1994 Ford Tempo / Mercury Topaz Rear Brake Pressure Limiters

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Folks, on the underside of the master cylinder for my 94 Topaz - for the lines that go to the rear drum brakes - there is a pressure reducing valve in-line... and immediately prior to where the line to the respective rear brake starts.

These are NLA - no longer available.

They were used on more than just the Topaz / Tempo.

What do folks suggest I use as a replacement for these two?

Tempo Master Cylinder Rear Brake Pressure Reducing Valve.JPG
 
Thank you for your help thus far. Totally right re the cost... and the cost surmounting the value of the car!!

I'm actually not sure that that is the correct model number. And also, is it possible that these are residual pressure valves... used to keep a wee bit of pressure on the drum brakes of a disc/drum car?

If they are residual pressure valves, I wonder if a generic valve could easily be plumbed-in.
 
Originally Posted by Cdn17Sport6MT
Thank you for your help thus far. Totally right re the cost... and the cost surmounting the value of the car!!

I'm actually not sure that that is the correct model number. And also, is it possible that these are residual pressure valves... used to keep a wee bit of pressure on the drum brakes of a disc/drum car?

If they are residual pressure valves, I wonder if a generic valve could easily be plumbed-in.


Hit up a pic'n'pull junkyard and take pull off a junked car or truck perhaps? They seem to have been used for a decade or so on F-Series, Econoline vans, Tempo/Topaz, etc. That's what I'd do before buying brand new stuff.
 
Originally Posted by pitzel
Originally Posted by Cdn17Sport6MT
Thank you for your help thus far. Totally right re the cost... and the cost surmounting the value of the car!!

I'm actually not sure that that is the correct model number. And also, is it possible that these are residual pressure valves... used to keep a wee bit of pressure on the drum brakes of a disc/drum car?

If they are residual pressure valves, I wonder if a generic valve could easily be plumbed-in.


Hit up a pic'n'pull junkyard and take pull off a junked car or truck perhaps? They seem to have been used for a decade or so on F-Series, Econoline vans, Tempo/Topaz, etc. That's what I'd do before buying brand new stuff.
You won't find much from last century in the yard anymore, and I used to frequent a great junkyard. The Junkyard sweet spot is 10-15 years for popular models. Trucks and vans are very often picked over because of their commercial uses.
 
Thx, All, re your input. Agree re finding one in the pic and pull. I also would prefer new ones.

I wonder if it is a residual pressure valve (10 psi) or some kind of pressure reducing valve. I am guessing, 'cuz it only has an in and an out port - that it is a residual pressure valve... to counter the brake springs.

If this is the case, then I wonder how brake balance is achieved... Would it be, say, the relative sizing of the front discs (and pistons) and the rear drums and wheel cylinders?

What I am thinking, here, is that a person could plumb-in this stuff... e.g. Willwood, or the like... and new stuff is available. It would take a few dry road (or wet road) tests.... with the proportioning valves (I would use two) set at progressively different lever-positions for ea. test...

I do wanna stay cheap... and rebuilt calipers and new rear wheel cylinders are cheap, cheap, cheap for this car...

Just wanna see if I can get it running and driving once more, more or less reliably. Sell it to a needy student... I just can't seem to decide to scrap it as it has but 145,000 km (~90,000 miles?) and it likely is good for many, many more miles. No automatic to blow up on it - and, in fact, a pleasant-shifting Mazda 5 speed... and interestingly - the best of the best set of pedals for effective heeling and toeing / double clutching of any car I've drivent!
 
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Originally Posted by Cdn17Sport6MT
Thank you for your help thus far. Totally right re the cost... and the cost surmounting the value of the car!!

I'm actually not sure that that is the correct model number. And also, is it possible that these are residual pressure valves... used to keep a wee bit of pressure on the drum brakes of a disc/drum car?

If they are residual pressure valves, I wonder if a generic valve could easily be plumbed-in.


I'd be stunned if they were residual pressure valves...wheel cylinders have used expanders so the valve is not needed since the 1970s, and they were universal since the early 80's.
 
Thank you for your response... I have done a bit of research, and I am starting to conclude that they are rear brake pressure reducing valves... I guess there are two because the diagonals comprise the two brake circuits... not front versus back (where you could then have a single valve to cater for the rear).

If they are pressure reducing valves, I wonder if they reduce rear pressure to a % below front pressure... They certainly do not take the load on the rear of the car into account.

If they are no longer available, what would my options be? Wilwood or the like? Then experiment, on dry roads, to determine what the optimal setting is? I wonder if the optimal setting would change in the case of a wet road?

Any comments would be much appreciated!
 
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