'68 D200 Camper Special WTB Distribution Block

[TechVP]

Hi,
Just finished doing a front disc brake conversion on my D200 that has a factory brake booster.
I had some trouble bleeding the rear drums, and thought it would be smart to replace the 50 yr old distribution block.
I want to buy a replacement Distribution Block. The old one may be ok, but I don't have experience knowing if seals in those blocks go bad, etc.

Who can I buy one from that will fit my '68 lines?

Advice appreciated.
-Karl

[nutz]

you need a proportioning valve

[PwrWgnDrvr]

The factory "block" is a safety pressure switch that indicates a failure in the system. There is nothing in it that affects function, wears out or needs replacing.

[TechVP]

Nutz,

Do you have a lead on a preferred mfg that requires minimal changes to a Sweptline's brake line fittings?

-Karl

[Wildergarten]

you need a proportioning valve

Adjustable proportioning valves are nice, especially with heavy loads on steep muddy slopes. I've actually put one under the dash before (yes, routing the lines through the firewall). Else, one doesn't bother with it.

[martincom]

Drum brakes actually have more stopping power than disc brakes, due to the larger contact area and self-energizing action. The advantage to disc brakes is far less heat fade. As such, on vehicles with discs up front and drums in the rear, the fluid pressure to the rear drums needs to be reduced. This is commonly achieved with a proportioning valve:

https://www.summitracing.com/search?Sor ... ng%20valve

Some disc brake vehicles utilized the same pressure differential safety switch as drum brakes. In this case, the proportioning valve was integral with the rear axle brake line tee or inline between the safety switch and rear axle tee. That maybe the simplest method for you.

Did you change the master cylinder? A disc brake master cylinder typically has a much larger reservoir for the front (disc) brakes. Unlike drum brakes, discs have no mechanical adjusters. The caliper pistons simply do not return as far, to compensate for wear. As such, the caliper retains more brake fluid as the pads wear. Thus, why the discs have a larger master cylinder reservoir. The diameter of the master cylinder piston will also impact the pedal force required.

[TechVP]

Of the proportioning valves on the Summit site, does this one look like a good fit:
https://www.summitracing.com/parts/clp-pv-2

Did you change the master cylinder?

I kept the original, as it has the upgraded vacuum boost and upgraded front/rear reservoir . I didn't think there was a next size up from what I already have.

Thanks.-Karl

commonly achieved with a proportioning valve:

Some disc brake vehicles utilized the same pressure differential safety switch as drum brakes. In this case, the proportioning valve was integral with the rear axle brake line tee or inline between the safety switch and rear axle tee. That maybe the simplest method for you.

[TechVP]

Thanks for the reply.
Where my issue came up is when bleeding brakes... it seems like there was a flow restriction around the distribution block towards the rear brakes.
When I removed the line to the rear from the distribution block, I had no problem flushing the line.

So in my understanding is that the original distribution block isn't designed to restrict flow -- like a valve. Instead its just there as an indicator --- is that correct?

The factory "block" is a safety pressure switch that indicates a failure in the system. There is nothing in it that affects function, wears out or needs replacing.

[Wildergarten]

Thanks for the reply.
Where my issue came up is when bleeding brakes... it seems like there was a flow restriction around the distribution block towards the rear brakes.
When I removed the line to the rear from the distribution block, I had no problem flushing the line.

So in my understanding is that the original distribution block isn't designed to restrict flow -- like a valve. Instead its just there as an indicator --- is that correct?

No, but it MAY need correction. PwrWgnDrvr is correct that it is a pressure switch. It has a plunger that actuates when there is a difference between front and rear pressure to turn on a warning light on the dash indicating the presence of a system failure while the other half of the system continues to function. What I do not know is whether that plunger is self-resetting after a failure has been corrected. If it is "locked" in position, it may occlude the flow to the failed side of the switch to prevent further fluid loss (which would be smart, as it would reduce the chance of damage to the master cylinder). That would mean in this case flow to the rear may be blocked off by the switch and it may need replacement unless it can reset itself. I don't know if that capability, but I dimly remember lore that the switch must be replaced if it actuates.

[martincom]

but I dimly remember lore that the switch must be replaced if it actuates.

