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Tony
 
Maxhouse97's Avatar
 
Join Date: Sep 2007
Location: Cincinnati, OH
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Brembo brake caliper rebuild questions - pistons hard to push back in

I've got everything apart, put new rubber seals in with brake caliper lube and am attempting to push the individual pistons back in. Everything I've read says you should not force them, and that you should push them in by hand. I was able to push one piston down all the way, but the other three I can only push about half way down.

Is this normal? My thought was to try again using brake fluid as a lube instead of the permatex lube that came with the rebuild kit, as well as the fact that since I got them half way in by hand they should be aligned and using a caliper spreader to push them all the way down should not be a problem. But I'm not sure. Thoughts?
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Old 06-12-2016, 05:24 PM
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I've always just used brake fluid on the seals before I push in brake pistons....Did this with my 930 Brembo's too. Now that you've got them half way in you may need to squirt a little in through the bleeder ports or supply line. You could always hit the supply port with a burst of compressed air to get the pistons back out. Put zip ties on the ones you don't want to go flying across the room.
Old 06-12-2016, 05:30 PM
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Wer bremst verliert
 
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Did you remember to back out or remove the bleeder plugs?
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Old 06-12-2016, 05:46 PM
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Tony, you probably know this but make sure they are going in straight, not "cocked". I've had that happen and no amount of pushing would get them in.
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Old 06-13-2016, 06:04 AM
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Tony
 
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Thanks guys. I thought about the bleeder plugs but the inlet hole for the brake fluid is open (I removed the hard line that comes from the car), so I thought there would not be a back pressure problem upon reinserting the pistons. But I will open them up anyways.

Hey Dave - yes I know about getting them straight as I put them in, however I thought they would bind if I had them misaligned from the beginning, which is why I thought it was wierd that they stopped moving half way down.

I will also try lubing up with brake fluid - it could be that half way down the lubricant on the seals runs out and they get sticky?

If I can't get them in should I use my caliper spreader tool or should I avoid that at all costs so I don't tear the seals?
Old 06-13-2016, 09:39 AM
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Maybe use a little force with the spreader but not much.
Old 06-13-2016, 11:57 AM
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Tony
 
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So I found the culprit - it's this:


Crazy because as you can see it's meant for rubber seals, and was sold to me by racing brake (a company that is supposed to be an expert in brakes). It's actually tacky, and as soon as I dipped the Pistons in brake fluid they slid right in by hand.

I was warned not to use brake lube during this process, but obviously thought it was ok with the reference to rubber seals above. I hope others can learn from this lesson...
Old 06-13-2016, 05:05 PM
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Made exactly the same mistake when I did my calipers!
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Old 06-14-2016, 12:32 AM
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Tony
 
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The saga continues - and I have found a new culprit. It's the seals made by centric (aftermarket source to save money over the expensive brembo seals). I tried the next set of pistons and couldn't get them in by hand. Even tried my caliper spreader, and could only get them part way before I figured I was pressing too hard.

So I took them out, put an old seal back in and it went in by hand no problem. Really frustrating. Going to call Rock Auto tomorrow to see if I can get a refund on the centric seals. I half want to put all the old seals back in, as they all looked really good (although they may be 15 years old). Guess I'll spring for new brembo ones.

DONT USE CENTRIC SEALS!
Old 06-14-2016, 05:37 PM
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It's the seals - I went through the same thing with a set of Boxster calipers. If I remember correctly, the larger diameter were ok and the smaller were not. I tried a number of sets and had no luck. I ended up paying for all the of actual Brembo seals. Stoptech also makes the seals, but I do now know if they are good or not. Stoptech is owned by Centric.
Old 06-15-2016, 06:26 AM
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Tony
 
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I have Racing Brake ones for the front. They are not made by Brembo, but cost as much. Racing Brake said they cannot get stock Brembo seals. Would you trust racing brake?
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Old 06-15-2016, 03:03 PM
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I would think they should be ok. You'll know as soon as you start putting the pistons in.
Old 06-15-2016, 04:28 PM
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When I did all 16 pistons from my 964 earlier this year (with all Brembo part$) they were still a struggle to install. I ended up using my giant channel locks and some heavy leather to squeeze them in.
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Old 06-15-2016, 06:15 PM
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I always use Sil-Glide and they slip right in.
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Old 06-16-2016, 05:19 AM
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Tony
 
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Another question - how do you guys get compressed air into the caliper to get the Pistons to come out? See the pics below - you have the inlet to the caliper where the hard brake line attaches ... how do you maintain a seal when you attempt to push compressed air in there? The tool I have off my compressor is below.


Old 06-16-2016, 04:33 PM
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Garage
You can get a rubber tip that will fit and seal. You will have to look around as I do not know where mine came from.

Rahl
Old 06-16-2016, 06:56 PM
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Mine came as part of the kit from Harbor Freight.
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Old 06-16-2016, 07:41 PM
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Tony
 
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Ok good theirs a HF near by.
Old 06-17-2016, 02:27 AM
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I have had good luck just wrapping a shop towel around the tip to seal it up.
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Christopher Mahalick
1984 911 Targa, 1974 Lotus Europa TCS
2001 BMW 530i(5spd!), Ducati 900 SS/SP
2006 Kawasaki Ninja 250, 2015 Yamaha R3
1965 Suzuki k15 Hillbilly, 1975 Suzuki GT750
Old 06-17-2016, 06:13 AM
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What I have done in the past is I freeze the cylinders and placed the calipers in front of a portable heater.. One constricts and the others spreads.. Then spread brake fluid on it and it has always slid in nicely..


Best of luck

Cheers
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Old 06-18-2016, 04:26 PM
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