[Gruber]

Thanks! Sounds expensive...

How do you tell if the shocks are dead? (Apologies if that's a stupid question)

And should I be splashing out on BMW discs or are Eurocarparts copies likely to be ok?

 

[BMWWGN]

Your local shock shop should be able to test them for you in situ.
Also you can inspect them to see if there are any signs of fluid leakage.

Wouldn't recommend fitting anything other than the OEM discs for the front brakes.
Are the existing discs OEM or aftermarket?

 

[Bayerische]

You could try getting the the discs skimmed.

I have heard it mentioned before that as the old discs have been through heating and cooling cycles that it is less likely to reoccur. Probably cheaper than buying new discs also. I have no first hand experience but perhaps worth a try.

The discs would be my first port of call before I started messing with expensive shocks.

 

[Mfiver]

Hello all

A bit of advice please...

I mentioned the juddering through the steering under heavy braking in earlier posts. Well the mechanic has duly replaced the control arms and bushes but the problem is still very much there - maybe even worse than before. Applying the brakes even gently / moderately results in very noticeable vibration through the car. He's now suggesting I need new discs, but the current ones have done less than 3k miles and I'm very reluctant to start spending more money in random attempts to fix the problem.

Hi Gruber,

Your current experience sounds just like mine of a few years ago.

Don't agree to replace nearly new discs, they may not be the problem. The run-out must first be checked with a dial gauge to confirm that they are within tolerance (or otherwise). I cannot remember the tolerance and don't have my manual to hand, someone will be able to quote it straight off. These parts are much too dear to replace on a 'suck it and see' basis. You could even do this yourself - as I did - a Chinese-made dial gauge and magnetic mount can be bought for about £35 - or about half (?) the cost of one OEM disc (they are different to other E28's so pattern parts are going to be less common if available at all).

If the front calipers (made by ATE) are seized, the pistons are likely to exert an asymmetric force on the disc. On my (relatively low mileage) car, I found that both inner pistons were seized on both calipers: I could free them off by levering the pistons back with the pads removed but the benefit lasted no time at all. Despite the seizure it still generated enough braking effort to easily pass the MoT test! I had the calipers rebuilt by an ATE agent (they can - or could back then - supply pistons, which BMW cannot). This was an expensive job but not as expensive as buying new calipers and completely eliminated vibration under braking which otherwise makes the car most unpleasant to drive - you have my sympathy.

Other simple stupid things to check (first) are that the discs are actually secured to the hub (small setscrew) and that the wheel fixing bolts are correctly torqued. Also, if the discs are new-ish, then it might not be wise to assume that the hub mating faces are clean either - there must be no dirt/debris/rust flakes trapped between hub and disc.

I hope this is some help; do let us know how you get on!

Regards

Mfiver

 

[Gruber]

Thanks all - hugely appreciated. I'll call the garage this morning and see what they say to all that.

Very grateful to you for taking the time...

:cheers:

 

[Mfiver]

Whilst the first job is to check that all pistons in both the calipers are free, I would add that in principle I agree with Bayerische - if the discs are proven to be out of tolerance, then it should be possible for a machine shop to skim them.

However, the M5 discs are substantial vented items, larger than a standard E28 (even an M535i which is nearly as quick) and although you will see plenty of people on line advocating uprated brakes for an E28 M5, it's worth remembering that BMW felt them perfectly adequate for road use (4-pot calipers rather than the sliders fitted to lesser models as well as the bigger front discs) - the contemporary motoring press found no fault in respect of braking.

I would be surprised if your recent Alpine exploits would be sufficient to cause distortion - unless perhaps you drove the car hard (down a pass?) and then for some reason stopped and held the car on the footbrake for some time immediately afterwards.

Whatever - we look forward to hearing what cures the problem!

Regards

Mfiver

 

[BMWWGN]

Just remember that it's not the uneven braking action due to caliper piston seizure that actually causes the shimmy.
It's the damage caused to the disc from the prolonged use of the brakes in this condition, resulting in ribbing or galling of the disc surface, or inducing hot-spots that can cause the disc to warp.
So there's a very good chance your disc rotor surfaces are out of whack - but whether or not this has been caused by uneven braking due to a seized piston, remains to be seen.

When I first purchased my M5, unbeknownst to me at the time the left front caliper pistons were either partially or completely seized in the caliper.
However, this did not result in vibration or shimmy during braking - rather the car had poor braking performance and would tend to move to the right under moderate to hard braking (not desirable for a RHD situation!).
I suppose the good thing was that this was the result of the car having had little prior use for several years, so the condition had not really caused any disc damage that would usually be seen from prolonged use with seized pistons.

Of course, skimming the discs is the first and most economical step if they're found warped or uneven, provided there is sufficient rotor thickness remaining.