The Chrysler & GM switches had springs within the safety switch to re-center the actuating piston, Otherwise, they would activate when bleeding the brakes and the brake lamp would remain illuminated. Fords were the problem child and probably what Wildergarden is thinking of. They didn't have springs to re-center the actuating piston. Rather they had caps on each of the valve body that you would remove to insert a rod and bump the piston back to center. It was a PIA. Another of Ford's "...better ideas..." which is worse than that "...great GM feeling...".

[TechVP]

Thanks for the reply.
Where my issue came up is when bleeding brakes... it seems like there was a flow restriction around the distribution block towards the rear brakes.
When I removed the line to the rear from the distribution block, I had no problem flushing the line.

So in my understanding is that the original distribution block isn't designed to restrict flow -- like a valve. Instead its just there as an indicator --- is that correct?

No, but it MAY need correction. PwrWgnDrvr is correct that it is a pressure switch. It has a plunger that actuates when there is a difference between front and rear pressure to turn on a warning light on the dash indicating the presence of a system failure while the other half of the system continues to function. What I do not know is whether that plunger is self-resetting after a failure has been corrected. If it is "locked" in position, it may occlude the flow to the failed side of the switch to prevent further fluid loss (which would be smart, as it would reduce the chance of damage to the master cylinder). That would mean in this case flow to the rear may be blocked off by the switch and it may need replacement unless it can reset itself. I don't know if that capability, but I dimly remember lore that the switch must be replaced if it actuates.

I did pull out the distribution block, and inspected it. Once pressure was removed, the valve was in the center (ie no contact). I checked to see that it had travel in both directions... and that worked. At the moment I reinstalled it.
That said, that's why I inquired about replacing it.

The consensus so far is to go buy a proportioning valve. At the moment I'm taking suggestions. The Summit part:
https://www.summitracing.com/parts/clp-pv-2
is the leading contender.

I wonder if a machine shop can help make larger fitting diameters, instead of replacing the lines.
-Karl

[martincom]

Of the proportioning valves on the Summit site, does this one look like a good fit:
https://www.summitracing.com/parts/clp-pv-2

Hard to say off the top of my head. If it were me, I'd want to check and see if the port position matched the existing, so you I could avoid making new lines and minimize bending the existing. The electrical connection, for the "Brake" indicator, will likely be better, but that kind of thing is easy peezy for me and I probably have the connector on-hand.

[martincom]

I wonder if a machine shop can help make larger fitting diameters, instead of replacing the lines.

Brake lines were typically 3/16 universally before they went metric. The getcha can sometimes be the line nut. Most took a 3/8 wrench, but some master cylinders and I believe safety switches may have utilized a fitting that required a 7/16 wrench, which meant the diameter/threads wee different.

[PwrWgnDrvr]

If you refer to the FSM brake section, there is a detailed drawing of the safety switch and description of its function.
If you haven't already done so, check/replace the rubber brake line hoses. They will swell up internally with age, restricting flow, even to the point of completely blocking off flow. (2 at the front wheels and 1 from frame to rear axle)

[BigBlockTrucks]

Drum brakes actually have more stopping power than disc brakes, due to the larger contact area and self-energizing action. The advantage to disc brakes is far less heat fade. As such, on vehicles with discs up front and drums in the rear, the fluid pressure to the rear drums needs to be reduced. This is commonly achieved with a proportioning valve:

https://www.summitracing.com/search?Sor ... ng%20valve

Some disc brake vehicles utilized the same pressure differential safety switch as drum brakes. In this case, the proportioning valve was integral with the rear axle brake line tee or inline between the safety switch and rear axle tee. That maybe the simplest method for you.

Did you change the master cylinder? A disc brake master cylinder typically has a much larger reservoir for the front (disc) brakes. Unlike drum brakes, discs have no mechanical adjusters. The caliper pistons simply do not return as far, to compensate for wear. As such, the caliper retains more brake fluid as the pads wear. Thus, why the discs have a larger master cylinder reservoir. The diameter of the master cylinder piston will also impact the pedal force required.

In addition to what has already been mentioned, there is also a residual pressure valve built into the master on these trucks, as they only came with 4 wheel drums from the factory.

