR), which would require a different design to the guard!

Hopefully they will eventually do something to fit an MQB platform car, as they have not carried over this part, & I will be keeping an eye open for it!


Rear lower arm stone guard/aerodynamic trim for Twist-Beam Rear Suspension.

http://www.partsbase.org/vw/golf-var...hock-absorber/

Item No. 17:- 5Q0 501 559 "C" or "D", Stone chip guard for under side of trailing arm left side.​

Item No. 17:- 5Q0 501 560 "C" or "D", Stone chip guard for underside of trailing right side.​

Item No. 18:- 5Q0 501 561, Stone chip guard for top side of trailing arm left side.​

Item No. 18:- 5Q0 501 562, Stone chip guard for top side of trailing arm right side.​

Item No. ??:- 8E0 825 267, 8mm spreader rivet. Unknown quantity required.​

​

These items I have not actually seen or fitted, but they appear on ETKA for the MK7 Golf with the Twist-beam rear suspension, so should fit & cover the trailing arm part of the rear twist beam.

 

[Mk620T]

Nice write up. What type of increase in fuel efficiency have you experienced. I suspect this makes the car handle better at high speeds too. I wonder how many of these parts are available in the U.S. - maybe they come on the eGolf.

 

[golfdave]

Nice write up. What type of increase in fuel efficiency have you experienced. I suspect this makes the car handle better at high speeds too. I wonder how many of these parts are available in the U.S. - maybe they come on the eGolf.

as I am running the car in I can't say for certain re the fuel consumption. However I got 52mpg on a 84mile journey on the motorway so speed 60 & 70mph............& it's a petrol!

As for stability , yep feels better, also quieter, however I can't wait to pin down the exact part for the rear axle cover when VAG make one, as this will show the greatest improvements!

As for the E-golf you missed in the first post my explanation of the E-golf parts!
"""""""However we do have the E-Golf (all electric) & it has different under trays (parts 5Q0 825 236P, 5QE 825 902B, 5QE 825 229B, 5QE 825 218C). But it would be unwise to use them as you will get too much heat soak into the cabin from the exhaust! Basically instead of two length ways covers between the front & rear wheels with a gap for the exhaust, the E-Golf has two width ways covers which totally cover the whole area up, as it has no exhaust! There is also a bigger rear cover under the axle/boot, but of course it has no exhaust which would also be covered up!""""""""

Basically I am using other parts not from the e-golf, you also missed in my first post

******VW make a full engine under tray which is NOT reinforced & just an aerodynamic mod. I am not covering this here. However, due to how low the factory sports suspension (in my view) is I feel that the “skid tray” is of more use to us for protection purposes as well as aerodynamics!******

The parts I have used just get from the parts dept at your VW dealers...........that's all I did...............& most of the parts are not options in the UK, so in theory should not be available in UK, but I got within 3 days each time!

 

[gogolf1]

WOW, great job!
How much quieter is the car now? Do you feel the difference in terms of general noise or maybe there is less road noise or/and engine noise?

 

[golfdave]

WOW, great job!
How much quieter is the car now? Do you feel the difference in terms of general noise or maybe there is less road noise or/and engine noise?

Thanks! The car is quieter, & I can confirm that the extra trim panels DO NOT act as a sounding board or drum, & DO NOT create extra noise. In fact they make the car quieter as the air flow under the car is more smooth & therefore there is less noise from turbulent air!

I would rate it as 10% to 20% less noise, the car is quiet anyway, so difficult to put an accurate number on it unless I did a before & after with a sound level meter!

 

[gogolf1]

thx - I find it not that quiet in terms of road and suspension noise It could be better

BTW. I have found full aluminium engine protection for Golf 7, it costs around 50 Euro, but it doesn't have those cooling channels for the gearbox:

 

[golfdave]

thx - I find it not that quiet in terms of road and suspension noise It could be better

BTW. I have found full aluminium engine protection for Golf 7, it costs around 50 Euro, but it doesn't have those cooling channels for the gearbox:

And it Will be Very Noisy as there is NO sound insulation/deadening! The stones will crash off it & it will act as a resonator/sound board & it will amplify any existing noise! Also as you state there is NO air cooling duct for the gearbox!!

Aluminium is very noisy as a material!
The main reason I use existing VW parts (from your VW parts dept at dealers), is so your warranty is not affected!

 

[gogolf1]

Yes, I'm also afraid of losing warranty and I have no intention to mount this cover in my car.
Just posted it as an available option.

 

[LeGti]

Sorry to dig this up, but just had to take a minute and thank you for such a thorough review!!

How have the shields affected temps in the summer heat?

Thanks again,
Ben.