brake line routing from master cyclinder

[The_Handier_Man1]

From: 72winniebrave1  (Original Message)
Sent: 1/15/2006 4:57 AM

Hey all! New to the group and started gutting out whats left of the brake system on my 72 brave ( m-300).  Managed to find a motorhome chassis parts catalog which gives me some help routing the lines - but not alot!  The "Tee" fitting (5-58-1) is more of a portioning block of sorts and houses the brake light switch lead.  The block has 6 ports and through the interior of it runs a push rod and two small pistons/"O" rings on either end.  Without very many of the orginal brake lines left in tact - I just can't figure out which lines go where.  I have what looks like 1/4" tubing O.D. and on the block are 2 - 7/16" flares at one end of the block and 3 - 1/2" flares at the other end.  I know that one of the  7/16"  and  one of the 1/2" goes to the master cyclinder - but which ones?

Thanks for any help
Rich   



From: Slantsixness
Sent: 1/15/2006 9:05 AM

Rich,

This is, in fact, a proportioning block.

Being an M300, I also will assume that you don't have the hydrovac boosters, and a single master cylinder with dual chambers, and drum front brakes.

With the warning light lead up and the mounting flange to the rear, there are two connections to the front brake lines at angles or on the right side as viewed.

There is only one connection to the rear brakes, out the left side

The mastercylinder connections go into the top. The one to the right of the brake warning light lead is the front brakes, and the one to the left is the rear brakes. They are different size fittings, so it will be obvious.

The master cylinder is mounted backwards, as you can see. The front brakes go to the rear most outlet, and the back breaks go to the frontmost outlet (nearest the mounting flange.) Careful here, it "looks" backwards, but it's not. If you changed to disc brakes, then it really Would be backwards, which is even more odd (don't let the rear facing master cylinder mess with your head....!)

If it were me, I would consider changing over to disc front brakes. If the front drums are worn bad or warped, it's probably cheaper.
all you would need:
Disc brake master cylinder
calipers
caliper  mounting hardware, front hubs (don't trust the discs that are on the hubs, they're probably warped from sitting) and all the assembly bolts (junk yard)
disc brake proportioning valve (new? or junkyard, they don't go bad..)
discs (new, not expensive)
Bearings
A tap for one bolt hole in the axle (don't even have to drill it out!)
I did my '72, it stops like a brand new truck. Total cost of my brakes was under $1000.00, including rebuilding the rears. Pretty cheap in the long run, I think and safer.

But, I will agree that  front drum brakes will work well enough, if they're in good enough condition. I just hate the constant maintenance of drum brakes, and brake fade on long hills.

Hope this helped you,

Tom



From: 72winniebrave1
Sent: 1/15/2006 2:21 PM

Tom,

Thanks for responding to my question....I'm still left scratching my head a little.  Your assumptions were all correct except my proportioning block  isn't installed as you described. 

I'm going to try to attach a quick drawing of the block nd the relative position it is attached to my frame ( brake switch "down" - mounting bracket "up".  The plug on the left side ( facing towards the rear of the vehicle ) houses a spring that keeps the pistons and connecting rod centered. I've numbered the flare fittings in the drawing to help orient my understanding a little better.  I'd rather sound like a complete dork in a message board than get it wrong- ya' know? The disc conversion is something for latter on down the road and I'll certainly look over your original post concerning it.

Thanks again for helping
Rich



From: Slantsixness
Sent: 1/15/2006 6:55 PM

Rich,

I'll take a picture of the proportioning block on Sparebago ('72 and still has drum brakes) the one I took off my other '72 could could have been different?

I'll tak a pix, add notes, and then post it here for you.

It'll be here later tonight....

Tom



From: Slantsixness
Sent: 1/19/2006 10:31 AM

Rich
It's next to near impossible to get a good photo, that's useful.

So I looked, and my other '72 Brave is different, and has this same block.

I edited your bitmap:

 
That should work.

Tom



From: 72winniebrave1
Sent: 1/19/2006 3:43 PM

Tom,
Thanks so very much for your time and tech assistance.  As a matter of fact - just got off the phone with Goeff from Alretta Truck Parts.   The service manual he was trying to help me from gave a completely different block altogether.  Thanks again for the info. -  It'll certainly aid in stopping this beast once we get it back on the road again!

Rich