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      09-06-2020, 02:41 PM   #1
seanyx11
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Traction control/wheel hop issues on corner exit

I went on a mountain run yesterday to Blood Mountain here in GA and we drive pretty hard up there. On corner apex and exit, I was experiencing some wheel hop. My tires were NOT breaking loose and in fact, weren't even squealing, but they felt like they were hopping instead of breaking loose.

I just bought some 18" Bimmerworld lightweight wheels w/ Yokohama Advan A052 tires for mountain runs/Track days. The specs on the tires are 265/35 front and 295/30 in rear, which makes the rear tires .3" smaller in diameter than the front tires. I just had these mounted and balanced on Friday, the day before our run yesterday on Saturday. So, they were basically brand new for reference.

I've read somewhere that having smaller rear than front could cause some traction control issues, but I was hoping maybe the ECU would compensate for it.

I have KW V3 and I'm also wondering if it may be a dampening issue with it being set too hard at 3 rebound & 4 compression all around. In combination with the new stickier tires, maybe it's causing the car to hop instead of breaking loose.

Any suggestions would help. I'm hoping it's as simple as adjusting the dampening too a softer setting on my V3s, but I have a feeling it might be traction control causing the issues. Thanks in advance for your help. Sorry for the long-winded explanation, but just trying to be detailed for better understanding of situation.
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      09-06-2020, 02:49 PM   #2
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Did you have DCS enabled or disabled? I find the power cut to more abrupt than a hopping issue with traction control - there is a thread on wheel hop somewhere around here though. I had it twice, both times on cold, slightly damp mornings with cold tires. Otherwise no wheel hop issues. Usually only occurs in a straight line for most though. May have just been the conditions. You also have a lot of tire on the car (295s) which some others have complained negatively impact the driving characteristics. Might just be too much tire for the power level so its trying to break them loose but not succeeding.
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      09-06-2020, 02:54 PM   #3
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Originally Posted by Mosely View Post
Did you have DCS enabled or disabled? I find the power cut to more abrupt than a hopping issue with traction control - there is a thread on wheel hop somewhere around here though. I had it twice, both times on cold, slightly damp mornings with cold tires. Otherwise no wheel hop issues. Usually only occurs in a straight line for most though. May have just been the conditions. You also have a lot of tire on the car (295s) which some others have complained negatively impact the driving characteristics. Might just be too much tire for the power level so its trying to break them loose but not succeeding.
I was in Sport mode, so DSC was on. As far as 295s being too much tire, I don't think that's the case. I previously had 265/30/R19 & 295/30/R19 Michelin PS4S. So, the only difference is the tire compound and the shorter rear tire now.
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      09-06-2020, 04:39 PM   #4
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Drive with DCS Off to see if you can recreate it. This will let you know if it's traction control or not.

Next you can try softening the rear shock compression a little. Maybe increase the rebound too, not sure. I'm basically recommending experimenting with shock settings because you already have adjustable shocks, so it's worth a shot trying. But...

Usually the biggest culprit for wheel hop in independent rear suspension cars is deflection due to rubber bushings.
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      09-06-2020, 05:00 PM   #5
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Originally Posted by Anthony1s View Post
Drive with DCS Off to see if you can recreate it. This will let you know if it's traction control or not.

Next you can try softening the rear shock compression a little. Maybe increase the rebound too, not sure. I'm basically recommending experimenting with shock settings because you already have adjustable shocks, so it's worth a shot trying. But...

Usually the biggest culprit for wheel hop in independent rear suspension cars is deflection due to rubber bushings.
That might be a bit hard to recreate since I was driving at about 8/10 on some very curvy narrow roads. So, if I want to recreate it safely without nannies on it would have to be at the track, which I won't be able to do anytime soon. I was hoping someone had some experience with this so I could go ahead and get some new rear tires if need be (or just adjust the rear suspension if need be)
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      09-06-2020, 05:43 PM   #6
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Quote:
Originally Posted by seanyx11 View Post
I went on a mountain run yesterday to Blood Mountain here in GA and we drive pretty hard up there. On corner apex and exit, I was experiencing some wheel hop. My tires were NOT breaking loose and in fact, weren't even squealing, but they felt like they were hopping instead of breaking loose.

