proportioning/metering/distribution valve clarification

[snate66]

Well my 66 Barracuda originally 9" drums... now 10" drums will be getting an almost complete 68 KH front disks as well as a 69 8-3/4.

The question of the correct or at least options of:
Early distribution block(BLK245 Inline) with the separate Rear proportion valve(pr104b- Inline Tube) ,
Or a combination 69-74 distribution block with the rear line restriction built in(BLK250- Inline) ,
Or the combo valve with the front line metering valve attached to the side sold on Ebay as MBM-PV6070MOP-Mopar 1960-70 Disc Drum Proportioning Valve (that I already bought).

I do understand that there is some debate on this mater.
Is the metering valve for the front lines required with the 68 KH set up? Why would a pressure restriction to the rear line AND a metering " delay" to the front be used at the same time? Seams like a slow progression of engineering "corrections".

I read through many conflicting posts and threads with pieces of info and opinions. My thoughts today with the info I have gleaned... I could remove the metering valve....

 

[mvh]

AFAIK none of these should have any restriction or metering of the front lines. I don't know what application that particular part (MBM-etc) is supposed to fit, but it wasn't a 1968 disk brake car. It says "60s-70s", but I'm sure it never went on a 1960s A-body, and probably not any A-body.

The 69-74 part will work with your combo, if you can source one that doesn't leak (there was a bad batch out there). I did the 9" drum to K-H disk swap on my 67 Barracuda, so I can vouch for that.

My other 67 had factory K-H disks, and it had the separate PV, but that would be a lot more difficult to retrofit, since you'd need to cut and flare brake lines (or bend the too-long one and hope it doesn't break, and source a short connector piece).

Actually, my advice is to buy all new front compartment brake lines while you are at it, since you are draining the system anyway, and you need the correct fittings for the dual line disk brake MC. The old lines will be brittle as heck, and the threads will be rusted.

 

[66fyssh]

IIRC my 66 with original KH had a residual pressure check valve in the brake line and a proportioning valve. When I put in a dual master cylinder I used a Summit adjustable proportioning valve and ditched the residual pressure check valve. They work GREAT now!!

 

[Mattax]

There really should be no debate on this matter. But yes, it does seem like there is. At least half the time its confusion caused by calling the parts by the wrong name. At least that's how I see it. :LOL:
The information from Chrysler is pretty authoritative.
All A and B bodies got a Proportioning Valve. Once the Hydraulic pressure hits 300 psi, the increase in pressure to the drum brakes is proportionally limited to 50% of the front. Two reasons for this valve. First as soon as duo servo drums start working, they self assist. Second, as the weight shifts forward during moderate to hard braking, there's less traction at the rear tires. Proportioning valves prevent lock up under these conditions.

Through 1966, there is a single resevoir master cylinder. So for disk brake cars, the residual valve for the rear drums was moved from the master cylinder to the T fitting outlet to the rear brakes.
Disc Brakes (Session 219) from the Master Technician's Service Conference

After 1967, the drum brake Residual valve is in the front outlet of the Master Cylinder.
Proportioning valve is a non-adjustable piece shaped like the state of Texas.
picture here in the 1967 MTSC pamphlet.
1967 Chrysler Imperial Disc Brake System From the Master Technicians Service Conference Session 233

Starting Jan. 1970 the proportioning valve was included in the distribution block with the "safety switch". Only the bigger cars with the new floating calipers got a metering valve. Chart here:
1970 Chrysler Imperial Hydraulic Brake Service Guide from the Master Technicians Service Conference Session 274
The metering valve was to help prevent early front lock up on icy or similar conditions. Again, not originally used with the K-H fixed calipers.

For the floating caliper cars, 1972 saw a change in the combo valves, but the K-H fixed caliper system for Darts and Valiants stayed the same.
1972 Imperial & Chrysler Disc Brake Service Repair Book from the Master Technician's Service Conference (Session 293)

The only real item of question that was an error in a photo showing the type of proportioning valve for the A-bodies same as the B-bodies. We figured that out by comparing the facts we knew were true. see Disc Brake Hold Off Valve
Also useful thread if you want to see '67-69/70 service manual pictures for mounting of those components.

My suggestion is if you are staying fairly stock, looking for ready to run, either early or late system will work as long as you switch to a dual resevoir master cylinder.
If you are planning to fine tune, race or autocross, you might want an adjustable proportioning valve, and that has to be seperate.
If you are using an early style single master cylinder, then copy that system; a combo valve can not be used.

 

[snate66]

There really should be no debate on this matter. But yes, it does seem like there is. At least half the time its confusion caused by calling the parts by the wrong name. At least that's how I see it. :LOL:
The information from Chrysler is pretty authoritative.
All A and B bodies got a Proportioning Valve. Once the Hydraulic pressure hits 300 psi, the increase in pressure to the drum brakes is proportionally limited to 50% of the front. Two reasons for this valve. First as soon as duo servo drums start working, they self assist. Second, as the weight shifts forward during moderate to hard braking, there's less traction at the rear tires. Proportioning valves prevent lock up under these conditions.

