Rembrant Posted December 24, 2020 Share Posted December 24, 2020 Corey, that's great information, thank you! Need just a little more though, at least for me, I'm slow! It seems I read somewhere that the use of the residual pressure valve is no more than an adapter. The post I read stated that and, in fact, the guy took the guts' out of it to utilize it merely as an adapter. I believe I read that here: https://www.ford-trucks.com/forums/1493345-swap-to-newer-style-mc-2.html Thoughts on this? If it's not merely an adapter for our purposes, why is it needed in the conversion when the OEM unit (cast unit) does not utilize one? I guess it depends on the situation. Since I removed the factory valve on the frame of my truck, I actually need the residual pressure valve on the later master, so for me it is more than an adapter. The purpose of the residual pressure valve is to keep about 10psi pressure on the rear brakes. Otherwise, the drum brake springs would overcome the brake fluid and push it back to the master...which in turn would cause me to require more brake pedal travel to activate the rear brakes. The factory proportioning valve on your frame serves this purpose. It serves a couple purposes, but one is that it has a prop valve for the rear drum brakes. If you are leaving it intact, then I guess you don't need the residual valve on the master cylinder, except to use it as an adapter. It looks like Gary has both installed, unless he also gutted the residual pressure valve? I don't know if that answers your question or not. You don't need both, but you definitely should have at least one or the other installed. PS: I have read where guys have swapped the later masters in (and nothing else) and reported no issues, so having both installed maybe isn't a problem? I don't know. Link to comment Share on other sites More sharing options...
Gary Lewis Posted December 24, 2020 Share Posted December 24, 2020 Corey, that's great information, thank you! Need just a little more though, at least for me, I'm slow! It seems I read somewhere that the use of the residual pressure valve is no more than an adapter. The post I read stated that and, in fact, the guy took the guts' out of it to utilize it merely as an adapter. I believe I read that here: https://www.ford-trucks.com/forums/1493345-swap-to-newer-style-mc-2.html Thoughts on this? If it's not merely an adapter for our purposes, why is it needed in the conversion when the OEM unit (cast unit) does not utilize one? I guess it depends on the situation. Since I removed the factory valve on the frame of my truck, I actually need the residual pressure valve on the later master, so for me it is more than an adapter. The purpose of the residual pressure valve is to keep about 10psi pressure on the rear brakes. Otherwise, the drum brake springs would overcome the brake fluid and push it back to the master...which in turn would cause me to require more brake pedal travel to activate the rear brakes. The factory proportioning valve on your frame serves this purpose. It serves a couple purposes, but one is that it has a prop valve for the rear drum brakes. If you are leaving it intact, then I guess you don't need the residual valve on the master cylinder, except to use it as an adapter. It looks like Gary has both installed, unless he also gutted the residual pressure valve? I don't know if that answers your question or not. You don't need both, but you definitely should have at least one or the other installed. PS: I have read where guys have swapped the later masters in (and nothing else) and reported no issues, so having both installed maybe isn't a problem? I don't know. I have both, the one on the frame and the one on the master. And I have no braking problems. The brakes work very well. Link to comment Share on other sites More sharing options...
