seanof30306

iTrader: (4)

this is actually two questions, but they have to be done simultaneously, so i'm going to combine them.

89 formula firebird ws6. 305 tbi. mods in sig.

brakes suck. need an upgrade.

have a set of 4th gen slp firehawk rims i plan to use. havent done so yet because there's a good set of michelin pilots on the stock rims and i wanted to get my use out of them.

did a 3.42 posi upgrade this summer. considered going to a 4th gen rear at that time but put a slp takeoff in the stock rearend instead, again, because of the tires.

came across a great deal on a rear end out of a 98 z28. the guy says it has ls1 brakes on it. i've realized this swap makes sense if, for no other reason, than that i can get the whole rear end for not much more than the wheel adapters would cost.

i've read the tech article on the reaarend swap, but i still have a few questions:

1. i've heard the rear rotors are prone to warping. i remember seeing something in a thread on here awhile back that there was an upgrade rotor commonly available. can't remember what it was.

2. what would be the biggest tire i can fit under the wheelwell with this wheel/rearend combination.

the same guy also has the front brakes off the same car for sale cheap. i've read the thread on ls1 fron brakes, but still have a few questions about that.

1. is this the best way to go, or would i be better off with c5 brakes?

2. where do i get the brackets for either the ls1 or c5 brake swap?

3. will the ls1 or c5 brake swap change the track width on the front?

seanof30306

iTrader: (4)

help! help!

Justins86bird

I'll try

1. Alot of 4th gen guys warped the stock rears I hear. I haven't heard any anyone who converted a 3rd gen to LS1 rears warping a rotor. The LS1 rotors are thicker then the 3rd gen rotors. AIMCO discs from Autozone are less prone to warping. You could also get more expensive ones like Baer Eradispeeds.


1a. The C5s are bigger then the LS1 brakes and I dont think anyone yet sells a LS1 bracket. But you have to run 17"s for the C5s to clear.

2a. The C5 brakets are made by Todd, his email in in the link
http://82lt1.cz28.com/brakes/brakes.html

3a. Yes, approx 1/4" each side so approx 1/2" total.

seanof30306

iTrader: (4)

thanks, justin.

let me make sure i've got everything .....

1. 4th gen rear will work .... aimco rotors to replace stockers if they warp.

2. ls1 front brackets aren't available, but c5s are (c5s are a bit better/bigger anyway, aren't they?). the 4th gen slp firehawk rims i'm going to are 17 x 9.5, so they should be ok, right?.

3. the c-5 brakes will cause my track to be about 1/2" wider at the front.

is there anything else i need to know about this swap?

thanks

Justins86bird

If you have rear drums now, you'll prolly need a 4wh disc prop valve. The 4th gen Firehawks should clear, but who knows for sure till it's tried.

ebmiller88

iTrader: (7)

Sean, sent you a PM also but I'll try to answer your questions in the thread:

I've never heard of the REAR rotors warping, just the front. I doubt the rears would get that much of a work out to cause them to warp;

Tire size will depend on wheel size and offset. There was a thread a while back on tire sizes for third gens, maybe a search would turn something up, but I'd think a 275 would be about the biggest without any mods to the chassis;

The question on whether to go with C5s or LS1s: What size wheel are you going to use? If you want to use the C5 brakes, you MUST go up to a 17" wheel. If you want to use a 17" wheel, then take your pick as all kits will work with that big of a wheel. Both the C4s and LS1s will fit a 16" wheel, and the C4s will fit a 15" wheel. The C5s and LS1s are essentially the same but the C5s force you to a 17" wheel. They both use the same size pads and have the same rotor thickness.

Todd (toddlsf) has the C5 brackets, and I have a source for the LS1 brackets, just shoot me a line;

All the front brake upgrades (LS1, C5, C4) will increase your overall track width about 1/2"-3/4" depending on rotor hat thickness.


Ed