HOW TO: Split the brake lines (many have asked)

[Str8axle]

Would the pushrod from a 67-70 non-power truck work for those who don't have an adjustable one? Just a thought...
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[Rich 5150 69]

I ran across and old post a while back in the 67-72 section, this might help as well ...
http://67-72chevytrucks.com/vboard/s...d.php?t=456859

[Str8axle]

Disc/drum master has one bowl smaller than the other. Disc/disc and drum/drum both bowls are the same size.
And no disc brakes til '71
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[jocko]

Awesome! Thanks Str8!

[ChiefRocka]

Again ... I grabed one from '67 Impala...bolted right up.

The Vette ones are perfect for use with all around discs.

[Str8axle]

I should add that a disc/disc master is considerably larger in bowl size than a drum/drum master.
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[jocko]

Thanks Str8 and ChiefRocka - picked up my 67 C10 MC this morning. Good to go. Same functionally as the 67 imp mc, just has the clip-held top vice the screw down type. Thanks again for the help!

[jocko]

Hey Chief - reviving this great thread one more time! Quick follow-up for you or anyone that has done this. I noticed that someone asked the question about whether or not the "forward" (i.e. the grill end) port on the master went to the front brakes and the "aft" (i.e. firewall end) port on the master went to the rear brakes. (this is on a DRUM/DRUM setup btw)

Your answer was yes. But I noticed that your fwd line on the master was the one you connected to the rear line's new union. Did that get switched later or something?

Or for anyone out there - on a drum/drum setup, which master cyl port (fwd/aft) goes to which brakes (front/rear), etc....

Thanks all!

[ChiefRocka]

The REAR PORT, closest to the PUSHROD is the main, or "primary" chamber.

This port is for the FRONT brakes....

The FRONT PORT, furthest from the PUSHROD is the secondary chamber....supplying the REAR brakes.

[jocko]

thanks Chief! You Rocka!!!

[ChiefRocka]

Originally Posted by jocko

thanks Chief! You Rocka!!!

[jocko]

Matt -residual valve and prop valve not required for the dual reservoir drum/drum master cylinder setup. Here's a link that may help, based on Chief Rocka's thread here - http://67-72chevytrucks.com/vboard/s...d.php?t=487384 When you go disk/drum, then you can buy a disk/drum (unequal) dual reservoir master cyl and the prop and residual valve. I'm not certain about whether or not you'll need the residual valve in either setup though - I always thought the res valve was only if you had a "low" mounted master cylinder. With a firewall mount, I do not believe it's necessary - but let's get that confirmed by someone on here. But for the drum/drum - you don't need either as long as the master is on the firewall, that much is correct.

[Rich 5150 69]

Residual valve is only needed when master is down low with the brakes to prevent fluid running back to master....Jocko is correct.

[old cruiser]

Thanks guys, that will make life a litle easier.

[lowmemory]

I did extend our push road for one inch.

Thanks for help!

[JrJc66]

I just finished reading this thread for the the fourth or fifth time. One question i have is, does it make a difference if you split the system front/rear vs front right left rear/ left front,right rear as I believe newer vehicles are?

[jocko]

yes it makes a differenence - do NOT do what you just mentioned. Aft port (closest to the firewall) goes to front brakes, forward port (closest to grille) goes to the rear brakes.

I won't swear by it - but I've never, ever heard of any vehicles, new or old, being plumbed the way you just mentioned. But definitely not correct for these trucks.

Excellent safety question, glad you asked! Big safety implications.

[JrJc66]

Thank you for the quick reply

[ray_mcavoy]

JrJc66, Actually a lot of cars do use a diagonally split braking system like you described. It's very common on front engine, front wheel drive cars. They don't have very much weight over the rear wheels so the rear brakes alone often aren't enough to safely stop the car if the front brakes were to fail. With the diagonally split system, at least one of the front brakes will still be working.

At first, it seems like that would be a good idea for a pick-up truck too since they don't have a lot of weight over the rear wheels either when they're not carrying a load. But from what I understand it's not done (or recommended) because the front suspension/wheel design usually has a positive scrub radius that would cause the truck to pull hard to the outside with only one front brake working. Cars with diagonally split braking systems are all designed with a negative scrub radius so they'll pull to a stop straighter (in theory anyway) with only one front brake working.

[hevymetl]

So I finally got to doing my swap over today. Took me a good hour of driving around getting more fittings to make it happen. Couldn't find the proper plug for the T so I just eliminated it and used a union. Anyway, I got everything in and bench bled the new master with no problems. I measured the new master and the depth of where the pushrod goes in and it was identical to old one. So I assumed I didn't need to mess with pushrod. I didn't get a chance to bleed the brakes yet but currently have no pedal whatsoever. Is this a bad sign?

[padresag]

an unbled system will have no pedal
ron

[hevymetl]

That's what I was hoping to hear. I'll report back once I've bled it all out. Thank you for the response.

[truckeroy]

I did this conversion to a 64 a few years ago and last year to my current 64. I hooked everything up like in the thread mentioned. I never did get the pedal height I like. I have done a little research and in my 1971 Chilton manual under the Camaro/Chevelle section there is a drawing of a "typical" 67-70 master cylinder. It shows the front port to the front wheels and the rear port to the rear wheels. It states- "Since 1967, a dual type master cylinder is used. The front portion of the master cylinder supplies hydraulic pressure for the front wheels. Pressure for the rear wheel brake application is supplied from the rear portion of the master cylinder." I just switched my lines and have more pedal now. I still have to re bleed the lines because I may have gotten some air in while switching the lines. I'm using a 70 truck booster/mc set up.

[jayoldschool]

That's what Captainfab has always posted, too.

[LostMy65]

I'll have to try switching mine.
My pedal height isn't what I'd like it to be.