So I am swapping my 5.0 TBI to a L98. I also plan on swapping in 3.73 gears in the rear so if i was going to change the axle assembly over to disc now would be the time. But is it really necessary? Does it make a big difference? I kinda think im fine just sticking with the drums... any input?

 

Necessary, no (some members seem to prefer drums, especially over the 82-88 rear braking system).

Difference? Since 70% or so of braking goes to the fronts, upgrading them first seems to be a better choice.

Input? Remember that the swap isn't a strict bolt-on. You'll need to modify the axle flanges or buy a kit.

There are several things to consider since you have a 91. If you attempt to fit the 82-88 style 10.5" rotors and iron Delco-Moraine calipers you'll have difficulty with the disc combination valve which has a different thread pitch than your 91 (using the newer 89-97 set-up with 11.7" rotors and alum PBR's would eliminate that problem as you can purchase the appropriate 1LE combination valve). The old style may also be problematic where the parking brake is concerned, not so with the new system.

The following link will provide more info on brake types, combination valves, master cylinders, speedo gears, etc.:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

 

In doing some research on this because I'm thinking of going disc too it seems that the rear brakes are very under used with disc or drum. I was thinking of blocking off the rear line from the prop valve and have the rear go through an adjustable valve. That way more force could be applied to the rear brakes even if you kept the drums. I know you'd lose the warning light if you lose the rear brakes but I don't see a way of keeping it and still get the full force available. Thoughts?