1968(or later) brake setup problems in my '65 c10

[Woogeroo]

The master brake cylinder in my '65 c10 is a 1968 or later chevrolet unit. I'm having issues around the MC at the moment. That is why I am posting this in the 67-72 forum. If this needs to be moved, I apoligize... and please to move it to the more appropriate forum.

-W

------ The Post ------


The problem I'm having right now is a lack of good pedal after bleeding my brakes on my 1965 c10 lwb stepside.

However, there were some things that led up to this problem, so here are the juicy details.

Yes this is a long post, but I think I need to give out all of the details if I'm going to find out what is going on.


Within this post:


MC = master brake cylinder



A little needed information before we get started:

The master cylinder in my '65 c10 is a dual pot(reservoir) master brake cylinder with the vacuum booster... which was not an option in 1965 as far as I know. I have been told previously by people who have seen pictures of my engine compartment or who have seen it in person that the MC was a 1968 or later model chevrolet unit. This unit was in the truck when I bought it in April 2003, until today, I have had issues with it.


Here is a picture of the MC from a few days ago before this grand adventure began:

http://woogeroo.home.mindspring.com/...262006/17.html


My truck has the stock 1965 style drum brakes all the way around. New pads and a lot of the internal drum hardware within the past 6 months.


--- The beginning of how all of this got started ---

This particular adventure all got started when this part(electric trailer brakes control box) here started leaking(brake fluid) inside the cab from out of the box unit itself, so I decided it was time for it to go.


For an image and details of the unit, go here:

Under dash box for electric trailer brakes

http://woogeroo.home.mindspring.com/...142003/28.html


----


So, the trailer brakes unit had an actual brake line that was running from the bottom of the box in this picture:

http://woogeroo.home.mindspring.com/...s/brakes02.jpg

This box is all tied in with the master brake cylinder. The line on the bottom, right with all the brake fluid on it. There was a brass T-fitting that the line that goes to the trailer brake unit box went into that has already been removed in this picture.

----

So, I removed the line and the brass T-fitting... and reinstalled the brake line and made everything snug. So, I figured I should bleed the brakes for good measure. Start at the rear passenger wheel... and then the other side, then the passenger side front, then the driver side front.

So, I start doing that... pump it up, hold, bleed(my dad was helping on the pumping up part). On the rear, everything went fine... when ya cracked the bleeder valve open, the brake pedal would go down to the floor.

When we got to the front and started cracking open the bleeder valves on the wheels, we started getting issues with the pedal being already down and having 'no pedal feel'. We tried bleeding them a few more times ,but very little fluid would come out, with little pressure behind it.

Right about this time we were '$#@!#$@%#@?!???'

So, we were like... hmn, the master brake cylinder didn't go out all at once while we were standing here did it? We added checked stuff, tried bleeding some more, same result... great pedal bleeding the back... no joy doing the front.

Well, I say hmnn... mebbe the master brake cylinder is whack. Maybe I should just replace it.


----

Now, the master brake cylinder that I took off is this one:


http://woogeroo.home.mindspring.com/...s/brakes05.jpg



The only casting number that I found on it is this:

T48 5452810
3

The 8 may be a 3... it was hard to read.

----


So I took that off and went on a interesting adventure at NAPA trying to look one up... and found one at another store.

----

The new Master Brake Cylinder:


http://woogeroo.home.mindspring.com/...s/brakes08.jpg


In the NAPA super computer, this master brake cylinder is for a 1969 chevrolet c10 1/2 ton - stock number: TS 10-1329


The casting number on this one is as follows:

T21 5452310

and on the other side, extra numbers:

C Delco-M C237


-----

I came home, did the bench bleeding thing per the instructions... hooked the lines back up. Filled up the reservoirs with fluid, put the top back on and we back to pumping it all up. Again, I started at the rear passenger wheel... and then the other side, then the passenger side front, then the driver side front.

So, again the rear wheel brakes are getting good strong pedal feel when we bleed them.

The front wheels are not squirting out fluid like they should, plus the pedal is not strong at all, to the poitn of having to pull the brake pedal back up with your foot.



-----

I think the MC is the same, it is the same length, same fittings, same shape... etc.. I could be wrong though, maybe there is some subtle and important functional difference.

I'm wondering if maybe this part(links to images below) is malfunctioning or if it needs to be different or 'adjusted' somehow since the trailer brake unit box is no longer connected?


http://woogeroo.home.mindspring.com/...s/brakes02.jpg <- with the MC uninstalled


http://woogeroo.home.mindspring.com/...s/brakes08.jpg <-- with the new MC installed

I have no idea what the part in the pictures above is.

Does the part in the picture above... is it a chevrolet part or something to do with the trailer brakes unit?

I am at a loss at the moment.


All help is appreciated.

Thank you.