I just bought some 18" Bimmerworld lightweight wheels w/ Yokohama Advan A052 tires for mountain runs/Track days. The specs on the tires are 265/35 front and 295/30 in rear, which makes the rear tires .3" smaller in diameter than the front tires. I just had these mounted and balanced on Friday, the day before our run yesterday on Saturday. So, they were basically brand new for reference.

I've read somewhere that having smaller rear than front could cause some traction control issues, but I was hoping maybe the ECU would compensate for it.

I have KW V3 and I'm also wondering if it may be a dampening issue with it being set too hard at 3 rebound & 4 compression all around. In combination with the new stickier tires, maybe it's causing the car to hop instead of breaking loose.

Any suggestions would help. I'm hoping it's as simple as adjusting the dampening too a softer setting on my V3s, but I have a feeling it might be traction control causing the issues. Thanks in advance for your help. Sorry for the long-winded explanation, but just trying to be detailed for better understanding of situation.
I don't know much about KW V3, but I assume they are adjustable? If so, I would dial in the softest or as close as possible to it. I tend to think a lot of people equate firmness with good handling which is not necessarily true. My guess is setup might be too firm and when car is unsettled with uneven road and some traction challenge, it bounces instead of maintaining traction. I had a similar issue when mine was to heavily sprung. Went softer and car handles amazing.

Edit: I also am on 255/35 19 front and 285/30 20 rear MPSS and Ohlins with TC Kline Springs. 400# front and 700# rear
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      09-06-2020, 08:05 PM   #7
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Quote:
Originally Posted by seanyx11 View Post
That might be a bit hard to recreate since I was driving at about 8/10 on some very curvy narrow roads. So, if I want to recreate it safely without nannies on it would have to be at the track, which I won't be able to do anytime soon. I was hoping someone had some experience with this so I could go ahead and get some new rear tires if need be (or just adjust the rear suspension if need be)
There are a lot of threads on wheel hop. Might be worth sifting through to see if you find something I haven't thought of. I can just give general advise because I haven't experienced it myself to have needed to find a solution.

https://www.google.com/search?q=f87+...w=1920&bih=977
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      09-07-2020, 06:49 PM   #8
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Quote:
Originally Posted by Anthony1s View Post
Quote:
Originally Posted by seanyx11 View Post
That might be a bit hard to recreate since I was driving at about 8/10 on some very curvy narrow roads. So, if I want to recreate it safely without nannies on it would have to be at the track, which I won't be able to do anytime soon. I was hoping someone had some experience with this so I could go ahead and get some new rear tires if need be (or just adjust the rear suspension if need be)
There are a lot of threads on wheel hop. Might be worth sifting through to see if you find something I haven't thought of. I can just give general advise because I haven't experienced it myself to have needed to find a solution.

https://www.google.com/search?q=f87+...20&bih=977
I definitely appreciate the input, but I've seen all of those threads as well. Most, if not all, are talking about wheel hop in straight line acceleration on street or drag strip.

I did happen to get a short mountain run in today and I softened the KW V3 by 2 clicks all the way around and it seemed to solve the wheel hop issue. Though, now the car feels like it has more body roll. I may just have to get used to it more with the new tires.

Thanks for everyone's help and suggestions, much appreciated
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      09-07-2020, 07:05 PM   #9
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Quote:
Originally Posted by seanyx11 View Post
I definitely appreciate the input, but I've seen all of those threads as well. Most, if not all, are talking about wheel hop in straight line acceleration on street or drag strip.

I did happen to get a short mountain run in today and I softened the KW V3 by 2 clicks all the way around and it seemed to solve the wheel hop issue. Though, now the car feels like it has more body roll. I may just have to get used to it more with the new tires.

Thanks for everyone's help and suggestions, much appreciated
Shouldn't matter if it's straight line or coming out of a corner. Forces applied are the same as far as wheel hop. The difference would be in the sway bars, but they don't affect wheel hop.

Stiffen the front back up to where it was, it should get rid of the body roll. Hence why I only said to soften the rear.

Otherwise, glad you got it sorted.
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      09-08-2020, 03:47 AM   #10
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I was one of the people who had TCS issues after going for square wheel setup. What DME software are you running?
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