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BMW 3-Series (E90 E92) Forum > BMW E90/E92/E93 3-series General Forums > Regional Forums > UK > Understeer after Eibach Pro install



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      07-13-2018, 04:18 AM   #1
Silver Streek
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Understeer after Eibach Pro install

Hi Guys

I installed Eibach Pro springs with Bilastein B4 (for M-Sport) dampers, with M-Sport spec bump stops. This is on an E91 325d SE, I have kept the SE anti roll bars due to having to drop the rear subframe to fit the upgraded rollbar on the back.

The handling is now much more planted, if not slightly on the crashy side (but I have gone from SE spec so am used to soft suspension).

One thing I don't like is on hard turn in, for example pulling into a side road quickly or going fast round a very tight roundabout it under steers.

My old E46 touring, had the milder sports suspension and never ever under steered.

This car does have a staggard set up, 225 18" front 255 18" rear. Is this a characteristic of the set up or are E90's set up to under steer rather than over steer for safety??

I don't like it, feels like driving a front wheel drive car.

Any ideas why this might be happening if it is not normal behavior???

Wondering if I should have jut fitted M-Sport springs, I have a set sat at home.

Thanks in advance for your helpfull advice

Andrew
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      07-13-2018, 05:49 AM   #2
dragerboy
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I take it you have had decent 4 wheel alignment/tracking etc done?
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      07-13-2018, 06:46 AM   #3
LucasAry
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Quote:
Originally Posted by dragerboy View Post
I take it you have had decent 4 wheel alignment/tracking etc done?
++1
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      07-13-2018, 06:49 AM   #4
Silver Streek
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Not yet, I have it booked in, in a couple of weeks. It cant be too far out, it drives well (apart from the understeer) and tyres have worn very evenly.

I noticed I get a lot of flex when cornering hard, which I assume is causing the under steer. Something I did not expect. I thought about upgrading the front anti roll bar to a 26mm thick bar as on M-Sport, but convention has that to reduce under steer you need to stiffen the rear end, hence why stiffening the front end would make the under steer worse?

Could weak anti roll bar links on the front have much of an effect?
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      07-13-2018, 06:49 AM   #5
rasa bmw
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tyres? budget crap will understeer at the drop of a hat
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      07-13-2018, 06:53 AM   #6
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Tyres are Bridgestone Potenza S001 so not budgets no.

Non runflat, pressures set to 32psi front 36psi rear
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      07-13-2018, 07:30 AM   #7
snedanator
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What they said.... alignment. And change the 225 front to a 235 :-)
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      07-13-2018, 08:21 AM   #8
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I'd sat purely down to geo.

You may think it's not far out but the toe will be way out from what it was.

Once geo done then see how it is.
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      07-13-2018, 12:50 PM   #9
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Quote:
Originally Posted by RajB View Post
I'd sat purely down to geo.

You may think it's not far out but the toe will be way out from what it was.

Once geo done then see how it is.
Yep, and the rear camber will be hilariously out too. I went from stock M-Sport suspension to a further 10mm drop on the rear and 25mm on the front and when the guy straightened up the rear, I was behind the car watching and I couldn't believe how visibly out it was. It's no wonder I was eating through rear tires!

Strangely though, the fronts weren't nearly as bad so I guess my rear end was out quite a bit anyway.

Point is, changing the suspension and dropping the car will always bugger up the geometry and will always require 4 wheel alignment afterwards.

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      07-13-2018, 03:14 PM   #10
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Thanks guys, I'm sure you are right, I shall see how it is after the 4 wheel alignment is done. Going to change the drop links too as they seem a little loose and 8m sure they are clunking over bumps.
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      07-13-2018, 03:15 PM   #11
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One other question, those of you that had eibach pro drop, what setting did they use to set the alignment?? Did they set it using m-sport cambers etc?

Thanks
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      07-13-2018, 06:57 PM   #12
bishbosh
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I have the bilstein b12 kit (Eibach Pro & b8 dampers.
Got the garage to align for m sport setup.
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      07-14-2018, 02:36 AM   #13
rasa bmw
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seems a bit low 32 psu and 36 psi,,i go 36 front and 38 rear and im sure thats stock pressure..
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      07-14-2018, 06:28 AM   #14
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My car has 0.5 degrees of camber on both front wheels and Michellin PS4's running 35 PSI front and 37 rear and I have perfect tyre wear and the car turns in really well and has never ever understeered. The back has come out plenty of times when driving hard.
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      07-16-2018, 02:32 AM   #15
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I have tried many tyre pressure combinations, so I went with the info on the plate in the drivers side door frame 2.2 bar (32 psi)front 2.7 bar (39 psi) rear. I dropped the rear pressure a little as the ride was too hard. car rides nicely with good tyre wear.

I'll try upping the front pressure a little.
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      07-16-2018, 05:28 AM   #16
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I find that all of my E92s understeer after coming from E36s and E46s. I mainly just drive to and from work now so opted for refinement over handling but otherwise the E9X is just dead as fuck compared to previous generation 3ers
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      07-16-2018, 06:13 AM   #17
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Quote:
Originally Posted by salimshk View Post
I find that all of my E92s understeer after coming from E36s and E46s. I mainly just drive to and from work now so opted for refinement over handling but otherwise the E9X is just dead as fuck compared to previous generation 3ers
I kind of agree, the handling on my previous car - E46 touring did feel better. This E91 feels much heavier and more ponderous.

I have read in my research that BMW introduced under steer purposely to increase safety as many people cant deal with over steer. Personally give me over steer any day!

However the extra oomph I get with the 3ltr 6 and the extra toys does make it worth it.

Still miss the E46 though.
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