OPG and NPD both list a rear disc brake conversion kits. The OPG kit (the basic kit, not the Baer kit) says "modifications required". The NPD kit does not make such a statement.

Are modifications required with some kits and not others? If so, what are they? Will I need to modify or buy different axles for my 12-bolt?

TIA

More than likely Rich the modifications involve turning down the outside diameter of the axle flange to fit inside the rotor hat. Anyone with an open throat lathe can do it in five minutes. The later model factory rear discs that are included in some of these kits (probably late 80's/early 90's Firebird T/A or Camaro 1LE) have a slightly smaller inside diameter in the hat area than the Baer and Wilwood performance kits. Many of the aftermarket axles such as Moser can be ordered that way. One aftermarket set of performance axles I have came that way.

The other option would be to open up the center of the rotor. I choose to machine the axles as David mentioned to avoid additional expenses everytime a rotor went bad. As far as I can tell both the F body and Cadillac rotors have the same center diameter. Both fit my machined axles.

I bought mine from True-Connections.com
THey're the Seville rear 11" rotors.

The only complicated thing I had to with that kit was to slide the rear axles out so I could get the drum brake backing plate off. After that exerything just bolted on. The rotors already come with the dual lug pattern driled in to match our 5 on 4.75" lug pattern.

Call and ask for Dick or Linda. Tell them Armando sent you. They'll treat you right. He's even got the modified parkin brake cables for tem.

Rich,
First off, what brakes are you running up front?

That's the first question you should be answering to make a decision on what to run in the rear.

Joe

Originally posted by 72SSAbody:
Rich,
First off, what brakes are you running up front?

That's the first question you should be answering to make a decision on what to run in the rear.

Joe Well, I'm not exactly asking WHAT brakes to run in the rear since I've already decided what to run. I just want to know what modifications may be required.

For what it's worth, I'm running 69/70 style a-body front discs. The rears I plan to run are intended to compliment that style of front brakes; I think they are modified late model F-body rear brakes. They come with all the mounting hardware and parking brakes and parking brake cables. They are supposed to be a direct bolt in item. From what I learned above, if I buy the right axles I shouldn't even have to do any modifications to install them.

Originally posted by Rich-L79:
Well, I'm not exactly asking WHAT brakes to run in the rear since I've already decided what to run. I just want to know what modifications may be required.

For what it's worth, I'm running 69/70 style a-body front discs. The rears I plan to run are intended to compliment that style of front brakes; I think they are modified late model F-body rear brakes. They come with all the mounting hardware and parking brakes and parking brake cables. They are supposed to be a direct bolt in item. From what I learned above, if I buy the right axles I shouldn't even have to do any modifications to install them. If that's the case you can do this swap much cheaper than the kit costs, thus enabling you to throw some money else where in the project.

Joe

I'll agree with Joe, that this swap can probably be done much cheaper than the kit, but then again, the kit is supposedly ready to go...

As for "Modifications required", I would agree on the axle turning. When I ordered my new axles from Moser, they did this at no additional charge.

I was also thinking that the parking brake cables hit the shock-mount on the rearend. RJ (AirRJ) knotched his shock-mounts, but this is on a wider (1970) rearend. I mocked up my 66 rearend, and the parking cables almost go throught the middle of the shock-mount... I'd be interested to look into those modified cables from True connections Armando mentioned...

Originally posted by 1966_L78:

I was also thinking that the parking brake cables hit the shock-mount on the rearend. RJ (AirRJ) knotched his shock-mounts, but this is on a wider (1970) rearend. I mocked up my 66 rearend, and the parking cables almost go throught the middle of the shock-mount... I'd be interested to look into those modified cables from True connections Armando mentioned... All you do is mount the stock f-body LH side backing plate on the RH side of the chevelle and vice versa for the other side.

I'll have to dig up some pics of the swap to show you guys how easy this is.

Take care,
Joe

All you do is mount the stock f-body LH side backing plate on the RH side of the chevelle and vice versa for the other side.
Thanks Joe,
But wouldn't you also have to do something on the calipers/cable arms/levers? Or would you loop the cables around? I haven't tried, but I am assuming the levers need to pull in one direction only, and by switching brackets side to sode (mounting the calipers in front, either the caliper would be upside down (bleeder screw down), or the calipers would also have to switch side-to-side, which would require cables to pull from the back and loop around to connect to the intermediate cable...

And would it make a difference using Cadillac brackets (1978 Seville), as the F-body rear disc brackets/setups are difficult to find (never seen one).

A few years ago I bought my axles from "Toms Differentials." (http://www.tomsdifferentials.com/) You'll find the ones your looking for at the bottom of web page 12 (http://www.tomsdifferentials.com/cat121.htm) They say they're for disc brakes, but they did have to be turned!

Tom told me when the web page was released before the the old stock was depleted.
As far as axles are concerned, I like the KA axles from Tom's. They are the same diameter from one end to the other, unlike the tapered stock ones.