Driving questions? Setup questions?

[MINI135i]

Wow, a bit of confusion on the whole DTC/DSC/E-LSD and ABS.

One second press activates the Dynamic Traction control (DTC) = this allows some spinning of the rear tires without intervention like with snow covered roads, etc. You will see a "DTC" on the dash lights.

Over 3 second press deactivates DTC and Dynamic Stability control (DSC) and activates the E-LSD. You will see the "warning triangle" on the dash lights.

DSC, when deactivated, allows the car to four wheel drift, move sideways and forward at the same time, rear end way out, etc. DSC is based upon all the accelerometer info and brakes individual wheels to correct car direction. It also has the ability to cut engine power. DSC is useful for helping correct your trajectory in an emergency when you slide out of control on the freeway or something.


DSC/DTC are an absolute annoyance on a track and should be turned off if you are going for fastest lap. They will slow you down. That of course means you have to drive the car without any saftey help from the cars computers.

E-LSD is supposively on when everything else is off. Uses rear brakes to stop inside wheel from loosing traction. We all know it has not been very effective in a track senario but some say it has helped in autocross senarios...jury is out still...when compared to a mechanical diff it is a sorry excuse for a LSD.

ABS is always on, no matter what you deactivate.

Page 66 in the manual has all the info for reference.


My three favorite track/autocross lights (low fuel, DSC/DTC off, race tires on) are shown below:

[HP Autosport]

135/335's desperately need a good mechnical LSD.

[philaf_666]

A good way to feel the e-lsd when everything is off is while doing donut.

Turn the steering all the way on whatever side when completely stopped, 1st gear engage and hit the gas. You'll see that the car will resist drifting at first and then when it reaches a certain speed, the back of the car suddenly start drifting like maniac.

Pretty sure that this is caused by the e-lsd trying to brake the inside wheel but then stop after a certain speed is reached.

Not sure if it the speed, a sensor calculating how much sideway you are or simply how much the gas pedal is pressed... but there is definitely something that gets in the way of making a nice donut, but then goes away.

[J Tyler]

Originally Posted by Carbonic

I am running Bridgestone Potenza RE55S Semi-slicks. Ambient temperatures are usually around 30 C (86 F), track temps obviously way hotter.

I don't know if it has any bearing on things, but pretty much the whole of SA is situated at an altitude of about 6000 ft.

Ok, I'd suggest starting around 35psi cold. I think that's a safe starting point, and then from there I'd bleed out some pressure until you feel the tires start to get greasy. At that point, go back up a few psi. See my earlier posts in this thread about tires

It's tough for me to say, because I've never run those tires. On the one hand, I want to suggest starting with a high psi because of the warm ambient temperature, but then on the other hand it looks like it's an R-comp tire which means it is designed to run at a lower pressure than a typical street tire. So I compromise and suggest 35psi cold. But, you really just have to get out there and experiment

Originally Posted by MINI135i

Wow, a bit of confusion on the whole DTC/DSC/E-LSD and ABS.

One second press activates the Dynamic Traction control (DTC) = this allows some spinning of the rear tires without intervention like with snow covered roads, etc. You will see a "DTC" on the dash lights.

- Thank you, we all know that

Over 3 second press deactivates DTC and Dynamic Stability control (DSC)

- Thank you, we all know that

and activates the E-LSD. You will see the "warning triangle" on the dash lights.

- This we are not sure about

DSC, when deactivated, allows the car to four wheel drift, move sideways and forward at the same time, rear end way out, etc. DSC is based upon all the accelerometer info and brakes individual wheels to correct car direction. It also has the ability to cut engine power. DSC is useful for helping correct your trajectory in an emergency when you slide out of control on the freeway or something.

- Thank you, we all know that

DSC/DTC are an absolute annoyance on a track and should be turned off if you are going for fastest lap. They will slow you down. That of course means you have to drive the car without any saftey help from the cars computers.

- Thank you, we all know that

E-LSD is supposively on when everything else is off. Uses rear brakes to stop inside wheel from loosing traction. We all know it has not been very effective in a track senario but some say it has helped in autocross senarios...jury is out still....

- Yes, again, this is what everyone is unsure about. "Jury is still out"

ABS is always on, no matter what you deactivate.

- Thank you, we all know that



***Please read the OP and the thread before posting a bunch of redundant material***

[SpeedballTrix]

Originally Posted by J Tyler

***Please read the OP and the thread before posting a bunch of redundant material***

QFT

[MINI135i]

My bad...I forgot this was your personal thread.

Cheers.

[J Tyler]

Originally Posted by MINI135i

My bad...I forgot this was your personal thread.

Cheers.

Thank you, I appreciate it.

If you do have some new info to post, that you are certain is factual, feel free to chime in.... I admit here are plenty of areas where my knowledge is lacking I just ask that you read the thread to keep redundancy to a minimum.


