RCR40 - Dragging Brakes

[Pasha Saleh]

Coming up on 500 miles on a new RCR40 build and getting nicely sorted. I have noticed that the car is crazy hard to push on a flat surface in neutral after coming back from a drive. Jacking it up, I found that the brakes are lightly dragging as the wheels turn with some effort. Cracking a brake hose fitting slightly immediately relieves the pressure but when I pump the brakes after re-tightening, they are dragging again.

I'm using a Tilton pedal box and have a good 1/4" free play/pedal travel before the pushrods start moving on the master cylinders so it seems the pedal adjustment isn't the issue. A mechanic friend suggested the residual valves could be the issue. Do they come in different sizes? I just used what RCR supplied. Can they be removed entirely?

Curious if anyone has experienced this issue and what else to look for.

 

[Bill Kearley]

First I would try giving it some more free play or remove the push rod to check.
I would for sure use residual check valves but no more than 2 PSI. If I recall that's what I used !!!!

 

[Brian Kissel]

If remember correctly, there was a issue with some of the residual valves. These are the valves that several forum members recommended.

https://www.amazon.com/gp/aw/d/B01GVIM8G8?psc=1&ref=ppx_pop_mob_b_asin_title

Regards Brian

 

[Neil]

Make sure the residual valve(s) are meant for disk brakes. Drum brake residual valves are about 10 psi.

 

[Brian Kissel]

The blue ones in the above Amazon ad are 2psi.

 

[Neil]

The blue ones in the above Amazon ad are 2psi.

...if someone didn't install the wrong spring.

 

[Pasha Saleh]

Thanks! Looks like mine are some generic blue residual valves. Ordered the Wilwoods and will see if it makes a difference.

 

[Howard Jones]

I really worry about ebay when it comes to things like this. A LOT of stuff gets illegally copied in China and these would be a perfect candidate for that. Buy them from Summit or Jegs. Amazon is great for a lot of other things just not my first choice for mission-critical brake parts. Note the difference in price. Can they really be that much cheaper?

Wilwood Disc Brakes 260-13783 Wilwood Residual Pressure Valves | Summit Racing

Free Shipping - Wilwood Residual Pressure Valves with qualifying orders of $109. Shop Residual Pressure Valves at Summit Racing.

www.summitracing.com

Wilwood 260-13783: Residual Brake Pressure Valve 2 psi - JEGS

Get the Best Performance with Wilwood Residual Brake Pressure Valve 2 psi 260-13783 parts at JEGS. Shop Now at the Guaranteed Lowest Price!

www.jegs.com

 

[Brian Kissel]

The ones I linked to from Amazon are GENUINE Wilwood. If I had any doubts about them being knock offs, I certainly wouldn’t have posted that. You are already dealing with knock offs as has been posted on here before.

Regards Brian

 

[Howard Jones]

I didn't intend to offend you, Brian. But you have to admit that there is a lot of garbage on eBay as well as some really good stuff. The problem is you really don't know what you will get until it arrives. I mentioned Summit and Jeggs because they are official vendors of Willwood Brake.

One of the vendors listed in that advert is Hoerr Inc. a well-known race car parts vendor. I would buy them from them, Interestingly they quote the same price as Summit and Jeggs.

Amazon.com Seller Profile: R/A Hoerr Incorporated

The low price is what got me, sorry.

 

[Phil G]

Same issue on mine...I removed the residual valves..no issues after that.

 

[Brian Kissel]

Not a problem Howard. I do see a lot of imported junk as you say. I prefer to pay a little more and only get top of the line stuff. Even then sometimes a issue pops up, but 99% percent of the time they stand behind it. Knock off stuff you have little customer support. I ordered off EBay a couple of aluminum Monza style gas caps. According to the listing, they were the proper size. Once I received them, they weren’t even close. The seller offered me half my money back. I refused and opened a claim with EBAY and was awarded my full return. Too much hassle.Lesson learned.
Thanks for reminding us of the poor quality stuff that is floating around disguising it’s self as the real thing.
Thanks Howard !!
Regards Brian

 

[Pasha Saleh]

Same issue on mine...I removed the residual valves..no issues after that.

Thanks for the report, Phil. No issues with fluid draining back into the master cylinder or whatever these things are meant to prevent?

 

[Neil]

One more thought regarding "dragging brakes". Back in the late '80s, I rebuilt my Series III 250GTE 2+2. After getting everything back together, I took it for a drive around the block. When I returned, a neighbor pointed out that my front disks were glowing red hot! Some investigation showed that the brake master cylinder push rod was not retracting all the way, essentially creating a check valve where the brake fluid would go o the front calipers but would not return when pressure was released on the pedal. Simply re-locating the M/C a few mm solved that problem. You never know what might be wrong- you need to eliminate potential caused one by one.

 

[Bob Putnam]

I don't know RCR's configuration for the brake reservoirs, but you only need the residual check valves if the reservoirs are below the level of the calipers and master cylinders. Otherwise, the normal fluid head pressure will keep the air out of the system and keep the pads from abnormally retracting.

 

[Pasha Saleh]

My reservoirs are above the caliper so I shouldn't have been using them. Believe it or not the hardest part is finding the hardware to connect the various invert flare fittings between the hard line and the flexible hose -- way too many different kinds of connectors and Napa doesn't have any of them!

 

[Randy V]

My reservoirs are above the caliper so I shouldn't have been using them. Believe it or not the hardest part is finding the hardware to connect the various invert flare fittings between the hard line and the flexible hose -- way too many different kinds of connectors and Napa doesn't have any of them!

Just pull the guts out of the residual valves and reinstall - or - just buy an NPT union And install your fittings on either end of the union. Make sure you use a good quality teflon thread tape on the pipe threads..

 

[Randy V]

BTW, it doesn’t hurt to use “good” residual valves regardless of your reservoir height. I have installed them many times in racecars where I had to reduce the diameter of the master cylinders to increase the hydraulic pressure multiplication. When you do this, you end up with longer pedal travel in order to move the volume of fluid. The residual valves just keep a light pressure in the line, decreases the pedal travel thereby giving you a higher pedal (important for heal/toe operation)…

 

[Pasha Saleh]

Thanks, Randy!

 

[Randy V]

Thanks, Randy!

You’re welcome!