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GS mod package

enobiko

Go Kart Newbie
Location
NE Ohio
Car(s)
2017 SE 6 MT
I've been running in GS for the last 5 years here in NE Ohio. I just saw this "

SCCA G Stock Mod Package​


https://www.fcpeuro.com/products/mk7-gti-scca-g-stock-mod-package-034-motorsport-sccags1

First off, yes to the rear sway bar to balance out understeer. I can't see spending $273 on the end links vs. Moog end links at about $20 each, but whatever.
I suppose flushing the brake fluid is a good idea for HDPE, but I see this as a regular maintenance procedure.

What I'm a bit puzzled about is the wheel spacers. I thought maybe those were more for appearance than performance. I've already upped my tire size to 235/40 vs. the 225/40-18 stock, though I doubt there will be any big change. BTW, these are Michelin PS 4S, since this is a daily driver. Note that I have chewed up the outer tread to some degree, as I cannot adjust the camber and tend to overdrive the tires a bit. Hey, I'm having fun! Since the sidewalls are soft (compared to track-day tires) I tend to run these a bit over the recommended cold inflation pressures, like... 38-40. I'm sure a stiffer sidewall would allow me to lower that.
So... are wheel spacers really helpful in autocross? Is there a disadvantage, like wheel bearing stress, or clearance issues? (I'm sure the wheel bearings get some additional stress, sure, but is this a recipe for breakage, or just a minor additional stress?)

Dean
 

xXDavidCXx

Autocross Champion
Location
AZ
Car(s)
2017 GTI SE DSG
First off, yes to the rear sway bar to balance out understeer
Why do you and many others think like this? Why take away grip?

How about you fix the broken end, and put a front bar on. This will reduce body roll and thereby reduce front camber loss due to body roll, which is why the front has so little grip. The rear does not need modification.

If you need the rear to be more compliant, run 1/8th of an inch total rear toe out.
 

enobiko

Go Kart Newbie
Location
NE Ohio
Car(s)
2017 SE 6 MT
I don't have the ability to do back-to-back comparisons, but the rear bar is pretty much the go-to from many different sources. The idea is to change the balance of the car to less understeer by fitting a larger rear bar. I get your idea, but others don't share your enthusiasm. It might work... but it is lots more work to install (drop the subframe, not easy on a gravel driveway). Whatever... my rear bar is already upgraded, and a front bar would knock me into a different class, where I'd be non-competitive without a bunch of other expensive upgrades.

Back to the main question of my post: will wheel spacers help me in any significant way? Or, is this mostly just for looks? I spend more time driving than looking at my car...
 

krs

Autocross Champion
Location
Las Vegas, NV
Car(s)
MKVIIS R
Back to the main question of my post: will wheel spacers help me in any significant way?
No.

The amount of handling change from 5mm spacers is very, very small. The reduction in weight transfer (about 0.65%) is very minor but, are you that good of a driver to notice that small of a change? I'm sure not. That's like emptying your bladder beforehand for the extra weight reduction.

Sure one can argue on paper they contribute to slightly improved cornering stability, where every small advantage matters. Even this small decrease in weight transfer could help reduce body roll, providing better tire contact patches during lateral loading and potentially allowing a driver to maintain slightly higher speeds through corners.

Now if you're using them to correct wheel offset, different tires, etc., then they may be needed. But to throw them on stock wheels, and hope to lay down drastically faster times in autocross... eh, likely not going to happen.
 

xXDavidCXx

Autocross Champion
Location
AZ
Car(s)
2017 GTI SE DSG
I don't have the ability to do back-to-back comparisons, but the rear bar is pretty much the go-to from many different sources.
And they are wrong, from an actual motorsport kinematic suspension analysis point of vew
The idea is to change the balance of the car to less understeer by fitting a larger rear bar.
You are not making it less understeery, you are reducing rear grip which makes the rear more oversteery
I get your idea, but others don't share your enthusiasm.
Does not mean I'm wrong

It might work... but it is lots more work to install (drop the subframe, not easy on a gravel driveway). Whatever... my rear bar is already upgraded, and a front bar would knock me into a different class, where I'd be non-competitive without a bunch of other expensive upgrades.
Put the rear back to stock, put on a front bar on someone else's concrete driveway
Back to the main question of my post: will wheel spacers help me in any significant way? Or, is this mostly just for looks? I spend more time driving than looking at my car...
I've given you the winning solution, and you come back to this question????
 

DerHase

Autocross Champion
Location
Hampton Roads, VA
Car(s)
2019 GTI Rabbit
Can confirm everything @xXDavidCXx tracks with what I've found.

