Hi Kids!

I am piecing together a front disc brake set up. I am eying kits from Wilwood and SSBC:

Wilwood GM D154 Brake Caliper Kit: [www.summitracing.com]

Sport Twin Quick-Change Caliper Upgrade Kit: [www.summitracing.com]

If anyone out there has direct experience with either or both of these calipers, I would appreciate some feedback.

There are also a plethora of aftermarket cast iron GM metric calipers for about 1/2 the cost of the aluminum ones. I could be convinced that cheaper is good enough.

I have the Scarebird Brackets ready to go but still need to buy the rotors and hoses (easy peasy). My Corvair is already set up with a disc/drum dual master cylinder (1" bore diameter) with an inline 10 psi residual pressure valve in the front circuit (works great but will be removed when the discs are installed), and a proportioning valve in the rear circuit. The front Hubs are turned down, rear brakes are stock, tires are a summer compound, and I like to drive "spiritedly".

One question up front is what piston area should I shoot for? It looks like the Corvair specific kits use single piston calipers with a diameter of 2-3/8". Its seems I should stick to that piston area or something slightly less (and balance the rears with the proportioning valve).

Happy Holidays, everyone!



Edited 1 time(s). Last edit at 12/02/2021 07:41PM by MattNall.

Is your goal to reduce unsprung weight?

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2023 KIA K5 GT/GT1 turbo-AKA ZIPPY II (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

I installed the single piston version of the Wilwood D154 on my 65 Corsa turbo last winter. They were NOS, so I got a stupid deal on them! I too used the Scarebird brackets and the calipers fit well, despite reports from a few years ago that they needed a little trimming to fit Wilwoods. Further, finding wheels that didn't rub those GIGANTIC calipers was a bit of a hassle. Since I wasn't going with custom wheels or something that looks cartoonishly modern, Rocket Racing Fuel Series wheels were the cheapest option that I could find that looked appropriate.

Daniel Atkinson
Tacoma, WA
65 Turbocharged Corsa

I used the Scarebird brackets - slightly modified for less weight- on the front of the race car. I installed the SSBC dual piston calipers all around - They fit the Cadillac rear brackets just fine as well (But no parking brake) With the S10 4WD rotors at all four positions. Slight mod to the hub, as you know) I am quite happy with the results.

Seth Emerson

Check my new Performance Corvair Web site: [www.perfvair.com]

Located in lovely San Jose, California

Good feedback so far. Thank you. This is why I post here.

JO,

My goals are (in order)

1) Decrease fade
2) Decrease unsprung weight
3) Increase cool factor

I've never had a daily driver that had really good brakes (best was my 86 Corvette but they'd only lasted a few laps on track days). I know the front of a Corvair is not highly loaded but I would kick myself if after all this effort I got a whiff of brake fade.


Daniel,

Good point on the wheel clearance. I'll do my homework. Are you running rear drum brakes? If so, do you know what the piston diameter is in your Wilwood calipers? I presume the brake balance work out well.

Anyone else have thoughts on the piston area question?

James
65 Corsa
SF Bay Area

You might check out southwest speed.

They have aluminum calipers at better rates.


On my last several setups I have used 2.5 inch piston calipers from them. Eases the pedal pressure a bit and feels like stock.

My car is just for fun in canyons, so I have drums in the rear. I went with single pistons only because they were the cheapest I could find. I think the bore is 2.5”, but I don’t know the coverage. Some people insist that singles cover more surface area than duals, but I ain’t building a race car, so I never bothered to learn any further. Discs up front will make a world of difference over stock drums and that’s all I needed to know. Make sure your lines are up to the task! Mine were rusty, so I installed all new lines and a 1” Wilwood master cylinder that was an open box buy. My wheel bearings were on their way out so I found a set of Timkens, cut my springs and added Konis from a GM A body in the front and Camaro in the rear.

Daniel Atkinson
Tacoma, WA
65 Turbocharged Corsa

what am I missing here? Other than the wow factor does a rear/ stock drivetrain corvair need FRONT disc brakes with 60% of weight on the rear wheels? The original engineering put larger brakes on the rear. I know with the independent suspension the rears are more difficult to convert, but for a real performance improvement why not go that route?


Ray Johnson Villa Park IL 63 Spyder Conv. 140 EFI

When I switched to front aluminum drums, fade resistance improved. I figure discs will be even better. Good point on the rears; they may end up being the weak link. One thing at a time, though.

James
65 Corsa
SF Bay Area

I used the Scarbird brackets with rebuilt S10 calipers. I also used a 1" bore master cylinder. Keep you 10 PSI residual for your rear drums. My 15" American wheels fit without problems. The difference is awesome for aggressive street use.

Bob
Paso Robles, CA

Central Coast Corsa
1966 Corsa Turbo Convertible
1966 Corsa 140 Coupe

Early Guy—I suppose I should have added that I relocated the battery, spare tire to the front and will soon mount my tool box there as well. I’m guessing that’ll be 70 plus pounds of weight removed from the rear.

Daniel Atkinson
Tacoma, WA
65 Turbocharged Corsa

I did exactly what you did. I also removed the heater and put in an electric one under the dash. That all really helps balance the car. You'll love it on twisty roads......


jazzworkerbee Wrote:
-------------------------------------------------------
> Early Guy—I suppose I should have added that I relocated the battery, spare tire to the front and will soon mount my tool box there as well. I’m guessing that’ll be 70 plus pounds of weight removed from the rear.

