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Old 09-04-2006, 09:38 PM
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Rear Disc & Front Drum - Is that ok?

I'm upgrading my rear end this winter. maybe a whole new housing? for sure new axles and ring/pinion. Anyway, in the process people are telling me perhaps to convert to rear disc brakes. with drums in the front, would that be ok or cause braking problems? Assume I won't upgrade the front for several years. This is a 72 nova street muscle car with a big block.

thanks.

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Old 09-04-2006, 11:57 PM
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This is just my opinion. I really do not know for sure but I think you will be creating a problem for yourself. Reason being that the front wheels do about 80 to 90% of the stopping force and disc brakes are more efficient at stopping than drums and they also require more pressure than drums. What you are thinking about doing is backward of what others, including myself are doing. I don't know how you would setup the proportioning valve to acquire a reasonable braking pattern. If I were you, I would go ahead and convert the front to disc as well. It is relatively easy to convert and really not all that expensive, PLUS you wind up with very good brake system. When it comes to brakes and steering, GO FIRST CLASS, your life depends on it. JMO

Al
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Old 09-05-2006, 12:02 AM
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I don't think this would work very well. Disc are far more aggressive than drum. If you experienced hard brake lockup at speed, the rear tires would lock and cause the rear end of the car to swing.

It would be a nightmare to plumb. You would have to have a metering valve on the rear brakes instead of the front (disc) and that would preclude an adjustable proportioning valve.

Front brakes perform let's say 80% of vehicle braking. The resultant brake bias would be very dangerous (IMO).
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Old 09-05-2006, 12:02 AM
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If you only have the money to do 1 end do the front. Because the front end is heavier to start with (especially with a big block) and because weight transfers to the front under braking the front brakes do most of the work. Your braking system would only be as strong as your weakest link. Swapping in only rear disc brakes would not improve your cars overall braking at all.

I do think you could make rear disc / front drum work, but it would take a bunch of odd parts (or odd use of standard parts) that would be of no use to you after you swap to disc up front.

Are there any other areas of the project you could skimp on to get disc brakes up front?
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Old 09-05-2006, 12:22 AM
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I would ask myself, this question.

Why, is there no properly engineered street car , anywhere, ever, with disc in the back only? (show me one, if there is)

Why don't you want to do it right?

Discs require alot more pressure than drums do to do an equivilent amount of work, up to a point. So the front brakes are going to do nearly ALL the work in a rear disc only system. Your car will probably stop worse than with drums all the way around.
If you try to valve the system so you cut pressure to the front, so you can get the rears to do some work, you are asking for trouble. I would bet that in a high speed panic stop where you get the fronts to fade, the backs will lock, and you are going to swap ends. In your nose heavy, BB nova, that won't be fun.

Follow the advice of everyone who is telling you it is wrong, and follow the example of every auto manufacturer and brake system designer and do the fronts first.

Hope this helps, mikey
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Last edited by powerrodsmike; 09-05-2006 at 12:33 AM.
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