Disc conversion dragging bad

[YungICY]

The only 2 places a residual valve can be is in the factory proportioning valve or MC. I’m gonna pull the prop valve out and run some new lines and clean things up a little. I’ll dissect the prop valve and see if it has the residual valve in it. Otherwise it seems it was common practice across manufacturers to put them behind the seat in the port of the MC.

 

[bobbywalter]

those ones usually screw out too.

 

[JoshT]

Otherwise it seems it was common practice across manufacturers to put them behind the seat in the port of the MC.

That's what I was trying to say. Not sure if it was on Rangers or F-100s, but that is what I've read about. I've done a front disc conversion on my F-100 (originally drum/drum) and studied a rear disc conversion on my Rangers, so I've read into both. Makes it difficult to keep them straight. Ended up using a later disc/drum master cylinder on the F-100 and will likely do the same with a disc/disc (Explorer) master cylinder on the Rangers.

 

[YungICY]

The plot is thickening fellas. I pulled the factory prop valve out and disassembled it. Definitely no residual check valve in there, just the shuttle valve separating the front circuit from the rear.
Proceeded to pull the the seat out of the port on the MC and also no check valve there either.
The only other possible cause at this point is ghosts *shrugs*
I’m going to reassemble the system without the factory prop valve this weekend and go from there.
Also, I’m trying to quote and reference y’all in my posts but I’m on mobile and it’s being a real PITA.

 

[JoshT]

Someone may have asked, but did you replace the soft line to the rear axle and calipers? Old lines can swell internally restricting fluid flow back to the master cylinder.

 

[bobbywalter]

Someone may have asked, but did you replace the soft line to the rear axle and calipers? Old lines can swell internally restricting fluid flow back to the master cylinder.

i would wager this since your not seeing any thing.


especially those shorty lines. i use the lugnut 4x4 stuff on my rear 60.

 

[YungICY]

Yeah, all new lines apart from the hard line between the factory prop valve and the frame end of the upper link. The stainless braided lines on either end of the upper link and the rubber lines at the calipers are the only soft lines in the system.
I will add too that with the last axle I had in there (f150 8.8 with drums) everything worked great.

 

[YungICY]

Re did all my brake lines today and here’s where I’m at.
New hardline from adjustable proportional valve to rear.
New front hardline from master to T fitting splitting directly to front tires.
Removed the factory proportional/shuttle valve.
Test drive it felt a lot better. Didn’t feel like I was missing half of my already dismally low hp. Pulled back into my driveway and I can manually roll the truck though it does feel slightly like it’s dragging. It may just be down to a slight misalignment on the caliper/rotor causing the minuscule drag I may be feeling at this point.

To clarify for future guys that may be reading this, I did not have a residual pressure valve in my master cylinder (85 ranger manual brakes). I did not see any sort of residual pressure valve in the factory proportional/shuttle valve on the frame rail. At this point the only thing that is different is the bypass of the factory proportional/shuttle valve. The pedal feels a little soft on the rear circuit which I believe is due to a lower volume output. I will put some miles on it and if it feels alright I will leave it be, if it leaves me wanting more I will look around for another MC to run and report back if I remember to.