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Author Topic:   metric brake calipers?
ford5
Dirt Forum Champ
Total posts: 711
posted May 17, 2004 06:21 AM  
Anyone else ever had problems with stock GM metric calipers, when using them on the rear of a IMCA mod? I am used to using after market 'racing' type calipers but this year tryed metric calipers on my IMCA legal car. Trouble is, can't seem to ever get a good feel in the pedal, despite lots of bleeding and all new master cyls. got the caliper brackets on straight and all that important stuff, but ain't having much luck getting the brakes to be very effective, running 1 inch MC. Could i be needing to get aftermarket racing type calipers? Seems like when bleeding the brakes the old fashioned way, that the fluid does'nt seem to 'shoot' out of the bleeders with a whole lot of force behind it? thanks .........ford5

Dman
Dirt Freak

Total posts: 270
posted May 17, 2004 08:02 AM  
You should be running a 7/8" master to the rear.This will give you better pressure.Go with a racing pad like the Hawk black pads.They are reasonably priced and give better pedal feel.Make sure the bleeders are clean.Sometimes they have dirt in them or they arent drilled real well. Good Luck!

Dman
Dirt Freak

Total posts: 270
posted May 17, 2004 08:05 AM  
Also I failed to mention the possibility of a warped rotor.A warped rotor will spread the caliper open further causing low pedal.

ford5
Dirt Forum Champ
Total posts: 711
posted May 17, 2004 05:40 PM  
we are running the Hawk Blue pads and everything is clean and is brand new. no warped anything or dirty.

avenger 11
Dirt Forum Racer

Total posts: 88
posted May 18, 2004 07:41 PM  
Are you running Jaamar master cylinders?

ford5
Dirt Forum Champ
Total posts: 711
posted May 19, 2004 05:19 AM  
no, wilwood composites

ss6m
Dirt Roller

Total posts: 21
posted May 19, 2004 10:00 AM  
A 7/8 mc will help. The other thing to check is to make sure both master cylinder pushrods are threaded into the pedal the same. If the rear is threaded into it too far you will not be getting a full stroke on the pushrod when you step on the pedal.
The front MC will bottom out and not let the rear one go all the way. If you are using plastic brake lines make sure the rear is not pinched somewhere (like with a plastic tie) Hope you find the pproblem.


de94wcc
Dirt Forum Racer

Total posts: 87
posted May 19, 2004 10:14 AM  
We had a Wilwood composite bad out of the box once. It could be that the MC is just junk. You could try swapping the lines at the MC's and see if you can tell a difference on your bias gauge. We have had more than our share of trouble with the composites, and we run metal now. No problems since.

ford5
Dirt Forum Champ
Total posts: 711
posted May 19, 2004 04:50 PM  
thanks guys.............I will investigate all your ideas tonite..ford5 i'm thinking the same thing ...that composites are not as good.

jakestevens
Dirt Full Roller

Total posts: 68
posted May 19, 2004 09:46 PM  
ford5, I had done some research on metric calipers and running them on modifieds. The problem I was having was the rears locking up when I applied the pedal. Metric calipers were designed to be on the front of a vehicle, so since most braking action is on the front of passenger car, the calipers will compress the piston faster and harder. The solution was to change from a 7/8" master cylinder to a 1" and also when bleeding the brakes, jack up one side of the car at a time and have someone at each wheel while someone is in the cockpit working the pedal. This will help you in getting the brake fluid to "squirt" out because just because you have your brake crank or proportioning valve to the front or back doesn't mean that 100% of the pressure is
going to that end of the car. Hope this helps.

fr1
Dirt Forum Racer

Total posts: 93
posted May 20, 2004 06:19 AM  
your piston might be out too far. The metric caliper is designed for a 1" rotor. You probably have .810" wide rotors. Coleman makes a brake pad spacer that takes out the slack. You can also make one out of an old brake pad.

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