Suspension Mod Results Question

[nachob]

I recently saw that one of the BMW head engineers said that the 1M could've used another year in development and he also mentions that they might have gone too firm with suspension which could be related to unforgiving nature at the limit. I know many of you modified your cars. Most of you did it to drop the car but I think the stock height is fine for street use. I am wondering if suspension mods like KW Coilovers, Dinan, etc made any difference in terms of reducing the twitchiness at the limit. I remember watching video of Larry's 1M at the track and you can see the tail wagging in a straight line down the track when stock.

so those of you that modified the 1M suspensions with performance in mind, not just looks, what changed?


I also recently saw the KW tour thread where they mention that they use all their expertise and track time to tune their shocks at the Ring but they don't list a Variant 1 or Variant 2 set for 1M coupe. Just the Variant three which is adjustable for compression and rebound. I would be interested in a preconfigured compression and rebound with done with all of their expertise.

thank you.

[The Wind Breezes]

Why do you ask? Do you track the car and you're having issues keeping things under control? 1Ms aren't exactly poorly setup, they just have a rather short wheelbase and stupid amount of weight behind the rear wheels to make the near 50/50 weight distribution. That's the crux of the problem, and there obviously no easy way to fix it unless you want to alter the car's balance by taking weight out from behind the rear axle while will cause other issues. That said, better dampers and a softer rear, plus a good alignment, will get you in the direction you want to go.

[MDORPHN]

My 1M is extensively modified, both drivetrain and suspension, and I spend a lot of time on track (30+ days/year).

Although better damping in back together with a stiffer rollbar in front will help some, it doesn't change the vehicle dynamics that significantly.

Best investment will be skid pad and on-track instruction.

Neil

[nachob]

Originally Posted by MDORPHN

it doesn't change the vehicle dynamics that significantly.

Best investment will be skid pad and on-track instruction.

Neil

Thanks Neil that's what I wanted to know!

[redux]

Neil is right. You'll never be able to completely remove the snap from the 1m (unless you chase ACR levels of aero). Get some cheap rear tires and rent out the Balcony at willow springs. $700 and you can get the whole pad to yourself for half of a day. You'll be controlling weight transfer like a boss if you put the cost of the KW's into track time.

[DCYT]

SO do I understand right that the 1M suffers from the pendulum effect because weight is not behind the axle but out outside of them?

Is it only the back or also the front?

[redux]

It's not a really pendulum effect. Think of it as combination of high torque, a light-ish rear end, and a wheel base shorter than a e-36. Getting rid of the PS2's and installing a tire with better break away characteristics (the Re-71r are my current favorite) does wonders for dampening some of the car's widowmaker tendencies.

[craina]

To reiterate what Redux and Neil have said, my time on the track has done far more to tame the 1M than the Ohlins I recently installed. I spent a lot of time on the track w/ the 1M on stock suspension and it taught me a ton about car control. Thats not to say that the Ohlins did not make a noticeable, albeit not drastic, difference in composure.

[CarJunkie]

I can comment on a different mod. This winter I installed camber plates and the M3 convertible front sway bar, otherwise stock. Camber is -2.7 F / -1.7 R. Only other change is RE 71r tires replaced RE11s.

I got to the track last weekend and had a blast. Last year, I was plagued by understeer. The temptation was to trail brake to improve turn in, but that often resulted in even worse push. Attempts to use the throttle to induce oversteer were also not very effective and there was a fine line between rotation and snap oversteer needing correction.

This year, with proper alignment, the car is turning in and rotating beautifully at neutral throttle and responds much better to throttle inputs and trail braking now that those techniques can be used subtly and are not being over relied on. I expected issues like "snap oversteer" to be more easily induced, but was pleasantly surprised to find the car more composed and planted in the rear despite much more camber in front.

The rear feels light under heavy braking, but seemed much more composed than last year in every other way.

FWIW.

[ayao]

Originally Posted by CarJunkie

I can comment on a different mod. This winter I installed camber plates and the M3 convertible front sway bar, otherwise stock. Camber is -2.7 F / -1.7 R. Only other change is RE 71r tires replaced RE11s.

I got to the track last weekend and had a blast. Last year, I was plagued by understeer. The temptation was to trail brake to improve turn in, but that often resulted in even worse push. Attempts to use the throttle to induce oversteer were also not very effective and there was a fine line between rotation and snap oversteer needing correction.

This year, with proper alignment, the car is turning in and rotating beautifully at neutral throttle and responds much better to throttle inputs and trail braking now that those techniques can be used subtly and are not being over relied on. I expected issues like "snap oversteer" to be more easily induced, but was pleasantly surprised to find the car more composed and planted in the rear despite much more camber in front.

The rear feels light under heavy braking, but seemed much more composed than last year in every other way.

FWIW.

Do you think that the front bar contributes substantively to this better behavior on track?

[CarJunkie]

Originally Posted by ayao

Do you think that the front bar contributes substantively to this better behavior on track?

It's hard to know, since I did both together. The M3 'vert bar is only about 30% stiffer than stock and I honestly don't see much difference in body roll.

I did it to balance out what I expected to be a huge increase in front grip with so much negative camber, but I still expected the car to become more tail happy. In all, I can say that the combination of the two has made a huge improvement, and RE71r's are very fun to push to the limit.

Regarding RE71r's, on a 55 degree day, they did not seem to overheat. I was in a long session at the end of the day and did hot laps for over 35 minutes. The quickest lap was #10, and the laps that followed were influenced by traffic and only 2-3 seconds off pace on a 2 minute track. In every session I did, my lap times were within 2-3 seconds and did not trail off toward the end of the sessions. We'll see what happens on a 100 degree day.

Sorry to get a little off topic.

[MDORPHN]

I also run the front roll bar from the E93 M3 and believe it primarily helps putting power down from the rear end.

I'm running 3 degrees camber in front and 2 degrees in back.

Neil

[ayao]

This was an interesting comparison of front sway bars for the M3 on Turner's website: https://www.turnermotorsport.com/t-t...-e92-sway-bars

Back on topic, sort of: I have Ohlins R&T installed on my car. I run full soft on the street and find that the rear can still get unsettled on off-camber, bumpy turns. It does feel more reined in than the stock configuration, best I can remember. There is somewhat less body roll on track, where I run close to full hard all around. I'm still experimenting with settings but the sad truth is that I'm not sophisticated or discerning enough a driver to be able to tell the differences. I'm still looking for ways to get the car to put the power down better, because the rear does tend to get light.

[CarJunkie]

I can't help with that just yet, but hope to have the same questions in about a year.

[///BYU]

Originally Posted by redux

Neil is right. You'll never be able to completely remove the snap from the 1m (unless you chase ACR levels of aero). Get some cheap rear tires and rent out the Balcony at willow springs. $700 and you can get the whole pad to yourself for half of a day. You'll be controlling weight transfer like a boss if you put the cost of the KW's into track time.

nachob, if you rent out a skidpad, I'll bring my 1M and split the cost with you.

[nachob]

Originally Posted by ///BYU

nachob, if you rent out a skidpad, I'll bring my 1M and split the cost with you.

Tempting! So glad you still have yours!!!

[bdaddylo]

I believe swapping the rear subframe bushings to solid ones would make a significant difference in traction. I'm hoping Mdorphn will be the first to take the plunge to confirm this.