Disc brakes for C-4 corvette front suspension

[Bill Musarra]

A CALL FOR HELP!!

I am in a dilemma. I will elaborate on the dilemma, and leave the story behind the dilemma for another post, which will be very enlightening to a lot of you. Here it is. I now have some 12” rotors for my Corvette front suspension. I have some Wilwood 6 piston calipers for those rotors. What I don’t have is a way to connect the two.
The problem in the beginning is that no one makes aftermarket brakes for the C-4 Corvette, except Corvette themselves. These are single piston units that have some serious drawbacks. I had these things made and purchased for me on the understanding that they would go together, or would be modified so that they would. I am now stranded with the parts and no way to get them together. I am including some pics and measurements for you engineering types to advise. As I am no engineer, I don’t know what my alternatives are. It would seem that a bracket that surrounds the two mounting holes of both pieces would work. The outside of the upright may have to be squared up for that to work. What I don’t know is if that is a feasible thing or not. Lord knows I wouldn’t want to be at speed to find out I was wrong. So I will throw it out there for you guys to advise. I really appreciate any help I can get.

Bill

 

[Jac Mac]

Bill,

This was the exact problem that I had just finished solving on the TVR I used to work on when I sent you the bump Steer info .
The previous clever clogs had machined the original caliper mount lugs off the C4 upright and made a new caliper bracket that mounted on the rear face of the upright by means of the four bolts that retain the wheel brg assy, In practice this method gave trouble as the caliper mount was not in line with the caliper & deflection was causing long pedal & uneven pad wear.The new mount bracket now fitted was made from steel (0.0200") and is sandwiched between the wheel brg carrier and upright as well as having another pair of lugs to pickup on the rear face of the upright on two of the hub bolts.This bracket is rock solid and cured all of the issues we were having in this dept.

Fortunately in the process we had to change Rotor Hats as well and as these were approx 0.300" thinner at the hub face area we still reduced rather than increased the scrub radius.

Now looking at your pics & before you even start to try and fit those calipers have you checked that they are going to clear the center of the wheel with those rotor/hub assy as there does not appear to be a lot of rotor offset in relation to the hub face.

Just looked again, can the rotor not be mounted on the rear face of the rotor hat to help, you may then be able to mount the caliper on a simple stepped bracket that uses the existing upright lugs with the caliper slightly higher ( caliper lugs straddling the upper lug of the upright.)

Jac Mac

 

[Lee]

Bill
Couldn't you just get a plate made up similar to these? These are using radial mount rather than lug mount calipers but you would just have caliper mount holes parallel rather than perpendicular to the hub mount holes.
The mount is bolted to the upright with bolts, nuts, and spacer tube to bring the hub mount holes down to 12mm.

 

[Lynn Larsen]

Bill,

I have a keen interest in how this turns out for obvious reasons. They say a picture is worth a thousand words, so here are a couple of your photos that I have annotated to show what I think Jac Mac is saying. The yellow box roughly outlines a flat plate drilled with 4 holes to connect the two parts. The arced arrow in the first picture is to indicate that the calipers could be rotated slightly either way, if need be, so that the ears interleave and the calipers are fully seated down on the rotor.

In the second picture, because of the slight angle, it appears that the rotor is not centered in the caliper if the plate were bolted in as shown. Would bolting the rotor to the backside of the hat, as Jac Mac suggested, put the rotor midway between the installed pads? If not, the plate could be milled and/or shimmed on the upper and lower halves independently, as needed, to get the rotor and calipers properly aligned.

Does that sound right, Jac Mac?

EDIT FOR LEE'S PICTURE - Lee, nice pic that must have been saved as I was typing. The obvious advantage to the radially mounted caliper is that the caliper and rotor can be aligned by simply drilling the caliper bolt holes in the right position. Worries over ears overlapping is also gone. Noticed also that Lee's rotors are bolted to the backside of the hat.

 

[Dave Bilyk]

Bill, as Jac Mac has already said, the caliper sits outside the wheel flange by a significant amount, and the fear is that it will foul the inside of the wheel.
What you need to do is;

1 determine the position the caliper must be in to leave say 5mm+ clearance from the inside face of the wheel. This then determines the position of the rotor to sit centrally in the caliper. If the rotor will foul the hub or lugs in this position, you are in a bit more trouble. Also make sure the caliper fits within the wheel inside radius.

