Stan944

I'm rebuilding brake calipers. Hayness calls for silicone to be used to lubricate the piston seals - I can't find it locally.

I found:
Permatex UPC 22063 Ultra disk brake caliper lube synthetic lubricant,
and don't know if it's good enough?

I'm putting super blue fluid, but if I put lubricant of lower boiling point, it will kill the purpose of using high quality brake fluid...

Anybody knows typical usable temperatures for such synthetic lubricants?
What do you guys use?

Thanks, Stan

Sam Lin

For the piston seals themselves, use clean fresh brake fluid. The Permatex lube is for caliper slider pins on floating calipers.

Sam

Scott at Team Harco

Yes. To double confirm what Sam said. If the grease is not specifically for piston seals do not risk using it there.

The use of fresh, clean brake fluid is always acceptable. Apply a film of brake fluid all around the seal and on the piston. Be sure the seal is properly installed in the groove. Also, be very careful to apply even insertion pressure to get the piston across the seal. Once you have the edge of the piston across the seal, insertion force will be reduced. Gentle pressure is all that should be necessary to push the piston in the rest of the way.

Good luck!

BruceWard

I rebuilt my calipers in January. I bought some factory rebuild kits that came with small brembro grease packets to lube the pistons. I used the seals and dust boots from paragon for the rebuild, but used two of the factory kits where I damaged pistons prying them out. I did all 16 pistons using a single packet very sparingly.

The grease probably did help, but what I believe really made a difference is that I soaked the seals and pistons in brake fluid while cleaning the caliper. Then I would make sure there was a good coat of fluid on the piston before inserting it.

I cleaned each caliper until I could push the pistons in with my thumb.

Stan944

Thanks for the tips.

The grease I bought says specifically to use on (among other parts) rubber seals and pistons.
But I don't know if it would handle high temps.

Anyway, I'll just use the fresh brake fluid, as it looks like it is sufficient.
And will definitely clean the calipers.
Thanks, Stan

89magic98

For piston removal, the factory service manual says to use compressed air.

Unfortunately, I only have access to a bicycle hand pump.

Is there anything I can use to adapt that pump fitting for use on a brake caliper hose fitting connection?

Also, I think the factory manual said that clean brake fluid can be used for the lubricant.

944_S_TYPE

Mabyee a rubber hose and a hose clamp.... What about the pump in your trunk for the spare.....

83na944

Stan,

Last year I rebuilt my calipers. I called the Permatex people to find out what grease to use on the assembly of the pistons to the calipers. They recommended the Ultra Disc lube. IIRC, its green grease in a small pouch that is more than enough for a single caliper. If that is what you have, then you can, according to Permatex, use it on the piston. I think that is really the purpose for whuch it is formulated.

I don't think its heavy enough for the sliding surfaces, so I use anti-sieze compund on the pins, back of the pads and the caliper friction surfaces.

It doesn't take much to get the pistons out of the cylinder. I think you probably could use a bicycle pump with one of those conical adapters for inflating toys.

Good luck,
Steve

83na944

Check the info in this link. It specifically says you can use it on pistons:

http://www.permatex.com/products/pro...&item_no=20355

BruceWard

On the pump issue, I need 100PSI to start mine moving out. I used a compressor that maxed out at 150 and some would not budge at 150. But the fluid in my calipers was too old and a lot of it had solidified gluing everything together and blocking the crossover pipes.

I bought a air gun with a cone shaped rubber end on it for $6 at Walmart and borrowed the compressor from a neighbor.

I also found that if I removed the crossover pipe I could blow the pistons out one side at a time.

Make sure you have a piece of wood 2x4 or 1x4 between the pistons before you try to blow them out.

Also please make sure you use correctly sized line wrenches.

Luis de Prat

Steve, any write ups on how to rebuild the 1983 floating calipers?

Stan, please post any details you care to on the procedure like you did with the manual steering rack rebuild. I for one would greatly appreciate anything beyond or confirming the description in the Haynes manual.

TIA

89magic98

Oops, the factory manual says:

"Coat cylinder bore, piston, and seal with a very thin brake cylinder paste."

Scott at Team Harco

If interested, I have an article that I wrote for "Speed, Style & Sound" magazine. It does a pretty good job of describing a generic caliper rebuild. It is not a Porsche caliper - but I did rebuild the calipers on my 85.5 and can say the exact same procedure applys.

If anyone is interested in a copy (complete with lots of photos) it is a 2.2 Meg Word file. Just send me a private note to this, and only this, address: harveys@ntcna.nissan-usa.com
Include your address and I will forward. Note: this is my work address so requests made off hours will not be filled until I return.

89magic98

Wow, I just got the procedure from Scott, it is really good reading.

The factory manual is not nearly as good.

Now I just need someone to do the sandblasting for me.

Stan944

Luis: Thanks for acknowledging my write up on rebuilding the manual steering rack. FYI: it's been close to a year and no problems.
And if I come up with something out-of-ordinary on caliper rebuild, I'll post it. But the description in Haness is quite elaborate. Incidentally, I use Hayness and Clark's garage as the starting point for most procedures on my (early) 944. FSM I checked is most often applicable only to 85.5 and later models, so I don't find it too helpful. It probably would be different if I had the manual for 924, which covers many aspects of early 944.

Kevin: about using compressed air. I currently have one caliper out (planning to finish over the weekend), and I can move the piston both ways by hand, so no need for air in my case. But I was wondering if it would be possible for you (even easier) to remove th episton in th efollowing way:
Remove the caliper out of the disk prior to disconnecting the hydraulic line, put a block of wood in front of the piston, and depress the brake pedal. The way I see it, the piston should jump out. I think such procedure would work well for single piston calipers, but would require some modification to work with 4-piston calipers.

Steve:
Thanks for your comment. What I bought is very similar. Independently on what I do, I'll contact Permatex to ask about the boiling point. And like you, will use anti-sieze at sections that do not contact with the hydraulic fluid.

cheers, Stan