Driver side front wheel noticeably hotter than others after a few autoX runs

[Amm5890]

Help - Drivers side front wheel noticeably warmer than passenger side after a few autoX runs.

What’s going on guys looking for some help on diagnosing a possible issue.

Yesterday after a few autoX runs my drivers side front wheel was noticably hotter than the passenger side. It wasn’t scolding hot but enough that I couldn’t touch the rim for much longer than ~10 secs.

There was no crazy changes in psi

Possible causes I could think of:

1. Obdeleven tweaks - XDS set to medium, hydraulic brake offset set to 7 (stock is 8 ), brake booster set to 3 (stock 4)

2. Dragging/clogged caliper - fluid was flushed 2 weeks ago just fine. No smoke or visible leaks from caliper though

3. Silent wheel bearing failure - no wheel bearing sound, no play when shaken at 12 and 6.

Weird part is that after my drive to work today, all of the wheels were cool to the touch.

Is it possible that XDS is really heating things up on sweeping turns?

What do you all think?

 

[xXDavidCXx]

XDF + overdriving can do this

 

[MonkeyMD]

That's what i was thinking. Turn ECS completely off.

 

[krs]

That's what i was thinking. Turn ECS completely off.

I hate when I get into about the 1st or 2nd corner and realize I left this on. I also fumble trying to turn it off then, but the run is blown by then.

 

[odessa.filez]

Was the course design a contributor?

I keep esc and xds off at events. I don't use xds as a daily driver setup either.

 

[xXDavidCXx]

Was the course design a contributor?

I keep esc and xds off at events. I don't use xds as a daily driver setup either.

XDF is required for the diff to work, so while you get less heat, the diff does not have any pre-load to operate (effectively).

 

[kep]

XDF is required for the diff to work, so while you get less heat, the diff does not have any pre-load to operate (effectively).

I disagree, I have driven PP GTi's with XDS disabled, and the diff is extremely effective

 

[odessa.filez]

I'm open diff, so maybe I'm different.

I also have a 'mental problem' with a feature that usea the brakes to improve cornering but who knows maybe I could be faster if I adjusted my driving.

 

[xXDavidCXx]

I disagree, I have driven PP GTi's with XDS disabled, and the diff is extremely effective

"
What about the “preload” problem?
The worst case scenario for any LSD or the FDL unit is that of "zero load". This could be described as having the car on level ground with all the wheels pointing straight ahead & all on ice, meaning there is no grip/torque difference between the driven wheels.

How the FDL unit deals with it:-
The FDL unit is not supposed to have this problem as its an electrohydraulic clutch pack diff lock. Unfortunately, it still has a “preload” type problem as it still requires a minimum amount of torque imbalance in Nm between the driven wheels to lock up. If the driven wheels cannot provide enough grip for this then the cars existing XDS+ systems within the ABS unit will be used to apply pressure to the brakes & create a torque imbalance between the driven wheels. This is why it draws heavily on the existing CAN system & sensors.

The FDL unit fitted to the Seat TCR car has an externally adjustable preload setting, with the recommended range being 50Nm (37lbft) to 100Nm (74lbft). Cold measured is 15% higher than warm measure, & preload decreases approx. 15% after 50kms of running. (info from the Seat Leon Cup Racer TCR owners manual)

An Automotive Engineering thesis was conducted in conjunction with Borg Warner AB in Landskrona (Sweden) in 2016. The aim was to develop real world driving scenarios on a test rig so that accurate computer algorithms can be made (instead of having to spend weeks sliding around a test track to get real world data). They did various driveline set ups that the Borg Warner Gen.V unit is used for (AWD, FDL, hang on front, transfer case etc). Unfortunately, they hit problems with the FDL (FXD) set up, quote:- “The FXD system is the most difficult to recreate due to extreme variations in driveline behaviour - The FDL system will not be implemented due to far to rapid driveline behaviour". They also found on the simulated hill tests that, quote:- "the torque that is applied upon the clutch pack coupling is varying a lot when the system oscillates & goes from zero to maximum several times. This affects the whole driveline behaviour". Basically, the unit in this configuration is very “reactive” but also “proactive” i.e. it reacts before. The driveline was oscillating like mad, as the unit tried to figure out which wheel to send the torque to! This resulted in huge differences in the recorded torque & angular velocities. This is all because it takes data from many sources, so is constantly adjusting, more so than in the other configurations & backs up my reasoning as to why they added a “bleed container” to remove air from the oil due to aeration.

Ultimately the FDL unit has no direct mechanical way of activating the clutches, so in effect it has a huge “preload” problem. The FDL cannot “sense” torque through the drive shafts & thus cannot use this to activate the pump to activate the clutch pack. It has to be “told” what the wheel speed is from the ABS sensors as it does not have its own sensors. Therefore, even if you leave the FDL unit powered but disconnect it from the CAN bus or just the ABS unit, it will not work as it is not a “stand alone” unit, & thus NOT a mechanical LSD!"

https://www.golfmk7.com/forums/index.php?threads/how-the-vw-golf-gti-performance-pack-pp-“front-differential-lock”-vaq-works.351185/

Also see post #42

 

[Oversteermybagel]

"
What about the “preload” problem?
The worst case scenario for any LSD or the FDL unit is that of "zero load". This could be described as having the car on level ground with all the wheels pointing straight ahead & all on ice, meaning there is no grip/torque difference between the driven wheels.

This sentence makes 0 sense and its hard to take anything else seriously that comes after it. You know what works perfectly with "zero load" an open diff. You know what also works perfectly with "zero load" a locked diff. In this hypothetical worst case scenario both those things are identical.