More juddering

[GinP]

I cannot see any exact similarity with other forumites juddering problems, so perhaps someone can advise on the following.

I have an '02 320CDI Estate with self levelling suspension. In the last 8k miles, I have had the following replacements by my specialist independent garage who maintain the vehicle: both front shock absorbers, new brake pads all round, new front discs (twice), two new calipers,two front tyres 5k miles ago..

I had some juddering 4k miles ago (December) and the discs were replaced as they had inexplicably warped, the pads were refaced and all was well until last month. The car then developed sever juddering at speeds between 65-70mph AND on braking firmly at anything above urban speeds.

I had the tracking checked,all four wheels rebalanced and the two rear tyres replaced as one was distorted and couldn't be balanced. Replacing the two rear tyres cured the speed vibration but that in turn revealed that the braking judder, which can be felt through the steering wheel and driver's seat was still there. Although not quite so bad it is still sufficiently severe to be alarming when the car is hauled down from fast speeds and noticeable at town speeds too.

The car has been back to the garage for a quick inspection and no fault with the suspension or steering gear has been found so far but the plan now is to take it back for a few days so that, in the first instance, new discs can be installed on the rear end- if this doesn't do the trick then they will be replaced with the old discs on a ' no cost' basis, very fair treatment I reckon.

However, since the juddering is obvious through the steering wheel I'm convinced, but without any evidence that it is a front end problem.

There is just one thing that I am uneasy about and will address, and that is that when my combined steering pump/self levelling oil reservoir fell to minimum about 9k miles ago, M-B sold me the wrong fluid even though they checked the VIN details on their computer. Seemingly many such cars have independent oil reservoirs, not combined units such as mine and it wasn't until I had poured in half the litre bottle of top-up oil that I noticed that the part number on the filler cap on the car and the part number on the bottle were different. On querying this with M-B they told me that a mistake had been made (my words not theirs!) and that the fluid I had introduced was never intended for steering pumps but that it wasn't a safety issue and it was my choice if I wanted to flush out and replace- I decided to wait until August this year when an 'A' service is due.

When I reported this to my garage they showed suprise as they too were unfamiliar with the combined reservoir arrangement(seemingly the more common steering pump reservoir is concealed under the engine cover which has not been needed to be removed,the car has done only 104k miles) and they tell me that they habitually use a generic ZHM type fluid such as Citroens use.

The reservoir level has remained unchanged since the my top up, so any mixing could be minimal but a similar quantity (perhaps 1L) was introduced at service last summer. Could this be a contributory factor in anyway?

 

[SJX]

HI, the fluid should not be an issue really, the standard MB fill for PSteering only is usually Pentosin CHF11S in Reality I have found its v.hard to find so Febi 06161 green Synthetic is used. (I dont know about combined systems however) Its easy done to use the Mineral green equivalent even the numbers are almost the same CHF7.1, not a long term good thing as MB would beef that seals will be manufactured for specific mix but lets face it its probably chosen for its stability and inability to absorb moisture as easily. Neoprene is neoprene and rubber rubber so IMHO dont worry unduly. I would wager for sure not the cause of your issue.

My rather old fashioned approach would be, in this order:

Inner steering rack ball joint ends (on rack end)
Outer steering ball joints

These are both sprung loaded ball and socket joints and must be checked for play with the weight on the car in a normal un-jacked position as the point of most wear will happen in this position. Jacking the car can tighten the joint in a new position so it appears fine !

I read the calipers were replaced, were the slide pins replaced or just the hydraulic main piece (re-sealed). The Slides let the caliper centre itself either side of the disc are prone to corrosion and if not free, or one sticking could make for some pretty interesting braking. Infact this is a common cause of the caliper sticking and overheating the disc to the pont of warp. Do you have excess brake dust appearing on your wheels, this is an indication that all is not well and some thing is maybe jamming or sticking.

Finally wishbone bushes, front lower and front upper. Brake forces would cause a movement of the wishbone inward or outward and in certain cases may cause a brake induced shimmy.

Thats all I can say really. Thats what I would be checking out if it were my problem. Hope it helps in some way

Steve

 

[GinP]

Since undergoing shoulder surgery 27 June (2 days after my original post) I have been unable to drive until recently so I haven't been following up on car matters until now.
Apologies therefore for seeming to ignore your helpful advice. The issue is still there but intermittent and doesn't seem to be due to brakes heating up but becomes more noticeable after driving 50+ miles so I'm thinking it is probably bushes- the car is going back into the garage tomorrow for further investigations.

Thanks for your input- albeit belated.

 

[Dieselman]

I suspect it is nothing more than pad deposition on the disks, I'm also skeptical about the original disks being warped, more likely they, and possibly these, are not sitting flush to the hub.

 

[GinP]

Well, I must rely on the workshop's report so here's an update just in case others have similar problems.

The garage tells me that for BMW and M-B cars they have used discs from Pagid-Textar and ATE for years without incident, with a preference for the first named as they are a little cheaper; they've never had a problem before my issues. As you will recall from the above I've had two sets of discs in quick succession(Pagid) and new pads- the car has only done very low mileage, this past year.

Anyway, the Pagid discs have been replaced by a pair of ATE's, keeping the same pads and suddenly the problem has been eliminated. The garage has made a warranty claim on Pagid, has charged me no labour for their investigations but I shall get a bill for about £20 for the extra cost of the two ATE discs as they are a little more expensive.(I see on the ATE website that the compound of their discs is said to be designed to prevent, amongst other things, brake judder).

It's been very frustrating for me and the garage, but I'm now well pleased and more than a little relieved.