-W



Below is the URL to the folder that all of these pictures are in. If you think it will help to see the rest of the pictures and what not, this is the breakdown of what each picture depicts.


http://woogeroo.home.mindspring.com/...iscimg/brakes/


Index of /Matraca/miscimg/brakes/


MC = Master brake cylinder


Image Index


brakes01 = vacuum booster with the master cylinder off

brakes02 = proportional/proportioning valve / trailer brakes mumbo jumbo?

brakes03 = MC that was removed shot 1

brakes04 = MC that was removed shot 2

brakes05 = MC that was removed shot 3

----

brakes06 = new MC out of the box shot 1

brakes07 = new MC out of the box shot 2

brakes08 = new MC out of the box shot 3

----

brakes09 = new MC installed shot 1

brakes10 = proportioning valve? / trailer brakes mumbo jumbo - up close shot

brakes11 = new MC installed shot 2 (other side)

brakes12 = new MC installed shot 3

[Woogeroo]

While in the board chat room in IRC, shifty provided me with these links to images of his '68 chevy truck engine compartment showing it's master cylinder:

http://satellitehead.com/images/68ch...swap%20010.jpg

http://satellitehead.com/images/68ch...pull%20014.jpg

It has that same box unit thing underneath the MC... shifty says it has something to do with drum brakes.

...

so...

I still dunno what I'm doing wrong.. or.. what's going on really.

yeesh.

-W

[special-K]

This is the parts section,you know.Guess It`ll find it`s way to the message board.Good luck with your quest.

[Woogeroo]

oops. clicked wrong.

-W

[Woogeroo]

I originally posted this in the ' 67-72 parts section'.

Ooops.

Thanks to the mods for moving it over here.


So far I'm guessing that valve thing is stuck or broke on the front brake side... or there is some gunk in the lines.

also, twillams3 sent me this bit of advice:

When I did my swap to disks I had a stuck proportional valve. I was able to unstick it by loosening the line on the output side of the valve while pressing the pedal down and then tightening the line back up without letting the pedal back up.

----

It's also been mentioned to me that I do not need that proporting valve or distribution block or whatever it is... using that vacuum booster '69 master cylinder.


Anyhoo, thanks for anymore tips or tricks folks.

-W

[northcountry67]

It sounds to me like when the trailer brake set up started leaking, the proportioning valve moved to restrict loss of fluid, allowing the rear brakes to get fluid, but none to the front. Try opening a rear bleeder and a front bleeder at the same time and slowly pushing the pedal down to the floor, allowing the valve to center itself. With the pedal down, close both bleeders and try again. You can also do this by cracking open both lines at the proportioning valve.

[Woogeroo]

" You can also do this by cracking open both lines at the proportioning valve. "

the lines coming out of the valve or going into it?

Thanks northcountry67.

----

I have this bit of information from nufsed:

----

nufsed:

I'll try to explain a bit. The device in your 'brake 2' pic is a
"Distribution Block with Warning Light switch" and was used 67-up Tandem MC drum brake trucks.

When disk brakes were installed on later models, this item was changed to a "distribution block with proportioning valve and switch". The addition of the proportioning valve makes only a slight difference in outward appearance, so its easy to confuse the two.

Your distribution block has a piston in it positioned so that it has pressure for the front brakes and the rear brakes pressing on either end of the piston...if the pressures are equal, the piston just sits there doing nothing. When the pressures are greatly different (a loss of fluid and heavy braking), then the piston is forced toward the lower pressure end of this block, grounding the switch contact and turning on the warning light on the dash. The contact is the bottom center pin in the pic. The end result is that the piston is still stuck at one end and restricting the flow of the fluid.

Two ways to remedy this:

1. Release a bleeder on the rear brakes and then try pumping up and bleeding the fronts. The pressure in the front system will force the piston back.

2. remove the brake line fittings on the front and rear of the distribution block use a screwdriver tip to physically place the piston in the center of it's travel;re-install the lines, LIGHTLY pump up and bleed the front then rear brakes. Once the systems are more or less equal, the switch will stay put.

----

It seems the unit on my truck is only a "Distribution Block with Warning Light switch"...

... also since the MC is a '69 c10 style and I'm running drum brakes front and rear that I do not need this "Distribution Block with Warning Light switch."

Maybe this means the 69 style does that stuff internally?

My warning light switch isn't hooked up to anything... I didn't even know that is what it was. It has been suggested to me elsewhere that whoever did this before I owned it, just took the setup off a later model truck and installed the whole thing.

--


-W

[truckdude239]

okay from the parts i read before i lost and got bored yes master cyliders can go out on bleeding. the cups in a mc only move so far when everything is right and anything pas the point where they move turns to junk and when you bleed you push the caps in the mc over the gunk and blow the master cylider. as to the bleeding and no fuild in front brakes p vavle been triped. after gettign everything bled if you still have a low pedel you need to adjust the push rod on the brake pedal should have about 1/2" play before mc kicks in. just my $.02