Limiting understeering and tire wear on BMW 135i

I just got a 2011 135i 2 month ago, bought Bridgesetone Potenza RE-11 225/40R18 in the front, and 255/35R18 in the rear, and been to six lapping sessions at Mirabel ICAR track. Im not the most experienced, and just got certified to enter the second category.

I want to limit understeer I exibit at the track, and outside tire wear, especially in the front. I was thinking about camber plates + E92 M3 control arms on my E82 2011 135i with stock M-sport suspension. I will use this car year round. It is a dual purpose car used on the street (mostly) and the track (~five 20-minute sessions/month). I have a dedicated set of 205/50R17 street alloys and winter tires that will go on the car from December to March.

Debating on whether I should get fixed or adjustable camber plates, because I need them to hold up to our winters in Quebec. Corrosion, noise, and harshness is a concern I have because of crushed stone, gravel, salt, snow, ice, and potholes on our roads. My 135i will see light winter useage, as it is not my primary winter car.

According to my research, lots of 1 owners upgrade their non-M E8x 1-series (128i and 135i) stock control arms with the E9xM3 control arms. This provides about -0.75* of camber and as an added bonus, arms are lighter, and bushings are stronger.

To gain a little more negative camber , Im also considering fixed camber plates (low-noise, low cost, low-maintenance) but choices are very limited. Seems like Dinan (another -0.75* of camber) is my only choice. Im hoping I can source them easily, rapidly, and cheaply in Canada or US.

For now, I got my tire shop to adjust my alignment on stock compoentns, but only gained -0.6* camber on front. They recommended some minor toe out on front + rear wheels, and equalized/reduced camber in the rear (was off on one side).

At the end of the day, Im aiming for -2.x to -3.x camber in the front. Adjustable plates would be nice, but owners on 1addicts forum complain that they get noisy, and are prone to wear.

Would really appreciate your input and your experience. What do you think are the right mods to address understeering on the 135i, based on the above criteria?

Thanks.

you can also mitigate understeer by increasing stiffness in the rear via a stiffer sway bar.

jerm__ said:

you can also mitigate understeer by increasing stiffness in the rear via a stiffer sway bar.

Click to expand...

Some BMWs don't follow that rule...both of mine.

dcaron,

I have seen a few 135s preform extremely well on the track.
I was actually talking with Seb R about this today.Maybe one for me down the road.

You may find some help at 1aadicts.com or bimmerforums.

Some have even got to the point where the car is a loose.
http://forums.bimmerforums.com/foru...-Video-Berk-Technology-BMW-135i-SuperLap-2008!

From my end I found that by lowering the suspension I received additional negative camber.
I would probably consider future suspension mods prior to any other options.

In addition , a square wheel/tire setup may help if you can stuff 245's or wider in the front.

Good luck for your solution and enjoy the tracks !

Dave S

J'ai réglé ce problème avec un square setup sur ma S2000.
Mais commencer avec plus de camber serait bon, ajustable si tu le fais.

I solved this problem with a square setup on my S2000.
But starting by adding camber is good, make it adjustable.

Superfly said:

J'ai réglé ce problème avec un square setup sur ma S2000.
Mais commencer avec plus de camber serait bon, ajustable si tu le fais.

I solved this problem with a square setup on my S2000.
But starting by adding camber is good, make it adjustable.

Click to expand...

Thanks Superfly.

When I got my tires, the ones I really wanted had limited sizes, so I "plussed 10mm" on the front and rear (from 215/40 to 225/40 in the front, and from 245/35 to 255/35 in the rear). I could have opted for square setup 235/40, but would have run into rubbing in the front, and decreased traction in the rear, which I did not want to do as a DME flash upgrade is in my horizon. When I change my fronts, I might opt for 235/40 or more, if by that time Ive added mods to gain negative camber, and hence a little more space for wider tires.

Shardik said:

Some BMWs don't follow that rule...both of mine.

From my end I found that by lowering the suspension I received additional negative camber. I would probably consider future suspension mods prior to any other options. In addition , a square wheel/tire setup may help if you can stuff 245's or wider in the front.

Good luck for your solution and enjoy the tracks !

Click to expand...

Thanks Dave.