I did the rear sway bar and ran it alone for a few autocross/track events and while it "feels" good on initial turn in... all it does is throw away grip out back while not adding anything up front. I initially threw the 26mm RSB on first just out of sheer laziness/because it's easy... and was honestly really underwhelmed. It feels better when you first turn the wheel, and then it plows like a pig as you overload the outside front corner onto the bump stop.

Your biggest enemy in a street class is your lack of camber. Preserve as much as possible and it will be able to corner faster.

1730556039529.png


The above was on stock springs and shocks FWIW. At subsequent events I found setting the front bar to stiff made it better yet.

People who go straight to the rear bar and think it's the best solution for every case don't understand the entire car. There's not enough weight out back to actually allow it to limit roll so the body rolls the same-ish amount of front, but the rear now hikes the inside tire sooner and is throwing away rear grip.

On a street class car I'd throw a big-ish FSB on (I'm pretty happy with the H&R 26mm, I've taken measurements on it and the soft setting while stiffer than stock isn't ridiculously so), and play with camber, toe-out, and tire pressures to sort out the balance. With the bigger FSB you'll want to be a bit more aggressive in trail braking to help turn-in and it will be faster. Most of the people who have claimed adding a front bar period is always a bad idea are... slow. There are exceptions like when the spring rates and stuff are so far from stock etc so I'm not getting into that... but on a near-stock suspension car there's a lot to be gained by limiting dynamic camber loss.

I imagine without a rear bar to "help" in street class, if it rains or you're on a really low grip surface, that setting the front bar on soft might be beneficial in those instances. With a big front bar and little grip up front (cold tires or wet surface) the car will be "edgier" to drive... though since I'm not in street class and have -3.2ish deg camber that might be a differentiator. My main point: play around with the settings in various conditions.

https://www.datadrivenmqb.com/suspension/swaybartheory

Time for a thought exercise:​

The above comparison also illustrates something that few people seem to understand. If you lessen overall body roll up front, you’re also going to lessen body roll in the rear.

Adding roll stiffness to the rear (in an attempt to limit overall roll) is only effective up until the inside rear tire comes off the ground. This happens because these cars have a ~60/40 weight distribution. Once the inside rear comes up, any additional stiffness is not doing anything to actually help body roll, just hike the inside rear tire higher (while raising the overall center of gravity in the process). To be fair, it will add comparably more roll stiffness on initial turn in, but it’s not doing anything for overall grip in a steady state fully-loaded turn.

When you add roll stiffness to the front, the entire body of course doesn’t roll as much, and the outside rear tire does not go as far into the positive (camber-wise).

After adding a front bar, it may be ideal to remove some camber from the rear to maintain balance. For what it’s worth I did not do that, the plan is to eventually add even more camber up front.



Let’s also consider something else: Even if the car now “pushes”… if the overall grip limit is higher is it not faster?

Setup 1: Stock front sway bar and 26mm rear bar, and the rear comes around at 53mph on corner entry

Setup 2: Bigger front sway bar and 26mm rear bar, now the front starts pushing but not until 55mph

Which one is faster around the track?



Some people also like to point to wheelspin: “Wheelspin on corner exit was worse with a big front bar”.

What if you have more wheelspin because you are pulling more Gs, unloading the inside tire more?



Taking a step back and considering things like this is exactly why capturing good data (at least to the best of your abilities) is paramount to actually making the car faster. Having measurable things to assess in an attempt to take the driver’s feel or bias or consistency out of the equation.

Suspension is a fun and highly debated topic. There are a thousand different ways to set up a car (more of them are closer to wrong than not), and every person will like each one a bit differently even if it’s not necessarily the fastest.

You have to be able to adapt to the setup and potentially change some inputs to get the most out of any change because you're adjusting the shape of the friction circle. There will be more on this in the next article (linked below)… with a more in-depth look at the testing data to show why I came to the above conclusions.








------------------------------------------------------






All that said, I totally get not wanting to do the work to undo a mod and install a front bar. But it depends on if you want to be competitive (or chase a lap time, etc) or not. I've installed and removed multiple parts on my car because it turns out most of the aftermarket is full of bullshit parts and the manufacturers don't even understand how they work or how to properly design stuff, and a large percentage of people who have these cars speak out of their ass and only recommend the parts they've put on their own car.

I'm going to guess you don't care about being competitive since you're not on a 200TW tire. In that case you shouldn't even be looking at wheel spacers as a tuning option. In my experience if there's a difference it's negligible.

IMO if you're not serious about being competitive then just do what you want to the car within the confines of STH or XA if there's something silly you want to do that will actually make the car not-miserable to drive. I run in XA due to some track-related mods and because fuck the SCCA camber rules.

