caliper rebuild

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Im rebuilding a R1 caliper and having an issue. I got all the piston seals in, no problem. 2 of the dust seals went in. The last 2 dust seals don't want to go. All the seals are original (old). You know how some rubber parts seem to expand if they soak up oil or grease? That is how these seem. Like the OD is too big.

I've got them sandwiched in some paper towels with a little weight on them in hopes they may dry and shrivel a bit.

Anyone have some pointers other than buying new seals? Need to dry these things out. The ones that wont go in are a bit bigger in Od than the ones that did.

There are two different sizes and I am putting the right ones in the right place

 

[bazwell]

Are you 100% certain you have scraped all the crap out of the seal grooves?

 

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Clean as new.

 

[maleko89]

Perhaps oven?

 

[bazwell]

That's what stopped one of mine going in all the way once.

I have never tried to shrink a rubber seal, but apparently dropping in boiling water for a minute or so helps.

 

[one2dmax]

I have used the shop microwave. 20-30 second intervals

 

[dannymax]

Just the opposite....ice 'em! Fill a baggie with crushed ice and pack the rubber seals inside for awhile.

It's an old tank testers trick for shrinking o-rings, should work with caliper seals also.

 

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Thanks for the tips guys. I read about the boiling water trick somewhere else and gave it a shot. I put one dust seal in the water for a couple mins. It did not seem to shrink it any.

I messed around for a while and did get them in. Not sure why those two seemed to grow so much more than the others. I found that I had to take it easy on the brake fluid. Too much and they kept popping out as I tried to put them in. Not enould and they would not slide around in the groove.

It was similar to putting 10lbs in a 5lb box. Once I had the seal in the groove all the way around I had a good bit bunched up that just wouldn't fit. It seemed like I could have cut 1/4" out of the seal and it would have been fine. Anyways, when I got to the point the groove was filled but I had a small psection hanging out, I kept trying to slide the seal around the groove in effect cramming all the excess in a tiny bit at a time. It took some patience but it worked.

Strange that the other dust seals popped in pretty easily compared to these two.

 

[one2dmax]

I meant to burn out the contaminate with the microwave. That has worked for me before though it's not always successful.

Sean