Man-A-Fre Dual Master Cylinder on 4-drum '67- Need confirmation.

[bb67tlc]

For safety's sake, we're installing a dual master on our '67 40. We're sticking with four drums for now. Just received the kit from Man-A-Fre with the Wilwood MC. Instructions weren't too clear for a 4-drum setup; on the phone they said to install the 10psi in-line residual valves in both front and rear lines, and install the proportioning valve in the rear line. Anyone have morsels of wisdom on this?

1- do you need the residuals in each line just to keep all drums from locking up too easily?
2- what's the procedure for knowing when/how to adjust the proportioning valve? Best discreet place to install?
3- any reason I can't put the old 9mm fittings on the brake line end of the new lines and the 10mm on the MC end? They seem to fit on the supplied line the same as the 10mm fittings.

Thanks

(picture shows a red and blue in-line residuals. my kit came with two red)

 

[Downey]

Drum brakes require about 10psi to hold the brake shoes up to the drums so that you don't have to pump them up to the drums every time you apply the brakes. Disc brakes only require about 2 psi to hold the pads up to the rotors. You have to make sure 2 psi is not built into the master cylinder MAF sold you. Soooooo you will need 10 psi front and rear for drums, and you could possibly want to proportion for more front braking than rear, I don't remember the percentage, so I'm sure a Mud brainiac can help with that (or your home town brake guy).

 

[bb67tlc]

Thanks Downey. That's one question down. Any other wise elders?

 

[4x4veteran]

I got my Wilwood setup through Cruiser Corp.
Your picture looks like what I got minus the red and blue fittings.
I have drums front and back and they work fine with the new MC.
When I bought the unit I had to specify disk or drum brakes.
I hooked the proportioning valve to the back line and after some driving and adjusting have it run almost all the way out.
For all the time I have had my Cruiser locking the rear wheels in an emergency stop has been an issue.
I have tested and it seems to work ok.
Forward stopping is fine but seems it doesn't want to hold as well backing down hill with the valve.
If you are pulling a trailer remember to open the valve.
Especially if the trailer doesn't have brakes.
I used a mix of old and new fittings with no problem.
If your fittings are in good shape I can't see why you can't use them.

 

[FJ40Jim]

The stock drum brakes are correctly 'proportioned' by the factory, i.e. the rears are not as effective as the fronts, so there is no need for a PV on 4 wheel drum trucks.

 

[65swb45]

/this\... except I wouldn’t say less effective. It’s just that the larger bore on the rear cylinders means the pistons don’t travel as quickly.

I run a dual circuit MC on all my Cruisers...and a PV on none.

 

[bb67tlc]

Great info, thanks Mark and Jim. No Proportioning Valve. What about the 10psi residual valves?

 

[65swb45]

Great info, thanks Mark and Jim. No Proportioning Valve. What about the 10psi residual valves?

That shouldn’t be, but actually is a fair question.

I understood the theory behind them when @Downey explained it to me 20 something years ago.

But the REALITY is that LANDCRUISER drum brakes have to be adjusted so tight to work properly in the first place that the residual valve becomes academic IMO.

 

[FJ40Jim]

Exactly what / he \ said.

The RPV is a hack to mitigate poorly adjusted drum brakes.

 

[FJ40Jim]

FWIW, it is less money and easier to do this using the JTO adapter block

and an OEM Aisin BMT051 brake master.

It looks like this on the firewall of a 1962 FJ45. BTW, that's a common 1978 clutch master next to it, also OEM Aisin from Rockauto.

Just posting this for informational purposes to anybody reading later about this same question.

 

[65swb45]

Ahem. I sell a firewall adapter too Jim. More compact. All steel. Screws with heads, not all-thread.

MUD vendor.

 

[wngrog]

So do larger bore cylinders need more or less fluid to move them?

My 1967 FJ-45 I’m redoing the 4 wheel drums and using 1” on all 4 corners.

I had it in my head that going from 1 1/8” DOWN to 1” in the rear would mean they needed less and would lock up less.

Since they designed this truck to haul and I don’t haul I was thinking stepping down would be a good move.

Maybe I shot myself in the foot.

 

[FJ40Jim]

It's not a question of needing more or less fluid.
It is simply that a smaller slave piston has less force, or a larger slave piston makes more force.
The opposite is true for the master bore size.

Going down in wheel cylinder size reduces the amount of braking force for a given pedal force.

 

[FJ40Jim]

Ahem. I sell a firewall adapter too Jim. More compact. All steel. Screws with heads, not all-thread.

Post a pic or a link, or it didn't happen?

 

[Spike Strip]

Half-way down page:

http://marksoffroad.net/1specials/1specials.html

 

[wngrog]

It's not a question of needing more or less fluid.
It is simply that a smaller slave piston has less force, or a larger slave piston makes more force.
The opposite is true for the master bore size.

Going down in wheel cylinder size reduces the amount of braking force for a given pedal force.

So, if I wanted the fronts to take most
Of the load for my never to be loaded down Long wheelbase 45 pickup I should have done 1 1/8” front and 7/8” rear.

 

[4x4veteran]

The stock drum brakes are correctly 'proportioned' by the factory, i.e. the rears are not as effective as the fronts, so there is no need for a PV on 4 wheel drum trucks.

Does larger tires effect the factory setting? Also suspension mods?

 

[65swb45]

Post a pic or a link, or it didn't happen?

Here’s a poor pic of the one in my LWB for the last 10 years or so:

 

[65swb45]

And a pic of the prototype I made for the 65SWB ...back in 1993:

 

[65swb45]

I should probably paint it, eh?