Residual Valves

[Zack]

I know this has been covered many times but i am still wandering if i should use them or not. I have heard conflicting stories about using them vs. not using them. Can some of you shed some light on this for me again? I have 4 wheel disc brakes on my Bucket. My pedal/MC will be mounted on the inside frame rail slightly above the front brake calipers elevation and slightly lower than the rear calipers elevation. I don't want to use them if i don't have to because once i run my hard line tubing with them installed and i take them out later, then i have a botched up brake line. This is what i am hoping to avoid.

Thanks

 

[409T]

I don't want to use them if i don't have to because once i run my hard line tubing with them installed and i take them out later, then i have a botched up brake line.

If you put them in and later decide that you don't need them, you just remove the valve, drill out the center and put it back hollow.

 

[Zack]

yeah, i guess i could do that. But, are they really necessary?

 

[bigfrank330]

I have built 1 with residual check valves and 1 without
The one with had a solid pedal first pump everytime
The one without before driving I had to pump the pedal and was always worried if the brakes would be there when I wanted them
They always were there it was just an uneasy feeling all the time
The next one I build will have the darn valves in it
Frank

 

[EX JUNK]

I have two streetrods, a '37 Chevy and a '25T, and they both have residuals. I have had absolutely no problems with them and I have excellent braking.

Jim

 

[Francis Blake]

The only experience I have with residuals is on the roadster I am building now. I have driven it around the neighbourhood some and it has excellent brakes without the residuals. I put them on, 10 lbs on rear (drum brakes) and two lbs on front, after bleeding the brakes it would not roll, so I had to take them off and then everything is ok. From what I read on here each car is different.

 

[409T]

I have two T's with 11" drums in the rear and Wilwood 175 discs in the front. Because of the way the Wilwood 175's are made they don't need front residual valves, but the rear brakes supposedly need one. One car has one, the other doesn't and I can't tell the difference. In both cases the master cylinder is below the bottom of the body, and I'm going to guess below the brakes as well. I can't remember if the valves are expensive, but if not, I think I would be tempted to put them in and if there is a problem drill them out. When I first built the 409T the rear brakes would lock up after driving a couple of miles and it would take about 15 minutes before the pressure in the lines would bleed down to the point where I could drive again. I blamed it on residual valves, but the problem turned out to be that I had the rod from the brake pedal to the master cylinder too tight and when I took my foot off the pedal the piston in the master cylinder could not return enough to allow the pressure in the line to bleed back to normal.

 

[Zack]

Thanks guys. I do have the valves and i will install them based on the info i have read here. They were very inexpensive so i will give them a try and see what happens. Thanks again for all the input.

 

[EX JUNK]

Make sure you install them correctly, they are directional.

Jim

 

[T-Odd]

Mine has them, but I know that Fat Pat didn't have any on the Screaming Eagle - four wheel disc brakes and it stopped on a dime. He is known to preach that they are not needed at all and I suppose he is correct since his bucket worked without them.

I have 'em because they are there.. and I figured I could always remove them if needed.

 

[Zack]

What exact purpose do they serve and why is there what seems to be an inconsistency in difference from car to car?

 

[Francis Blake]

The reasoning for them is that the brake fluid slowly seeps back to the mc if it is lower that the brakes and than the brakes need to be pumped once to put the fluid back to the wheel cylinders . In my case it seems not to do this, even after setting for several days. With the residuals some pressure is maintained at the wheel cylinder.

 

[2old2fast]

I "think" that some M/C's have built-in residual valves , could be the disparity from car to car, also , disc valves are 2 lb. , drum are 10 lb. [to compensate for return springs,] , if you have them run them , but chk. your M/C for valves first . ...dave

 

[Zack]

I will do that. Thanks Dave

 

[Track T-4]

Francis Blake said " I put them on, 10 lbs on rear (drum brakes) and two lbs on front,..."

If they vary in "pounds", how do I know which to use?

 

[EX JUNK]

They are color coded, red for the rear and blue for the front.

Jim

 

[2old2fast]

I may have missed it but, don't forget a proportioning valve of some sort.

dave

 

[Zack]

Bought a nice one with brake sender

 

[McDenny]

OK, I have a question....how do I tell if the master has residual valves in it? I am going to use a Wilwood proportioning valve and I am going to run disc brakes all the way around too, I was not going to use residual valves until I read this and now I am second guessing myself. I have heard stories about them not releasing the pressure in calipers and making the brakes get hot. But like it was mentioned before, I don't want to run all my brake lines then figure out I need them.

 

[Lee_in_KC]

I have discs all around and no residuals or proportioning valve, and everything locks up about the same time. My understanding is you only need residuals and a PV if you have a mix of drums and discs. Where is Fat Pat when you need him??