135i at Thompson raceway initial thoughts

[hatepotholez]

Wassup guys, at lunch right now at Thompson. Having a blast, but the tires can't keep up.

This is my first track event with the 135.

A few thoughts before I write a full review.

-power is good
-dct is great on track
-tried dsc off and the car was uncontrollable with the run flats.
-did I mention I'm sliding all over the place with these run craps?
-I think I was under pressure as I was rolling over the front left tire shoulders. I increased it by 5psi.
-car is "squishy" and leans a bit.

I'm going to run through these run craps and replace them with direzzas(or something similar) and call it a day for next season.

As always any input is greatly appreciated.

[3002 tii]

How much experience do you have?

[hatepotholez]

Originally Posted by 3002 tii

How much experience do you have?

I would say intermediate.

[1GrayBulldog]

Bridgestone RE-11. Go up to 225 front 255 rear and you'll have all that your experience level can handle.

[Elsabor67]

Have you replaced your rear subframe bushings to the M3 or Poly bushings? If you feel your rear sort of squishy, that should firm it up a bit.

[hatepotholez]

Originally Posted by 1GrayBulldog

Bridgestone RE-11. Go up to 225 front 255 rear and you'll have all that your experience level can handle.

Ok I'll look into these.

[hatepotholez]

Originally Posted by Elsabor67

Have you replaced your rear subframe bushings to the M3 or Poly bushings? If you feel your rear sort of squishy, that should firm it up a bit.

I haven't installed these. Like metioned before, the furthest I will go are tires. I don't plan on keeping this car, it'll be stock with the only addition being tires.

I used to have a dedicated track car but sold it. It handled on rails, obviously I'm not expecting that with this car but I find it unacceptable to be sliding all over the track.

[Pyrat 2]

Check tire pressure. RFTs as well as most tires get very greasy if they are hot at too high of a pressure. I try to keep mine at 38-40 max HOT (right after I'm off track) which is generally 30-32 cold.

Also, you are probably understeering badly. If you stay staggered I would go 225/245 or 235/245 instead of 225/255 or 214/245. I run 235/245 but will be 245/245 after I finish my current tires off. In the mean time 2 more psi in front will help the understeer a little.

[hatepotholez]

Originally Posted by HeelToe

Check tire pressure. RFTs as well as most tires get very greasy if they are hot at too high of a pressure. I try to keep mine at 38-40 max HOT (right after I'm off track) which is generally 30-32 cold.

Also, you are probably understeering badly. If you stay staggered I would go 225/245 or 235/245 instead of 225/255 or 214/245. I run 235/245 but will be 245/245 after I finish my current tires off. In the mean time 2 more psi in front will help the understeer a little.

it was unbelievable the amount of understeer I was experiencing. I raised the pressure a little and it helped. If I recall correctly I was 36 psi when coming off the track and then raised it to 40.

My rear tires looked fine btw, I'll consider the 225/245. What tires do you run? Are you on OE wheels, if so which ones?

[Pyrat 2]

Dialing out the understeer on a 1 unfortunately requires investment. I'm running 234/40 and 245/35 MPSS on 8.5x18ET45 wheels. I have Dinan camber plates and am set at -1.5 camber. My understeer is almost completely gone. Running 245 square I'm sure will kill anything that remains.

If you don't want new wheels or to do suspension work then about the only option is to go to a 225 front and leave the back at 245. This will reduce the understeer for sure but it will still be there.

[John_01]

Where to start? The stock suspension is soft and underdamped. The car doesn't have enough front camber for track use, and excessive body roll makes it worse. The rear subframe bushings move around a lot and make the handling unpredictable. Before you go very far, front camber plates and upgraded rear subframe bushings are two fairly important mods for track use.

[Ryan239]

I'd invest in more seat time alongside or before any serious mods. If you like the mods though, I don't think they will hurt but you will definitely go faster with more seat time.

There's another event at Thompson with the club I instruct with in a couple weeks, they run a great event and have good instruction if you want to check it out. http://www.comscc.org is the link.

I have done 2 events in my 135, which is bone stock. I ran NHMS chicane-chicane in July, and Watkins Glen this past week. I really don't see a lot of what folks are complaining about with the understeer and tires. It's certainly not perfect, but I have had stock cars that were much worse off (my '05 and '11 STIs were understeering pigs in stock form). My E92 M3 was more balanced out of the box, and had much better brakes and grip, but it also had better tires

That said, for runflats the stock tires weren't awful, but I think better (and wider up front/all around) is a great idea.

Out of the box, I thought the car handled a lot better than I expected. In terms of tire pressures, I found more grip running at about 38psi hot than I did at 40psi hot. The car seemed to pick up about 7psi during a session, so I would go out at about 31psi cold.

I did not notice an excessive amount of understeer; quite the opposite, I thought the car was pretty well balanced out of the box. I did have it aligned in July prior to going to NHMS, so I am sure that helped. I had about 1/16th toe out in the front, zero toe in the back, -1.4 camber in the front and -2 camber in the rear (I drilled the front alignment pins prior to the alignment). Where I did see some understeer was in 2a at NHMS (more my driving than the car, I tended to not slow enough) and on occasion in T1 at the Glen (my line I think had more to do with it more than the car). Those are slow to mid-speed turns. High speed understeer I didn't notice a lot of.