Im pretty happy with the Sport suspension on my 135i for now, and ground clearance. If possible, I would like to keep it instact for now. Having said that, the Dinan plates will raise the front end by 1/8" inch, so a set of shorter springs would compensate for this. I want to do the mods gradually, and in the best sequence, budget is a limiting factor, and lapping season is almost over. May decide to wait until Spring of 2014 ...

jerm__ said:

you can also mitigate understeer by increasing stiffness in the rear via a stiffer sway bar.

Click to expand...

Thanks Jerm.

I guess this would make the car tail-happy, and compensate for the sliding front, but is it the best approach?

Ok then, keeping it simple lets focus on some technique !

A favorite adage comes to mind "Slow in, Fast out."

A direct quote, thanx to one of our favorite instructors- Mr. Dave Parcigneau
link here: http://www.trackpedia.com/wiki/Turn_by_turn_guide_to_the_Autodrome_St-Eustache_track

The hair pin


The name itself is a clue that this is a tight curve and the hair pin is the second slow section of the track. The hair pin’s entry is another hard braking and downshifting zone. It is also well suited for passing. Upon exiting the “dog leg”, aim for the right edge of the track in as much of a straight line as possible. Make sure you sacrificed enough speed. If you have not done so, the car will understeer (plow) and your exit speed will be greatly reduced. Remember, the hair pin launches you on a straight section. Enter deep enough before initiating turn-in steering input and look at the apex. The hair pin’s apex are the speed bumps making the corner (refer to figure). Brush them but don’t go ever them. From here on, progressively unwind the steering and accelerate. Focus your vision on the exit marker and let the vehicle drift out toward the wall. The visual marker for the exit of the hair pin is the third lamp post of the oval straight. It is at this location, that the vehicle must be closest to the wall, but then again, don’t rip out the mirrors! From here, draw a straight line toward the bill board where the stands are.

Entering a turn too hot will initiate understeer in your car.
My solution is to brake hard and downshift before the steering input.

With your torque monster , you don't even need to downshift !
But you will need track pads and fluid ! (See Perry performance !)

I would also research oil cooling for your car for track use.

Dave

Shardik said:

Ok then, keeping it simple lets focus on some technique ! A favorite adage comes to mind "Slow in, Fast out."

Click to expand...

Thanks Dave, I definitely have to work on entering the tight corners at the right speed. Two corners (see #9 and #13 on diagram below) are giving me a bit of trouble at ICAR (one is in fact a hairpin).

Also, I will reduce my front tire pressure, as I noticed quite a build up of heat/pressure in them last time at ICAR (up to +10PSI). Next time, I will probably do two laps, come into the pit, and lower the pressure in them. I may just start with 30 PSI in them, and take it easy for the first two laps.

Oil temperature has been pretty good on my 2011 M-sport 135i, which has a stock air cooler already (passenger front wheel well).

I ran into slight brake fade last session, and changed my OEM fluid to Motul RBF-600 fluid, with a thourough brake bleed at home a day later. I have Titanium cooling plates, and Cool carbon brake pads sitting at home, waiting for my OEM pads to wear out.

Also got alignment done on the 135i, to squeeze out minor negative camber (-0.6*) out of the front wheels, add some toe out on all fours, and equalize the camber on the rear to -1.5* (they were off).

First of all, 135/335 really lacks camber adjustability.

What we have done for a customer: M3 full control arm ( about .75 degree more), inversed top plate, and still had some camber issue. The best is to go right away with a vorshlag camber plate. You want to bring those to around -2/-2.5 and the tire wear should start too look good.

The M3 control arm, are going to help you out for the toe adjustment!

These car need camber, otherwise you will eat the outside of the tire

Alex@VAGMotorsport said:

First of all, 135/335 really lacks camber adjustability.

What we have done for a customer: M3 full control arm ( about .75 degree more), inversed top plate, and still had some camber issue. The best is to go right away with a vorshlag camber plate. You want to bring those to around -2/-2.5 and the tire wear should start too look good.

The M3 control arm, are going to help you out for the toe adjustment!

These car need camber, otherwise you will eat the outside of the tire

Click to expand...

Thanks Alex.
What about NVH (Noise, Vibration, Harshness) with the Vorshlag plates, using stock springs and shocks?
How are they for every day driding, and do they resist to our Quebec roads and four seasons?

I'm surprised that you're understeering in 13 rather than 1.

You should listen to Dave about the swaybar. I've stiffened the front, and sometimes run without a rear swaybar.

