I've read that stock disk brakes sit the wheels at a wider stance than the stock drums.Does anyone know exactly how much this is?Thanks for any help on this matter thats been bugging me now for too long......68 camaro.

I've never heard that, but it may be true. If it is (and I doubt it), they don't sit out much farther. If you are thinking of switching to DB, you'll be amazed at how much better the car stops.

What the deal is, is that the hub's wheel mount face for drums sit's right at 9/16" closer to the S/F vs the 2-piece rotor/hub and cast 1-piece hubs.

Therefore disc cars have a wider wheel flange mount track than drum cars by about 1-1/8" or thereabouts..

I always figured that GM compensated for this by varying the rim b/s'ings between the two designs.

And that this is the track difference between 1st and 2nd Gen. cars but never could prove it??

Anyway, David Pozzi's great site has a pic of both hubs side by side if you want to check this out.

pdq67

PS., and this 9/16" flange mount number difference is called "Joe" b/c Joe over on Team Chevelle 1st looked into it IF I remember right??

It's been years.

Thanks pdq67.

You might want to double check that I thought the difference was 3/8" per side.

You might want to double check that I thought the difference was 3/8" per side.

Maybe even a little less say 5/16" per side.

No, it's like a 1/2" to almost 9/16" per side and David gave me a 2-piece hub that's on my car now w/ my "pdqCBB" 13" front disc set-up.

Please eye-ball David's great site and you will see that it's a 1/2" or slightly more per hub b/c he has them side-by-side.

pdq67

Paul I did the conversion, front and rear... In a nutshell you pull the drum off the hub in front and axle flange in the rear and push the rotor back on after turning down the flange and hub to fit inside the hat in the rotor!

Right Dennis,

I had to cut my 12-bolt axle flanges down to I forget the number and it's on the Boards somewhere. And also I had my hubs done the same so the rotor hats fit plus just very lightly kissed the center hub chamfers.

pdq67

My '67 Camaro has '69 spindles and '69 disk brakes. The front wheel tread width is 61". I believe the stock tread width is 59". Any comments would be appreciated.

Tom Sholl

What the deal is, is that the hub's wheel mount face for drums sit's right at 9/16" closer to the S/F vs the 2-piece rotor/hub and cast 1-piece hubs.

Therefore disc cars have a wider wheel flange mount track than drum cars by about 1-1/8" or thereabouts..

I always figured that GM compensated for this by varying the rim b/s'ings between the two designs.

And that this is the track difference between 1st and 2nd Gen. cars but never could prove it??

Anyway, David Pozzi's great site has a pic of both hubs side by side if you want to check this out.

pdq67

PS., and this 9/16" flange mount number difference is called "Joe" b/c Joe over on Team Chevelle 1st looked into it IF I remember right??

It's been years.

there is a comparison of an older 2 piece rotor hub and a drum hub, but i don't see any pics of the difference between a stock one piece disc brake rotor hub and a drum brake hub. personally, i think the later one piece rotor is designed to put the wheel in the same place as it would be on a car with drum brakes.
but if you put later Vette rotors on a drum hub, it's gonna kick the wheel out about 1/4" due to the thickness of the rotor.

The replacement 1-piece rotors put the wheel mounting surface about 1/4 to 5/16 further toward the outside. When I bought my 68, the 14x6 rallys (XG code wheels for disc brake use) needed a 1/4 inch spacer to clear the tie rod ends. When I put the discs on (using the replacement 1-piece rotors), I no longer needed the spacer.

There are different wheels for 1st gens depending on drum or disc brakes; I assume the difference is just a little backspace.

just my 2 cents, if you machine a drum brake spindle 500. in the right place, it becomes a disc brake spindle, moves it towards subfram, a half inch

You are talking about cutting back the top bolt boss is all.

I pitched my wore out '74 Apollo front 1-piece disc's and I swear their "joe" was the same as the 2-piece hubs!

Looking back, I wished I would have kept them b/c I would have used my trusty HFT 4.5" angle grinder and removed the worn out disc portion and made hubs out of them for later!

pdq67

The replacement 1-piece rotors put the wheel mounting surface about 1/4 to 5/16 further toward the outside. When I bought my 68, the 14x6 rallys (XG code wheels for disc brake use) needed a 1/4 inch spacer to clear the tie rod ends. When I put the discs on (using the replacement 1-piece rotors), I no longer needed the spacer.

There are different wheels for 1st gens depending on drum or disc brakes; I assume the difference is just a little backspace.
disc brake wheels had the center section contoured different to clear the brake calipers.