Front Brake Caliper Dragging
06-20-2022, 09:40 PM
#1
Rennlist Member
Thread Starter
Front Brake Caliper Dragging
The right-front brake caliper on my 91 GT is dragging, looking for parts, it appears that the rebuild kits available include the piston, which makes it pricey to do a full rebuild of both front calipers. This begs a few questions:
- Are rubber-only kits available?
- If not, does this imply that once the seal is compromised, the piston is toast? (they are never salvageable?)
- If not, should I just leave the working pistons alone and not try to preemptively replace the seals on the unaffected pistons?
- It looks like I'm looking at $300 per caliper for all 4, not the end of the world but where the seals haven't failed, it sure would be nice to throw a $20 seal at the problem instead of a $75 piston/seal kit.
The following users liked this post:
gazfish (06-21-2022)
06-21-2022, 10:40 AM
#3
Rennlist Member
I would also agree to check the brake line to ensure it is not pinched, nor internally collapsed - thereby preventing a release of pressure. If original, perhaps easiest just to replace and remove that from the equation.
Further, I would examine the caliper in question and start with removing the pistons - once out, you will be able to ascertain if there is any visible damage/pitting/etc to the pricey pistons. I have had very positive results with a simple reseal and reinstall. Be sure the use the appropriate brake seal lube upon reassembly (Porsche sells, as well as ATE) to ensure the seals do not bind or fail to properly seat.
I don't have the source handy where I purchased the seals, but were not much and did not require the added expense of pistons (as all my pistons were fine).
Front calipers are 44/36 mm pistons for reference.
Also, a good time to freshen up the calipers when off the car...
Further, I would examine the caliper in question and start with removing the pistons - once out, you will be able to ascertain if there is any visible damage/pitting/etc to the pricey pistons. I have had very positive results with a simple reseal and reinstall. Be sure the use the appropriate brake seal lube upon reassembly (Porsche sells, as well as ATE) to ensure the seals do not bind or fail to properly seat.
I don't have the source handy where I purchased the seals, but were not much and did not require the added expense of pistons (as all my pistons were fine).
Front calipers are 44/36 mm pistons for reference.
Also, a good time to freshen up the calipers when off the car...
Last edited by huskeric; 06-21-2022 at 10:45 AM.
06-21-2022, 11:10 AM
#4
Rennlist Member
Thread Starter
Good thought, will check. Its the front LEFT actually (I wrote front-Right), and I've felt some shuddery feeling while braking from that corner. I think a set of brake hoses would be prudent in any case, they weren't terrible to get at when I did my S4's last month. Thanks!
06-21-2022, 11:27 AM
#5
Rennlist Member
Thread Starter
I would also agree to check the brake line to ensure it is not pinched, nor internally collapsed - thereby preventing a release of pressure. If original, perhaps easiest just to replace and remove that from the equation.
Further, I would examine the caliper in question and start with removing the pistons - once out, you will be able to ascertain if there is any visible damage/pitting/etc to the pricey pistons. I have had very positive results with a simple reseal and reinstall. Be sure the use the appropriate brake seal lube upon reassembly (Porsche sells, as well as ATE) to ensure the seals do not bind or fail to properly seat.
I don't have the source handy where I purchased the seals, but were not much and did not require the added expense of pistons (as all my pistons were fine).
Front calipers are 44/36 mm pistons for reference.
Also, a good time to freshen up the calipers when off the car...
Further, I would examine the caliper in question and start with removing the pistons - once out, you will be able to ascertain if there is any visible damage/pitting/etc to the pricey pistons. I have had very positive results with a simple reseal and reinstall. Be sure the use the appropriate brake seal lube upon reassembly (Porsche sells, as well as ATE) to ensure the seals do not bind or fail to properly seat.
I don't have the source handy where I purchased the seals, but were not much and did not require the added expense of pistons (as all my pistons were fine).
Front calipers are 44/36 mm pistons for reference.
Also, a good time to freshen up the calipers when off the car...
Thanks for anticipating my "3-questions from now" The calipers on this car cleaned up REALLY well, but the "PORSCHE" logos are half missing. Assuming those are some sort of special heat-resistant sticker, or do I need a stencil?
I appreciate the willingness of everyone to share their knowledge on this forum. I was trolling for threads last night that I thought I could offer some help on, closest I came was the "intermittent window motor" thread, but someone had already pointed to door-looms at the hinge! I have 3 wires patched on my S4 driver door. BRITTLE
06-21-2022, 04:53 PM
#7
Former Vendor
This is starting to be a chronic issue with the 928 Brembo calipers.
By all means, replace the hoses and bleed the system.....the hoses are old enough to warrant that.