Machspeed Posted December 24, 2020 Author Share Posted December 24, 2020 I have both, the one on the frame and the one on the master. And I have no braking problems. The brakes work very well. Thank you gentlemen, appreciate ya. I did a Rock Auto search on 91 F150 and came up with a Motorcraft Master Cyl that appears to have that residual pressure valve. I may go with it. https://www.rockauto.com/en/moreinfo.php?pk=1832506&cc=1121982&jsn=1458&_nck=ZExt1ysfqhqWnq%2BEvUNdS3Txyey60IDtnjPWF5UU9J0BWQv7pvqZbkEUk86%2BAYIhteHnM8iYlR42ABYumiydqeDsVaKATbzthYoKxu7WdO3L0RLABETRJS3oXrKgETnvdclw0V5gXaS0MFv%2BoNr49Ml6Y7r4yquuS%2FERxIG46x%2BToE7K7F58lfRhGFUdcmPnS%2F74O6ZDMmPFyDNAZbVRh9oioas0VZw0oEh8UvV7z6yUYko4wE3QumAN4QEBZAQpH0l14gD2ssYRuwv4YFYXdxBe6tZrZoejJdn74kljGza1RTJWu8VgJrxBymv0V8pfgHcpJZjEzKIsdLFjgiY7Aa5Q9WkR9G14&jsn=1458&_nck=ZExt1ysfqhqWnq%2BEvUNdS3Txyey60IDtnjPWF5UU9J0BWQv7pvqZbkEUk86%2BAYIhteHnM8iYlR42ABYumiydqeDsVaKATbzthYoKxu7WdO3L0RLABETRJS3oXrKgETnvdclw0V5gXaS0MFv%2BoNr49Ml6Y7r4yquuS%2FERxIG46x%2BToE7K7F58lfRhGFUdcmPnS%2F74O6ZDMmPFyDNAZbVRh9oioas0VZw0oEh8UvV7z6yUYko4wE3QumAN4QEBZAQpH0l14gD2ssYRuwv4YFYXdxBe6tZrZoejJdn74kljGza1RTJWu8VgJrxBymv0V8pfgHcpJZjEzKIsdLFjgiY7Aa5Q9WkR9G14&jsn=1458&_nck=ZExt1ysfqhqWnq%2BEvUNdS3Txyey60IDtnjPWF5UU9J0BWQv7pvqZbkEUk86%2BAYIhteHnM8iYlR42ABYumiydqeDsVaKATbzthYoKxu7WdO3L0RLABETRJS3oXrKgETnvdclw0V5gXaS0MFv%2BoNr49Ml6Y7r4yquuS%2FERxIG46x%2BToE7K7F58lfRhGFUdcmPnS%2F74O6ZDMmPFyDNAZbVRh9oioas0VZw0oEh8UvV7z6yUYko4wE3QumAN4QEBZAQpH0l14gD2ssYRuwv4YFYXdxBe6tZrZoejJdn74kljGza1RTJWu8VgJrxBymv0V8pfgHcpJZjEzKIsdLFjgiY7Aa5Q9WkR9G14 Link to comment Share on other sites More sharing options...
Rembrant Posted December 24, 2020 Share Posted December 24, 2020 Thank you gentlemen, appreciate ya. I did a Rock Auto search on 91 F150 and came up with a Motorcraft Master Cyl that appears to have that residual pressure valve. I may go with it. Well boom, there you go. I bought mine locally from CarQuest, and it didn't come with the valve. If it's included, then all the better, Nice find. If you can move your existing lines around, it's a pretty straight forward install. Link to comment Share on other sites More sharing options...
Gary Lewis Posted December 24, 2020 Share Posted December 24, 2020 Thank you gentlemen, appreciate ya. I did a Rock Auto search on 91 F150 and came up with a Motorcraft Master Cyl that appears to have that residual pressure valve. I may go with it. https://www.rockauto.com/en/moreinfo.php?pk=1832506&cc=1121982&jsn=1458&_nck=ZExt1ysfqhqWnq%2BEvUNdS3Txyey60IDtnjPWF5UU9J0BWQv7pvqZbkEUk86%2BAYIhteHnM8iYlR42ABYumiydqeDsVaKATbzthYoKxu7WdO3L0RLABETRJS3oXrKgETnvdclw0V5gXaS0MFv%2BoNr49Ml6Y7r4yquuS%2FERxIG46x%2BToE7K7F58lfRhGFUdcmPnS%2F74O6ZDMmPFyDNAZbVRh9oioas0VZw0oEh8UvV7z6yUYko4wE3QumAN4QEBZAQpH0l14gD2ssYRuwv4YFYXdxBe6tZrZoejJdn74kljGza1RTJWu8VgJrxBymv0V8pfgHcpJZjEzKIsdLFjgiY7Aa5Q9WkR9G14&jsn=1458&_nck=ZExt1ysfqhqWnq%2BEvUNdS3Txyey60IDtnjPWF5UU9J0BWQv7pvqZbkEUk86%2BAYIhteHnM8iYlR42ABYumiydqeDsVaKATbzthYoKxu7WdO3L0RLABETRJS3oXrKgETnvdclw0V5gXaS0MFv%2BoNr49Ml6Y7r4yquuS%2FERxIG46x%2BToE7K7F58lfRhGFUdcmPnS%2F74O6ZDMmPFyDNAZbVRh9oioas0VZw0oEh8UvV7z6yUYko4wE3QumAN4QEBZAQpH0l14gD2ssYRuwv4YFYXdxBe6tZrZoejJdn74kljGza1RTJWu8VgJrxBymv0V8pfgHcpJZjEzKIsdLFjgiY7Aa5Q9WkR9G14&jsn=1458&_nck=ZExt1ysfqhqWnq%2BEvUNdS3Txyey60IDtnjPWF5UU9J0BWQv7pvqZbkEUk86%2BAYIhteHnM8iYlR42ABYumiydqeDsVaKATbzthYoKxu7WdO3L0RLABETRJS3oXrKgETnvdclw0V5gXaS0MFv%2BoNr49Ml6Y7r4yquuS%2FERxIG46x%2BToE7K7F58lfRhGFUdcmPnS%2F74O6ZDMmPFyDNAZbVRh9oioas0VZw0oEh8UvV7z6yUYko4wE3QumAN4QEBZAQpH0l14gD2ssYRuwv4YFYXdxBe6tZrZoejJdn74kljGza1RTJWu8VgJrxBymv0V8pfgHcpJZjEzKIsdLFjgiY7Aa5Q9WkR9G14 