Wobble under braking

[frozenwaffles]

I suffer from this too....
I bought some shitty china/USA suspension arms from eBay. I've replaced them already with warranty ones and the replacements are starting to fail. I have my good ones from ecs tuning reeady to go in!

[Cole]

I have a similar problem when braking from a relatively high speed, especially with a low loading on the steering. I also had new control arms fitted last year, and the wobble has started since then. I have been told by my indy that I need to replace the front wishbone, part number 31-12-6-760-275/6. I haven't got the cash to do this at the moment so can't tell you if this works, but if anyone else has been down this road I would appreciate some confirmation before I bite the bullet? Item 10/11 in the OEM diagram below...

[Ricky Bobby]

OP,

Did you do the replacement of the thrust arms or did an indy? Just wanted to be sure if an indy or you did it that you torqued the thrust arms with the wheels on the ground, if they were torqued in the air they will fail prematurely.

I replaced my thrust arms with Meyle HD, ball joints with Febi, and wishbone control arms with Febi 6 months ago and the truck rides like new in the front.

Clunking or wobbling during braking is usually warped rotors (pad deposits) but in our cars its very likely its thrust arms, if you confirm yours were replaced and torqued properly I would look into the rotors.


With rotor warping (or pad deposits as some would say), sometimes you can remedy it without replacing the part. All you need to do is heat up the brakes enough to get the pad deposits burnt off, then let them cool.

Do this:

1) Do about 4-5 stops from 30 mph down to 10 mph at moderate braking, do not stop the car completely. This is a warmup.

2) Do 10 stops from 60 mph - 10 mph and do this on hard braking, but DO NOT LET ABS KICK IN, and DO NOT STOP THE CAR COMPLETELY, you may notice some brake fade after a few stops but keep going.

3) After 10 stops make sure you are on the open road and drive at 50-60 mph for about 10 mins or so without stopping, this is to allow brakes to cool. If you stop the car while the brakes are still hot you will get more pad deposits on your rotors.



If it gets better after that, you may need to cool the brakes completely and start the process from the beginning. Hopefully I helped save you some money!

[Bulk]

Thanks Ricky - I replaced them and torqued them with the weight on the wheels. I didn't replace the control arms though just the front thrust arms (+ bearings) so I'm thinking maybe I need to replace the upper control arms as well......

[Ricky Bobby]

well if thats the case I would say not to worry about the Meyle HD's being bad, I can't see how that is the case.

Try bedding the brake pads in again and see if that does the trick for you, and you're correct you may also have other worn parts of the suspension, I couldn't tell you because I replaced all my parts at once so it went from riding very poorly to riding very well in one day lol.

[oztme]

Hi Guys,

Rotor warping and pad deposits may feel the same but they are different things (root causes). I spent a lot of time working on rally/racecars where the symptoms of these things are far more noticable.

Rotor warping, is where the rotor is no longer a flat pancake shape, and/or no longer uniform thickness. This can happen for a bunch of reasons. Common with cheap aftermarket rotors..

At the same time, or independantly, you can get uneven pad material buildup. If you look at the rotor surface, there is usually some resin that is deposited there from bedding in brakes. This needs to be a nice smooth layer, laid down by bedding in the brakes. If the layer is not smooth, each time you brake, the pads may grab at the little mountains in the layer, leaving a LITTLE more material in that spot each time, eventually building up a series of lumps. This will be felt as slowly progressively worsening brake shudder.

You can have pad material issues regardless of wether your rotors are perfect or not.
ie: can have warped rotors, warped rotors + pad material problems, or perfect rotors + pad material problems.

Pad material problems I had were usually because I'd changed brand of pads / usuing new low quality pads on fine but used rotors.

This method of bedding in has served me well over the years (and over 50 sets of pads). The method *might* be a bit aggressive for an X5? I can't advise on that. I'm on my 2nd pair of pads on my X5, and did a gentler version of this bedding in..

I personally tend to use genuine BMW parts where I can, because the cost of the labour to replace these things in AUstralia is usually more substantial than the part cost. REgarding the Meyle parts and stuff, I believe they're not bad from the start; but what's been seen in here in OZ, is that they tend to wear out quickly ( sometimes in < 12 months), and so may not be an overall saving...

HTH

Cheers,
Scott.

[upallnight]

Are these the original wheels or are they aftermarket or wheels from a different series BMW? Helped another X owner on another forum who had a vibration problem, turn out she was running wheels from an E39 which has a bigger hub diameter so she needed hub rings to center the wheels on the hub.

[Bulk]

Originally Posted by upallnight

Are these the original wheels or are they aftermarket or wheels from a different series BMW? Helped another X owner on another forum who had a vibration problem, turn out she was running wheels from an E39 which has a bigger hub diameter so she needed hub rings to center the wheels on the hub.

They're off the 4.6iS of the same model - I've tried putting hubcentric rings on but no benefit, plus the conical shape of the wheel nuts causes lugcentric centring stability anyway.

All the posts relating to the rotors being warped or buildup, I don't have any pulsating through the pedal (none, nada). Do you still think it could be that? They're not aftermarket rotors or pads

[upallnight]

Originally Posted by Bulk

They're off the 4.6iS of the same model - I've tried putting hubcentric rings on but no benefit, plus the conical shape of the wheel nuts causes lugcentric centring stability anyway.

All the posts relating to the rotors being warped or buildup, I don't have any pulsating through the pedal (none, nada). Do you still think it could be that? They're not aftermarket rotors or pads

Are they genuine BMW wheels or Replicas? Another BMW owner on another forum brought a set of M parallel wheels at a good price. Turns out the front were replicas and the rear were real. Hub centric ring solved his problems.

I'm surprise that you were able to get a hub ring on it since if they were real BMW wheels the wheel would never fit into the hub ring. Yes it's that tight of a fit. Also did someone install studs on your hubs? Last time I looked my X wheels were secure to the hub with lug BOLTS not NUTS.

[Bulk]

The hubcentric rings didn't work because they were plastic and they just got smooshed because the wheels were a correct fit (I'm 99.9% sure they're original however if someone can remind me how to check that would be great).

I got it up on jack stands and got a mate to wobble the wheel horizontally and the control arm ball joint (not the wishbone) was moving up and down (in and out of the joint) by about 3mm. I'll replace those bits and let you know how that goes......