I'll need to check inventory, but I generally stock completely rebuilt front (and rear) calipers (with the correct piston sizes for your car) for $350 each, exchange.
(Your calipers must be not physically damaged. There is a core charge, until your calipers arrive and are inspected, by us....we can't rebuild junk!)
These are extremely nice, as you would expect, from us.
Completely disassembled (including the pad side plates.)
Cleaned and checked for wear.
Powder coated, instead of anodized with a clear coating.
On the calipers with decals, the calipers have a clear applied to protect the decals.
All new seals and pistons, when needed.
Install, bleed, and forget.
By all means, replace the hoses and bleed the system.....the hoses are old enough to warrant that.
I'll need to check inventory, but I generally stock completely rebuilt front (and rear) calipers (with the correct piston sizes for your car) for $350 each, exchange.
(Your calipers must be not physically damaged. There is a core charge, until your calipers arrive and are inspected, by us....we can't rebuild junk!)
These are extremely nice, as you would expect, from us.
Completely disassembled (including the pad side plates.)
Cleaned and checked for wear.
Powder coated, instead of anodized with a clear coating.
On the calipers with decals, the calipers have a clear applied to protect the decals.
All new seals and pistons, when needed.
Install, bleed, and forget.
Last edited by GregBBRD; 06-21-2022 at 05:55 PM.
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06-21-2022, 06:29 PM
#8
Rennlist Member
Thread Starter
This is starting to be a chronic issue with the 928 Brembo calipers.
By all means, replace the hoses and bleed the system.....the hoses are old enough to warrant that.
I'll need to check inventory, but I generally stock completely rebuilt front (and rear) calipers (with the correct piston sizes for your car) for $350 each, exchange.
(Your calipers must be not physically damaged. There is a core charge, until your calipers arrive and are inspected, by us....we can't rebuild junk!)
These are extremely nice, as you would expect, from us.
Completely disassembled (including the pad side plates.)
Cleaned and checked for wear.
Powder coated, instead of anodized with a clear coating.
On the calipers with decals, the calipers have a clear applied to protect the decals.
All new seals and pistons, when needed.
Install, bleed, and forget.
By all means, replace the hoses and bleed the system.....the hoses are old enough to warrant that.
I'll need to check inventory, but I generally stock completely rebuilt front (and rear) calipers (with the correct piston sizes for your car) for $350 each, exchange.
(Your calipers must be not physically damaged. There is a core charge, until your calipers arrive and are inspected, by us....we can't rebuild junk!)
These are extremely nice, as you would expect, from us.
Completely disassembled (including the pad side plates.)
Cleaned and checked for wear.
Powder coated, instead of anodized with a clear coating.
On the calipers with decals, the calipers have a clear applied to protect the decals.
All new seals and pistons, when needed.
Install, bleed, and forget.
06-21-2022, 06:36 PM
#9
Rennlist Member
Thread Starter
Thanks Gary, I'll poke around. I put a set of 10-spoke 18" Panamera wheels on this car so the calipers are pretty visible now. The original D-90s were chromed and look pretty tired in the recesses, showing copper (brass?) where the chrome has gotten thin.
06-21-2022, 09:51 PM
#10
Former Vendor
And the idea behind the pricing is to deliver a fantastic/beautiful rebuilt part, for around the same price as just the parts cost for someone to do them at home.
Our idea is that if the customer factors in the price for powder coating, stencils, and their time is worth anything, doing them at home ends up making little/no sense.
Frankly, it's an experiment, with experimental pricing.
I'm going to be fairly critical about the cores, since if we start getting junk back as cores, the idea becomes unsustainable.
We can "control" the cores on the cars that come into our shop, of course, but cores that come in boxes could be an issue.
Your calipers sound like our "target" market, which is why I mentioned this, to you.
We will also be able to supply both stock brake lines and Goodridge stainless steel/teflon brake lines, as well as brake pads, sensors, and rotors, if needed.
One stop shopping at great prices.
Last edited by GregBBRD; 06-21-2022 at 09:55 PM.
The following 2 users liked this post by GregBBRD:
Adamant1971 (06-21-2022),
RennHarry (06-22-2022)
06-22-2022, 11:02 AM
#11
Rennlist Member
Thread Starter
Yes, same price, for the rears.
And the idea behind the pricing is to deliver a fantastic/beautiful rebuilt part, for around the same price as just the parts cost for someone to do them at home.
Our idea is that if the customer factors in the price for powder coating, stencils, and their time is worth anything, doing them at home ends up making little/no sense.
Frankly, it's an experiment, with experimental pricing.
I'm going to be fairly critical about the cores, since if we start getting junk back as cores, the idea becomes unsustainable.
We can "control" the cores on the cars that come into our shop, of course, but cores that come in boxes could be an issue.