Bob
Paso Robles, CA

Central Coast Corsa
1966 Corsa Turbo Convertible
1966 Corsa 140 Coupe

Does anyone make a set of brackets to fit the C4 Dual Piston calipers>

Thanks,
Dave
CA Central Coast & Los Angeles

1969 Monza-Coupe 140 4-Speed

jetcat Wrote:
-------------------------------------------------------
> I did exactly what you did. I also removed the heater and put in an electric one under the dash. That all really helps balance the car. You'll love it on twisty roads......
>

Where’d you get an electric heater, where’d you install it, and how well does it work? Thanks!

Rocco

What everyone needs to keep in mind is that stock, over the counter brake shoes, are fine for everyday normal driving and even autocross but when you start pushing the envelope with with multiple hard stops the brakes will fade. To help that you can add ventilation to the backing plate for cooling, of course this reduces the wet performance some. Then if you are real serious you can get performance brake shoes that take a lot more before they fade.

Now what most of the racers also do is increase the size of the front wheel cylinders! I do this routinely on my street cars to 15/16" and on the race car I have 1" front wheel cylinders! Yes I still race with drum brakes so it can be done.

With that you want the largest front caliper piston you can get. Even then you really need an adjustable proportioning valve to reduce pressure to the rear. With the largest piston the reduction to the rear will be less and you will have better all around braking with the combo of disc/drum. Then if you do rear discs you want the smallest caliper piston you can get for the same reason as said above.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

Hi Kids!

I have run into a problem with the parts I have collected for my disc brake conversion (I listed them above). I think its the Scarebird bracket but I'm hoping that some feedback form this group will either confirm or deny my assessment.

The issue is similar if not exactly what solo2r ran into in this thread:

[corvaircenter.com]

I did a little measurement and it appears the nuts welded in are not in the correct location relative to the surfaces that the calipers butt up against. I think I am right to assume that the imaginary line between the nuts should be perpendicular to the edges of the caliper slot (if that makes any sense). I've attached pictures. The depth gauge is butted up against the edge of the caliper slot. I don't think the ~.10" gap measured with the dial calipers should be there. I flipped the caliper and the problem persists.

I've emailed Scarebird (does any one have a phone number?). If this is their issue, hopefully they will stand behind their product.

I feel a little silly in that these parts have been sitting on my bench for a month and I didn't think to check them. It wasn't until I started to assemble the disc parts that this problem was discovered.

I am contemplating buying a set of OEM replacement calipers to test the theory that the Wilwood calipers are part of the problem. It would be very surprising if that was the case but I can't rule it out at this point.

Anyway, if it looks like I am missing something or if my assessment is in fact the problem, let me know.

James
65 Corsa
SF Bay Area

I think your ok , as long as the bolts go in and the pad isn’t sitting above the diameter of the rotor. the bracket is what takes the load , the bolt/pins just guide the caliper as the pads wear

1964 Bill Thomas Monza Replica Racer
1964 Spyder Street Car
1998 Honda Prelude Dirt track car
1967 Crown V8 under construction
Mike Levine
Cumming Georgia
North of Atlanta

The problem manifests as a misalignment of the pin bolts. I can get one or the other to screw in but not both.

When I line up one of the holes, the other is off. To line up the other, I have to slide the caliper along the caliper slot. When I do this, the first hole does not line up. And I can't rotate the caliper in the bracket to get both holes to line up. (If I could rotate the caliper in the bracket, I would have another problem)

I realize this is hard problem to verbally describe. In the post I linked above, solor2 had to machine the bracket a little bit to get things to go together. I'd rather not do that.

Scarebird emailed me back. I hope its just faulty brackets as I was looking forward to aluminum front calipers.

James
65 Corsa
SF Bay Area

I understand stand now , they just drilled the hole wrong . I’m sure they will take care of it . I bet if you take the rubber bushings out of the caliper the pins would go in. They might rattle, I don’t run the rubbers so the pads don’t drag on the race car.

1964 Bill Thomas Monza Replica Racer
1964 Spyder Street Car
1998 Honda Prelude Dirt track car
1967 Crown V8 under construction
Mike Levine
Cumming Georgia
North of Atlanta

Quote
Ken Hand
Now what most of the racers also do is increase the size of the front wheel cylinders! I do this routinely on my street cars to 15/16" and on the race car I have 1" front wheel cylinders! Yes I still race with drum brakes so it can be done.

With that you want the largest front caliper piston you can get. Even then you really need an adjustable proportioning valve to reduce pressure to the rear. With the largest piston the reduction to the rear will be less and you will have better all around braking with the combo of disc/drum. Then if you do rear discs you want the smallest caliper piston you can get for the same reason as said above.

I think this question about brake balance may be more complicated than some people think. I have Wilwood disk brakes front and rear on my autocross car. I use the same rotors and the same caliper with the same sized pistons front and rear. Most people seem to suggest that you need to design the system with smaller caliper pistons at the rear, so that you will have less braking pressure at the rear than at the front. And even with that, they say that you may have to reduce the braking pressure further at the rear with a brake proportioning valve.

With my car, I have not found that to be the case. With the same calipers, rotors and pads front and rear, I have had to put a proportioning valve in the front. Without it, the car overbrakes in the front. This is not because I have poor front/rear weight distribution. The car is 44/56 without me in it. I do run much wider tires in the rear than the front. Also, the car is set up for very little change in attitude when braking (not much dive).

Just my two cents...

Jonathan Knapp
Wheeling, WV
'66 Corsa Autocrosser