mrman5917 wrote on 08/08/11 at 02:04:18:
Is it only a requirement to have the same sized brakes because of how short the wheel base is?
No, I never said that. What I said was that a short wheelbase magnifies the problem created with mismatched brakes.
mrman5917 wrote on 08/08/11 at 02:04:18:
I haven't dealt much with brakes in anything older than a late 80s GM compact, but even that car had a larger (albeit disc) brake than the in the rear. Would the fact that it's a disc make it so that size between the two is less of an issue?
Modern disc brakes are an entirely different horse; dual master cylinders and line pressure compensators for starters. The shoes on drum brakes are retracted away from the surface of the drum when not being used. That's not the case with disc brakes. On disc brakes the pads are not retracted and are always in contact with the rotor but no pressure is being applied. That's why you'll replace three sets of front disc pads before you ever need to even
look at the rear shoes. When you apply pressure to the brake pedal, compensators regulate how the two different systems are applied, so you can see they are entirely different from the Bendix system used on these jeeps.
Keep this in mind as well, the brakes on these jeeps are not self-actuating, meaning the rotation of the drum does not increase braking by applying more pressure on the shoes. Most 11" brakes
are self-actuating so it's not just the size difference that makes them more efficient. With 11" self-actuating brakes on the front and 9" Bendix type on the rear you are always at risk of the fronts locking up. That's OK if you're doing 30 mph on dry pavement, in a straight line but, on wet pavement? in a curve? on stones? There's a reason these flatfenders are prone to rollovers; high CG, short wheelbase, narrow track. Mis-matched brakes increase the risk.
Larry