Ok I did a little search and the only thing I could find on the differences between the two setups was the ebrake. I thought the LS1 rears were larger than the lt1? Since im in the process of swapping out my rear for a 4thgren rear, are the LS1s that much bigger to really make a difference? thanks- TOT

 

the LT1 rears are abit wider.... i found that they are 3.8 inches wider hub to hub than third gen rears while the Ls1 is about 3.5 inches wider hub to hub than thirdgens


also the LT1 uses the same rear brakes as the 89 up Fbody PBR style brakes.
the LS1 uses bigger rotors at 12 inch i think over the 11 inch LT1's. different calipers and such.

check this thread i made for 4th gen swaps... its got some good info in it that i found thru hours of searching

https://www.thirdgen.org/techbb2/sho...hreadid=336190

 

All 4th gen rears, LT1 or LS1, are the same width, and both are wider than a 3rd gen rear by about 2 inches per side. Besides the e-brake differences are the differences in rear caliper design and whether they have TCS, ABS, or both.

Ed

 

Ya I knew the width was more than our thirds, I have zr1 wheels on there now so im trying to kill three birds with one stone. bigger brakes, fix rear noise, and get rid of needing spacers. so if I understand you right my car as it sits (91) has the same brakes as a 97. and only 98+ has the 12" brakes.

could I use a pre 98 rear with post 98 brakes? without any modifications? thanks- TOT

 

as far as REAR brakes go:
97+ got the later brakes (aka LS1 style)
93-96 got the "LT1 brakes".. these are ALMOST identical to the late 3rdgen PBR rears.

 

thats what I thought. I guess its kinda pointless to swap out to a pre 96 rear.

2nd question I know I can pick up a couple 4th rears locally for 200-250 but they dont have ANY brake hardware, can I take my existing aluminum calipers and hardware and bolt it to the 4th gen rear?

 

Yes, same as the '97 with a minor change to the e-brake cable mounting bracket..otherwise identical;

Yes, you'd just have to swap to LS1 backing plates and brakes onto the LT1 rear.

Ed

 

Super.. big help guys! thanks - TOT

 

i wouldnt say pointless..

if you ever want to fit 15" drag rims to the rear of your car, you dont want the LS1 rear brakes.... unless you dont mind grinding the crap out of calipers.

 

I believe that Orr89RocZ is correct. The LT1 axle is marginly wider than the LS1s.

A friend and myself converted our 92 RSs to rear disks. He used LS1s and I used LT1s. The LS1s bolted on directly, but the LT1s required spacers to move the rotors further out to work with the caliper.

 

In your opinion do you think its worth having the ls1's over the lt1's?

 

Thanks for correcting me...I've been wrong before.

Ed

 

IMHO, it depends to some extent on what brakes you have up front.

The piston diameter in the LS1 rear caliper is 4mm larger than the '89-'97 PBRs, also the rotor is 0.3" larger in diameter -- so the LS1 setup shifts the brake bias about 5% more to the rear than what you'd have with the LT1 calipers.

Personally, I think the LS1 rears are balanced best with either the LS1 front caliper on a 12" rotor, or the 13" C4 HD or C5 brakes up front. LT1 rears don't quite do their full share of the work if combined with any of those three front setups.

OTOH, 1LE fronts, or C4's cut down to 12" (e.g. Baer HD), go better with the '89-'97 rear setup. The way the piston sizes compare, there's a little too much rear bias with the LS1 rear calipers, although this can be corrected via the proportioning valve.

Thermally, the LS1 rear rotor is better, but both seem to hold up just fine in most apps, so I'd argue that overall balance is more important if you have a choice between the two rear setups.

HTH,

 

great info and thats exactly what I was looking for. Im in the proccess of doing the C5 swap im the front. thanks again for the info!

 

I milled .075" off of the caliper mounting bracket instead. works great.

It was a HUGE improvement over the stock '82 rear disks.

Here is the whole story...

https://www.thirdgen.org/techbb2/sho...hreadid=326318

 

Bringing this back. I ended up getting a sweet deal on a 95 4th gen rear, but all it has is the brackets for the lt1 brakes. I have a set of C5 rear calipers sitting here and want to know If I can modify my LT1 brake backing plate or do I need LS1 backing plates? or I think I saw a post were Ed said he had C5 rear backing plates that work. also I havent seen to many posts about the rear c5 swap, does anyone have any detailed pics? thanks for the help - TOT

 

ok after searching I found a couple threads that addressed the c5 rotors and calipers. so could someone just answer this

If I used a c5 caliper with LS1 backing plates and rotors. I would still have and emergency brake?

 

You will still have the e-brake, you never touched it right? But I'm not sure if the calipers are a direct swap. The more I work with this the more I am sure the rotors are cast differently so the calipers are also cast a bit different.

Best way to know is to try it.

Ed

 

Thanks for info Ed - TOT

 

i have a complete ls1 rear in my 88 i didn't change a thing all brake lines and parking brake cables hooked up fine i used the ls1 parking brake cables they work a hundred times better then the ones from my 9 bolt but i don;t get around to doing the prop. value yet i was just looking into the 4th gen master cylinder swap and ls1 or c5 front brake swap

 

I ended up scrapping the C5 rear brake idea and stuck with the tried and true LS1 rear set up. I almost have all the parts for the rear and jsut need to pick up a set of mounting plates for the front C5 calipers.

 

I just modified my drum axle to mount the 94 PBR's so I know what thats like. I also noticed that the rotor had to be spaced out so I had my friend laser cut some .100" spacers from 10awg steel for me. The rotor was hitting the caliper bracket! But its all done now so its all good.

So now I have to do the 4th gen MC swap and figure out how to mount the front 94 brakes on my 89. Is this the same kinda thing as doing the LS1 or C5 swap?

And how do you mount those rotors to the integrated hub/disk? I was going to take an extra pair of rotors to the brake lathe and cut the disk off to make a hub.

 

As far as the rears go, the C5 and LS1 calipers are almost identical, and will interchange as long as you use the appropriate antirattle clips.

There is a big difference in the C5 & LS1 rotor offset, but that's accounted for in the brackets and backing plates, not the caliper.

 

You don't necessarily have to change the MC. Thirdgens with the PBR rear discs got the same MC from the factory that the drum cars did. The cast iron rear discs ('82-'88) cars came with a different (larger) MC.

Get yourself a combi valve from a disc rear car, and you should be good to go for the time being, at least until you decide you want to upgrade the fronts.

I wouldn't bother messing with the '94 front brake parts. It'd be as much work as any of the common front brake upgrades (1LE, LS1, C5, wilwood, etc.), but when you got finished, you'd be only have increased the rotor diameter by 0.4", and the calipers would be no better than what you have now (slightly smaller pistons, otherwise they're the same). Hardly worth the effort, in my book.


That's pretty much how the majority of front brake upgrades happen.