Through 1966, there is a single resevoir master cylinder. So for disk brake cars, the residual valve for the rear drums was moved from the master cylinder to the T fitting outlet to the rear brakes.
Disc Brakes (Session 219) from the Master Technician's Service Conference

After 1967, the drum brake Residual valve is in the front outlet of the Master Cylinder.
Proportioning valve is a non-adjustable piece shaped like the state of Texas.
picture here in the 1967 MTSC pamphlet.
1967 Chrysler Imperial Disc Brake System From the Master Technicians Service Conference Session 233

Starting Jan. 1970 the proportioning valve was included in the distribution block with the "safety switch". Only the bigger cars with the new floating calipers got a metering valve. Chart here:
1970 Chrysler Imperial Hydraulic Brake Service Guide from the Master Technicians Service Conference Session 274
The metering valve was to help prevent early front lock up on icy or similar conditions. Again, not originally used with the K-H fixed calipers.

For the floating caliper cars, 1972 saw a change in the combo valves, but the K-H fixed caliper system for Darts and Valiants stayed the same.
1972 Imperial & Chrysler Disc Brake Service Repair Book from the Master Technician's Service Conference (Session 293)

The only real item of question that was an error in a photo showing the type of proportioning valve for the A-bodies same as the B-bodies. We figured that out by comparing the facts we knew were true. see Disc Brake Hold Off Valve
Also useful thread if you want to see '67-69/70 service manual pictures for mounting of those components.

My suggestion is if you are staying fairly stock, looking for ready to run, either early or late system will work as long as you switch to a dual resevoir master cylinder.
If you are planning to fine tune, race or autocross, you might want an adjustable proportioning valve, and that has to be seperate.
If you are using an early style single master cylinder, then copy that system; a combo valve can not be used.

Very well put and supporting links as well!
I changed to a duel drum MC years ago when i moved the 10" drums from my first 66 (that turned into the parts car). I have the duel disk MC on the way as well. I just clicked too early on the misrepresented later style combo unit with the metering portion. Just wasn't patient enough. I am just counting on removing the metering block and using the main valve hoping that is still in the design ranges to accommodate my vehicle.
I hate returning parts.... and buying misrepresented parts for that matter.

Thanks guys.
N

 

[snate66]

The 69-74 part will work with your combo, if you can source one that doesn't leak (there was a bad batch out there). I did the 9" drum to K-H disk swap on my 67 Barracuda, so I can vouch for that.

Leak? an external leak in the switch seals of fitting connections... or are you speaking of leaking past the PSI set point of the PV?

 

[snate66]

=Mattax said: ↑
All A and B bodies got a Proportioning Valve. Once the Hydraulic pressure hits 300 psi, the increase in pressure to the drum brakes is proportionally limited to 50% of the front

So... I believe this PV6070MOP that i received with the collection of parts is (as close as i can guess) the '71 b-body/ 70-71 E-body version with the matching front metering valve. This is listed with a different part number than the 69-74 block/pv/switch. Maybe the difference is just the mounting configuration.
Would the pressure settings be the same on these valves listed for larger vehicles? If they are I am set and can use what i have minus the metering portion.
Or I buy more parts (bolstering the a body parts market)...

 

[Mattax]

Is this what you got?
PV6070MOP - O.E.M. Mopar Proportioning Valve
which looks the same as this but viewed from the other side

I agree it looks like it's for a B-body (or e) after Jan 1970
1970 Chrysler Imperial Hydraulic Brake Service Guide from the Master Technicians Service Conference Session 274

So then the two questions are:
1. If the metering valve is seperated, is there room to mount the combo switch/valve
and is the repop version made with a plug that can be removed? (see page 12 of the 1970 MTSC Brake pamphlet ) If not, then it would be an experiment to use the metering valve and see if the delay to the front is acceptable.
2. Is the proportioning the same for the 1970 floating disk cars as the earlier versions?
According to pages 10-11 seems like the answer is yes.


If this is all too much a PIA, and especially if you're not going to use the brake warning light then you can just plumb in a seperate proportioning valve and be done with it. This is assuming that your tandem master cylinder curently feeds a distribution block with one line out to the rear wheel cylinders.
You could then just use the 'Texas' version, or the Mustang style cylindrical version or an adjustable.
Yes, you'll have to play with the adjustment a little but that's not hard. You can get the adjustable ones in different sizes and shapes. Direct Connection/Mopar Perfomance used to sell a cast one made by Kelsey Hayes. It was pretty big. Then they sold a small one I'm pretty sure was made by Wilwood. Maybe the smallest out there now is made or branded by Russell. Lots of choices in between. They all work about the same. You'll still have to make a bracket and/or install a thread-sert into the frame rail or other spot that's convenient.
If you make your own connecting tubes, using the coil armor will add some protection from rocks etc (just like the factory did). But getting OT.

PS. For fixing the quotes. Go into edit and look for a missing bracket or something in the [/quote] which should end a quoted section. Hope that makes sense