However with regards to wheel spacers and their effects:

Running the numbers through load transfer calcs on a spreadsheet of mine... confirms that you'd probably never ever notice a difference. But if you do it... placebo is a hell of a drug so if it makes you think you're faster then go for it. I played with wheel spacers on a prior track/autocross car (a 2200lb Mazda2 built for STF originally), and it was very subtle/effectively negligible.


Stock stock:
1730557387246.png


Adding 0.4in to track width front and rear (5mm per side):
1730557466974.png


Adding 0.4in to track width rear only (5mm per side):
1730557556259.png
 
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golfdave

Autocross Champion
Location
Scotland (U.K.)
Car(s)
Mk7 Golf GT Estate
Sorry to jump in to this thread but I noticed one piece of advice that really stood out & I wish more people actually followed it...

People who go straight to the rear bar and think it's the best solution for every case don't understand the entire car. There's not enough weight out back to actually allow it to limit roll so the body rolls the same-ish amount of front, but the rear now hikes the inside tire sooner and is throwing away rear grip.

The Hatch is nose heavy & rear light. The MK7 Estate is circa 54kg heavier after the rear axle compared to the Hatch, so it helps keep the rear end pinned down. This also affects the moment of inertia & shifts the point away from the front of the car & towards the middle.

My 1.4lt estate is on factory "sports" suspension (as GT spec), so it has lowered springs, but the ARBs are interesting! The front is the same as the CCS & the rear is the smallest/softest they make!

So having a lighter 1.4lt engine & lighter manual gearbox, means I have a light nose weight, & with a stiff ARB keeps the front more level. The rear although 54kg heavier is allowed the "roll" as it has a much softer ARB. This combined with the multilink rear & factory toe-in, means the car effectively "rear-steers" in corners! This I can feel as its very playful, & you can get it to oversteer!...

Grip & control of grip in all situations is the best!...

Specs from 2014yr UK brochure:-
1.4lt 140PS GT spec MK7 Golf (2014/15yr) manual gearbox
Estate = 1354kg
5 door Hatch = 1300kg
DSG adds an extra 14 to 20kgs to both the above

3 door GTi engine/spec with manual gearbox = 1351kg
with DSG = 1370kgs
with PP adds a further 31kg
5 door adds a further 30kg
Therefore a 5door GTI-PP DSG is 1432kgs.

3 door R is 1476kgs manual or 1495kgs DSG...
5 door adds a further 30kg

The above unladen weights include the fuel tank 90% full , driver (68kg) and luggage (7kg) in line with EU directive
95/48.
 
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enobiko

Go Kart Newbie
Location
NE Ohio
Car(s)
2017 SE 6 MT
DerHase:
Thanks for answering the question about wheel spacers (the actual subject of my post). I won't be wasting time and money on them.

I do get the idea that, since the car is camber-limited, a front bar would *in theory at least* preserve camber and therefore improve grip. But... WWVWD? (What Would VW Do?) They used a European Clubsport S, where they increased the spring rates on the rear, apparently some hub carriers give more negative camber (not allowed in my class anyway), adjustable dampers, and Cup 2 tires. I don't see they upgraded the front sway bar, I could be wrong about that. I don't know the full extent of the mods to get my car close to a Clubsport S spec , but since I have the SE with the heavy sunroof etc, my car is not ideally suited to chasing 10ths of a second, and I'm not all that great of a driver. My PAX times are usually mid-pack, but recently I've been in the teens (out of 50-some drivers). A set of better tires might put me in the top 10, but it would take a new "me" to drive well enough to better that. That's a work in progress.
On a side note... I find it odd that so many manufacturers go to the Cup 2 tires on their track-day cars. Why not some 200w tire? Maybe the specialized tires won't work as well with the non-optimized camber on the GTI? Maybe the 200w tires aren't legal on European roads?? I considered Cup 2s, but since this is mostly a daily driver in bumpy NE Ohio, with some autocross, I figured I'd make the "sensible" choice. I still have fun! I don't want to get too serious trying to be competitive, if that gets in the way of having fun. Getting a little more serious? Yeah, that's OK. :) Ideally, I'd go with Koni Reds and better tires, but I'm budget-limited.
 

xXDavidCXx

Autocross Champion
Location
AZ
Car(s)
2017 GTI SE DSG
VW does not optimize the car for autocross because they still have to sell the car to the public who may not even have any interest in racing, even for the club-sport.

I'm giving you this advice as a multi National trophy winner, with a MK7, that I have personally tested and tuned into a winning package.
 
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