PSA about Stoptech brakes on track
05-09-2019, 09:21 PM
#1
PSA about Stoptech brakes on track
Got an ST-40 kit from Stoptech mid last season. For the most part it's been a huge upgrade, but I've been having one issue with it, which I've discovered is pretty common. Two of the bleeder screws (one on each caliper) seep fluid during track sessions. They're totally fine on the street and even autocross, but every track session they leak a small amount of fluid—just enough to have a drip running down the front of the caliper. It doesn't drip onto the wheel or anything, but it has already started messing up the paint on the caliper, if nothing else.
When I contacted Stoptech, they first claimed that this was just residual fluid from the top of the screw coming out, despite the fact that I had said I checked for that. (It's definitely not that. Go out for a session and there are drips down the calipers. Wipe them off, blow out the tops of the screws, go out for another session. New set of drips.) Then, they claimed it was installation error. The only way to install bleeder screws wrong though would be to over- or under-torque them, which I didn't do. Nor are they cross-threaded.
Did a bit of reading and found this is a common thing with Stoptech. Here are some examples
https://www.m3post.com/forums/showpo...postcount=7109
https://www.bimmerforums.com/forum/s...-screw-leaking
https://www.svtperformance.com/threa...aking.1067447/
It seems like the issue is that it's difficult to get a good seal between steel bleeder screws and aluminum calipers, and the quality control from Stoptech on that isn't good.
I've read about two fixes that have worked for people. One guy removed the threads from a spare bleeder screw to turn it into a sort of plug, then used a small amount of lapping compound on it to correct the mating surface on the caliper. Another person said installing Speed Bleeders solved the problem. That makes sense because the included check valve would have a small amount of resistance, which would probably be enough to block the bit of fluid seeping out past the bottom of the bleeder.
I'm going to try these solutions, starting with lapping the surface. Would rather not switch to speed bleeders, because I like to gravity bleed, which they would prevent. In the meantime, thought I'd post this up in case it helps someone's decision on which BBK to buy. Or if you do buy Stoptech, you might want to proactively deal with this, before the brake fluid ruins the paint on your caliper.
When I contacted Stoptech, they first claimed that this was just residual fluid from the top of the screw coming out, despite the fact that I had said I checked for that. (It's definitely not that. Go out for a session and there are drips down the calipers. Wipe them off, blow out the tops of the screws, go out for another session. New set of drips.) Then, they claimed it was installation error. The only way to install bleeder screws wrong though would be to over- or under-torque them, which I didn't do. Nor are they cross-threaded.
Did a bit of reading and found this is a common thing with Stoptech. Here are some examples
https://www.m3post.com/forums/showpo...postcount=7109
https://www.bimmerforums.com/forum/s...-screw-leaking
https://www.svtperformance.com/threa...aking.1067447/
It seems like the issue is that it's difficult to get a good seal between steel bleeder screws and aluminum calipers, and the quality control from Stoptech on that isn't good.
I've read about two fixes that have worked for people. One guy removed the threads from a spare bleeder screw to turn it into a sort of plug, then used a small amount of lapping compound on it to correct the mating surface on the caliper. Another person said installing Speed Bleeders solved the problem. That makes sense because the included check valve would have a small amount of resistance, which would probably be enough to block the bit of fluid seeping out past the bottom of the bleeder.
I'm going to try these solutions, starting with lapping the surface. Would rather not switch to speed bleeders, because I like to gravity bleed, which they would prevent. In the meantime, thought I'd post this up in case it helps someone's decision on which BBK to buy. Or if you do buy Stoptech, you might want to proactively deal with this, before the brake fluid ruins the paint on your caliper.
05-10-2019, 05:26 AM
#2
Community Organizer
So this happened on my prototype set of STR-43s. I just removed them, cleaned the bleeder, flushed out the caliper, and reassembled. Never had an issue again. Even when it was happening, it only leaked a tiny bit and I just torqued it down a quarter turn, which seemed to solve it.
05-10-2019, 10:13 AM
#3
So this happened on my prototype set of STR-43s. I just removed them, cleaned the bleeder, flushed out the caliper, and reassembled. Never had an issue again. Even when it was happening, it only leaked a tiny bit and I just torqued it down a quarter turn, which seemed to solve it.
05-10-2019, 11:50 AM
#5
Sure you didn't mushroom the bleed screw seat?
05-10-2019, 12:12 PM
#6
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05-10-2019, 12:51 PM
#8
Yeah, I did convince stoptech to at least send a new set of screws, so I'm planning to try that once they arrive. Not super hopeful from what I've read (the issue is usually with the seat, not the screw), but it's worth trying.
05-10-2019, 01:29 PM
#9
Loctite 542 maybe
05-10-2019, 01:35 PM
#10
Install the Wilwood style double part bleeder - the outer is brass and threads into your current caliper thread with some threadlock/sealant, then the smaller steel inner is used for bleeding the caliper. Should be a cheap fix, I like putting them on calipers that don't run them anyway because a siezed/snapped bleed nipple is an easy fix - undo the brass bit and replace the assembly.