Well im at the point where I have the calipers and rotors off my rear end, im wondering if while i have everything apart in the back should I upgrade to ls1 now and convert the fronts to ls1 later, or just cough up the 200 bucks napa wants for remaned stock calipers? And what would i have to do to the backing plate on my 9 bolt to play nicely with the swap?

 

The LS1 backing plates are designed for a 10-bolt. I'm uncertain of how you would modify the 9-bolt axle flanges to accommodate the swap.

JamesC

 

You can get LS1 brake brackets for the 9-bolt rear. You can't use the stock 4th gen 10-bolt brackets though.

 

Do you know where i could get those brackets?

 

I've seen them before but not made anymore (dunno why but the link is dead). All I see now are C4 & C5/C6 caliper brackets. Dunno what the difference is between LS & C5/C6 calipers is.

 

I did the ls conversion on my rears and still sport stock up front for now. HUGE improvement so far with just that. I did also swap proportioning valve too...

 

Thats good to know, I cant stand the stockers.

I think im gonna go to a wrecking yard and see if i can snag some 10 bolt backing plates and drill new holes

 

Just to be sure, if i use the a 10 bolt backing plate from a thirdgen, ill have no issues with the ls1 swap correct?

 

Since the bolt pattern on the axle flanges is different between the 9- and 10-bolt, the two aren't interchangeable.

Note the backing plate in the following link:

http://www.flynbye.com/catalog/i60.html

JamesC

 

My plan was to drill new holes in the ls1 backing plate, and weld up the old holes

 

Backing plates are cast aluminum. Welding isn't going to go very well.

Also the backing plates have a flat on the back where the outside shape of the axle flange fits nice. It is not likely the 9 bolt flange will fit very well.

Finally the 9 bolt holes are quite close to that of the 10 bolt. But of course well enough different that they aren't interchangeable. Your best bet is probably to use the C5 rear brakes.

 

Another option would be the so-called 1LE's. A 9-bolt backing plate is made for that application.

JamesC

 

Yup, excellent point. Frankly even the old 10.5" iron setup works just fine when adjusted correctly.

 

Here is how close the holes are. And because 10-bolt are c-lip axles & 9-bolts are bolt-in axles you'll need to fabricate a spare as well.