But if you have to replace them (hopefully not at a mere 3k miles!) just bite the bullet and fit the OEM rotors.

My very experienced local BMW technician once told me that the majority of brake problems he sees are the result of aftermarket rotor and/or pad installations.

Let's hear the result of your inspection then and, whatever the problem, I hope it's a straightforward fix.:M5thumbs:

 

[Gruber]

Thanks again - very useful stuff.

Mfiver - thanks for the PM. I tried to reply but a message flashed up telling me I need a post-count of 45 (and I'm only on 18... 19 now!). :Thumbdown:

I'm in Battersea - so the right side of town. Would be good to get the cars together at some point! But for the time being, it's down in West Sussex with the mechanic. Just waiting for a diagnosis.

Very grateful for all the tech support - much appreciated, especially as I'm a bit naive when it comes to some of the mechanical stuff, so it's massively helpful to have all the expertise from you guys to draw on.

Thanks again!! :M5thumbs:

 

[Gruber]

The saga continues...

Discs have been replaced under warranty, but there's still very noticeable juddering under braking. I haven't driven the car - it's still with the mechanic. He's checked for play all over the front set-up etc but can't find any.

The juddering happens under light and moderate braking at speed - say 40mph upwards. Hit the brakes really, really hard and it pulls up straight without fighting - so only occurs under light to moderate braking.

Any ideas o wise men of the internet?

Tomorrow he's going to work his way around bearings, suspension components, etc...

At least I have a nice new set of discs!

 

[raymondw]

Any ideas o wise men of the internet?

- Shock-absorbers and/or strut top-mounts
- Correct tighterning of suspension ball-joints and bushings under load

 

[BMWWGN]

Yep - I too would be starting to suspect an issue with the front shocks or mounts, as raymond suggests.

 

[Gruber]

Some good news!!

It seems the drivers' side wheel bearing is the culprit. A new one has been fitted and (I'm told) the juddering is gone. It'll be the weekend before I get to pick it up and try it for myself, but very hopeful that it is sorted.

In other news, the central locking has packed up... but that's a job for another month / pay cheque...

Thanks again to you all for the input, advice and suggestions.

 

[Bayerische]

Glad you got it sorted in the end and it is also a result that it was a relatively cheap fix, and you got a new set of discs out of the deal.

Since your on a bit of a lucky streak of cheap fixes, I would check the fuse for the central locking.

Twenty six year old cars are going to throw the odd tantrum.......it's part of their charm.

 

[BMWWGN]

Gruber,

Have you still got your M5?

The reason I ask is that 4-Star Classics are selling one that looks identical to No. 132.

BMW E28 M5 » 4Star Classics

New front panel and new front discs, black mirrors, etc, tells me this is your car.

Do tell, please.

 

[jez 8464]

Gruber,

Have you still got your M5?

The reason I ask is that 4-Star Classics are selling one that looks identical to No. 132.

BMW E28 M5 » 4Star Classics

New front panel and new front discs, black mirrors, etc, tells me this is your car.

Do tell, please.

It is defo 132 spoke to James Mann earlier this week and he confirmed is D590BPB. They last sold it in October 2011 with 169013 miles on clock

 

[Gruber]

Gruber,

Have you still got your M5?

The reason I ask is that 4-Star Classics are selling one that looks identical to No. 132.

BMW E28 M5 » 4Star Classics

New front panel and new front discs, black mirrors, etc, tells me this is your car.

Do tell, please.

Evening all

Yes - sadly it is mine.

Family circumstances mean it's just too much cash to have tied up in an occasional toy at the moment. It was bought for the summer Euro trip - and was awesome - and I'll be very sad to see it go, but now I bearly have time to drive it and it makes no sense to have it sitting in the garage for 340+ days of the year.

If it doesn't sell I'll gladly have it back, so let's see what happens.

It is awesome though...

 

[BMWWGN]

I know exactly how you feel Gruber, having just sold my own lovely M5 - for similar reasons, by the sound of it.

At least we can say that we had the privilege of owning one of these rare and beautiful beasts!:M5thumbs:

GLWS

 

[Gruber]

Change of plan...

I'm keeping it!

A couple of things have happened - we've signed a two year lease on a flat, so don't need the money out of the car for a deposit, and the car is just about to be featured in a magazine article, so I just knew that if I sold it and then saw the glossy photos I'd immediately regret it. And I've just signed up to take it to the Silverstone Classic event in July, which seems to include a parade lap for M and Z cars through the BMWCC...

Happy days! :wroom:

I'm retrieving it this weekend, all being well, and can't wait to drive it again.

 

[sutts]

Well played Gruber, having seen your M5 close up I can see why you wouldn't want to part with it. :cheers:

 

[BMWWGN]

Well done Gruber - it would seem that you were meant to own it and keep it!

Which magazine is running the article on your car?