Wilwood master cylinder? Please help!

[70SBC10BOB]

I may have missed this. What diameter is the master cylinder?

You also said "no play" in the push rod. Are you sure the master cylinder is able to completely return? There should be a little wiggle in the rod at rest. Just a few thousandths. If the piston in the master can not return completely, it may not uncover the internal bleed port and significantly reduce fluid flow.

Bob

[Palf70Step]

What about the proportioning valve? Since you went from drum-drum to disk-disk, you should have one to handle that combo (and not the disk/drum one that comes with conversion kits).

Mostly thinking out loud. Your line/bleeder situation on the rear disks baffle me. I have never seen a disk setup with the line mounted that low and the bleeder that low.

[garykirby25]

1 inch bore
Things I've done

1.Got verticals loop out of line
2. No part of line runs above master anymore
3. Plug rear port and had solid front brake
4. Plug front and had solid rear brake
5. Plug both and had solid brake pedal

If 1/4 line to rear was the problem, wouldn't I have spongy pedal when I plugged the front?

Thanks again for all the responses

[garykirby25]

I'm using wilwood combination proporting valve

[farmallboy15]

Originally Posted by garykirby25

Need some help guys! I bench bled my master and bled the brakes. I've got no pedal on the first pump, but after that I start to get some pedal. I've bled them like five times and get liquid and no air. Theres no play from pedal to master. Any other thoughts?????


Wilwood 1inch bore no booster
Wilwood combination proportioning valve

Thanks
Gary

I had the same problem with my k2500 in the beginning. Front disc conversion. I had the calipers switched left to right, keeping air in the system. Bleeders should be on top. Could be your problem, might not, I didn't read through the whole thread...

[70SBC10BOB]

How much braided line are you running?

Bob

[Tom Vogel]

[QUOTE=

If 1/4 line to rear was the problem, wouldn't I have spongy pedal when I plugged the front?

Thanks again for all the responses[/QUOTE]

I have a hydroboost setup with the 1" Willwood master and prop alve AND 1/4" rear lines. No spongy pedal here. rock solid.

[hotrodder]

I had the exact same problem with a conversion I did on a 61 Chevrolet pro street car. never did get it resolved. Told the guy that bought the car to let me know when he got it fixed, never heard back from him. I will be following this discussion to see what the cure is.

[garykirby25]

After doing a lot of searching, I've read that the rear caliper is crap! A lot of people can't get the rear adjusted correctly causing a spongy pedal. Something to do with the travel distance to the rotor. Also a forum member told me that you have to use emergency brake so the caliper can adjust. I wasn't really planning on running emergency brake, I'm think about upgrading to some wilwood brakes. Any other thoughts before I pull the trigger?

[70SBC10BOB]

1) How much braided line are you running? Any more than replacing the original rubber flex hoses is too much.

2) How much clearance do you have on the rear pads to rotors? If my memory banks aren't too dusty, I think it should be about 10 thousandths of an inch. (Yes that means using a feeler gauge.)

3) If the clearance is too much, you can screw the rear caliper piston out or actuate the parking brake until you reach the proper clearance.

The rear calipers are great units once you get them adjusted. They do not deflect or drag like the all aluminum "racing" calipers. Adding more new stuff may add additional headaches.

Eliminating the parking brake could get you in hot water in some states. They could impound your truck or require a complete safety and light inspection. What a pain.

Bob

[garykirby25]

Thank you 70sbc for all the help! I replaced all the standard hose, but also added about 15 inches to connect 1/4 to the (rear stainless was to short.) Also will check the measurement once I get off the golf course.

Thanks

[67 cst swb]

You need to get the Master Cyl lines changed. So that no part of these lines are above the master cyl ports. The fluid in these lines are draining back into the master cyl, so on the first pedal pump... you refill the lines... then on the second pump it works normally...
You gotta change these before you try anything else... shorten the lines and have them go down hill directly to the prop valve.

Oops... Sorry didn't read post #53 before posting....

[k2rm]

Check out post 22 in this thread. It details my experience. It took awhile to dial in my el dorado rear calipers, but now they work great. Pay attention to the residual valve comment. Also, from what I have learned, there are a lot of poorly rebuilt calipers out there. I am on my 3rd set. The first set had a bad ratcheting mechanism. The second set worked great, but one of them leaked. The third set I bought new from TSM which work great and do not leak. http://www.tsmmfg.com/

Edit: forgot to add the link to the other thread.
\http://67-72chevytrucks.com/vboard/s...d.php?t=603827

[garykirby25]

Originally Posted by k2rm

Check out post 22 in this thread. It details my experience. It took awhile to dial in my el dorado rear calipers, but now they work great. Pay attention to the residual valve comment. Also, from what I have learned, there are a lot of poorly rebuilt calipers out there. I am on my 3rd set. The first set had a bad ratcheting mechanism. The second set worked great, but one of them leaked. The third set I bought new from TSM which work great and do not leak. http://www.tsmmfg.com/

Edit: forgot to add the link to the other thread.
\http://67-72chevytrucks.com/vboard/s...d.php?t=603827

That gets me pumped up to tackle them this weekend, it said you used 10 lbs residual valve. All 10lbs I see are for drum, does that mater?