Your calipers sound like our "target" market, which is why I mentioned this, to you.
We will also be able to supply both stock brake lines and Goodridge stainless steel/teflon brake lines, as well as brake pads, sensors, and rotors, if needed.
One stop shopping at great prices.
And the idea behind the pricing is to deliver a fantastic/beautiful rebuilt part, for around the same price as just the parts cost for someone to do them at home.
Our idea is that if the customer factors in the price for powder coating, stencils, and their time is worth anything, doing them at home ends up making little/no sense.
Frankly, it's an experiment, with experimental pricing.
I'm going to be fairly critical about the cores, since if we start getting junk back as cores, the idea becomes unsustainable.
We can "control" the cores on the cars that come into our shop, of course, but cores that come in boxes could be an issue.
Your calipers sound like our "target" market, which is why I mentioned this, to you.
We will also be able to supply both stock brake lines and Goodridge stainless steel/teflon brake lines, as well as brake pads, sensors, and rotors, if needed.
One stop shopping at great prices.
06-22-2022, 02:51 PM
#12
Drifting
Greg’s price sounds excellent and I bet the calipers are work of art!
Is the brake actually overheating? You mentioned shudder which could be plate lift at that caliper rather than seizing on, which is more likely to be flexi-hose collapse than caliper failure.
A few years ago I rebuilt all the calipers with same piston/seal sizes as yours on my MY91. I only needed new dust seals, piston seals and guide plates (the steel plates that lift when corrosion builds behind them on alu caliper body). It was a lot of work so bear Greg’s offer in mind - in my case I enjoy this kind of thing but removing the side plate dome screws was a pain!
The front 36/44 seals are same as the 996, so it was very cheap to get entire Brembo axle kit (may have been aftermarket - need to check). I think rear kit 28/32 was same as Cayenne so similarly cheap (around $60 for axle kit). The plates were horribly corroded but pistons like new - amazing quality.
Took time repainting with high temp caliper black paint. Got hold of new decals on eBay and sealed with high temp clear. New bleed valves of course.
One of best jobs I ever did on the car. Six years later the brakes still feel fantastic (all new hoses too). Still smile whoever I hit the brake pedal! Different league from original ‘wooden’ feel and very powerful. My DIY spray nowhere near as good a finish as the pros, but satisfying to DIY. It’s down to ow you like to spend your time!
Is the brake actually overheating? You mentioned shudder which could be plate lift at that caliper rather than seizing on, which is more likely to be flexi-hose collapse than caliper failure.
A few years ago I rebuilt all the calipers with same piston/seal sizes as yours on my MY91. I only needed new dust seals, piston seals and guide plates (the steel plates that lift when corrosion builds behind them on alu caliper body). It was a lot of work so bear Greg’s offer in mind - in my case I enjoy this kind of thing but removing the side plate dome screws was a pain!
The front 36/44 seals are same as the 996, so it was very cheap to get entire Brembo axle kit (may have been aftermarket - need to check). I think rear kit 28/32 was same as Cayenne so similarly cheap (around $60 for axle kit). The plates were horribly corroded but pistons like new - amazing quality.
Took time repainting with high temp caliper black paint. Got hold of new decals on eBay and sealed with high temp clear. New bleed valves of course.
One of best jobs I ever did on the car. Six years later the brakes still feel fantastic (all new hoses too). Still smile whoever I hit the brake pedal! Different league from original ‘wooden’ feel and very powerful. My DIY spray nowhere near as good a finish as the pros, but satisfying to DIY. It’s down to ow you like to spend your time!
Last edited by StratfordShark; 06-22-2022 at 02:57 PM.
12-03-2022, 06:47 PM
#13
Rennlist Member
Thread Starter
Even though this is a near 6-month old thread, I figured I'd update it with the solution: a slightly warped rotor. I was convinced that this issue was a lazy or sticking brake caliper but once I dove in, I could see that the caliper seals were pliable and the pistons moved as freely as pistons do. I replaced the calipers and did a crude check by spinning the rotors and holding a pencil against the caliper: the left-side rotor was very slightly warped. I swapped a good used set onto the front and the issue went away.
12-03-2022, 06:55 PM
#14
I have had luck getting seals from paragon. But you really can’t beat Greg’s deal.
12-03-2022, 07:20 PM
#15
Drifting
Even though this is a near 6-month old thread, I figured I'd update it with the solution: a slightly warped rotor. I was convinced that this issue was a lazy or sticking brake caliper but once I dove in, I could see that the caliper seals were pliable and the pistons moved as freely as pistons do. I replaced the calipers and did a crude check by spinning the rotors and holding a pencil against the caliper: the left-side rotor was very slightly warped. I swapped a good used set onto the front and the issue went away.