all new system/bad brakes

[willysz28]

Hello all,
I recently upgraded to later 3/4 diffs on my 68 sub. I also added power brakes at the same time, using tuff stuffs kit, and a wilwood prop valve. I have bled out the system, but have a hard pedal and ****ty brakes. They are better in reverse actually... but still suck.

I have trouble shot and the vac canister holds air after I shut down, I'm getting 20in vac at idle, and the pedal drops when I start it. Tuff stuff's booster is a 11" single diaphragm, and is universal for 67-72's with a bracket that addresses the "rod issue." I see that the 73-87 trucks were dual diaphragm though... Is this my issue? Shouldn't an 11" single still have good stopping power?

Any help is greatly appreciated!

[CG]

Im going to ask a mod to move this to the trucks area. While you are driving a burb, it uses the same brake system as the trucks and you will get a lot more views in the truck area ... better chance of getting a little help =)

And you definitely don't want my opinion on making your truck stop better heh

[HO455]

It sounds like you have no or little pressure to the front brakes. Put a 2000 PSI gauge in one of the front bleeders and check. You should have at least 1000PSI, then compare to the rears. You may have a master cylinder check valve issue, proportioning valve problem, or the wrong master cylinder reservoir plumbed to the front brakes. Not all master cylinders use the front reservoir for the front brakes. The check valve issue is common as drums and disks use different PSI checks and the wrong one will cause the wrong amount of fluid to drain back to the master cylinder when the brakes are released. Check with Willwood as to the listed application of your master cylinder. It is not out of the question that it is the wrong configuration or has the wrong part number on it. The brakes working better in reverse is a good sign of that the fronts are not working. When stopping hard in reverse it should be easy to get the fronts to lock up. I am currently doing battle with a 68 Lemans brake conversion that is giving me similar issues.
Good Luck. Your results may vary.

[infinite-foamies]

Are the rears adjusted? I had the same issue after a frame off and the shoes were a 1/4" from contacting the drums xD

[willysz28]

Actually, after getting nowhere with their customer service and tech dept, I took off the tuff stuff booster and master and replaced with a stock setup and had better brakes. I still do need to rebuild the rear end so I will check the brakes. Thanks for the reply though. And a piece of advise for other guys, maybe find another company for your brake conversions... I wanted to support an American company, but in the end just ended up with Chinese rebuilds, damnit!

[infinite-foamies]

On that note I highly recommend inlinetube.com I had bought full stainless prebent lines and hoses from them, had some fitment issues because I lifted it and they took back the old and sent me new only charging me the difference.

They also replicated my e-brake cables in SS after I sent them in. Good prices and great service.

[ERASER5]

Possible problem is the "New" after market MC may not have had the required 10 pound residual valve installed in the rear brake port. This requires a residual valve to be install somewhere in line.

The stock setup had the residual valve already installed.