warped discs - again 2004 E53 3.0 D

[X5-D-Sport]

Hi again SMEE...
no questions here are stupid... all relavent & the fab thing about this site is that the knowledge is learned the hard way - by experience..
Believe me... I ask my fair share of dozey questions lol.

Brakes are a delucate issue, due to the life threatening nature of a failure...
so... keep asking the questions..
the motto is...." Ask and Yee shal learn" 

re the spare disk.... personally, I would only swap disks as a matched pair.... NOT one corner on its own - its inviting trouble.!!
If you stil have a wobble after doing the piston change, THEN get a new pair of disks....
But judt do the pistons 1st... as we can be confident that is the primary jamming/siezure issue based on the symptoms...
and the fact that shorter journeys give no wobble, it is a good guess it will solve the problem.
ensure you scrape out the slots where the pads sit in the calliper..
AND
thouroughy clear the rusty debris that will have accumulated on the edge lip of the pison bore where the rubber dust seal lives... this is usually the location that is causing the seizure issue.
..
but remember.. a disk swap is a 15 minute job & ultra simple to do if needed another day.

Re prep for the job.....
ensure you have a new bottle of brake fluid (do not shake it up) & keep topping up the fluid as you pump the cylinder out with the brake pedal.
have an old washing up bowl under the strut leg too... as it will be messy.
get a brake pipe clamp too, to stop fluid pouring out while doing the job, to gently clamp the flexi pipe at the calliper.

PM me if you want to share a phone number incase you hit any snags.
regards
Grant B

[Raj]

[quote="Smeeagain"]
so why does it only wobble when it is hot and not when it is cold ?
[/quote]

Because as the disc gets hot it expands and so does the slight runout on the disc. In other words the runout becomes more pronounced with expansion.

[Smeeagain]

Might have been something to do with the corrosion on the offside calliper piston ......


Smee

[X5Sport]

That certainly looks in poor condition.

[Smeeagain]

Ok, so two weeks later the wobble has come back. But this time the sypmtoms are different. I was steaming along the motorway on Sunday night for 200 miles at a fair rate of knots (circa 70mph  ) and if anything was sticking and going to heat up and warp this would be the time. But everything was fine. But commuting from hotel to office everyday when everything is cold there is a wobble. Took a drive to another meeting last night 50 miles up the motorway - no issues. Driving tree miles to office this morning - wobble is back

Thoughts?

Smee

[Smeeagain]

Ok, so an update after having driven another 200 miles this evening. it is not so much when the engine is cold as a low speed wobble (mostly) ie short commute in the mornings = low speed drive = wobble.

But, ......I've noticed it is mainly when the suspension is under load - uphill or down hill braking results in the strongest wobble.

Front control arm bushes .... ????

[Smeeagain]

[quote="X5-D-Sport Salisbury"]
NO....dont replace the calliper... just get a repair kit off Flea-Bay..
i did my fronts & rears  when I had a jamming front calliper 6 months ago....

each kit does Both fronts or Both rears & cost about £30 each kit.
came with both pistons, the O ring seals & an outer gaiter for each side.
Took about an hour each side... and easy too...
[/quote]

So the wobble is back, having replaced the piston, then the discs (again).

So I guess now I have to replace discs, pads and callipers?

Smee

[AW8]

Did you cause thrust bushes to be checked ?

I would check bushes, swap as/if needed & then if further issues look to go OE or OEM on any worn brake parts unless user needs dictate BBK is is needed.

[Smeeagain]

Bushes were checked over before but happy to have them checked again. Does seem to happen as soon as the car heats up though (makes me think previously the piston was sticking but the new piston is sticking in the old calliper)

What does BBK mean ????

[Smeeagain]

[quote="AW8"]
Did you cause thrust bushes to be checked ?

I would check bushes, swap as/if needed & then if further issues look to go OE or OEM on any worn brake parts unless user needs dictate BBK is is needed.
[/quote]

Are the thrust bushes different to front control arm bushes?

[X5-D-Sport]

With a process of elimination from whats described....

a few questions ??
1. When you took the calliper off, did you scrape out the slots where the pads go .
2. When you fitted the new pistons & seals... did you scrape the rusty crud off the entrance perimeter of the where the pistons go into ?? As this can cause binding with new pistons if not cleaned off ?
3. The slider pins that the calliper floats & centralises on... are these greased up & free to move ??

The fact that the wobble comes n goes still hints at some thing not free moving, and binding causing the disks to heat up & warp again..

The worst case scenario is that the disks were cooked begore the pistons replaced & the slightes heat re- introduces the warp...
but it would always be there..

my thoughts are that some thing is still binding...

[AW8]

[quote="Smeeagain"]
[quote="AW8"]
Did you cause thrust bushes to be checked ?

I would check bushes, swap as/if needed & then if further issues look to go OE or OEM on any worn brake parts unless user needs dictate BBK is is needed.
[/quote]

Are the thrust bushes different to front control arm bushes?
[/quote]

No - same.

BBK equals Big Brake Kit. Only required if really pushing normal kit beyond capabilities. I posted a considerable while ago re OE consumables if wanting to replace worn OEM items. Brembo discs plus textar & jurid pads (sorry I can't recall which are front and rear brands).

Advice above seems a better place to start. I have swapped pads and discs before & had a seized caliper one daughters Toyota. I am capable of replacing consumables basics correctly but the info from Salisbury better than I could offer & worth some consideration.

[Smeeagain]

Ok thanks

So if I recall correctly there are both upper and lower front control arm bushes. Obviously both sides should be done at same time? Presumably upper and lower should also be done at same time.
As a further update, i was driving into a quiet car park yesterday with no roadnoise, traffic etc and noticed a huge creaking sound front the front end. Could the creaking also be bushes or more likely to be ball joint?
Smee

[AW8]

Item 7 is what I had replaced.... http://www.realoem.com/bmw/enUS/showpar ... Id=31_0521

My symptoms were vibration juddering under breaking and most noticeable around 50 mph.

Not saying that is your problem - could be any one or more of a number of issues.  So many parts - I saw  something re caliper bushes so maybe worth considering that - I am not a mechanic so place bets on someone else than me.

No idea on the noise at slow speed although the ball joints can fail at low mileages albeit can also last a while in kind use.

Unless you have a thorough understanding re brakes and suspension workings and replacement (in abscence of any specific part failure info), I would advise a visit to a decent BMW Indy.

[Smeeagain]

So this is now fixed.

Replaced brake discs, pads and callipers. also one lower front control arm bush was kackered. Symptom free now

Smee