Working Man's Burbon

[HO455]

It's official! I've gone from, out of coupons, to just plain bad luck!
I've put fifty or so miles on the WMB and while the brakes worked, the pedal feel wasn't great and it seemed to be getting worse so I parked it until I got a day off to check things out.

When that day came I popped the hood and immediately noticed that there was brake fluid everywhere. UHGGGG! So I had the wife step on the brakes while I watched for the source of fluid. It only took one pump of the pedal to see fluid spraying out of the fitting at the inlet to the front brake circuit residual valve. I initially thought the fitting had somehow backed out but when I put a wrench on it it just fell apart.

Fortunately I had a spare fitting in the horde. Once it was replaced I bled the brakes again but i didn't achieve any real change in the pedal feel. To say the least I'm getting fairly frustrated with this! At this point the only part that hasn't been replaced is the distribution block. So my next step will be to take it out of the system and see what happens.

The other exciting part of all this is most of the paint on inner fender well is now bubbling up and the alternator was soaked with brake fluid. I'm hoping that my washing everything down with the garden hose will be enough to keep the alternator alive.

[FLYNAVY30]

I feel for you.....I cant help but wonder if those D52 calipers were intended for the weight of the C10 truck, and not the weight of the Suburban. My brakes are "ok", and safe to drive, but they just dont have that initial bite Id like them to have.

[HO455]

Unfortunately for me at this point haven't gotten a firm pedal yet. I would love to have a hard pedal and lackluster braking. Until then I have to assume there is still air in the system.

I do believe that the D52's are up to the task as GM used them most 3/4 ton trucks through the mid-80's including the 454 Suburbans. The calipers I removed were GM D52's (single piston diameter of 2.95). The Wilwoods I installed are the dual 2 inch piston versions which in theory will give the same clamping power with more even pad wear.

[FLYNAVY30]

Im using the dual piston D52s in the front with the single piston D52s in the rear....11 inch booster and the Wilwood 1.25" master

[HO455]

The first thread helped me with the brake changes on my Firebird. You may have already seen it as I know you're on the Pro-touring site. If not maybe it will help you.

During my discussions with Wilwood they stated I should use a 1" bore master cylinder with the D52 calipers I have..

https://www.pro-touring.com/threads/...clamping+force

This 2nd link goes to a gentleman who's having a similar issue as you or it seems similar from this side of the screen.

https://www.pro-touring.com/threads/...rakes-Wrong-MC

[FLYNAVY30]

Thanks for those....I'll read through them. I mis-spoke, I do in fact have the 1" bore Wilwood master cylinder on my truck right now.

What I really need to do is measure how much pressure Im getting at each corner and go from there.

[HO455]

The brake pressure test set I bought is nice but if I were to do it again I would just get the two adapters for the bleeders I needed and a guage. The set has metric adapters I'll probably never use and it doesn't have the Wilwood bleeder adapter.

[FLYNAVY30]

yea, Ive got the Wilwood gauge that goes right on the bleeder because both of my builds run Wilwood calipers.

perhaps its shameful, but my 80 series and the wife's 4Runner go to the Toyota stealership 2 miles down the road....I just dont have time these days to wrench on the project cars AND the daily drivers

[HO455]

Made some progress on the brakes. I've been frustrated to say the least and I needed to change directions.

I was on the verge of going out replacing the the new calipers with the old ones to see if it made a difference when I came to the realization that the only pieces of the system that were still original to the truck are the pedals and the distribution block. I'm confident the pedals are not the problem but the distribution block is an unknown.

I gathered up enough fittings to bypass the distribution block. (See the cobbled up mess in the photo!) Doing this has made my pedal feel better and the front brakes are working better. How much at present I can't say for sure today, as it's raining here and when I try a hard braking test everything is locking up. Definitely need dry pavement for brake testing.

I did do a test with the front brake circuit bypassing the block while the rear circuit still included the block. The pedal felt better after being bled and when I checked the empty front brake ports in the block I noticed a drip of fluid. I wiped it off and cleaned things up before pumping the brakes 20 times. No drip was detected so I did another 20 pumps and this time when I wiped it with a clean rag there was a small amount of fluid on the rag. So the rear portion of block is passing some fluid but maybe it was also allowing air to get drawn into the system. At present I'm assuming the front side of the block is doing the same thing but, I would have to rig up some sort of test rig to verify.

Now I have to decide if I should find another distribution block so can I maintain the brake light in the dash or just delete it completely with different plumbing.

