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2019 GTI 6MT Performance Issues I'd Like to Correct

GTIfan99

Autocross Champion
Location
FL
My car is a daily and I track it, but I'm staying stg 1, so it'll be DMF and SRE for me.
 

dosjockey

Go Kart Champion
Location
South
Does he mean the differential?

If so, that makes me wonder if the VAQ system is just plain stuck in the car due to integration.

I'd rather have a Quaife unit. I love those things. Very progressive.
 

dosjockey

Go Kart Champion
Location
South
Yes. Single Mass FlyWheel and Limited Slip Differential For The Win. ;)
I'm more of a torque-biasing differential guy, but either way mechanical traction aids are outstanding.

Can an electronic or electro-mechanical system be better? Sure. Most are, actually; but a mechanical unit only does one thing; and it does it the same way every single time it happens.

There's a lot of value in eliminating variables.
 

dosjockey

Go Kart Champion
Location
South
On that note, actually, it was the exact wrong kind of rain last night; lots of cars in ditches. Given I have access to a small number of private roads, I thought I'd see what all this gadgetry was actually capable of.

While I kept it within the break-in limits, I did drive like an idiot with it all turned back on.

To be entirely fair to Volkswagen, the stuff works; and it works very well. It would be very difficult to get yourself into trouble with this car out of the box.
 

dr_mat

Go Kart Champion
Location
Berkshire
The stated goal of torque limiting in first and second is to avoid wheel hop breaking drive shafts, iirc. It will feel way worse if your regular road surface is gravel because once all the limiters and traction control steps in so much sooner.
 

golfdave

Drag Racing Champion
Location
Scotland (U.K.)
Car(s)
MK7 Golf GT Estate

dosjockey

Go Kart Champion
Location
South
The stated goal of torque limiting in first and second is to avoid wheel hop breaking drive shafts, iirc. It will feel way worse if your regular road surface is gravel because once all the limiters and traction control steps in so much sooner.
It might. We'll see in a few miles, I can't be sure what problem they were trying to solve until I feel it without the nannies in the way.

I'm waiting until a 500 mile fluid change (approaching soon) to change anything else.
 
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dosjockey

Go Kart Champion
Location
South
If you want to know what the VAQ system is read my thesis on it here:-

https://www.golfmk7.com/forums/inde...p-“front-differential-lock”-vaq-works.351185/
Thanks, man! I hadn't seen that. (y)

You've got to be kidding me. That is legitimately going twenty miles out of their way to complicate something that has no reason to be anything other than incredibly simple. :rolleyes:

I'm going to print that to go through it more thoroughly, but damn. Doesn't make a lick of sense from a design perspective mechanically or electrically, and my concern that the systems expect each other to be functional and communicative seems warranted now. It also explains why turning systems off doesn't really produce the effects I'd expect normally.

No wonder it's all over the damned place. It can't not be. One of my earlier postulations was a note in regard to the engine and transmission expecting instantaneous signals from one another, and simply letting a human pick the gears potentially threw a wrench into all of that cleverness; making guesswork of computational convention. My hypothesis was that, given it's further integration and data feed to the ECU and traction control system, the DSG produces an objectively better car, and that the manual-equipped GTI was broken on paper before it ever hit the road because it doesn't have that further integration.

I think the exact wording was something along the lines of "This is one event in which another computer might actually be the answer", or something to that effect. Looks like I wasn't too far off.

What happens if I replace that differential with a conventional mechanical unit? Is that even possible within reason, at this point? On one hand, it doesn't look complicated to remove mechanically, but there's always more to it, and I don't know how the electronic systems would react. Do people ever remove these and fit something normal?
 

dosjockey

Go Kart Champion
Location
South
That differential smells more like patent squatting than performance, to me.

Whatever. I guess it works as advertised in sloppy conditions; but so would a conventional design with tacked on wizardry.

