E34 wobble over 80kph/under braking - FIXED

[roo 41]

Hi team

My E34 has a slight wobble between 90-110kmh that gets a lot worse under braking. I have recently replaced the drag link, tie rods and sway bar links as these were all shot and this has made it much better and tighter but there is still a slight wobble and can get pretty bad under braking, often it feels worse if I'm turning right.

The fact it's worse under braking - does this immediately point to warped/old discs or can braking amplify a bad wheel balance/worn out suspension bush too?

I know the car has non-genuine front discs and pads and that BMW's typically don't like non-genuine brake stuff.

I am going to have the front wheels balanced on the off chance that fixes it and then that can be removed from the equation.

Any ideas?

Edited August 31, 2014 by roo

[kingkarl 136]

Checked the control arm bushes?

[qube 3570]

thrust arm bushes, warped brake disks, buckled wheel or wheels wheel alignment, maybe you or a tyre shop has lost the hub centric rings if you have them on your mags.

Edited August 13, 2014 by QUBE

[Allanw 1071]

Bushes - our E39 had a very slight wobble under light braking about 90km/h. Didn't touch the brakes, just did a front end rebuild, and no more wobble at all.

[728besitzer 0]

_{For me I replaced the front brake discs and instant result}

[roo 41]

Traction arm/thrust arm could be culprit after reading this:

On the BMW E34, E28 and E32, upper control arms, also called thrust arms are attached to the subframe through bushings and to the steering arms by ball joints. The bushings are well known for failure because they take most of the load in the front end under braking and may cause the car to shimmy if worn.Shaking of the front end is often cause by worn thrust arm bushings.

Failure syndromes:

- The 50-60 Mph shimmy.

- Severely enhanced brake shimmy.

- Clunk noise (cause by defective ball joint).

- Bushings torn or with small cracks.

You might want to change the whole arm instead of just changing the bushing if the ball joints are worn. Bushings must be pressed into the arm.

[BM WORLD 1283]

yes most common part to wear out first , thrust arm bush , takes all the load from braking etc.

then go over the others , brakes , control arms , steering arms , track rod etc etc

correct wheel hub size etc etc

[_ethrty-Andy_ 2132]

i recommend fitting 750iL bushes, they are the heaviest duty without going for a non-rubber material.

there are three grades of bushes available, 4/6 cyl, 8cyl and 12cyl.

[kiwi535 538]

well known e 34 problem

[jeffbebe 1559]

All of the above are possibles but start by skimming the brake discs if there's enough of them left. Has cured shaky braking on many a car for me. No point spending up on suspension parts until you've ruled that out.

[yng_750 247]

Agree ^ but ive never had brakes cause shaking when nit slowing.

Ive done thrust arms a couple of times. Stab the brakes. If you hear a big thunk its the thrust arms.

[roo 41]

Cheers guys. As said in first post, I've already replaced drag link, sway bar links and tie rods due to them all being shot/sloppy. So really the only front suspension parts I haven't done are upper and lower control/thrust arms. I may end up doing these regardless. Car has done 180kms so why not.

Starting with front wheel balance and brake rotor skim and then re-evaluate. Although I would have thought that both of these would get much worse with speed, whereas my issue is just around 80-100kph which lines up with what a lot of people on the net have experienced when dealing with worn thrust arms.

http://forums.bimmerforums.com/forum/showthread.php?930392-What-repairs-have-fixed-your-e34-shimmy

[qube 3570]

just quickly accelerate from 79km to 101km and set cruise control. problem solved!

haha but really, thrust arms are worth doing regardless and might as well get all 4 wheels balanced instead of just front 2

[728besitzer 0]

If youre paying someone to skim the brake discs you might as well buy new discs. Not much difference price wise.

[roo 41]

just quickly accelerate from 79km to 101km and set cruise control. problem solved!

haha but really, thrust arms are worth doing regardless and might as well get all 4 wheels balanced instead of just front 2

That's my thinking too. I bought new tyres for the rear less than a month ago so rears don't need doing.

If youre paying someone to skim the brake discs you might as well buy new discs. Not much difference price wise.

What? Last time I had discs skimmed it cost around $40. Genuine new discs are $500. Aftermarket around $200.

Edited August 15, 2014 by roo

[kiwi535 538]

But you lose 1000 s of ks of wear too.Dont forget to check the front wheel hub bore size/ hub centric rings, e 34 very sensitive to that too, bet your shimmy is worst at 95km hr

[roo 41]

The car currently has factory wheel setup on it as I thought it could be bore size/locator ring thing too.

[kiwi535 538]

Almost certain to be control arm bushes then

Edited August 21, 2014 by kiwi535

[antil33t 90]

What? Last time I had discs skimmed it cost around $40. Genuine new discs are $500. Aftermarket around $200.

BMW rotors are not very thick, you get like 2mm of wear on them before they are out of spec, I've had no issues with aftermarket rotors on any of my old BMW's...

I got the last pair for around 60+GST each. (could even look at Brembo (bros) made OEM rotors?)

But since your 540i is really nice, Genuine might be a good idea.

[Eagle 1662]

Ive had no issues either and good lifespan so i zero benefit for me buying expensive pieces of steel. Ive never had any BMW rotors machined as they are just too thin as Michael has said and cheap to buy anyway.

540i front rotors are alot cheap than rears.

[roo 41]

Replaced the thrust arms with Lemforder items over the weekend - wobble gone. Thanks team!

[d.p.n.s 15]

Replaced the thrust arms with Lemforder items over the weekend - wobble gone. Thanks team!

did you do upper and lower arms or just the upper....got the same problem with my e34 at the moment.

[kiwi328i 118]

If you have an E34...

Replace everything that you can and even things you don't really need to, replace them as well. OEM if possible or 'better'.