Moving on... Since we're still unsure about exactly what the E-LSD is & does, I'll make it a point to really pay attention to the electronics next time I drive a stock 135i/335i. This is all I got when we had an open diff:

[pkcormier]

Jeff,

As you may recall from my earlier questions, I have a 135i with the following mods for the track:

1) camber plates and M3 lower control arms - can be set to -3 camber
2) Breyton 8.5" wheels
3) 245 R compound tires on all four corners
4) HT10 pads

I am considering my next performance mod. Please give me your opinion re: replacing F & R stock sway bars with either the adjustable uuc version or the non-adjustable H&R product. Or perhaps just F or just R. For warranty and resale purposes, I am trying to stay away from power mods and coilovers. This is also my daily driver (I swap our wheels and pads between events, and bring front camber back to about -2).

Thanks,

Philip

[J Tyler]

Originally Posted by pkcormier

Jeff,

As you may recall from my earlier questions, I have a 135i with the following mods for the track:

1) camber plates and M3 lower control arms - can be set to -3 camber
2) Breyton 8.5" wheels
3) 245 R compound tires on all four corners
4) HT10 pads

I am considering my next performance mod. Please give me your opinion re: replacing F & R stock sway bars with either the adjustable uuc version or the non-adjustable H&R product. Or perhaps just F or just R. For warranty and resale purposes, I am trying to stay away from power mods and coilovers. This is also my daily driver (I swap our wheels and pads between events, and bring front camber back to about -2).

Thanks,

Philip

Hey Philip, here are the sway bar combos we've run and my thoughts on them. Both are with 255 tires all around and KW V3 coilovers (all stock suspension arms):

Stock front bar + H&R rear bar = Car is way too loose (oversteery), cannot put power down due to too much inside rear tire lift, but very fun drift car. Ex: http://vimeo.com/1845567

H&R front bar + H&R rear bar = Car is well balanced handling-wise, but the rear bar is still too stiff for an open diff. It unloads the inside rear too much, causing big inside rear wheel spin.


We just switched back to the stock rear bar. We have not run this setup yet but I am confident it will be pretty good. So, my suggestion is to try an aftermarket front bar first and see how you like that. I don't know what the UUC bars are like, but I can say that the H&R front bar is not a drastic change from the stock bar rate; it's mildly stiffer (I'd guess around 20% stiffer?) so you may want the UUC bar if it's stiffer than the H&R.


$.02, hope that helps!

[pkcormier]

Thanks Jeff. H-Sport (Hotchkis) has a 32mm hollow front bar that they claim is 95% stiffer. The H&R bar is a solid 27mm bar, as is the UUC bar. The H&R is not adjustable, whereas the UUC has three adjustment holes. I don't know what % increase in stiffness each of the three UUC bar settings equates to, but likely at least one or two settings is stiffer than the H&R bar.

Question - knowing I am riding on the stock springs/struts, if I were to get a stiffer front bar only, what would happen to the balance of my car? With 245 rubber on all four corner, and some added negative camber and a wider track up front, the car is getting close to neutral (still a little understeer). I'd hate to go back to heavy understeer for the sake of less front end body roll.

In the end, what setup would you think would turn a faster lap? I know that is a tough question without trying it and clocking them both.

[J Tyler]

Originally Posted by pkcormier

Thanks Jeff. H-Sport (Hotchkis) has a 32mm hollow front bar that they claim is 95% stiffer. The H&R bar is a solid 27mm bar, as is the UUC bar. The H&R is not adjustable, whereas the UUC has three adjustment holes. I don't know what % increase in stiffness each of the three UUC bar settings equates to, but likely at least one or two settings is stiffer than the H&R bar.

Hmm ok. Looks like the Hotchkis is a little stiffer than the H&R/UUC. If so, I would go with the Hotchkis bar based on our experience with the H&R bar (we run on street tires and I would like a little bit more front bar on our car).

Question - knowing I am riding on the stock springs/struts, if I were to get a stiffer front bar only, what would happen to the balance of my car? With 245 rubber on all four corner, and some added negative camber and a wider track up front, the car is getting close to neutral (still a little understeer). I'd hate to go back to heavy understeer for the sake of less front end body roll.

The stiffer front bar will add understeer. But, on the plus side it will probably make the car more nimble and easier to control, and probably will result in a slightly faster overall car. To compensate for the understeer, all you need is more front camber.

In the end, what setup would you think would turn a faster lap? I know that is a tough question without trying it and clocking them both.

I assume you mean stock bar vs aftermarket bar? If so, I think that on a real racetrack the stiffer bar will be a little quicker. On an autocross course, I'm not sure.


Overall I think the biggest issue with these cars is getting more negative front camber. BMW's strut-type front suspension looooves lots of camber...


BTW, we just had an event at Willow Springs International Raceway -- should have some new video & pics up soon. It was a fast track! 100mph average speed!

[Jcrewsn]

Originally Posted by J Tyler

That's what I've read, but like I said, I know what the e-Diff feels like, and it was NOT activating on the two cars I've driven (our 135i and a friend's 335i). It's obvious to me when it's acting and when it's not.... I believe the owner's manual agrees with what you said, but from my personal experience it is simply not true.

Anyone want to loan me a stock 135i for further, ah, testing?



