Ate brake calliper assembly

[jamestnewsonr65]

I'm just about to start rebuilding my calipers now that I have all the new bits, but with the assembly instructions for the new seals it mentions using ate brake preserving grease for coating the cylinders and seals.

Would it be feasible to use clean brake fluid, or are there any alternatives out there that people have used and are effective. Guess it needs to be a rubber friendly grease.

[Bob_Roller]

Use clean brake fluid .

A general rule to follow, is to lubricate seals, O-rings, with the fluid they will be exposed to, except fuel, then use a light grease or oil .

[Tony Smith]

Brake fluid will be just fine. If you want to spend money you could buy something like PBR "rubber grease", but I would not bother. the really important thing is absolute cleanliness.

[Mike V]

Use clean brake fluid  
A general rule to follow, is to lubricate seals, O-rings, with the fluid they will be exposed to....

Brake fluid will be just fine. If you want to spend money you could buy something like PBR "rubber grease", but I would not bother. the really important thing is absolute cleanliness.

Dito!

You should use brake fluid on internal brake parts as a cleaning agent too.  I used to use soap and warm water then a thorough rinse with water but have now changed to use brake fluid only, as a cleaning agent and lubricant.  "Clean" is key for all brake parts.  Make certain all o-ring lands and valleys are very clean of debris. Especially in the corners.  A plastic or wood pick makes for a good tool to carefully scrape the corners ... if needed.

Your pistons should slide into the calipers with low to moderate thumb pressure only.  Never force the pistons and never use a hammer!  Be sure the lubricated square o-ring is forced outward into the caliper valley (seat) to it's largest resting diameter possible. If the piston doesn't slide through the square o-ring easily - try to reposition the piston so it is parallel to the caliper bore.  Grease should not be needed, in my personal opinion.

[Barry]

The only place I would put grease is under the rubber dust seal as it will be much better than brake fluid at protecting the piston against corrosion.  If it's an anodised piston then not really necessary but an older chromed steel piston that perhaps you have already had to polish some corrosion off would be better with rubber grease as the exposed brake fluid would attract moisture. The original ATE pistons are poor in terms of corrosion protection.

[jamestnewsonr65]

The original pistons which I took out were very corroded and rusty.
I bought some new pistons from one of the links which someone provided on here. http://www.etypeparts.com/products/ate15-bmw1

They seem to fit as I tried a quick test when they arrived yesterday and i've got all new replacement parts. The outer calliper bodies have been vapour blasted so I just wanted to make sure I get them put back together in the best manner.

I've ordered some ATE brake cylinder assembly paste so will use that with the piston seals.

[jamestnewsonr65]

Does anyone know where to get the small washer type rubber seals which sit between the calipers. I don't think motorbins or motor works do them.

The ones I had on there have perished and split.

Everything else went together smoothly with the brake fluid as a lube, so thanks for the advice.

[Tony Smith]

Does anyone know where to get the small washer type rubber seals which sit between the calipers. I don't think motorbins or motor works do them.

Square section "O" ring IIRC.
I used the closest round section - the square section ones were available, but I would have had to buy a very large box of them for about $30.

If you have a choice, buy viton seals.

[Barry]

Originals were square section O rings.  Mike Valenti did some work to determine that a suitable substitute was 5mm x 2.5mm in EDPM.  Definitely do not use a common Nitrile NBR Buna N  O ring.

What torque value are you going to use on the clamping screws. Great debate about this as there is no published figure owing to ATE not approving disassembly. That's Probably also the reason the O ring is not available.  Quite a few have split them without apparent problems though.

[montmil]

Does anyone know where to get the small washer type rubber seals which sit between the calipers. I don't think motorbins or motor works do them.

The ones I had on there have perished and split.

Recheck Motobins. I did and they have them in stock.

[jamestnewsonr65]

I think the one on there is a rounded one for the earlier ate type. If not, could you post up the part no as I can't seem to find it.

[jamestnewsonr65]

Thanks Barry for the Mike Valenti hint.  I found his document which had the sizes he used and i've ordered some for testing.

[arvo92]

Very good info on the square o-ring in between the caliper halves. At the moment I have self made o-rings made of whatever piece of rubber I found on the garage table.

I guess you could use whatever, just put a thick piece of rubber with a small hole inside in between the caliper halves and torque the halves together so no fluid can trespass outwards. Until the brakes fail doing 60 miles an hour on twisty road... I hope it never happens to me

[Adrian]

Hi there - if its not too late can I suggest DOT 5 Silicone brake fluid. I used this the last time I overhauled my brake system at my previous rebuild back in 1995. It has a higher operating temp tolerance and doesn't absorb water moisture like a DOT 4 fluid will. I finally took mine old fluid out of the system when I stripped the bike down in 2010 to start this current rebuild. It was still perfectly clean and there was no residues or any kind of build - up in the calliper or master cylinder. I admit I did leave it in there too long - I should have flushed it thru with new stuff perhaps every 5 years - but its a testimony to the stuff that it lasts for so long without causing any problems. Good luck with the brakes ...... Adrian  

[jamestnewsonr65]

I will have a look into the DOT 5. I do have a new bottle of DOT 4 ready for the bike, but maybe 5 is better.

Also I'm not sure on the torque values I was going to use for the fixing of the brakes. I was hoping I would be able to find some info somewhere on this once I was at the stage of fixing them on. Any suggestions welcome on this one.

Thanks.