2 from this rotor position and the hub flange dimensions, determine the bell required to mount the rotor.

3 all being well you can then design the caliper mounting bracket. If you are lucky it could just be a piece of flat plate. I suggest you could do some hand sketches to explore the possibilities.

It may help to see my threads which contain some pictures and section drawings. Do an advanced search on my username for threads started by me and look for threads on the front, and especially the rear brakes you will see some pictures of mine and others brackets.

Dave

 

[Mike Drew]

Bill wrote:

The problem in the beginning is that no one makes aftermarket brakes for the C-4 Corvette, except Corvette themselves.
Bill

Bill,

I found it extremely difficult to believe that nobody makes aftermarket brakes for the C-4 Corvette. I did a Google search on "Wilwood Brakes C4 Corvette" and found dozens and dozens of links. The very first one turned up a complete kit to enable you to bolt on six-piston Wilwoods onto your C4 Corvette:

http://www.dougrippie.com/drm/braking_products.htm#C4 Corvette DRM Wilwood Brake Kit

Now, these outfits are in the business of selling ALL the pieces, not just the mounting brackets. But it's possible you could sweet-talk them into sending you just the brackets for a price. And if not, there's lots of alternatives to choose from.

Best of luck to you!

P.S. Subsequently went to Wilwood's site and found that they, themselves, offer a complete C4 six-piston front brake kit:

http://www.wilwood.com/Centers/Information/applicationguide_frnt/chevrolet/c48896.asp

So maybe they would be willing to sell brackets alone. Failing that, it might be easier to buy their brackets and rotors (and use your existing calipers) rather than trying to get custom brackets made for your rotors (did you mention their make/model? I don't think so?)

Again, good luck!

 

[Jac Mac]

Bill,
As Lynn , Lee & Dave have shown there are a couple of ways of solving this problem.
Lynn , yes that is what I was trying to describe, it would be easier to move the caliper up towards the top balljoint as it is further inboard, movement down usually means contact with lower A- arm on full lock. It may be necessary to machine a small amount off the top dust shield bolt boss for clearance, but thats about all.
Lee's suggestion of the radial mount caliper has a lot going for it particularly if you feel you may upgrade to a larger rotor dia in the future as a simple spacer plate & longer bolts will be all that is reqd to shift out the caliper to match.
Again along with Dave I would repeat, sort out the possible caliper/wheel center contact issue first.

Jac Mac

 

[Lynn Larsen]

Mike,

The Wilwood kits are for 88-96 C4s. The uprights on DRBs and on Sabres are 84-87 C4 parts. This is typical of the commercially available kits for "C4" Corvettes.

The kits on the DRM website do not specify which range of C4 years are supported with their kits. BUT, they do have a conversion kit that allows the use C5 front calipers on 84-96 C4s, which is an upgrade over stock. They also have upgrades for 88-96 C4 rear brakes (this year range of parts is an option that I have on my DRB rear uprights and that I think Bill may have also), which is a bit of rarity also. I have looked for rear upgrades in the past with no luck at all. Even this year range of C4 rear brakes are pretty wimpy considering the increased braking effectiveness that should be available with the weight of the engine/transaxle just ahead of the rear axle.

Lynn

 

[Dimi Terleckyj]

Hi all

I had a similar experience with my front brakes.

I originally used the C4 Corvette front calipers and discs but after an altercation with the rego gods I ordered a C5 upgrade kit from VBP (Vette Brake Parts) in the US.

I have to say this was one of the most complete and high quality kits I have seen.

They supplied new Calipers,Rotors,abuttment brackets,adaptor brackets,braided SS hoses,pads and all bolts.

Total for the kit was about 800 USD.

When it all arrived it was just a case of fitting and bleeding the lines and all was done.
The only thing I supplied was labour and brake fluid.

The staff at VBP could not have been nicer or more helpful and their service was second to none.

If anyone needs to upgrade give VBP a call.

Dimi