BBagman

Does anyone know who makes or sells JB9 brake adapters for 85-87 C4's ?
Thanks Brian

WVZR-1

Maybe you need to clarify what you're attempting to accomplish. The JB9 reference is only I thought just a "light weight" usually mentioned when discussing B and W bodied GM cars.

Are you wanting to add '88+ 12"(JL9) or maybe '88+ 13"(J55) or maybe C5 to an earlier car? CTS-V stuff or ...............

Now for a GM truck JB9 would be a hydro-boost I believe. Does that interest you?

BBagman

I'm sorry. I meant the JL9 88 12" brakes! is there an adapter for these to an 85 knuckle ? I know about the C5 adapters. I'm curious if the upgrade to 12" is possible

c4cruiser

The stock '85 front rotors are 11.5" in diameter. Why would you want to "upgrade" to a JL9 12" rotor? The front rotors for the '88 and later J55 brake option is 13" in diameter as is the C5 front rotors. But either of those would require special brackets to mount the caliper properly. And the 13" rotors would require 17" diameter wheels.

If you are looking to improve braking performance, I would recommend going to a performance pad. The cost will be far less and there are some very good pads for the early C4's Hawk makes some good pads as does CarboTech.

BBagman

Thanks for your reply
As you know, a 12" rotor with a dual piston caliper and larger pad will out perform a 11.5 rotor and single piston caliper and smaller pad of the same compound!
The JL9 fits in an 16"wheel (which i have 12 of)
I've read various posts that mention such an adapter and Im trying to identify it and where to get it . It would be a good option for my purposes!
so if anyone knows of them,it would be a big help!
Thanks

Gibbles

I have an 84 and the brakes I'm sure were great back in 1984, but i found them seriously lacking on the freeway when everyone else has a modern brake system with abs.

I did the C5 brake conversion, it's much better now.

There is also a bias spring for the rear brakes, i hear it will improve a stock brake system as they really underpowered the rear brakes.
​​​​​​​Cost is about $20 shipped, search the forum, there should be a few references to the site (DRM maybe).

BlowerWorks

Take a look at page 84 of my Sales Guide - I have one set left. You can view the Sales Guide in the 'Downloads' section of my website: blowerworks.net
greg

WVZR-1

I've looked for a "sales guide" link in the past and actually never stumbled upon it. There's a variety of documents but I've never seen a "sales guide" that was all encompassing. I just glanced quickly again and didn't see but maybe I've overlooked it AGAIN!!

How about a link to "sales guide"!!

BlowerWorks

So go to BlowerWorks.net then to the Dowloads button then to:

"Carroll C4 Corvette Supercharging Sales Guide (37M)"

It's there - let me know if you find it - OK ??????

WVZR-1

Yes - it's been found and that's the way I thought I remembered the conversion to "dual piston" from early "single piston" design.

c4cruiser

Look here in the C4 Parts For Sale section. Looks like it's a complete set and has been on sale for a few months.

WVZR-1

The use of the "dual piston" abutments and calipers I'm quite sure is just a hydraulic upgrade and the original C4 early rotors are used. In the link you provided the OP could only I believe use the calipers, the rotors and the abutments NOT. If there were good pads then those also.