Quote:
Originally Posted by KQQL IT
So I'm researching parts.
And apparently the c10 and c20 use a different master cylinder. The fittings are switched front to rear.
Can someone tell me which master cylinder this truck has?
As it's a originally a manual brake c10 that's been swapped to 8 lug stuff.
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So, there's a lot going on here!
The mc pictured appears to be from a pre-71 C10 (all 1/4" lines; front res line goes to front of distrib block, and on to front brake wheel cylinders). Is that what old Blue started as, a pre-71 C10?
If you're converting a pre-71 C10 to a 4-wheel disk C20, all bets are kinda off for using a factory mc since there was no such animal from the factory for a truck.
You are correct that a 3/4 ton mc is different than a 1/2 ton mc in the disk/drum years of 71-72. For a 71-72 3/4 ton, the front reservoir fed the REAR drum brakes and had 1/4" lines - whereas the rear reservoir fed the FRONT disk brakes and had 3/16" lines. But, BOTH were designed for a disk/drum brake system.
You have a unique scenario with a 4 wheel disk setup - none of the stock master cylinders are designed for that. I'd recommend that you install an aftermarket mc recommended by the disk kit mfgr (and make sure they know you need an mc for a truck with 3/4 ton running gear). OR, I'd consider a Vette 4-wheel disk type mc as a viable option also. But I'd definitely replace the current mc - and I'd try to install one that is designed for a 4-wheel disk setup.
I'd also talk to your kit mfgr for line size recommendations. Generally speaking, disk system lines are 3/16" - and I'm suspecting you have all 1/4" lines today. That is probably ok, the brakes will still work - but IF you happen to be replacing lines, I'd ask the kit mfgr what they recommend as they may recommend 3/16" all the way around. Again, I wouldn't lose too much sleep if you have all 1/4" lines - that's ok. But IF you're replacing stuff - keep in mind that in a 4 wheel disk setup, the MC "should" be designed for 4 wheel disks and you'd probably want to install an adjustable proportioning valve to be able to fine-tune your system. And you'll want to ensure your lines are at least all the same size across the entire system.