I completed the TC disc brake rear swap this evening...everything went great!! Took two hours from start to finish. The 3.55's pull much nicer than the 3.08's. I still need to acquire the appropriate e-brake cables (already read the sticky about that). But before that...I could not get the rear brakes to work. I'm getting fluid through the bleeder but no caliper action.
Now I must say that it is possible that the calipers are froze...the donor rear did set for a couple years. But if that is not the case, is it possible that the proportioning valve is not passing enough fluid to the rear calipers? The front brakes and MC are stock '88 Sport (for now...and likely for a while). I have a prop valve from the donor TC that I can swap if that will help with the problem.
Your thoughts?
If you are trying to use a stock disc/drum prop block with rear discs, you aren't going to get them to work much, if at all.
Swap to the proper prop block first. Then if you still don't have caliper movement, time to deal with seized calipers.
That's exactly your problem.
Usually calipers don't freeze in the open position,they freeze in the closed position.
If you where able to turn them in then they are fine.
Your problem lies in the prop valve and master cyl.
Rear drum brakes require very little fluid to operate and the prop valve is set up to deliver most of it too the front.
You need to get an adjustable prop valve and re proportion the fluid to the rear.
Your master and booster must also be changed to a 1993 cobra which had the exact same combination as you are running now.
Your current master does not have a big enough fluid reserve for the rear and i don't believe that the 93 master will fit the stock 88 booster.
I was kinda hoping this was the issue. Through some searches I did find where several folks said they were running the stock MC w/ four wheel discs with no problems but I never found anything stating that the prop valve was swapped or left stock. Knowing the front/rear bais with stock dsic/drums I thought this may be the problem.
It's not a guarantee that the rear calipers aren't seized, but they wouldn't work regardless if you're trying to use the disc/drum prop block.
I completely understand...and I'm fully prepared to replaced the rear disc parts with all new. But I don't want to do that then find out the prop block is still a problem. I'd prefer to start at the front and work out the kinks as I go back.
Is this a fact that the 93 master cyl will not work with the 88 booster? Does that mean you need to use a 93 cobra prop valve?