Driver Rear Caliper keeps failing

[8bitmime]

I've been taking my 05 GT to the track for about a year and I keep blowing out the seal for the drivers side rear caliper. I've tried everything I can think of:

• New calipers, remanufactured calipers that have been tested, replaced bolts, caliper brackets, the works
• Removing the pin from the pad in case it's not aligned properly
• More thermal grease, less thermal grease, better thermal grease
• Different pads (Carbotech XP8, Carbotech XP10, G-Loc)
• GT500 14" conversion
• Removing the dust shields
• Checked to make sure it's plugged into the right spot on the ABS distribution block

During my last HPDE in June, the caliper and rotor were ~600 degrees (IR thermometer) on both sides. It always leaks at the piston. I'm running Motul 600 with 200TW 275/30R18 tires in the back.

Is there anything else I can try / check? The only thing I've got left is to try removing ABS using a delete block. I'm about to change the caliper for the seventh time (thank goodness for "lifetime warranties").

 

[JAJ]

I've been taking my 05 GT to the track for about a year and I keep blowing out the seal for the drivers side rear caliper. I've tried everything I can think of:

• New calipers, remanufactured calipers that have been tested, replaced bolts, caliper brackets, the works
• Removing the pin from the pad in case it's not aligned properly
• More thermal grease, less thermal grease, better thermal grease
• Different pads (Carbotech XP8, Carbotech XP10, G-Loc)
• GT500 14" conversion
• Removing the dust shields
• Checked to make sure it's plugged into the right spot on the ABS distribution block

During my last HPDE in June, the caliper and rotor were ~600 degrees (IR thermometer) on both sides. It always leaks at the piston. I'm running Motul 600 with 200TW 275/30R18 tires in the back.

Is there anything else I can try / check? The only thing I've got left is to try removing ABS using a delete block. I'm about to change the caliper for the seventh time (thank goodness for "lifetime warranties").

It's the kind of problem that a sticking ABS valve or defective control module might cause. Something is pressurizing the rear brakes and keeping them that way. Other than that, I'm out of suggestions.

 

[PatientZero]

Check your ebrake cables

 

[EF1]

Are you running with traction control on or off?

 

[JDee]

I run with full nannies on and I've never had any brake issues. Yet. (touches wood).
I do this because it helps me avoid overdriving the car, if the light flickers, I'm doing something wrong, sliding tires don't grip all that well.
I'm hitting 70 this year (when and how the hell did that happen?) and I need all the help I can get!

 

[EF1]

I am not sure on the 05 but with my 2011 the traction control applies rear brake under certain conditions when it thinks you are going to lose traction. It causes the rear brakes to heat up and wear very quickly on the track and the idiot lights never come on. On my car it affects the drivers sold more than the passenger side for some reason.

 

[Norm Peterson]

I am not sure on the 05 but with my 2011 the traction control applies rear brake under certain conditions when it thinks you are going to lose traction. It causes the rear brakes to heat up and wear very quickly on the track and the idiot lights never come on. On my car it affects the drivers sold more than the passenger side for some reason.

That actually makes a little sense in terms of directional stability. Braking the left-rear individually would tend to keep the forward traction forces at the contact patches in better balance, given that it's the right-rear that inherently wants to spin first while the left rear still has grip to build still more acceleration tractive force with.


Norm

 

[8bitmime]

Are you running with traction control on or off?

I run with TCS off unless it's raining.

Check your ebrake cables

I think the ebrake is okay. There's no drag when the car is up and it engages and disengages smoothly. I'll take another look today when I have it all apart today.

It's the kind of problem that a sticking ABS valve or defective control module might cause. Something is pressurizing the rear brakes and keeping them that way. Other than that, I'm out of suggestions

How do you check something like that? I'm not getting any codes or anything.
Are there mechanical things I can inspect or would checking the caliper pressure show a problem there?
New valve assemblies (PN 4R33-2C353-AG) don't seem to be for sale so if I replace that I'll have to go with a used part.

I guess that's another point for deleting ABS. I'm considering this delete block:

prbmachining-absdeletemanifolds.com

 

[Grant 302]

)

• GT500 14" conversion

OEM or aftermarket?

 

[8bitmime]

OEM or aftermarket?

OEM brackets, the rotors were Stoptech/Centric for the 13/14 GT500.

 

[KazarS197]

Welcome to TMO! if you do a vehicle profile with all your mods and stuff that's still stock it may help others assist with diagnosing. Plus we love mustang photos! What calipers, pads and rotors are up front? How are the front pads wearing compared to back? Are the rear brakes being over worked? 2005 - has the brake system been completely flushed including the abs module bleed?

 

[DipstickMotorsports]

All the remans fail. Only get OEM. Its because they sandblast the remans and they will leak from the pistons with any track duty. Also look into rear Girodisc to help with heat. I would crack the centric and oem replacement rotors in one event. Since I put the Girodisc on rear I've run 15 events on them and they haven't cracked yet. And the heat dissipation is forsure beneficial to those junky rear calipers.

 

[Grant 302]

All the remans fail. Only get OEM.

^This.

OEM brackets, the rotors were Stoptech/Centric for the 13/14 GT500.

What about the calipers?

 

[8bitmime]

Welcome to TMO! if you do a vehicle profile with all your mods and stuff that's still stock it may help others assist with diagnosing. Plus we love mustang photos! What calipers, pads and rotors are up front? How are the front pads wearing compared to back? Are the rear brakes being over worked? 2005 - has the brake system been completely flushed including the abs module bleed?