I believe the car needs a traction aid to reach it's performance potential. I don't believe it needs anything this complicated.
 

golfdave

Drag Racing Champion
Location
Scotland (U.K.)
Car(s)
MK7 Golf GT Estate
What happens if I replace that differential with a conventional mechanical unit? Is that even possible within reason, at this point? On one hand, it doesn't look complicated to remove mechanically, but there's always more to it, and I don't know how the electronic systems would react. Do people ever remove these and fit something normal?

You can rip off the VAQ unit, fit the non VAQ parts to the gearbox case & swap out the open diff & fit an LSD.....then spend ages coding out the VAQ unit from the Canbus….then tell modules like the engine & ABS that the VAQ is NOT fitted.. ..

The are way too many electronics in these cars....some good some bad....even on my lowly 1.4lt I had to leave it in spirt the whole time & slacken off the nannies...to get it to drive input to output...
 

dosjockey

Go Kart Champion
Location
South
You can rip off the VAQ unit, fit the non VAQ parts to the gearbox case & swap out the open diff & fit an LSD.....then spend ages coding out the VAQ unit from the Canbus….then tell modules like the engine & ABS that the VAQ is NOT fitted.. ..

The are way too many electronics in these cars....some good some bad....even on my lowly 1.4lt I had to leave it in spirt the whole time & slacken off the nannies...to get it to drive input to output...
Yeah, that's what I was worried about. Mechanically (despite it's complexity) it shouldn't be difficult to remove; but that's not the problem, is it? Maybe it's worth looking into, but my knowledge pool tops off at your wonderful explanation of the system. I'll have to look into what would need to be changed; because if I ever have a problem with this unit I'm going to be interested in using that as an excuse to replace it.

Honestly, the chassis might actually be good enough to be worth the trouble if it's possible at all; but that sounds like something I'd just want to leave to a performance shop. I don't have that kind of energy anymore; so, let's just tack an arbitrary ten grand price on swapping that differential for now.

This thing would be worlds more progressive with just a regular old Quaife in there, and there would be nothing to go wrong in the future. They just plain work.

There are many other things to do before digging into that craziness, though; and so far it's worlds better than it was. At 500 miles, we'll see if I can get anything else out of it.
 

golfdave

Drag Racing Champion
Location
Scotland (U.K.)
Car(s)
MK7 Golf GT Estate
Don't look at the Mk7 GTI Clubsport (S or not)…..

Nothing "Clubsport" about it...same heavy sliding fist, single piston brakes as the GTI PP/R, plus badly designed cheap two piece (permeant) front discs & specific pads....so no lightweight 4 pots which are on other VAG cars...

Also you still get VAQ unit..plus they ripped out the rear seats & sparewheel...usually "Clubsports" do this to fit a half cage...guess what?..NO half cage & yet the Clubsport which was tested around the 'ring had a half cage made by Weichers..which you can buy from Weichers!!

If it wasn't for the fact there are internal parts differences between the GTI engine & the R/Clubsport engines there is so far NO proper analogue GTI/Clusport....

A plain GTI modifed in some respects can end up being a far better car...

P.S...forget the Quaife…fit a Wavetrack...
 
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dr_mat

Go Kart Champion
Location
Berkshire
These are not expensive cars... Just how it is I think.
 

dr_mat

Go Kart Champion
Location
Berkshire
If you want to know what the VAQ system is read my thesis on it here:-

https://www.golfmk7.com/forums/inde...p-“front-differential-lock”-vaq-works.351185/
Great write up. Have to say it seems quite an elegant solution. Complex (only in the way it has to be activated), yes, but so much more flexible than a mechanical lsd.

The engineers now have the ability to linearly control the amount of diff slip at any time by adding a few lines of code. You could even have a button on the dash to lock it at any time. Does it react fast enough? As fast as the anti lock system. Probably can detect slip within less than half a turn of the slipping wheel, but I don't know how fast it can pressurise the plates to react and lock.

I think we may have to change the first letter in the acronym ECU, given it no longer just controls the Engine...
 
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