Thanks again for all the help
Gary

[k2rm]

I wish I kept the link to the website that said El Dorado calipers needed a 10 lb residual valve. Basically it said that because the parking brake return spring retracts the pads, there needs to be a residual valve to keep them from retracting too far. Calipers without the parking integrated parking brakes don't need them.

I have read that some people used a stock disk/drum proportioning valve when they switched to rear caddy calipers and they worked great. The reason is that the stock disk/drum proportioning valve already contains the 10 lb residual valve.

I put my residual valve inline along the passenger side frame rail.

[garykirby25]

Ok guys, got the calipers measured and the 10 lbs residual valve in. Can't tell much difference, might of helped a little. Next weekend going to pull it out of garage and see how it does.

Thanks,
Gary

[davepl]

Originally Posted by Fitz

There's never a software geek around when you need one to fix a hardware problem!

Here's three to brighten your day. I condensed them for brevity's sake.

Q: How many programmers does it take to change a light bulb?
A: The light's not burned out when I try it in my office...

An engineer, a mechanic, and a programmer are driving down a mountain pass when the brakes fail. After a terrifying ride to the bottom they discuss the problem. The engineer says "I don't think the brakes were designed for that kind of road". The mechanic says "Sure they are, it's just brake fade, we should install discs instead". The programmer says "Let's push it back up to the top of the hill and see if does it again".

A pilot and his passenger are lost in a dense Seattle fog. They approach an office building, so the passenger writes with a Sharpie on a sign: "Where are we"? The office worker writes out and holds up a sign that says "In a helicopter". With that somehow giving him his bearings, the pilot flies directly to the airport. The passenger is amazed, and asks "How did that help?". The pilot explains "Well, if the help he gave is that useless it's clearly Microsoft tech support, and I know where that building is".

[davepl]

Originally Posted by garykirby25

Ok guys, got the calipers measured and the 10 lbs residual valve in. Can't tell much difference, might of helped a little. Next weekend going to pull it out of garage and see how it does.

Thanks,
Gary

I honestly don't think these require a residual valve. It's only drums that need it, and I double-checked at Master Power Brakes who sells kits with those calipers.

It's the job of the parking brake in these units to keep the pistons properly adjusted to the rotor. You have to have a properly working parking brake and you must set it each and every time you park the vehicle, even if its an auto. How they got Cadillac owners to do so I have no idea. It'd be interesting to know if the Caddy used residual valves (or if it was integral to the combo valve) or not.

If someone can find a reference indicating otherwise, I'd love to see it, because if I'm wrong then I need to install them too!

[k2rm]

DavePL, I never found an official publication that says a residual valve is needed for the caddy calipers. I have also never seen an official publication that says they aren't needed. I just know what is working for me and giving great brake performance with the caddy calipers. I have no problem locking up the rear calipers. But, I understand your logic and agree that the residual valve may not be needed.

Gary, did you adjust the parking brake cable so that it will hold the disks when the parking brake is engaged? If not, you won't get a good pedal. The way I adjusted the brakes was to push the pedal three clicks in, and then tighten the cable using the adjuster until I just couldn't turn the wheels by hand. Then, when pushing the brake pedal all the way in you should get a pretty good parking brake hold. When the parking brake is disengaged, you should see a gap between the parking brake level arm and caliper. If there is no gap to begin with, your parking brake is not properly adjusted.

Lastly, on my first set of calipers. I could adjust the parking brake to get good performance, but then after about three or four cycles, it would be gone. That is when I figured out it was a bad ratcheting mechanism in one of the calipers.

If the parking brake is adjusted properly, then I have to believe you still have air in the lines. There are plenty of posts around the web that says the caddy calipers are notorious for being difficult to bleed. While bleeding mine, I would take the caliper off the brackets and rotate them slightly and tap them. This would usually get a few more bubbles to come out. The caddy calipers are a pain to setup, but once you do they work pretty darn well.

[ericjon262]

Originally Posted by davepl

Well, if you bled them really fast the viscosity of the oil would be high enough that it'd push the air out of the way. Can you tell I'm a programmer and not a hydraulic engineer? I can spot weird exception cases but add no actual value :-)

you're best to re-do the lines and get them lower.

[mattfranklin]

Somewhere on this site I read about a hard stomp method to get the trapped bubbles out. It went something like this... If you push too slowly, the fluid slips past the bubbles and the bubbles stay there. With the hard stomp, the combination of speed and inertia of the fluid and the viscosity not letting it slip around the bubbles forces the whole slug of fluid and bubbles out.

But I also agree with the comments about height of lines and bleeders, and about minimizing the braided hose (but there are special braided hoses specifically for brake systems, I believe).

[mattfranklin]

Hey, isn't the residual valve for drums and not discs, or do I have that backwards?

[colgad]

On my 67 C10 I use the same calipers in the rear, stock 71's in front. Corvette MC and hydro boost, braided lines in more than just for replacing the rubber ones. I do have the emergency brake connected and adjusted.
I had no issues bleeding or them functioning.
I really hope you can get the issue resolved.
My neighbour had a 49 chevy pickup that had the same issue and never did get it fixed (sold it).
So make sure when you do tell us what fixed it.