Sinking brake pedal

[AndyBaur]

This may sound silly but have you searched your vin on real oem? Also is this any help?
http://www.ebay.com.au/itm/BMW-320-E21- ... e8c&_uhb=1

I normally use BMWFans.info.

The main dealer can supply a seal kit for £80 (which seems a tad excessive) and they are also on back-order.

By the time postage from Oz is taken into account (again, excessive for the size & weight of a seal kit) or the one from Egypt (ditto) they aren't substantially cheaper than BMW. At least with BMW I know I'll be getting BMW approved parts. That isn't always the case with alternative suppliers.

I was hoping to get in touch with ATE but they don't list an email address on the website. I have another couple of avenues to explore before I go to the dealers.

Thanks for suggestions though. I may have to go with one of those if BMW class them NLA as has happened for other parts.

[Jeroen]

Did you check any local general brakes/friction parts specialist?

[AndyBaur]

Well I emailed Bigg Red & he had a seal kit which looks like it will do the job for £21.95.

I drained the m/c reservoir with a big syringe & the seal into the m/c itself was disintegrating as I watched! I'm planning to get it off & stripped down this weekend. Fingers crossed!

[AndyBaur]

Right, I've got the m/c off, removed the stop bolt & got the circlip off. The Haynes manual says the primary piston should 'eject' but mine doesn't. In fact there's a solid 'clunk' when you let go of the piston. It sounds like there's another stop bolt or some sort of retainer but I can't see one.

Any ideas?

[jimbob]

theres a bolt to undo to relesae it. its on the main body of the mc

[AndyBaur]

theres a bolt to undo to relesae it. its on the main body of the mc

If you mean the 10mm stop bolt, it's out. There are no other hex heads (internal or external) to remove.

As I understand it, the 'stop bolt' is only for the secondary piston, not the primary. When the retaining circlip is removed the primary piston should come out, quite forcibly in fact. Looking inside the piston assembly is below the circlip groove. Could this be corrosion stopping the piston. If it was I would expect it to sound a bit 'crunchy' with a gradual seizing motion. This is a definite 'clack' & immediate stop.

http://bmwfans.info/parts-catalog/E21/E ... #1120218_1

[nas80]

No you have to yank it apart. It doesn't pop out

[AndyBaur]

Cheers Nas, that did it. Some other posts indicated it came out with a bang when you removed the circlip.

Why do the Haynes manuals always leave out important info ???

[AndyBaur]

When I pulled the primary piston out it seemed to have separated.



I assume it's supposed to be screwed together.

I got the new seals on but I seem to have a couple left over (compared to the pic above)



The online parts diagram implies there's another seal on the primary piston behind the circlip/plastic washer/seal/metal washer, i.e after no. 1 on the diagram.

Does it go here?



Apologies for the size of the pics - they came out rather larger than I was expecting

[AndyBaur]

Can no-one help?

This is my problem:-



This would indicate there should be another seal on the primary piston.

[Jeroen]

Looks like it has to go there indeed but as I've never rebuilt an E21 MC I don't know for sure...

[nas80]

Yea I'm sure it was in a couple of bits it was so long ago I don't remember.

Rebuild it how it came out.

[nas80]

Cheers Nas, that did it. Some other posts indicated it came out with a bang when you removed the circlip.

Why do the Haynes manuals always leave out important info ???

That's why they call it the book of lies my friend.

[AndyBaur]

Ok, I think I figured it out.

There's a extra thick seal which is the same thickness as the two seals in tandem on the primary piston. I suspect you can use either. My particular primary piston only had a single narrow seal despite the parts diagram showing two. Had someone been in there before me?

I fitted two seals & it all went back together ok.

However, the two rubber plugs that the master cylinder fits in to are too small. My old ones were starting to disintegrate so I will have to order new ones from BMW - they aren't expensive.

This is the D1123 kit for the E21 from Bigg Red. He doesn't list the seal kit so I emailed them. Tony Brain was very helpful & saved me about £60 over the kit from the main dealer.

[Jeroen]

Guess us Dutchies should start ordering from Biggred as well then!