Put big brakes on your Ls1 F body cheap, video!

Knowklew

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Very nice write up/video Alex!
 

Knowklew

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I think Alex said he has 750 into his setup.
 

Sprayed 01

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Yes about $750. Then you can sell off your ls1 brakes to someone with an lt1
 

sickmint79

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nice video, music sometimes a little too loud.

[MENTION=2449]ilikemtb999[/MENTION] harasses me and says everyone knows and fixes this - however the video seems to ignore anything with brake bias and the real possibility of making the brakes perform worse.
 

Sprayed 01

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nice video, music sometimes a little too loud.

[MENTION=2449]ilikemtb999[/MENTION] harasses me and says everyone knows and fixes this - however the video seems to ignore anything with brake bias and the real possibility of making the brakes perform worse.
Thanks!
Are you referring to the possibility of having too much braking force in the front now?

The first body cars have been know to have a brake bias in the rear stock. This really evens it's out nicely.

Fortunately I'm not the first to do the mod. It's a pretty proven upgrade
 

ilikemtb999

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He's referencing the bias moving towards the rear and you not using an adjustable proportioning valve to dial it back to a more front bias setup.
 

Sprayed 01

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Hmm, I don't think that's the case here. Maybe with some other setups. I could see putting large brakes in the rear and not the front.

Either way it works great, hope the video helps
 

sickmint79

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Thanks!
Are you referring to the possibility of having too much braking force in the front now?

The first body cars have been know to have a brake bias in the rear stock. This really evens it's out nicely.
i ran numbers for BRZs and WRXs recently and the bias was pushed a ton forward for ATS caliper swaps. on the kits actually designed for the car the bias stays the same, or goes a little to a lot more towards the rear, with the expectation of more aero being present as it is moved towards the rear.

i'm under the impression that in general most cars err towards high ends of front and most BBKs start with a modest push towards the rear. the ATS caliper swaps on the subarus pushed bias a lot to the front though, which has negative consequences - those brakes do more now, so more heat (although they dissipate it better) and the tires also do more - if factory settings got it right, that probably means the rear brakes are doing too little now, and your braking distance is actually worse.

this car seems odd since the front rotors are smaller than the rear? i looked for info and did find a lot here: GM Brake Upgrade Option Measurements - Thirdgen F-body Brake Upgrade
i put them into this calculator: Bias Calculator

rear: 12.01 rotor and 1.77165 inch piston
front stock: 11.92 rotor and 2x 1.75 inch pistons
bias: 0.630 or 1.7 F:R ratio

front cts-v and camaro rotors: 14.37 rotor and 1.5748 + 1.73228 pistons
bias: 0.702 or 2.35 F:R ratio

(.702-0.630)/.63 = 11.4% deviation from stock towards front (highest i've calculated!)

for reference, here are values for my car - everything below the OEM line is a kit actually designed for the car.



that's actually a really huge change. if it's actually much better i would think GM fucked up really bad in the first place. i trust stoptech to find good values and this kit appears to be the right one for this car https://www.summitracing.com/parts/sph-83-183460071 however it doesn't have any piston info so we can't calculate what bias they ended up with. i e-mailed them to ask though.

Fortunately I'm not the first to do the mod. It's a pretty proven upgrade
certainly the parts fit but that doesn't mean the car is braking better than when it started. check this out from a couple weekends ago; same model car, same model BBK designed for it, same front pad compound (polymatrix b):





car 1: minimum 10 track days on these rotors. guy is hard on brakes, he is harder than me on them, and is turning laps 2 seconds faster than me. this pic was taken at the end of the day.

car 2: this guy is newer and turning laps 9 seconds slower than me. this was near the end of the day but not the end. he also sat out one session, and it was wet and drizzly for 2. this is the FIRST track day on these rotors. look how much they wore already! also note these rotors are only 2 weeks old - the prior set had 2 (cold/wet) track days on them and like a year of street driving, but the slots were completely gone. he also said his braking never felt quite right while driving on the track.

the difference is, car 1 has the rear kit wilwood made for this car, and car 2 does not. even with a fairly aggressive pad in the rear (carbotech xp10, i personally run xp8 front and rear) this car still has a ton of front bias. it doesn't look like wilwood ever designed this kit to be run front only. front only on this car deviated 4.45% towards the front. front and rear is -7.17% towards the rear. i think that is probably too much without a big wang, there are more modest rear kits from RR racing for this car in the rear though and i think my buddy needs to pick up one to fix his bias. note this is kind of weird/wrong to do anyway - he doesn't need a rear BBK to dissipate heat... he needs one just to fix the problems this front BBK created.
 
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SHARKBITEATTACK

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Damnit I just put 315s on my car and a catback earlier this year. 4:10 diff gears are coming soon. I've got the mod bug and would love to do this mod considering how cheap it is. But at the same time I'm always tempted to sell the fbody for a vette.
 

sickmint79

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i contacted stoptech and for kit 83.183.4600.71 they use 38 and 42 mm piston sizes or 1.49606 and 1.65354. this is on a 13.0709" rotor.

this came out to be a front bias of 0.632 vs 0.630 on the calculator so virtually no change at all.
 

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