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E46 Bump Steer

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E46 Bump Steer

Postby The_Hoff » Fri, 02 Dec 2011 23:59:05 UTC

I hope somebody can shed some light on this problem I have with my E46 Compact, its driving me nuts!

The problem I have is every time I go over a bump in the road the steering wheel will pull to that side and proves difficult to turn out of this. I think this is referred to as bump steer? Correct me if Im wrong!

I replaced the large front control arm bush (the one that sits on the back of the wishbone and bolts to the passenger footwell area) this solved the steering wheel shake I had under braking but nothing else
I then resorted to buying 2 brand new tyres as the old ones were worn out. Turns out not even the Eagle F1 Asymmetric tyre will solve this! The wheel alignment also didnt make a difference.

I have done some research and people suggest everything from wheel geometry to the steering rack and I am frankly very confused! I dont like the thought of spending lots of money for it to not make a difference :(

The car is a 2004 which has done 64k. New bushes have done 200 miles, tyres are 100 miles old

Any help and suggestions greatly appreciated!

Thanks
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Re: E46 Bump Steer

Postby Vor » Sat, 03 Dec 2011 06:24:33 UTC

Did you replace bush on both sides ?? You should One new and one original will upset the cart

Try <<http://www.alignmycar.co.uk/>>

Worked an absolute treat on mine after replacing my wishbones and bushes left me with the same symptoms and was driving me NUTS

IMO well worth the cost But not cheap find your local one and negotiate
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Re: E46 Bump Steer

Postby The_Hoff » Sat, 03 Dec 2011 10:21:50 UTC

I did replace both yes, turned out that only the driver side was worn but replaced both anyway

I had an alignment done only yesterday and was told it was absolutely spot on and was in tolerance on the sheet i received

I think i might replace the front stabalizer bars today, not a massive cost and was also reccomended by a trusted garage. Has anyone had any luck with changing these?
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Re: E46 Bump Steer

Postby slim_boy_fat » Sat, 03 Dec 2011 12:50:27 UTC

Tyre pressures?
Never underestimate the power of thrawn.
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Re: E46 Bump Steer

Postby The_Hoff » Sat, 03 Dec 2011 13:31:31 UTC

all at 32psi...

quite stumped to be honest, after researching this it seems that nobody has a definite answer to what it is, seems almost specific and unique to every car.

other than the control arm bushes are there any other common fault that would cause this?
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Re: E46 Bump Steer

Postby starkie7 » Sat, 03 Dec 2011 20:38:17 UTC

wishbone ball joints are very common, track rods can wear on both the inner and outer joints and there are a few people who have had to have the steering rack changed to sort it.
had similar steering on my two previous bmw, one was cured perfectly with powerflex wishbone bushes, the other made no difference with p/f bushes.
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Re: E46 Bump Steer

Postby MikeS » Sat, 03 Dec 2011 21:30:36 UTC

Technically this is NOT bump steer. Bump steer is a mechanical/geometry thing where the wheel toe changes as the suspension compresses, and falls.
The steering reaction you are getting is because the E46 uses negative offset KP geometry which results in it having a very narrow tolerance window. Many things can then throw it out, worn suspension joints, incorrect tyre widths, pressures etc. Also wheel offsets tend to be a biggy, so has your car got the original OEM wheels fitted and original spec tyre as the first question. E46's don't react kindly to wheel and tyre size changes when they are not within the right dimension to preserve the steering/suspension geometry.
Until you've driven a modern diesel of this calibre, you just won't get it!
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Re: E46 Bump Steer

Postby The_Hoff » Sat, 03 Dec 2011 23:27:55 UTC

steering rack change isnt what i wanted to hear :( LOL i contenplated p/f bushes but thought against it as the car is fairly stiff anyway

It is 100% standard as far as i can tell, it has the BMW 17 inch wheels (7 spoke) rather than the 16 inch wheels. The 17s are 225/46/17 with goodyear eagle f1s. The old BMW i had did have the 16s with 205/55/16 bridgestones on and no tramlining/bump steer. Is this the answer? Maybe the 17s should be tracked differently im not sure. What do you think?
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Re: E46 Bump Steer

Postby joebreezelondon » Wed, 09 Jan 2013 15:02:00 UTC

Any luck with this? I'm experiencing exactly the same on my E46 325ti, despite new tyres, new front bushes and a proper alignment...
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Re: E46 Bump Steer

Postby The_Hoff » Sat, 19 Jan 2013 11:23:51 UTC

Hi joebreezelondon, i experienced no end of problems like this with the car and drove me mad so ended up selling the car :( its a shame as this was the only thing to make me sell it! Ive owned 2 compacts, both with the se suspension setup, one on 16" and one with 17". What suspension and tyre size / tyres are you running?

James
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Re: E46 Bump Steer

Postby joebreezelondon » Mon, 21 Jan 2013 15:39:22 UTC

I've got standard 17s on the Sport suspension. If I don't sort it I will have to sell the car, but there's nothing out there in my budget that fits all my needs like it does, so I'm a bit lost about a replacement!

What else did you try before selling it?
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Re: E46 Bump Steer

Postby Greg330d » Sun, 27 Jan 2013 04:06:26 UTC

I replaced a few steering joints on E46 vehicles to sort this problem. 360576190931 is a item number on eBay for the part I'm referring to. You need to buy a new one and the correct one, the item number is to just show you what I'm on about!
What happens is they wear, so allow enough "free movement" in the steering, so as you hit a rut in the road, the free play allows the wheels to turn just enough to allow the car to wonder around! Hope that helps!
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Re: E46 Bump Steer

Postby joebreezelondon » Mon, 28 Jan 2013 12:04:28 UTC

Hi Greg,

Sounds like this might be the solution... What do I tell my mechanic to replace - both steering knuckle couplings right? If this works I will find out where you live and hug you (a year of bumpsteer can send a man mad!)

Cheers
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Re: E46 Bump Steer

Postby Greg330d » Mon, 28 Jan 2013 22:44:36 UTC

Yes mate get them done while your there, it'll drive lovely after!
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