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Track experience with S550 6 Piston?

qtipconnoisseur

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I have the Brembo Pro Grand Am brake kit. I go through a 25mm pad in 4 -5 track days. I run Pagid RST-1s. If I switched to something like an RSL-1, I would probably get better pad life, but lower initial bit a level of friction.

The people I know running the S550 brakes tend to get about the same pad life. The S550 pad has a much larger area than the Grand Am pad but isn't as thick.

I believe @captdistraction is running the Kohr brake booster and master. Comparing a couple of different S197s with the Kohr booster and the factory booster and master, my observations is that the Kohr has a longer, softer, and more progressive pedal vs. the factory S197 booster and master. If you make the swap, I would try the factory booster setup first and then decide if you want a more progressive pedal.

Replacement rotor costs should also be part of your assessment. With the S550 calipers, you can run factory rotors which are about $120 each. In comparison, a set of rotors and mounting hardware for the Grand Am kit (380mm x 35mm) will run you about $1,200. I go through one to two sets of rotors each year.
Thanks for the info! Yet another testament to the cost-effectiveness of the s550 calipers. I've heard the the stock boss booster/master paired with the s550 calipers gives slightly more modulation than stock. I'm a big fan of the stock brake feel (with ss lines, good pads) so a similar feel is a positive in my book. One worry I have with the s550 calipers is the reports of knockback, which doesn't seem to be entirely cured by a 2pc rotor, which also could drive up the cost of the s550 option. I could go for those calipers and cheapo 1pc rotors if the knockback isn't too bad.

To elaborate further, My Brembo set up came from @JAJ.
He ran them on his GT-500 on the street and some track days, then passed them to me and I have about 5 track days on them and I'm ready to start the SCCA season on:

(drum roll please)
The same pads.

Yes, I am still on the stock pads that came in the kit and they still have about 70% left. I believe it's a ST42 compound. The brakes are deep annulus, so they are not only long pads but very wide and thick. 20mm thick. Very happy with these brakes.
That's hilarious and awesome that your "take-off" pads are still good. Another point for race brakes. Feels like I'm ping-ponging back and forth between these brake options.
 

captdistraction

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Thanks for the info! Yet another testament to the cost-effectiveness of the s550 calipers. I've heard the the stock boss booster/master paired with the s550 calipers gives slightly more modulation than stock. I'm a big fan of the stock brake feel (with ss lines, good pads) so a similar feel is a positive in my book. One worry I have with the s550 calipers is the reports of knockback, which doesn't seem to be entirely cured by a 2pc rotor, which also could drive up the cost of the s550 option. I could go for those calipers and cheapo 1pc rotors if the knockback isn't too bad.


That's hilarious and awesome that your "take-off" pads are still good. Another point for race brakes. Feels like I'm ping-ponging back and forth between these brake options.
I should state that I still have the anti rattle clips in my girodiscs. When I replace the rings I’ll remove those and that should settle the knockback some more. Also I tend to see it most on fresh Hoosiers, where the grip levels are highest and only on particular courses. There’s other options like anti-knockback springs but I’ve not been bothered enough to explore.


Sent from my iPhone using Tapatalk
 

Fabman

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Another point for race brakes. Feels like I'm ping-ponging back and forth between these brake options.
I have no direct experience with the S550 calipers but I've heard good things.
Had I not come across these Brembo Race brakes I would have gone with the s550 setup.
From a cost standpoint it's almost a no brainer.
 

JAJ

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...One worry I have with the s550 calipers is the reports of knockback, which doesn't seem to be entirely cured by a 2pc rotor...

...your "take-off" pads are still good...
Those pads were awesome.

Knockback happens when you have a fixed caliper (not the base model floaters) and there's flex or wheel bearing play at the wheel hub. Movement at the hub allows the rotor to move off-centre in the caliper, pushing the pistons back into their bores. If you have floating calipers, it doesn't matter what the hub does - the calipers move with the rotor and there's no knockback.

This is important because the base Mustangs have floating front calipers, and fixed calipers are available as an upgrade (sport packages, etc). Even though these cars have become more capable over the years, it appears that Ford hasn't stiffened up the front hubs to control knockback. At least they didn't until they started making Mustangs with high lateral G capability that were likely to actually spend time at the track.

The GT350 has a massive forged aluminum front knuckle with a bolt-on hub borrowed from the rear axle of an SUV, rather than the simpler forged iron knuckle with a threaded spindle used on the rest of the Mustang S197 or S550 models. The GT350 brakes have the best feel of any of the Mustangs I've driven and you don't get that unless the whole assembly is super-rigid. I'm speculating here, but I think Ford changed the knuckle and bearing assembly to get knockback under control. They had other reasons too, but I'm sure that making the whole thing stiffer was a major goal.

So, if you're trying to control knockback on a Boss 302, your best bet is to change the front wheel bearings regularly and make sure that the spindle isn't worn and that the hub nut is properly torqued.
 

qtipconnoisseur

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Those pads were awesome.

Knockback happens when you have a fixed caliper (not the base model floaters) and there's flex or wheel bearing play at the wheel hub. Movement at the hub allows the rotor to move off-centre in the caliper, pushing the pistons back into their bores. If you have floating calipers, it doesn't matter what the hub does - the calipers move with the rotor and there's no knockback.

This is important because the base Mustangs have floating front calipers, and fixed calipers are available as an upgrade (sport packages, etc). Even though these cars have become more capable over the years, it appears that Ford hasn't stiffened up the front hubs to control knockback. At least they didn't until they started making Mustangs with high lateral G capability that were likely to actually spend time at the track.

The GT350 has a massive forged aluminum front knuckle with a bolt-on hub borrowed from the rear axle of an SUV, rather than the simpler forged iron knuckle with a threaded spindle used on the rest of the Mustang S197 or S550 models. The GT350 brakes have the best feel of any of the Mustangs I've driven and you don't get that unless the whole assembly is super-rigid. I'm speculating here, but I think Ford changed the knuckle and bearing assembly to get knockback under control. They had other reasons too, but I'm sure that making the whole thing stiffer was a major goal.

So, if you're trying to control knockback on a Boss 302, your best bet is to change the front wheel bearings regularly and make sure that the spindle isn't worn and that the hub nut is properly torqued.
Hmm I knew about how the hub affects knockback, and to treat them as consumable on our cars, but not why. I had just assumed I was learning about another wear item for all cars that see some track time. I hadn't even considered that they weren't designed to handle extended high grip levels. Thank you for that information. Now wishing we could somehow retrofit beefier hubs on the s197s!
 

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