[FLYNAVY30]

Just curious, did the Wilwood guys tell you to run the residual valve on the front circuit? Ive never seen that before but I make zero claims to be an expert!

[biketopia]

A couple of things. I would suggest a Willwood combo valve like this, https://www.summitracing.com/parts/w...EDnpVUQI3P-rqY It will clean up your install, give you a brake light switch, and a proportioning valve. That part number also comes with the short lines and a bracket to mount it to the master, nice and clean, or get just the valve and make your own lines. Second, get rid of those sections of 5/16 or 3/8 line; you need volume to move the fluid in that, and even though it's a very short run, it can still give you fits. Run 3/16's line everywhere. Lastly, with a disc/disc setup, Rob at No-Limit Enginering told me to run 2lb check valves to the front and rear. I'd also suggest you run the same.

[FLYNAVY30]

Did Rob indicate why you need the check valves? I was under the impression those were only needed if your master cylinder sat at or below the plane of the calipers/drums.....as in a traditional hotrod with the master cylinder mounted to the frame rail.

[biketopia]

Originally Posted by FLYNAVY30

Did Rob indicate why you need the check valves? I was under the impression those were only needed if your master cylinder sat at or below the plane of the calipers/drums.....as in a traditional hotrod with the master cylinder mounted to the frame rail.

I asked the exact same question.

[FLYNAVY30]

Originally Posted by biketopia

I asked the exact same question.

Thats interesting....and might be worth a shot in my case as my primary complaint is that the initial "bite" when I depress the pedal isnt what I feel it should be.

[HO455]

First off thanks everyone for all your input I do appreciate it!

The weather has cooperated this morning and I got some proper testing done. The brakes are definitely better than before!

Now to which direction to move forward.

Biketopia: A couple of things. I would suggest a Willwood combo valve like this, https://www.summitracing.com/parts/w...EDnpVUQI3P-rqY It will clean up your install, give you a brake light switch, and a proportioning valve.

I looked into the valve you suggested and found that the switch is a pressure switch for brake light operation. Wilwood does not have a differential pressure sensor block to replace the factory sensor. That Wilwood valve would be an easy way (Although expensive way) to clean up the current mess of lines that all previous mucking about has lead to. The plan got lost somewhere. Going that way would mean the currently installed adjustable valve would have no home and it would end up hanging on the wall in the garage. If this Wilwood valve had a pressure differential valve I would have it on order now. Thanks for directing me to it.

All this has forced me to do further research this morning and now this question.

Has anyone had experience with Right Stuff brake components? They make a 67 factory style distribution block that would replace the old one I removed. See link.

https://www.jegs.com/i/Right-Stuff/965/PV05/10002/-1

I also have a used generic CPP valve that's been hanging in garage for at least a decade if I want to go down the cheap and possibly more frustrating path. (Photo below) I don't know the history of it other than it came with a bunch other stuff years ago.



FLYNAVY30: Just curious, did the Wilwood guys tell you to run the residual valve on the front circuit? Ive never seen that before but I make zero claims to be an expert!

During the conversation with Wilwood about their first master cylinder I mentioned that it seemed to me that after applying the brakes the caliper pistons were retracting farther than I was used to seeing. The tech rep said I could put a residual check valve in the circuit to limit the movement. By the end of the conversion he decided to warranty the master cylinder and we never got back to the subject, I decided to install one as it wasn't going to hurt anything and I could learn more about them through trial and error.

[pjmoreland]

I put that same CPP combination valve on my '68 C/10 five years ago. I installed it when I did a front disc conversion. I used stock 71-72 calipers, ACDelco pads, plain rotors and a Delco Moraine style 1-1/8" bore master cylinder. I know lots of people say those CPP combination valves are junk and that they leak, but ive had no issues with mine, the brakes have lots of initial bite, and the pedal is very firm. My only complaint is that the rear brakes lock up easily under heavy braking, but my truck doesn't have much weight on the rear wheels.

[FLYNAVY30]

can someone educate me as to the difference between a combination valve and a proportioning valve? I know the proportioning valve allows you to limit the amount of pressure to the rear circuit in order to ensure the fronts lock up first but Im unclear as to what the combination valve does.

[HO455]

My understanding is, technically a proportioning valve is a stand alone valve that bias the brake system to allow balanced braking power front to rear. It can be fixed or adjustable.

The stand alone proportioning valve (GM version in link) was replaced by the "Combination Valve" which combined the earlier distribution block (with the differential pressure sensor) with additional internal valving to bias the front to rear braking power.

