yesterdayscorvettes

I have a 85 and I want to upgrade to a 13" rotor. I'm having trouble finding what wheel will fit. I want to use a 4" or 5" wide rim up front. I was interested in what rims other C4 owners used and if you need a spacer?

Thanks,
Dan

Zix

Why upgrade the brakes but then go with a narrower front tire?

cv67

Stock brakes plennnty for a pizza cutter.

yesterdayscorvettes

I want to upgrade to a 13" front rotor because I'll have manual brakes. No more power brakes due to lack of vacuum from a larger cam. A 4 or 5 inch front rim because than is what drag racers do.

Nathan Plemons

With a tire that narrow you'll run out of traction WAY before you run out of brakes.

yesterdayscorvettes

What about with the 13" rotor and caliper from a '90 to '96 vette?

Vette Daddy

I don't think he's looking for traction on the front tires.

Nathan Plemons

Traction is just as important to braking as it is to acceleration. Too little traction and your brakes will just lock up.

cv67

believe me the stock brakes are more than enough.
Are you going to be running a 15 in wheel?

Do you already have the manual brakes put in?
If not have you tried a vacuum reservoir?
Electric pump?

Running a pretty good sized cam (260@.050 108 lsa) only makes 7 in but stops a heavier car real well with a simple vac reservoir on it.

c4cruiser

Upgrading to a larger rotor and different caliper will require a custom adapter bracket to mount either a later C4 J55 brake upgrade or a C5 brake upgrade. At that point, any narrow front wheel available for an 88 or later C4 or C5 should bolt on.

There are a number of lightweight narrow front wheels available, but you have to make sure that the wheel will clear the caliper. Start by checking out the various wheel manufacturer's websites for fitment or call them and ask what the have available. With a brake upgrade, you will need a 17" wheel so make sure that a 17x4 or 17x5 wheel is available, along with the proper skinny tires.

I would also suggest that you consider a vacuum pump with a reservoir. The stock C4 brakes with the right pads will provide more than enough stopping power for drag strip use. It might be easier to find narrow 16" wheels too.

You may even find that some 15" wheels will bolt on with the stock brakes. It's also possible that using adapters to move the wheel out from the rotor would help. But check with your sanctioning body to make sure you can use them and they pass tech.

When I first started doing HPDE's with my 87, I installed fresh replacement rotors and Hawk HP+ pads and kept the OEM 16" wheels. At the time, that was plenty of braking power for hauling the car down from 130+ repeatedly over 20 minute sessions.

Also with skinny front tires, you will want to install some sort of brake bias spring or use an adjusting valve to change the brake bias. Skinnys up front will not provide the same level of brake performance as stock width tires.

Zix

I see. that makes sense, it's just not something I see done very often so I had to wonder!

cv67

Good idea

With the larger rotors would he need the different master with the larger piston?

Used to run 90/10s skinnies no bias valve/spring change and a Big block on another car yrs ago . Wanna talk about terror in a hard stop let alone rain. Sheesh.

Corner too quick or one good pothole its over.
Id do a 5" wheel if you can if its street driven a lot

dukeallen

At first I thought he was going for that rare bicycle-tire look!

383vett

I'm not sure why you are converting to manual brakes in the first place. If you are seriously into drag racing, you would want to have the lightest brake assembly possible, rather than going backwards putting a larger, heavier rotor up front. People spend good bucks to go with lightweight assemblies from Strange, Aerospace, Willwood, and others to shave a few unsprung pounds up front.