Posted by rickyracer (IP: 209.20.170.54) on February 27, 2000 at 12:48:42:
In Reply to: Re: posted by T.L. on February 27, 2000 at 12:39:51:
:understand what you're saying, but the thing is if there is anything you want to work right on a car is the brakes, especially on roads that are wet or otherwise. I have an adjustable prop valve on one of my cars, but only because I use it for racing and gutted the orginal prop valve on the manual disc brakes.
All I'm saying is that it's a REAL pain in the ass to change the prop valve on these cars because the fittings are a different size which means a LOT of cutting & flaring or replacing ALL the lines on the car (PITA!@#$!!!). While if you simply swap to discs and use the proper master cylinder, your braking improvement will already be 5 times better than the drum setup you had. I have driven a '75 V-8 Comet with the factory manual disc system (w/ prop valve) and my '73 Mav with the system I installed and My car brakes as good if not better. I had no problems and neither did a friend of mine who did the same thing on his '72 Grabber. I am not saying one should not change the valve; I was just trying to save people some of the hassle involved with this swap. If you're gonna take the trouble to change the prop valve anyway, I am a strong advocate of adjustable proportioning valves...
: : In case you went around working on cars in 73, they were just starting to really put disc brakes on cars. Mostly it was an option because they hadn't worked out all the bugs yet. On a 73 it is just a junction block, why do you think they went to a prop valve, after 74? because of the brake bias. If there isn't a problem with the bias then why would you even suggest a adjustable prop valve? They made the later blocks a different fitting so as not to get them mixed up. The power assist booster has nothing to do with the brake pressure. It's for pedal pressure. That's why on later cars the brake pedal rod has a different ratio for applying the brakes when you have a manual system.
: : Check your early Stang 2+2 front disc manual brakes. They used a different junction block on it to.
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: : ...you don't absolutely need to change it if it is manual...We've been through all this before on the MMB...On '74 disc brake models Ford used the SAME prop valve as the '70-'74 drum brake models. I converted to disc on my '73 and used the stock "junction block" (which is all it is) with NO problems. The proportioning valve helps reduce rear-wheel lockup on these vehicals. You only need it IF you experience a problem with that, in which case, an adjustable prop-valve would be even better. I admit that '74 calipers were different from '75-'77 but the original '73 "junction block" seems to work fine with my '75 calipers. I assume he's going with the power setup since he got everything from the granada in which case he must swap the valve because the power brakes will be much more "touchy"...
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: : : : you need to change it, power or manual. It is pressure actuated and makes the bias in the disc system work properly.
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: : : : just brought disc brake setup off a Granada. Do I need to change the proportional valve too? The one off the Granada is different.