Over time the term "Proportioning Valve" has been applied to any component between the master cylinder and the calipers.

https://www.jegs.com/i/Right-Stuff/965/PV05/10002/-12

[HO455]

Originally Posted by pjmoreland

I put that same CPP combination valve on my '68 C/10 five years ago. I installed it when I did a front disc conversion. I used stock 71-72 calipers, ACDelco pads, plain rotors and a Delco Moraine style 1-1/8" bore master cylinder. I know lots of people say those CPP combination valves are junk and that they leak, but ive had no issues with mine, the brakes have lots of initial bite, and the pedal is very firm. My only complaint is that the rear brakes lock up easily under heavy braking, but my truck doesn't have much weight on the rear wheels.

Thanks for the recommendation. I should take the time to clean and inspect it before going in a different direction. The fact that the lines to the master cylinder are cut and the front brake line is still attached may be a sign it was removed from a working vehicle as opposed to a bad unit removed and replaced.

[CG]

This thread has taught me so much. Close to ten years since you started it. Much appreciated!

[HO455]

YIKES! That means I'm ten years older? What the....

Seriously though thank you for the kind words, I really appreciate them but I must to pass most of the thanks on to the members of this forum. Much of what I've posted I've learned from other members who have posted their knowledge.

[HO455]

Time for an update on the brakes.

First off I found a part number after giving the proportioning valve a good cleaning ànd it is for a rear disc system, so it's going back on the shelf.

I got the Right Stuff directional valve installed and resized the lines on the front brake system as suggested by biketopia. In addition I replaced the hose to the rear axle just in case it was causing issues.

But the brakes still weren't right. I talked with a friend about the ongoing issues and he suggested I try a larger diameter bore master cylinder and being at a loss as to what my next move should be I decided to try that.

My math and Wilwood's tech line both said that a one inch bore was the correct size, as well as the original drum brake master cylinder was a one inch bore and I was happy with it for the past 60k plus miles. But for lack of any other ideas I picked up a 1 1/8" bore master cylinder and installed it.

After bleeding I had a nice solid pedal but poor stopping power without standing on the pedal with everything I could. The solid pedal was a first since I started this whole parts swapping circus.

The poor stopping power made sense as the larger bore would give less hydraulic pressure than a smaller bore. The hard pedal meant there wasn't some hidden issue with air being trapped somewhere as I had achieved a rock hard pedal. Once again the master cylinder looked to be the problem unless the rear hose had been the issue all along.

Before swapping the one inch master cylinder back on the truck I decided to tear it down and inspect it and low and behold I found one of the seals has a small cut on it. (See photos)

I called Wilwood to order a rebuild kit for the master cylinder and was told they don't sell replacement parts for this master cylinder as there they don't consider them to be serviceable outside of their facility. The gentleman at Wilwood asked when I bought the master cylinder and since it was within the 12 month warranty period he sent me a new one. It arrived mid-day on Friday and after thrashing all afternoon and into the evening I got yet another master cylinder installed and bled. And for the first time in months I have good brakes! Woo Hoo!

With engine off the pedal is hard after about one inch of travel. With the engine running the total travel is about 2 inches with the brakes starting to work in the first 1/2" to 3/4" inch of pedal movement.

I am so relieved to have this issue solved! I must thank my wonderful wife for all her help with bleeding the brakes. She must have 10 hours of pumping brakes through out this whole ordeal.

Not only is it great to have the WMB back on the road again. (I got to drive it to work this morning ) it is especially good timing as my other truck, the LT1 Blazer came home on a wrecker on Thursday with something broken between the engine and the driveline. No forward or reverse movement is possible at present. I haven't jacked it up to see if it is a clutch or transmission issue yet. Anyone want to guess what I'll be doing next week?

Both of the other Wilwood master cylinders I got came from Summit and this one came directly from Wilwood. I don't know it Summit got some counterfeit or rebuilt ones from a vendor other than Wilwood or if I just have had extra long a run of bad luck!

[pjmoreland]

Excellent! What a nightmare this has been. And, you got confirmation that your wife really does love you.

[HO455]

Originally Posted by pjmoreland

Excellent! What a nightmare this has been. And, you got confirmation that your wife really does love you.

Although yesterday when I asked her if she could come help she mentioned she was going to have to start billing me for her hours.

[LockDoc]

Originally Posted by HO455

Although yesterday when I asked her if she could come help she mentioned she was going to have to start billing me for her hours.

HaHa, that's a good one..... Smart gal.

Glad you finally mastered it.. So to speak.