oldeskewltoy Dork
4/12/13 7:05 p.m.

I've been dragging my feet on swapping the rear axles in my Corolla project because I want to make sure the brakes are not dodgy after the swap. I'm swapping in a rear diff with rear disc brakes for the existing one with drums. What I need is to understand the differences in hydralics. I want to understand better because I have a couple of options available to me.

The first option would be to just swap the axle... and use the drum hydralics with the disc brakes

the second option is to swap in a disc brake proportioning valve (I have)

The third option is to use an adjust/set/forget aftermarket valve so that I can tailor the braking performance to my desire. IF I choose this, do I use the disc brake proportioning valve, or the drum brake proportioning valve to begin with?

DrBoost PowerDork
4/12/13 7:10 p.m.

If you're swapping in a disc brake setup that existed on that car, I'd just swap in the factory prop valve. If you're swapping in something that never belonged (i.e. Explorer 8.8 into a miata) I'd use an adjustable prop valve.

GameboyRMH UltimaDork
4/12/13 7:30 p.m.

You might have to experiment with the two factory proportioning valves. Changing the system to fully adjustable bias is the best but most expensive and difficult solution. The cheapest and least potentially troublesome is to swap in the disc brake proportioning valve - you'll get something in the right ballpark but probably not optimal.

HappyAndy SuperDork
4/12/13 8:01 p.m.

Did the disk brake axel and proportioning valve come from the same car, and is that car very similar to your corolla? If so, check and see if that car uses the same MC and front brakes. If it does, then it should be straight forward, or maybe you will also need to change the MC.

Streetwiseguy UltraDork
4/12/13 8:30 p.m.

Prop valve is one thing, but there is probably a residual pressure valve in the master cylinder for the drums. It has to come out, or the discs will drag and bake.

AngryCorvair PowerDork
4/13/13 1:50 a.m.

Yeah, they've pretty much covered it.

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