Hi, I'm completely new to Firebirds, but have so far loved restoring a 1968 with my daughter. As far as we can tell, it is mostly original. The first thing we worked on was a conversion to disc brakes. Front breaks went smooth.
Though not really necessary, we decided to convert the rear drums to disc too, using a Right Stuff kit. Then it got weird - after a lot of trial and error we realized that the flange of our rear axle hub was 6.25" diameter (the hub diameter itself is the standard 2.78"). This makes it too wide to fit into most rotor hats (we learned that inner diameter of most rotor hats is around 6.2").
Right Stuff said we should just machine 1/8 off the diameter - but I really don't want to modify an original axle. Anyone run into something similar? Anyone have any ideas on how to solve?
You can also upgrade the rear factory drums to the 11 inch GM HD taxi drum unit. The kit I got from Master Power brakes bolted right on to my 8.2 BOP rear. No issues with the OEM emergency brake system either.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI
Been there and done that. I had same issue with my factory axles. I took the rotors and axels to local machine shop and they took off just under an 1/8 from total diameter of axel flange. Charged me only 20 bucks for both and no one will ever know. Still plenty of stock surrounding the lug bolt holes.
I wonder if the aftermarket kit, like most I've come across, is for a Camaro and not a Firebird. Seems like most in the dark aftermarket world don't know there's a difference between a BOP rear and a chebby rear.
Thanks for the suggestions. In comparing part numbers for the rear disc conversion kits, I think you’re right - that company might be just renaming a Camaro kit.
One surprising thing I learned - it is really hard to find out the inner diameter of a rotor hat online (aka clearance id). Hardly any company publishes that spec.
And it’s really hard to find the axle hub flange diameters of different rear assemblies. I couldn’t find that spec in any of the Firebird material I’ve been collecting, or on the info on this site, or even on pages about 10 bolt BOPs. Anyone ever come across that info? Just in case it’s ever useful to anyone, the 68 Firebird rear axle hub flange is 6.25†diameter.