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...
SKID TRAY VW 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)***
***=Only these items required from the dealers in my project!***
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.
Other parts which may be required:-
M8x25mm hex head flange bolts DIN6921 type (x7), M8x DIN9021 type washers (x7), all in stainless steel.
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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,
Thuis 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!
