VetteTheWorld

I have finally gotten around to upgrading my front brakes on my 1991 coupe to the J55 option (13 inch brakes instead of 12 inch). It has been a hassle getting the parts needed from MA Motorworks so my parts are still in the process of getting to my house. I ordered new caliper brackets, SS brake hoses, and new pads. The only concern is that my calipers will not fit the brackets. Does anyone have any idea if the calipers I have now will work with my upgrade? Am I going to have to buy new calipers from a 1995 or 1996 to fit my 1991? Your help is very much appreciated.

Churchkey

You need calipers for the 13" rotors as they are thicker than the 12" rotors.

12" C4 front rotor data
# of Bolt Holes : 5
Bolt Circle Diameter : 4.75"
Brake Rotor Diameter : 12"
Brake Rotor Discard Thickness : .72"
Brake Rotor Thickness New : .79"
Brake Rotor Type : Disc Brake Rotor Only
Center Hole Diameter : 2.78"
Height : 2.21"

13" C4 front rotor data
# of Bolt Holes : 5
Bolt Circle Diameter : 4.75"
Brake Rotor Diameter : 13"
Brake Rotor Discard Thickness : 1.04"
Brake Rotor Thickness New : 1.1"
Brake Rotor Type : Disc Brake Rotor Only
Center Hole Diameter : 2.79"
Height : 2.21"

jrzvette

This might help

https://www.superchevyperformance.co...les.asp?ID=123

Goldcylon

You need J55 Calipers and abutement brackets to fit the 13 inch rotors. All three will fit on that 91.

drmrman

MAM sucks.... :/ They never get their $hit out on time they miss ship your order (usually leaving parts out) and are real difficult to get your money back from when you cancel your order!!! Eklers isnt that good either...

VetteTheWorld

Thanks for all your help. My rotors and brackets are on now and I am only waiting on my brake lines and calipers. It seems that about this time everyone is out of SS brake lines. I cancelled my order from MAM and re-ordered from Zip Corvette (hopefully a better experiance than MAM).

joe@zip

VetteTheWorld - PM me your order number and I'll make sure everything gets taken care of. Lately we have been selling more Wilwood kits for C4 owners that are looking to upgrade form the 12" rotor.