[nutz]

if it has a hold off valve you will most likely have to remove it from the front /disk so the rate of brake applacation is the same
drum brakes have quicker response to your foot
the size of the master cylinder piston in relation to your caliper piston size and wheel cylinder piston size will have a lot effect on this too
now smaller brake lines 3/16 vs 1/4 can effect of cooling the fluid so if fluid is getting too hot in your disk brakes you might have up size your lines and most disk brake systems they put a cooling loop in the line under master
some of the master cylinders will use larger lines in the front
but most use the same size ...some just use a larger fitting just so you can't swap the front and rear lines
so just adding disk brakes is more then hanging rotors and calipers ..a lot of things to get them to work together

[swptln]

First off, you can't use a factory master cylinder with disc brakes in the front.
As mentioned already there are residual pressure valves in your master for drum brakes, disc's can't use the pressure valves.
The factory master cylinder is not going to work even if the pressure valve is removed, not enough volume to work the disc caliper correctly.
Most likely your bleeding problem too, your most likely not getting enough volume of flow because the distribution block valve is shuttling to close off the rear line when you try bleeding it.
Replacing the rear hose would also be a must as mentioned also, depending on how old it is.
The factory 68 distribution block will need to be changed as well, your going to need a later model proportioning block not a drum distribution. Do some research, there is a reproduction proportioning block for the 74-up Dodge trucks, if my memory serves me correctly there's only one company (Carolina Classics) or something like that, that has them. I looked around recently to replace my 69 D100 setup with 84 D100 front disc's and they were the only ones with them. The aftermarket adjustable ones are not the same as a factory proportioning block, they function totally different, I wouldn't recommend using those adjustable ones on a street driven vehicle as they don't function or have the safety features as a factory unit.
Lastly, a disc/drum proportioning valve will most likely not fit your stock brake lines, your going to need to modify them for sure. Fittings are all different. My recommendation would be to just buy new lines for a late model Dodge truck and go from there or make up everything new with the correct fittings.

[Wildergarten]

First off, you can't use a factory master cylinder with disc brakes in the front.
As mentioned already there are residual pressure valves in your master for drum brakes, disc's can't use the pressure valves.
The factory master cylinder is not going to work even if the pressure valve is removed, not enough volume to work the disc caliper correctly.
Most likely your bleeding problem too, your most likely not getting enough volume of flow because the distribution block valve is shuttling to close off the rear line when you try bleeding it.
Replacing the rear hose would also be a must as mentioned also, depending on how old it is.
The factory 68 distribution block will need to be changed as well, your going to need a later model proportioning block not a drum distribution. Do some research, there is a reproduction proportioning block for the 74-up Dodge trucks, if my memory serves me correctly there's only one company (Carolina Classics) or something like that, that has them. I looked around recently to replace my 69 D100 setup with 84 D100 front disc's and they were the only ones with them. The aftermarket adjustable ones are not the same as a factory proportioning block, they function totally different, I wouldn't recommend using those adjustable ones on a street driven vehicle as they don't function or have the safety features as a factory unit.

Great post!!! Good to see you back.

[swptln]

First off, you can't use a factory master cylinder with disc brakes in the front.
As mentioned already there are residual pressure valves in your master for drum brakes, disc's can't use the pressure valves.
The factory master cylinder is not going to work even if the pressure valve is removed, not enough volume to work the disc caliper correctly.
Most likely your bleeding problem too, your most likely not getting enough volume of flow because the distribution block valve is shuttling to close off the rear line when you try bleeding it.
Replacing the rear hose would also be a must as mentioned also, depending on how old it is.
The factory 68 distribution block will need to be changed as well, your going to need a later model proportioning block not a drum distribution. Do some research, there is a reproduction proportioning block for the 74-up Dodge trucks, if my memory serves me correctly there's only one company (Carolina Classics) or something like that, that has them. I looked around recently to replace my 69 D100 setup with 84 D100 front disc's and they were the only ones with them. The aftermarket adjustable ones are not the same as a factory proportioning block, they function totally different, I wouldn't recommend using those adjustable ones on a street driven vehicle as they don't function or have the safety features as a factory unit.

Great post!!! Good to see you back.

Thanks, was bored on FB lol and decided to see what was going on here