Single to Dual Res Master Cylinder Conversion

[jocko]

i agree protrash, I tried my best to mimic ChoifRocka's over the belly bending method, but I think he's practiced on a few more than I have, took me 2 tries...

ol skool - prop valve not required on a drum/drum setup. You CAN install one, but really same dia wheel cyls all around, same size line all around, AND, most importantly, a true drum/drum master cylinder is set up such that some pseudo-proportioning is done by the way it is designed, i.e. this is why the line to the front brakes is attached to the rear port on the master - it is designed such that the front brakes "lead" a little bit, or something like that - but even a dual drum setup doesnt equally apply front back all at the same time (a single res master cylinder would though)

Again, I think you certainly can install a prop valve is you want to fine-tune - but, unfortunately, I had to "test" my brakes yesterday when some moron decided to slam on her brakes in the middle of the intersection because the light turned yellow... I almost creamed her, but the new brakes worked very well. Skidded just a bit, very controllable, etc.

Whew....

[LostMy65]

Originally Posted by jocko

i agree protrash, I tried my best to mimic ChoifRocka's over the belly bending method, but I think he's practiced on a few more than I have, took me 2 tries...

ol skool - prop valve not required on a drum/drum setup. You CAN install one, but really same dia wheel cyls all around, same size line all around, AND, most importantly, a true drum/drum master cylinder is set up such that some pseudo-proportioning is done by the way it is designed, i.e. this is why the line to the front brakes is attached to the rear port on the master - it is designed such that the front brakes "lead" a little bit, or something like that - but even a dual drum setup doesnt equally apply front back all at the same time (a single res master cylinder would though)

Again, I think you certainly can install a prop valve is you want to fine-tune - but, unfortunately, I had to "test" my brakes yesterday when some moron decided to slam on her brakes in the middle of the intersection because the light turned yellow... I almost creamed her, but the new brakes worked very well. Skidded just a bit, very controllable, etc.

Whew....

I was just splitting mine using ChiefRocka's thread.
I did a search for the words:
drum master rear port
and this thread came up in the search.
Thanks for the answer for which ports go to front & rear.
Posted via Mobile Device

[**grumpy**]

I just did this on my 64 as well.
except I think I asked for a 69 C10 mc..
looks the same except mine has a bolt thru center holding cap on versus the snap ring.

We went ahead and replaced every hard line, all 3 rubber hoses, hardware, shoes, and wheel cyclinders....

plus used synthetic brake fuild. Local old timer says it'll help with brake fade when in traffic.

I thought Id have to adjust my rod from pedal, but as it was with single mc, the rod is touching, in rest position, the inside of the mc.

If I adjust it into the mc, it's going to put pressure on...

Anyone else NOT have to adjust their rod?

[LostMy65]

Originally Posted by **grumpy**

I just did this on my 64 as well.
except I think I asked for a 69 C10 mc..
looks the same except mine has a bolt thru center holding cap on versus the snap ring.

We went ahead and replaced every hard line, all 3 rubber hoses, hardware, shoes, and wheel cyclinders....

plus used synthetic brake fuild. Local old timer says it'll help with brake fade when in traffic.

I thought Id have to adjust my rod from pedal, but as it was with single mc, the rod is touching, in rest position, the inside of the mc.

If I adjust it into the mc, it's going to put pressure on...

Anyone else NOT have to adjust their rod?

Didn't have to adjust mine either.
I would guess the single and dual manual master cylinders are the same depth.
Posted via Mobile Device

[ChiefRocka]

Now that I'm married, I feel rod adjustment happens more often ... lol ...

[jocko]

grumpy, i didn't have to adjust mine - the single and dual res non-power master cylinders are the same depth indent in the piston, so shouldn't need much, if any adjustment. It's when one changes from non-power to power (or power to non-power, for that matter) that a major adjustment in rod length is required.

[**grumpy**]

Good deal..
that musta been what I was thinking..
I changed pwr mc last yr on a 65. I knew I had to lengthen the rod on one of them...

[LostMy65]

So, if a rear wheel cylinder goes out and leaks all the rear fluid out, do I still have front brakes with this dual master cylinder setup?

[**grumpy**]

Yes you do....
but dont panic stop...

[rideblue00]

nice bending work!

[rideblue00]

Just thought i would bring this back up for myself and others, as im going to do this to my truck soon.

[jonzcustomshop]

Originally Posted by rideblue00

Just thought i would bring this back up for myself and others, as im going to do this to my truck soon.

thanks,

[jmguy]

hi guys

am struggling with my power brake conversion on my 62 GMC
installed the Captains bracket, using S10 power booster, using 1968 dual master cylinder
can not for the life of me, get any balance in the brakes, the back will lock up easily and not much on the front
vacuum bled all the lines, bench bled the master
rears still locking up
drum drum set up
suggestions Please

[ChiefRocka]

Are the lines in the correct ports ?

[Captainfab]

The S10 booster will have a short intermediate pushrod. The '67-'70 master needs a long intermediate pushrod. Did you change the intermediate pushrod?

X2 on the correct ports. The front port is front brakes on that master.

[jmguy]

hi guys

thanks so very much for all your suggestions

will try them all and see if I can sort it out

regards JM

[LostMy65]

I did this several months back.
Now I'm wanting to add power brakes.
I would rather not have to bleed my brakes again.
Is there a way to use my existing dual master cylinder with a booster?
Is it just a matter of using the right intermediate rod?

[Captainfab]

Yes you will need the correct intermediate pushrod for the master that you have. Which master did you use?

Originally Posted by LostMy65

I did this several months back.
Now I'm wanting to add power brakes.
I would rather not have to bleed my brakes again.
Is there a way to use my existing dual master cylinder with a booster?
Is it just a matter of using the right intermediate rod?

[LostMy65]

I think I found the answer here:
http://67-72chevytrucks.com/vboard/s...d.php?t=482770

[LostMy65]

Originally Posted by Captainfab

Yes you will need the correct intermediate pushrod for the master that you have. Which master did you use?

I'm trying to remember.....

I think it was either the 67 impala or a 67 c10.

[LostMy65]

Yep, It's for an Impala:

Originally Posted by LostMy65

Got the brakes split using a impala mc like ChiefRocka suggested.
That thread is closed, but jocko's thread is still open:
http://67-72chevytrucks.com/vboard/s...d.php?t=487384

[LostMy65]

I've been searching the forums.
Is there like two or three different lengths of intermediate rods?
I mean, if my master has a deep bore, is there a such and such length versus the length of the intermediate rod for the shallow bore master?

[Captainfab]

To my knowledge there are only 2 different lengths of intermediate pushrods. There is one for the deep bore in the back of the master cylinder piston and one for the shallow bore. Some of the aftermarket boosters have an adjustable intermediate pushrod.

[LostMy65]

Originally Posted by Captainfab

To my knowledge there are only 2 different lengths of intermediate pushrods. There is one for the deep bore in the back of the master cylinder piston and one for the shallow bore. Some of the aftermarket boosters have an adjustable intermediate pushrod.

Thanks,
Here was another good thread I found on the topic:
http://67-72chevytrucks.com/vboard/s....php?p=6337677

[LostMy65]

Originally Posted by LostMy65

I'm thinking of just making a rod to slip into the master cylinder like this:

http://www.nookandtranny.com/mm5/mer...ry_Code=BRKMAS