Thanks. I just put one up. Up front the calipers are the same ones the car came with in 2005, as is the other rear caliper. I have 6 piston Brembos but my wheels don't clear them. I have new wheels on order.
The front pads are wearing about twice as fast as the rears and when I replaced the rotors and pads in June they were cooked - I'll need to put some ducting or something up there.

The ABS module bleed is probably a good catch - I've had the system flushed a few times now but I wasn't aware of the ABS module bleed and it's possible that the shop that did it wasn't aware of that process. I bought a replacement ABS pump so I'll make sure I do that when I install it.

All the remans fail. Only get OEM. Its because they sandblast the remans and they will leak from the pistons with any track duty. Also look into rear Girodisc to help with heat. I would crack the centric and oem replacement rotors in one event. Since I put the Girodisc on rear I've run 15 events on them and they haven't cracked yet. And the heat dissipation is forsure beneficial to those junky rear calipers.

I'll put a set of OEMs on next. I didn't know the Girodiscs held up better - I just thought they were lighter. I'll order a set.

^This.

What about the calipers?

The blown caliper is a remanufactured one from OReilly (this is the sixth caliper and the third one replaced under warranty). I'm going to put a new OEM one on.

 

[JAJ]

All the remans fail. Only get OEM. Its because they sandblast the remans and they will leak from the pistons with any track duty. Also look into rear Girodisc to help with heat. I would crack the centric and oem replacement rotors in one event. Since I put the Girodisc on rear I've run 15 events on them and they haven't cracked yet. And the heat dissipation is for sure beneficial to those junky rear calipers.

Hmmm... that car in your sig looks eerily familiar... as I said yesterday, good catch in turn 12...

To the OP, pay attention to @80KM2E's advice here - he's got his brakes dialed in!

 

[ZOO]

I logged in today to post this exact same question. Some good leads here -- I'll start with a new caliper.

 

[DipstickMotorsports]

I logged in today to post this exact same question. Some good leads here -- I'll start with a new caliper.

Surprisingly enough I've yet to replace my oem rear calipers. Still on the original ones with 110k KM on them. Haven't had dust boots on them forever either. This off season I need to source some OEM replacements just to be safe. They are becoming hard to find and are expensive. Might try some scrap yards too.
A friend of mine replaced his with the remans and only does a few events a year and had them leak twice now. Not worth the time, missing events, ruining an event, and the safety even if the remans are 1/10th the cost of new OEM Ford units.

Does anyone know if Ford makes a rebuild kit for seals? I know rock auto has some from centric, but I don't trust any of their junk products- the seals they manufacture are likely cut out using dull kitchen scissors... Might not even be worth the effort to try and take them apart and rebuild anyways if you can just buy the whole caliper from Ford and be on your way without as much time and mess.

Wish someone made a billet bracket or upgraded pistons, or anything to make those rear calipers even slightly better. They are such an eyesore.

 

[DipstickMotorsports]

Hmmm... that car in your sig looks eerily familiar... as I said yesterday, good catch in turn 12...

To the OP, pay attention to @80KM2E's advice here - he's got his brakes dialed in!

Thanks. Nice seeing you out there at Area 27, we got pretty lucky with the weather. You missed the afternoon, but someone dumped coolant from 1-3 which basically ruined the rest of the day anyways..

 

[xr7]

Surprisingly enough I've yet to replace my oem rear calipers. Still on the original ones with 110k KM on them. Haven't had dust boots on them forever either. This off season I need to source some OEM replacements just to be safe. They are becoming hard to find and are expensive. Might try some scrap yards too.
A friend of mine replaced his with the remans and only does a few events a year and had them leak twice now. Not worth the time, missing events, ruining an event, and the safety even if the remans are 1/10th the cost of new OEM Ford units.

Does anyone know if Ford makes a rebuild kit for seals? I know rock auto has some from centric, but I don't trust any of their junk products- the seals they manufacture are likely cut out using dull kitchen scissors... Might not even be worth the effort to try and take them apart and rebuild anyways if you can just buy the whole caliper from Ford and be on your way without as much time and mess.

Wish someone made a billet bracket or upgraded pistons, or anything to make those rear calipers even slightly better. They are such an eyesore.

If you want a massive stiff caliper mounting bracket there is the 13-14 GT500 bracket. It is cast iron, requires the axles to be pulled and you also need the larger rear rotors. The original calipers and hoses fit without mods.

 

[DipstickMotorsports]

If you want a massive stiff caliper mounting bracket there is the 13-14 GT500 bracket. It is cast iron, requires the axles to be pulled and you also need the larger rear rotors. The original calipers and hoses fit without mods.

I'm not interested in the rear GT500 set up solely because the rotor choices are non- existent. A few including myself have reached out to Girodisc to make rotors in that size, but the market is so tiny for it. They'll do it if someone shells out around 10k for the tooling and a 10+ minimum order which no in their right mind is going to do in this camp, haha. And imo, having good rotors is more important than size. Moving to the rear Girodisc in the oem size has helped tremendously for heat back there which is also going to help out with the caliper. I think the only major upgrade would be that camber axle from cortex, but that is some serious $$ especially if it's a non competition vehicle. I believe it would pay dividends in rear tire wear, the rear caliper would work better with removing axle slop, less pad taper and uneven wear and more consistent rear brake performance. A lot of benefits with that unit, so the cost does start to seem pretty reasonable actually.

I know blowfish used to make some billet brackets for both the GT500 and the oem size. But they seem to have closed up. Don't know if this would make much of difference other than a tiny bit of unsprung weight benefit and also removing some of the orange rusty eyesore back there even though it's behind.