I do agree with the car having too much power and not enough tire; the skinny front tires hurt overall grip and braking, and the rear tires just can't cope with the torque. At NHMS t3, the car was really fun, but slow, going up the hill sideways.

This is where I have a big complaint on the DCT; even with DSC off, Sport mode on and shifter in the manual position, the car would still downshift on me when I went full throttle. Given the abundance of torque and lack of tire, 2nd gear was bad for lap times so I would use 3rd in t2b and t3 @ NHMS. Half of the time, the car would downshift to second even though I manually selected (and was driving in) 3rd. While I love the full throttle upshifts, this was a real pain in the neck and hindered my lap times. Shifting into 5th, flat to the floor, at the apex of t3 in the Esses at the Glen was pretty awesome... but I'd still prefer the manual.

The one real area of weakness I saw were in the brakes. The front brakes heat up quickly, so pad selection is important. I ran some Hawk HP+, which were not very good. I normally run DTC60s on my race car, but I thought they would have too much initial bite for the street tires, and I wound up with the less torquey HP+. They bite better than stock, but don't deal with the heat so well. I think the HP+ would be ok for the rear but a DTC30 or 60 up front would be much better (or some other equivalent brand). I didn't have a lot of faith in the brakes so that held me back a bit.

The DSC definitely needs to come off if you want to have any chance at a fast lap (in the dry at least). I wonder if having it on helps add to the understeer you saw? If you have trouble keeping the car straight with the DSC off, definitely work on you before the car. You won't be able to take much advantage of better suspension, bushings or brakes if you aren't comfortable with a little slip angle. I don't mean that in a bad way, but I think the oversteer-ability of the car balances out the plowing, but you can't get oversteer with the traction control and stability control on.

I'm not going to the Thompson event, but we have some great RWD instructors going so if you want to hit the event, PM me and I can give you some names to request.

[hatepotholez]

Originally Posted by Ryan239

I'd invest in more seat time alongside or before any serious mods. If you like the mods though, I don't think they will hurt but you will definitely go faster with more seat time.

There's another event at Thompson with the club I instruct with in a couple weeks, they run a great event and have good instruction if you want to check it out. http://www.comscc.org is the link.

I have done 2 events in my 135, which is bone stock. I ran NHMS chicane-chicane in July, and Watkins Glen this past week. I really don't see a lot of what folks are complaining about with the understeer and tires. It's certainly not perfect, but I have had stock cars that were much worse off (my '05 and '11 STIs were understeering pigs in stock form). My E92 M3 was more balanced out of the box, and had much better brakes and grip, but it also had better tires

That said, for runflats the stock tires weren't awful, but I think better (and wider up front/all around) is a great idea.

Out of the box, I thought the car handled a lot better than I expected. In terms of tire pressures, I found more grip running at about 38psi hot than I did at 40psi hot. The car seemed to pick up about 7psi during a session, so I would go out at about 31psi cold.

I did not notice an excessive amount of understeer; quite the opposite, I thought the car was pretty well balanced out of the box. I did have it aligned in July prior to going to NHMS, so I am sure that helped. I had about 1/16th toe out in the front, zero toe in the back, -1.4 camber in the front and -2 camber in the rear (I drilled the front alignment pins prior to the alignment). Where I did see some understeer was in 2a at NHMS (more my driving than the car, I tended to not slow enough) and on occasion in T1 at the Glen (my line I think had more to do with it more than the car). Those are slow to mid-speed turns. High speed understeer I didn't notice a lot of.

I do agree with the car having too much power and not enough tire; the skinny front tires hurt overall grip and braking, and the rear tires just can't cope with the torque. At NHMS t3, the car was really fun, but slow, going up the hill sideways.

This is where I have a big complaint on the DCT; even with DSC off, Sport mode on and shifter in the manual position, the car would still downshift on me when I went full throttle. Given the abundance of torque and lack of tire, 2nd gear was bad for lap times so I would use 3rd in t2b and t3 @ NHMS. Half of the time, the car would downshift to second even though I manually selected (and was driving in) 3rd. While I love the full throttle upshifts, this was a real pain in the neck and hindered my lap times. Shifting into 5th, flat to the floor, at the apex of t3 in the Esses at the Glen was pretty awesome... but I'd still prefer the manual.

The one real area of weakness I saw were in the brakes. The front brakes heat up quickly, so pad selection is important. I ran some Hawk HP+, which were not very good. I normally run DTC60s on my race car, but I thought they would have too much initial bite for the street tires, and I wound up with the less torquey HP+. They bite better than stock, but don't deal with the heat so well. I think the HP+ would be ok for the rear but a DTC30 or 60 up front would be much better (or some other equivalent brand). I didn't have a lot of faith in the brakes so that held me back a bit.