For tire pressure I would recommend starting between 28 and 30. Your warmup lap will bring them into the range.

For your suspension, you can't have it both ways unfortunately. I would suggest getting what you need to run the camber you want in the summer, and reverting to a stock alignment for winter. You'll just have to suffer with tire wear during the summer if you want more performance on the track. You'll need to maintain all adjustable aspects of your car throughout the winter.

Stiffer springs will help you feel more confident as well, as long as you're getting new ones anyway.

I'm also a bit surprised at your toe-out in the rear, I would have thought you would go with a little toe-in at the back.

Square tire setup.... spacers in front... Get the car to rotate going into the corner..

Camber and alignment.... -1/32 up front and maybe 1/16 in at the rear...

I've seen a few racing drivers at work and it is often the same song: It pushes like a MoFo in the hairpins, and it is loose and squirelly in the fast corners.

It is quite often driver induced... People attack really hard in the slow corners and are not so gung-ho in the fast ones.

I would make sure it is really the car instead of the driving technique before investing massive amounts of time and money into the car.

Big Pat said:

I've seen a few racing drivers at work and it is often the same song: It pushes like a MoFo in the hairpins, and it is loose and squirelly in the fast corners. It is quite often driver induced... People attack really hard in the slow corners and are not so gung-ho in the fast ones.

I would make sure it is really the car instead of the driving technique before investing massive amounts of time and money into the car.

Click to expand...

Thanks Pat.

It is probably a little of that (driver inexperience), and the understeer dialed into this car by default, for the average Joe. I admit that my speed is too high in some of the tight corners, but at least I notice when I make that mistake. On the fast corners, my 135i + tires are pretty confidence inspiring, but DTC is also assisting me. Im not experienced and confident enough to take the nanny off of the car for now. Ill be careful with tire pressure next time, and hopefully gain more technique and finesse with time.

Gregster said:

Camber and alignment.... -1/32 up front and maybe 1/16 in at the rear...

Click to expand...

Thanks Gregster. Here's my last alignment report, on stock suspension. Have not tried it on the track yet.

Chasse = Caster adjustment
Carossage = Camber adjustment
PARA = Toe adjustment

builtbyseb said:

Square tire setup.... spacers in front... Get the car to rotate going into the corner..

Click to expand...

Thanks Seb. Im kicking myself now, but I should have opted for this simple solution first (spacers + more rubber up front). Will keep this in mind when I wear the tires out.

FifthGear said:

I'm surprised that you're understeering in 13 rather than 1.

You should listen to Dave about the swaybar. I've stiffened the front, and sometimes run without a rear swaybar.

For tire pressure I would recommend starting between 28 and 30. Your warmup lap will bring them into the range.

For your suspension, you can't have it both ways unfortunately. I would suggest getting what you need to run the camber you want in the summer, and reverting to a stock alignment for winter. You'll just have to suffer with tire wear during the summer if you want more performance on the track. You'll need to maintain all adjustable aspects of your car throughout the winter.

Stiffer springs will help you feel more confident as well, as long as you're getting new ones anyway.

I'm also a bit surprised at your toe-out in the rear, I would have thought you would go with a little toe-in at the back.

Click to expand...

Thanks FifthGear. I should have bought an M3 (E46 is only one in my price range) in the 1st place ;-)

I will definitely run with lower cold tire pressure next time.

Im not planning to change springs or struts anytime soon.

Adjustable camber plates would help compensate when Im off/on the track, or help me to get proper alignment during summer and winter.

See my alignment report in this thread.

*contract* I shall repeat to myself "Slow in, Fast Out". "Slow in, Fast Out"."Slow in, Fast Out". *contract*

dcaron999 said:

Thanks Pat.

It is probably a little of that (driver inexperience), and the understeer dialed into this car by default, for the average Joe. I admit that my speed is too high in some of the tight corners, but at least I notice when I make that mistake. On the fast corners, my 135i + tires are pretty confidence inspiring, but DTC is also assisting me. Im not experienced and confident enough to take the nanny off of the car for now. Ill be careful with tire pressure next time, and hopefully gain more technique and finesse with time.

Click to expand...

*tu* willingness to learn is the key to better performances!

It may noy be excessive speed in the turn, it could also be excessive enthusiasm with the steering wheel on corner entry! But it is true that road cars have understeer dialed in...