I was always under the impression that both PBR rear brake setups used the same rotors. However when doing a part search the LT1 rotors do not match the 89-92 rotor part numbers. The LT1 rotors are cheaper and I am swapping the brakes from a 96 TA to my drum 91, so can I go with the LT1 rotors over the more expensive 89-92 rotors.

 

Well my 96 rotors were almost .1 inch to small to turn, however I'm just going to buy some 93-97 rotors anyway, saves me almost $40.

 

 

I compared the 89-92 with the 93-97 rotors and they appeared the same. I didn't measure them but there must be a small difference, they were different part #'s

 

i was curious about the same thing. what all is interchangeable in the 3rd gen and lt1 rear disk brakes?

 

i too am curious as to what the diffrence is. i am working on upgrading the 82-88 rear setup i have on my 92 tpi s10 to the lt1 style. i have sourced backing plates(82-88) and received my ebay calipers the other day and was needing rotors and knew the calipers interchange and that they are very close in diameters. so the only thing i can see being diffrent was the hat depth. measured the 93-97 tonight and it was 1.25 deep from rear face to where it stops. (sorry for the poor description) at over 3 times the price for the 89-92 rotors, its hard to justify paying that much if the lt1 style will work. the only thing else that comes to mind is that the lt1 year rotors are designed to fit many car lines and the holes are slightly enlargered to fit a few patterns. anyone else shade any more light on this problem?

 

The difference is the LT1 rotors are 2 piece they have a thin stampd steel hat with the rotor cast on that ... the L98 89-92 are 1 piece cast iron

 

can you use either or?

 

the replacment ones i looked at last night were a cast one piece rotor. as long as they are made right and give the proper rotor offset the only thing i see them doing is pushing the wheel out slightly.

 

I did the PBR swap last fall on my 83 T/A, and this is what I learned. My car originally came with rear disc brakes.

The parts I bought for the swap came off a 1997 Camaro.
The backing plates bolted directly up, without modification.
I also used the complete 4th gen hard brake line from the union block located on the axle, to both of the calipers, left and right.
Even though the rotors were in bad shape, I took one for fit, and found it sat too far in, on the hub, and rubbed the inside of the caliper mount.
A new replacement 4th gen LT1 PBR rotors, fit the same way, so I used the ones for the 1990-92 PBR f-body. These rotors centered very nicely. Just for some extra "piece of mind" ,I clearanced the caliper mount just a little, so there wouldn't be any problems, while the axle moves in and out.

Hope this helps.

Leon.

 

i will be using the 89-92 backing plates. i guess since the 93-97 can be had cheap and easy. they will simply be my first choice to see whats going to work with what.

thanks for the help.

 

ebmiller led me to beleive that the rotors you used were dependant on the backing plates you used. since he seems to be the brake guru around here- i went with that. another reason i went with that option was because i didn't have to have the axle flanges machined down a little in order to get the rotor hub to fit over the axle flange.

 

They aren't the same and this is what I think is the main reason. Raybestos part numbers are as follows:

'89-92: 6995
'93-97: 56407

Different part numbers mean a slight difference in the castings. From what I know, the '93-97 rotors will have a bigger flange mounting diameter on the back of the rotor so there's no need to have to turn the axle flanges down. Therefore, if swapping discs on a DRUM rear, go for a '93-97 rear rotor setup so your axles won't be affected but be aware that you MAY need to space the carrier out or in, especially if you use 3rd gen backing plates. I think 4th gen backing plates will take care of that.


HTH...

Ed

 

This thread is turning into a who do you want to believe type of thing. I went from drums to discs last year. I used 90-92 backing plates with 93-97 calipers and rotors. Sorry to be adding to the confusion in this thread but that is what I used.

 

i dont know if its a whos believes who. but just simply no ones really stated that weither or not those years will interchange. obviously if you have used the older backing plates and the newer rotors, it works. so im good to go on my setup once i get around to buying rotors and put the work into swaping things around.

thanks for all the help and insight.

 

Heh.. I swapped in a 93 rear and used 89-92 rotors! They looked different in the hub area, but worked the same.

Kevin D.

 

sorry to bring back a dead thread but if i understand this correct you can use drum axles with lt1 rotors with any disc 89-92 backing plates without turning them down? My old calipers are cast does that mean anything?