S197 3V Brake Pedal Travel

[BlueGTGS]

I could actually see the pad and piston moving in and out while someone was pressing and releasing the pedal. Dont think its sticking, just not staying in position.

 

[Grant 302]

How should this be corrected, if the pistons are sliding back in/retracting, should the caliper be replaced?

Is the pad in the problem side/area tapered?

 

[BlueGTGS]

On problem side, both pads are tapered. both are thiner on the outside area, looks like they may have been binding. They were hard to slide out and there was alot of tire rubber stuck in there. Suspect that the brake cooling ducts picked up some trash a dumped it in there. I'm going to get everything disassembled and cleaned up. Also install inlet screens on the ducts.

 

[Grant 302]

I strongly suggest replacing the calipers in both sides.

Without getting into any discussion/arguments over the cost, value, cause or whatever reason(s) to rebuild that others may suggest...that is what I’d do with these.

I see it as a good time to upgrade, if that’s feasible for you. The ‘15+ parts seem reasonable to me if you aren’t firm on sticking with 14”.

 

[BlueGTGS]

I'm totally onboard with the upgrade. Right thing to do. Will/would this require any changes with the master cylinder or brake booster.

 

[captdistraction]

No changes to master/booster - I went down that road chasing a firmer pedal, but there's nothing to do there. I actually like the pedal now and I've been racing the S550 setup for about 4 years now, and I'd put it up against any of the cars running motorsports brakes. the big advantage to the guys running the $7k kits is the pads last a LOT longer, but I can go through lots of boxes of pads before reaching that number.

You just need the 2015-2020 calipers, a pair of 13-14 GT500 rotors (I prefer floating, but that's $), and a set of stainless lines and your choice of brake pad. I used to run a small hardened shim to center the caliper, but the offset isn't much and hasn't affected anything for me without. @OPMustang Tim is my go-to for this stuff.

 

[BlueGTGS]

Rear good with stock/OEM components with appropriate pads to support the front?

 

[captdistraction]

yes, there's no need to change the rears on these cars - the balance is well maintained. I run the larger 13.8" rotor from the GT500, but its really just giving me a bit more pad longevity - I've tried everything from street pads out back to race pads (in racing conditions on slicks) and the balance has been favorable.

 

[BlueGTGS]

Sounds good, got a plan moving forward. Thanks for all the input.

 

[OPMustang Tim]

On problem side, both pads are tapered. both are thiner on the outside area, looks like they may have been binding. They were hard to slide out and there was alot of tire rubber stuck in there. Suspect that the brake cooling ducts picked up some trash a dumped it in there. I'm going to get everything disassembled and cleaned up. Also install inlet screens on the ducts.

Check the pads to see if the backing plates are still flat, it sounds like you had a lot of pickup on that side. If the pads do not move freely in the calipers that can give you a problem. When the pad and calipers get warm they grow so if you have a pad that is slightly tight in the caliper body, it can get stuck, pad taper is normal for non racing brake systems, rotating pads side to side can help even out wear. Make sure the pins are not worn, the locating pads inside the caliper are smooth (where the pad fits into) We do recommend using the anti-rattle clip so the pads always have tension on them, one hard curb jump and knock the pad out of position and in the next braking zone lock that pad up in the caliper or even bend the pad. Depending on the track one side can also run cooler or hotter depending on braking demands, left vs right turns. Remember the outside tire will always carry more speed, so if a track puts a lot on one side vs a balance of left and rights, pads will see more wear and heat on the busier side. Typically the inside pad will wear faster than the outside, some of this is due to trapped heat in the wheel well, ducted cooling works but the outside rotor surface will tend to run cooler because its in open air. The other reason the inner pad can wear more is due to the leverage of the caliper mounting. The inner pad is closer to the mounting point, under heavy braking the caliper will deflect, the outer pad will do less work because it is further away and sees the most deflection. Race brake systems have stiff calipers that are radial mounted for this very reason, this is why the GT350 brakes are so good, the upright was designed for radial mounting it deflects very little. Even on motorsport brake systems the adapter bracket needs to be very stiff to maintain the caliper position, but it is only as strong as the upright.

OE Brakes work very well and you can use a lot of pads through a set of $200 OEM calipers before you reach the cost of a $1400 caliper. This is what @captdistraction points out, does his system have limits? yes but knowing how to work around them and exceed or match racing brakes keeps the cost of racing down and everyone on the planet makes a brake pad in that shape.

 

[Norm Peterson]

On problem side, both pads are tapered. both are thiner on the outside area, looks like they may have been binding. They were hard to slide out and there was alot of tire rubber stuck in there. Suspect that the brake cooling ducts picked up some trash a dumped it in there. I'm going to get everything disassembled and cleaned up. Also install inlet screens on the ducts.

Thinner on the outside area - do you mean at the rotor OD here as opposed to near the rotor hat diameter? If so, that sounds like the caliper may be spreading under heavy braking. Low-mu pads would tend to exaggerate this (you need greater caliper piston force to achieve the same amount of braking torque). Tall tires would also cause greater piston forces for the same amount of deceleration. Sticky tires would allow you to demand higher braking torques and pad to rotor / caliper-spreading forces.


Norm

 

[BlueGTGS]

Thinner on the od of the rotor. Found that both calipers are experiencing the same issue as far as pads thinner on the rotor od. Last two events are the first time i have run sticky tires (200tw) and r16 pads. Past was 340tw and r10s. Makes sense that calipers are spreading. Thanks for the input, everything keeps leading to brake upgrade or slowdown.

 

[Norm Peterson]

My bad for not proofreading my previous post thoroughly enough. It's been fixed, obviously so, I hope.

Sorry.


Norm