+1. When DSC/DTC are all the way off.

I have a week old stock 2009 135i with a little over 500 miles on it. Maybe when I've completed the break-in I'll let you take her out to figure the e-diff situation... I'll be in Tustin until August so PM me if your interested.

[pkcormier]

Thanks Jeff.

[J Tyler]

Originally Posted by pkcormier

Thanks Jeff.

Let us all know what you end up with and how it works!

[akak1997]

I've installed the Hotchkis front bar, it does reduce body roll a lot and the car is more composed when cornering. However, one weird thing I notice is when I go thru speed bumps, the rear seems more bouncy than the front. I'm not sure if it behaves like this stock, maybe I'm just didn't pay attention before. When I go over speed bumps, the front will settle after maybe 1 oscillation where the rear takes 2-3 oscillations before it settles.
I want to know if anyone notice this rear bounciness after a front only sway bar upgrade.

[lib]

There's a 2-day open autocross practice event this weekend and I'm planning to spent part of the time playing with the various modes out of curiosity.

Are there any specific experiments you'd like me to try with DTC/DSC?

Currently I'm planning to compare all 3 modes; when entering a corner too fast, in a long sweeping corner, in a slalom (but I suck in slaloms ) and accelerating early out of a slow corner.

[white911]

jeff,

As you may recall I mentioned that I had quite a bit of time to experiment on different skid pads. We are putting on an event at the Shenandoah Circuit this weekend and I have set up the skid pad for instructor training for the whole weekend. Time permitting - I will continue to refine my testing of the different modes which were covered in an earlier report.

If you don't mind please describe an effective E-LSD test --

[pkcormier]

Originally Posted by akak1997

I've installed the Hotchkis front bar, it does reduce body roll a lot and the car is more composed when cornering. However, one weird thing I notice is when I go thru speed bumps, the rear seems more bouncy than the front. I'm not sure if it behaves like this stock, maybe I'm just didn't pay attention before. When I go over speed bumps, the front will settle after maybe 1 oscillation where the rear takes 2-3 oscillations before it settles.
I want to know if anyone notice this rear bounciness after a front only sway bar upgrade.

Do you have any other suspension upgrades other than the sway bar? Have you tracked you car with the Hotchkis bar?

Thx

[philaf_666]

Originally Posted by akak1997

I've installed the Hotchkis front bar, it does reduce body roll a lot and the car is more composed when cornering. However, one weird thing I notice is when I go thru speed bumps, the rear seems more bouncy than the front. I'm not sure if it behaves like this stock, maybe I'm just didn't pay attention before. When I go over speed bumps, the front will settle after maybe 1 oscillation where the rear takes 2-3 oscillations before it settles.
I want to know if anyone notice this rear bounciness after a front only sway bar upgrade.

I've noticed the exact same thing after installing the Hotchkis front sway.

At that time, I had the KW v2 set at max and the m3 front tension rods and wishbones.

I realized that the front of the car was now too stiff overall for the rear so I installed the UCC rear sway, m3 rear bushing and 700lbs swift spring in the rear only and the car is now really well balanced.

I do noticed the one wheel spin getting out of a tight corner, but since I'm not tracking the car, it's not a big thing for me. The rear sway is set at stiff so I might try the soft setting to see if it helps. That's the problem with open diff!

[akak1997]

Originally Posted by pkcormier

Do you have any other suspension upgrades other than the sway bar? Have you tracked you car with the Hotchkis bar?

Thx

I've a Strut Bar and I it's making the front even stiffer, I guess that adds to the differences between front and rear.
I haven't tracked the car with the Hotchkis yet, work has been pretty crazy lately, I hope I can get 1 or 2 track/autox in before end of this year.

I've noticed the exact same thing after installing the Hotchkis front sway.
At that time, I had the KW v2 set at max and the m3 front tension rods and wishbones.
I realized that the front of the car was now too stiff overall for the rear so I installed the UCC rear sway, m3 rear bushing and 700lbs swift spring in the rear only and the car is now really well balanced.
I do noticed the one wheel spin getting out of a tight corner, but since I'm not tracking the car, it's not a big thing for me. The rear sway is set at stiff so I might try the soft setting to see if it helps. That's the problem with open diff!

I'm gonna get KW V3 and some M3 parts and maybe a Rear strut bar as well, but all these upgrades probably won't happen until next year
Good to know I'm not crazy
Thanks for the reply

[SpeedballTrix]

Well I managed to get a two wheel burnout this week with the E-Diff on.
Which seems to verify my theory that the E-Diff action goes to full-open-diff at a certain percentage of load.
It wasn't a big smokey burnout. It was actually a botched launch with too much clutch =P

When I get a chance I'd like to try to replicate it on purpose with the camera rolling, but I'm currently running on a patched rear runflat... so it might have to wait till I get new tires.

[pkcormier]

Originally Posted by J Tyler

Let us all know what you end up with and how it works!

Jeff, if you had $2,500 to spend to make a stock 135i more track worthy, would you get coilovers or a LSD?