Yep, looks like a perfect fit to me. You'll have to finish out this thread when you install it. And, maybe write it up in Upgrades? Link to comment Share on other sites More sharing options...
Frogger2662 Posted December 25, 2020 Share Posted December 25, 2020 Looking at Rock Auto for a 1990 f150 they list a Motorcraft master cylinder with what looks like the valve ya'll are talking about. Is this the valve? BRMC 63 is their part number. Link to comment Share on other sites More sharing options...
Machspeed Posted December 25, 2020 Author Share Posted December 25, 2020 Looking at Rock Auto for a 1990 f150 they list a Motorcraft master cylinder with what looks like the valve ya'll are talking about. Is this the valve? BRMC 63 is their part number. Exact same MC as the one I posted earlier for a 91. Yes, that's the valve. Link to comment Share on other sites More sharing options...
Frogger2662 Posted December 25, 2020 Share Posted December 25, 2020 So if i am understanding this i can use this on my 84 f150 just by swapping brake lines from front to rear? Thread sizes the same? Link to comment Share on other sites More sharing options...
Machspeed Posted December 25, 2020 Author Share Posted December 25, 2020 So if i am understanding this i can use this on my 84 f150 just by swapping brake lines from front to rear? Thread sizes the same? As I understand it, the unit can be used and you will have to swap the brake lines. I cannot vouch for the fittings though. Link to comment Share on other sites More sharing options...
Rembrant Posted December 25, 2020 Share Posted December 25, 2020 So if i am understanding this i can use this on my 84 f150 just by swapping brake lines from front to rear? Thread sizes the same? Hey Frogger, I have one in my 1984 F150, and I'm almost positive that the fittings are the same, but I did not do a direct swap. When I was rebuilding my truck and fixing up the frame, etc I ripped out all of the brake lines and original master cylinder. I didn't install the new one until several months later. I made all new lines, but I'm pretty sure I re-used the larger of the two fittings because I didn't have a new one, and the other fitting is just one of the regular sized 3/16" brake line fittings. I did read just recently that a guy went to the junkyard and grabbed a later master cylinder, and all he had to do was reverse his original lines, and everything bolted in place no problem. Take that with a grain of salt, but I'm pretty sure the fittings are the same, just reversed for front and rear. I can measure the hex of the fittings if it would be any help. Link to comment Share on other sites More sharing options...
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