C2 disc brake conversion

[Dennis H.]

Re: C2 disc brake conversion

Mike, Thanks for your response, but the GM parts manual says 65-67 is Pt.# 3964023 and 68 is 3924384 and 69 up is 3953416. The Hollander interchange manual says 65-67 will not interchange with the others. I am assuming that the hub to hub distance is different. A 68 up setup pushes the wheel out .5 inches on each side. I could live with that except with my exhisting non stock wheels,it looks a little strange. Afterall looks are everything. Thats why I have I will have to find a set of 65-67. Thanks again for your help. Dennis

[David D.]

Re: C2 disc brake conversion

Dennis, I am sure I will probably get some comments on this, but there is another option, other than newer spindles. This is what we did in the early 70's. We used the existing 63-64 drum brake spindles for the disc brake conversion, essentially making it a 65-67 disc brake spindle. We removed 5/16 (or was it 3/8) inch, of material from the outer part of the upper boss, that the original brake shoe pivot bolt went into (also held the backing plate). The hole is threaded deep enough, and the same thread, so the disc brake caliper bracket/splash shield bolt that replaces it, will work fine. I believe you can also use the existing front hubs, with the 65 up front brake rotors, but I really don't remember, for sure. This can also be done on early Camaro's, Nova's, and I believe some Chevelle's that originally had drum brakes. It may sound like a crude or bubba job now, but all we used was a hacksaw to trim the boss. We just cut it straight across and as square as we could, it is pretty soft material and cuts easily. FWIW. Dave

[Chris D.]

Re: C2 disc brake conversion

To answer your question directly, yes, using the same wheel and with disks installed, any 65 to 82 spindle/hub combo will bolt up without a difference in track width.

All hub and spindle combinations from '63 to '82 have the same cross-car hub flange to hub flange location. There are a number of differences along the years but hub flange to vehicle centerline stayed consistent. The extra width in '65 comes not from the hub but from the much thicker disk. Drums have a thinner stamped steel web. So the actual wheel mount surface did move but the hub surface didn't. All changes to track since '65, as pointed out by others, were changes in wheel.

That's also why in '65 the center wheel pilot diameters on the hubs were extended and why longer wheel studs were fitted as well. I have seen '63 spindles reworked as previous poster describes. They can be made to function. However, that's a fair bit of work to ruin a two year only component. There should be plenty of cheaper 65-82 pieces to fuel your hot rod urges.

Personally, I'd stick with the drums on your '64 and get some upgraded shoes if better performance is your goal.

[mike cobine]

Re: C2 disc brake conversion

The wheels are going out further because the wheels are wider and they set out more, not because the spindles stick out, because they don't. In 1969, they used larger diameter bearings in the hubs, so the spindles were different.

'68 used the same size bearing as '65-'67 but there is another change I can't remember right now. It may have had to do with alignment and maybe roll center of the front, as the rear roll center dropped in '68 about an inch for better handling.

If you tried to put a '69 up spindle ONLY in a '65 car using '65 hub and other parts, it won't work. You have to use the full '69 assembly.

But in a conversion like this, you would most likely be putting in a complete assembly (spindle, hub, bearings, caliper brackets, etc.) from an existing car. The easiest way for many is to simply unbolt the a-arms from top and bottom of a donor car and bolt them on your frame.

While many do this, you really don't accomplish much unless you put the disc brakes on the rear, too. And you will find that is a lot of work. The rear bump stop snubber must be moved inward. The caliper may hit the frame at full upward travel, although many successfully avoid this by keeping the rear end up higher. Setting up emergency brake cables are not straight forward and some engineering has to be done, at least on a '63. The '64 setup under the floor is more like the '65 and may make this easier.

If you are running non-stock wheels, this can all be a problem. Are they disc brake wheels for Corvette? Corvette calipers require at least a 1/4 inch cut in the wheel for the calipers to clear. Many wheels like Cragar SS do not have this and require spacers, which set the wheels out more. Unless the wheels were specially ordered for Corvette disc brakes, you may not clear the caliper.

Also, if you didn't special order the wheels, then backspacing may be wrong. Custom wheels are frequently around 3 inches backspacing. The Corvette wheels are 4.5 inches backspacing, which means the custom wheels sit out an extra inch and a half. This can be a clearance problem on the upper lip and at the rear of the wheelwell when the front tires are turned and the tread can catch the lower fender lip or the inner fender panel.

Many used to get around this on the '63 and '64 by running 14 inch wheels on the drum brakes, but you cannot do that with the disc brakes.