The DSC definitely needs to come off if you want to have any chance at a fast lap (in the dry at least). I wonder if having it on helps add to the understeer you saw? If you have trouble keeping the car straight with the DSC off, definitely work on you before the car. You won't be able to take much advantage of better suspension, bushings or brakes if you aren't comfortable with a little slip angle. I don't mean that in a bad way, but I think the oversteer-ability of the car balances out the plowing, but you can't get oversteer with the traction control and stability control on.

I'm not going to the Thompson event, but we have some great RWD instructors going so if you want to hit the event, PM me and I can give you some names to request.

Thanks, i'll check out the site. I agree that DSC would bring faster lap times, but I wasn't confident enough to turn it off. The moment I felt the rear slip excessively I let off the throttle and turned DSC back on. Thankfully I'm not new to RWD on the track coming from a turbo 240sx or I would have been in real trouble with the DSC off.

I wasn't really aiming for lap times but more of trying to get the right line for the track and smoothness(I had no instructor with me and had no idea where they were, which is obviously my fault). I didn't adjust my pressures until my first session was over, this was a big mistake on my part and now my left tire has no shoulder. To add to this, most of my day was trying to find the right line.

For the understeer I think there are 2 factors I noticed, one my line was off no doubt about it and second my tire pressure was low. If I could have corrected the tire pressure BEFORE I went on track and had the right line I could have partially saved the tire and the understeer would have been less. I agree that letting the rear slide out a bit would have helped the understeer but like I said, I was not confident enough to leave it off. The driver behind me said my car looked balanced but my tires were giving out, he said all 4 tires were sliding and it looked like I needed grip badly.

I didn't have an issue with the DCT, it gave me full control. It didn't do any shifting for me at all.

My brakes did fairly well, but I only hit 120 on the straight so I can't say I really pushed them too hard.

Since I toasted my front left tires shoulder, I'll be replacing the whole set to a 225/255(I will be adding a JB4 also) either to RS3's PSS, RE-11, s04, or Z2s. There's a event on Oct 4th at lime rock, depending on space I'll try and make this one or the NJMP event that same weekend with PCA, depending on space.

Do you guys run at lime rock? My buddy and I are aiming for Watkins Glen next year.

[Ryan239]

We don't run at Lime Rock anymore; not enough track time for the club once they changed their policies a few years back. We run NHMS, Thompson, Watkins and sometimes Mosport, Tremblant and Pocono. NHMS is a pretty fun track, and is about 2.5 hours or so from Thompson.

[hatepotholez]

Originally Posted by Ryan239

We don't run at Lime Rock anymore; not enough track time for the club once they changed their policies a few years back. We run NHMS, Thompson, Watkins and sometimes Mosport, Tremblant and Pocono. NHMS is a pretty fun track, and is about 2.5 hours or so from Thompson.

Ok thanks!

[Pyrat 2]

Originally Posted by Ryan239

...This is where I have a big complaint on the DCT; even with DSC off, Sport mode on and shifter in the manual position, the car would still downshift on me when I went full throttle...

Agree completely with this complaint. I've checked with BMW to see if this could be disabled - no. So I've installed a very small rubber grommet in the accelerator pedal that prevents the kick down at WOT. The OBD port indicates that the throttle is still at 100% only now it doesn't force a kick down at WOT. I've been running this way for over a year and several track events and I'd suggest you consider this. Only takes a couple minutes to install and if you don't like it you can take it out just as quickly.

[CAVU]

Originally Posted by HeelToe

Agree completely with this complaint. I've checked with BMW to see if this could be disabled - no. So I've installed a very small rubber grommet in the accelerator pedal that prevents the kick down at WOT. The OBD port indicates that the throttle is still at 100% only now it doesn't force a kick down at WOT. I've been running this way for over a year and several track events and I'd suggest you consider this. Only takes a couple minutes to install and if you don't like it you can take it out just as quickly.

I'm going to look into this. I may do some testing to figure out where exactly along the pedal travel a WOT signal is sent... hopefully BMW didn't calibrate it to be at or beyond the kick down point. I've got a spare accelerator pedal that I can drag into a box store and choose the best grommet to stop the pedal from traveling past WOT.

[Pyrat 2]

On my own 135is I have confirmed that you can still get WOT with the grommet in place. I used an OBD connection to validate.

[Groundpilot]

Originally Posted by HeelToe

Agree completely with this complaint. I've checked with BMW to see if this could be disabled - no. So I've installed a very small rubber grommet in the accelerator pedal that prevents the kick down at WOT. The OBD port indicates that the throttle is still at 100% only now it doesn't force a kick down at WOT. I've been running this way for over a year and several track events and I'd suggest you consider this. Only takes a couple minutes to install and if you don't like it you can take it out just as quickly.

This is very interesting. Can you elaborate on that rubber grommet a little more? A picture of it and how to install it would be great.

[DietTab]

http://www.burgertuning.com/downshift_blocker_BMW.html

[Groundpilot]

Thanks man. I have never heard about downshift blocker. I assume our cars have type C pedal.

[Pyrat 2]

Originally Posted by DietTab

http://www.burgertuning.com/downshift_blocker_BMW.html

woah. My home made version isn't nearly as elegant. Mine is a rubber grommet that has electrical tape holding it to the pedal.