Rebuilding calipers - a few questions

[jacovdw]

Gentlemen,

Pardon me if this is not entirely pagoda related, but the underlying principles in rebuilding the calipers are the same. I am nearing the end stages of rebuilding the ATE brake calipers on my 114 and have a question or two about the final assembly process.

Cleaned everything thoroughly with methylated spirits and bought OEM rebuild kits from my local MB dealer which, it turns out, is manufactured by FAG and not ATE.

Now, the literature (service manual) states that one can use ATE brake cylinder paste (not to be confused with brake PAD paste available from MB) or brake fluid to lube the pistons during final assembly.

I have also read that one can use a product called PBR rubber grease which is formulated for exactly for this purpose (Castor oil based I believe).

In South Africa, both ATE brake cylinder paste and PBR rubber grease falls in the same group in the periodic table of elements as unobtainium.

I feel a little uncomfortable using brake fluid as assembly lube seeing that it is hydrophilic and that eventually it may cause premature rust behind the dust seals - or am I a little paranoid here? I think my paranoia is based partly in the fact that our climate here in Durban is humid and tropical and the condition of the calipers when I removed the old seals.

There was quite a substantial buildup of rust and gunk under the dust covers and the part of the bore before the seal that the piston slides through. Fortunately the bores and pistons are free of pitting and rust although full of sludge in the bottom of the bores and the recesses behind the pistons.

To my mind, it would make more sense to use a special type of rubber grease formulated for this application (vegetable based instead of mineral oil based) that would not be so hydrophilic compared to ordinary DOT4 brake fluid.

In view of the difficulty obtaining the above mentioned products, what about the red rubber grease from Castrol? According to the manufacturer it is vegetable based and can be used in the assembly of brake and clutch hydraulic components.

Have any fellow group members have experience in any of these products or tips to share?

Any input would be much appreciated and if there is sufficient interest, I could post a photographic record of the rebuild process in a separate thread.

Thanks in advance.

[mdsalemi]

Jaco--isn't it possible to avoid the "unobtanium" by ordering on the internet?  Can't be THAT expensive to ship, we're not talking large items here.

Alternatively, have you searched for, and spoken with people IN South Africa that work with brakes?

http://www.powerbrake.co.za/general/about.htm
http://www.steves.co.za/Enquiries.html
http://www.carmag.co.za/buyers-guide/category/repairs-rebuilds/

I suspect if you make a few phone calls, you can find what you need "in country".  Also try talking with the various clubs, such as BMW, etc. that have branches in SA and you will probably find a wealth of information.

Good luck and report back!!!

[jacovdw]

Thanks Michael.

I have taken my queries quite wide and even higher up the food chain by talking to ATE South Africa directly - had a nice long chat with a gentleman there, but to cut a long story short, ATE does not import rebuild kits into South Africa anymore.

There are plenty of companies that offer non-OEM brake parts and rebuild kits, but that is where I draw the line. Let's face it, I'm a bit of an OEM part snob... 

What bothers me the most is the vacant stare you get back from the sales assistant when trying to find information or even trying to order something and the pure unwillingness to go the extra mile (perhaps due to ignorance?). Most people just shrug their shoulders and tell you it can't be done... 

When I had the master cylinders and boosters of both the 114 and pagoda done last year, the brake specialist used what looked like the Castrol Red rubber grease for assembly. Now this product is available locally, hence my query if any of the members here used a similar product.

The local guys in the MB club just use plain brake fluid, but I want to know if there is not something better to use...

I guess if you go through all the trouble to do your research and start the project to give some release to your perfectionistic tendencies, it gets a bit disappointing. In the end, I will probably end up ordering what I need via the internet as the act of ordering and the shipping costs is not a big deal at all.

The question is, do I have enough patience to wait a couple of weeks for the shipment to arrive... 

[mdsalemi]

"I feel your pain" Jaco, which is a common political refrain around here.

My take on it is this--you usually get get what you need.  Sometimes after getting the responses you are getting you might just come across someone who has the stuff you need.

[jacovdw]

Thanks again Michael.

I guess I just had to rant a bit to rid myself of some of the frustration... 

Come hell or high water, the brakes will get done as I have not driven my 114 in over a year (shame on me, I know...  )