65-66 K-H Disc Brake Proportioning Valve Adjustment

[mygt350]

Understand thread count for Mustang use of a 65-66 K-H Disc Brake Proportioning Valve is 11 threads exposed. What would the proper adjustment be for use on a 65 GT350?

[Bob Gaines]

Understand thread count for Mustang use of a 65-66 K-H Disc Brake Proportioning Valve is 11 threads exposed. What would the proper adjustment be for use on a 65 GT350?

13 or 14 is what I have seen typically. That is a good starting point for fine turning. Loosen the thin lock nut and turn the threaded adjustment portion with a wrench using the flat section. You want the the front brakes to lock up just before the rear do.

[6T6/7]

Not meaning to contradict, only to understand...but, what little info I've seen seems to indicate fewer threads exposed (about 7 - 9) for GT350 setting, compared to Mustang (about 11 - 13 threads).  Maybe that's not correct?
Thanks,
Mark

[6s1640]

Not meaning to contradict, only to understand...but, what little info I've seen seems to indicate fewer threads exposed (about 7 - 9) for GT350 setting, compared to Mustang (about 11 - 13 threads).  Maybe that's not correct?
Thanks,
Mark

Hi Mark,

Your assessment is consistent with what I have observed.

   Stock Mustang - Non GT350 is 11 to 13 exposed threads

   GT350 is 7 to 8 exposed threads

Best of luck

Cory

[Bob Gaines]

Not meaning to contradict, only to understand...but, what little info I've seen seems to indicate fewer threads exposed (about 7 - 9) for GT350 setting, compared to Mustang (about 11 - 13 threads).  Maybe that's not correct?
Thanks,
Mark

Now you have me second guessing myself which way more or less. I know it was 3- 4 threads off the Mustang setting . Regardless there is fine tuning involved as I mentioned for best results on a driven car. That is if you drive your car and care to get the best bias for spirited driving.

[rockhouse66]

Recent discussion;

http://www.saacforum.com/index.php?topic=7587.msg63609#msg63609

[Bob Gaines]

The bigger Shelby Brake pads need less pressure to the rear compared to smaller stock brakes.

[Bob Gaines]

Not meaning to contradict, only to understand...but, what little info I've seen seems to indicate fewer threads exposed (about 7 - 9) for GT350 setting, compared to Mustang (about 11 - 13 threads).  Maybe that's not correct?
Thanks,
Mark

Now you have me second guessing myself which way more or less. I know it was 3- 4 threads off the Mustang setting . Regardless there is fine tuning involved as I mentioned for best results on a driven car. That is if you drive your car and care to get the best bias for spirited driving.

I check my notes and survivor pictures and the GT350 proportioning valve had more threads showing then the Mustang version.

[texas swede]

Hi guys and Merry Christmas.
Did Ford at San Jose add the big rear brakes for the 65's  If so, did they also adjust the proportioning valve?
In the SA parts list for 65 the only proportioning valve mentioned is for the R-model.
Very confusing to me as there should be a separate part number for a GT350 street model or did Ford use the
R-model number S1MR-2091-A for both street and race models.
Texas Swede

[6s1640]

Hi Texas Swede,

There is a part number in the MPC for 1966 GT350 proportioning valve.  I did post in a prior thread.  I will have to find again.

Cory

[Bob Gaines]

Hi guys and Merry Christmas.
Did Ford at San Jose add the big rear brakes for the 65's  If so, did they also adjust the proportioning valve?
In the SA parts list for 65 the only proportioning valve mentioned is for the R-model.
Very confusing to me as there should be a separate part number for a GT350 street model or did Ford use the
R-model number S1MR-2091-A for both street and race models.
Texas Swede

I believe the big rear brakes were installed on the 9inch rear end from the subcontractor and the complete assembly was shipped to the SJ assemblyline to be installed. I believe that the proportioning valves were pre adjusted for the bigger brakes at KH just like the Regular Mustang units were adjusted for the stock Mustang brakes. The GT350 valve was painted black at KH showing it was a different unit from the gray painted regular Mustang units. This was most likely so it would be easier to NOT confuse the units by assembly line workers when they were installed on the different specified cars. If they were adjusted at SA there would be no reason to take them off ,paint them and reinstall them. Since the units were identical to the regular Mustang unit but just adjusted different may have played a role in how they were serviced by Ford given all you had to do was back off the adjuster of the regular Mustang unit and you have the base line adjusted GT350 unit. The R model unit bias was most likely adjusted for the individual driver and road conditions of the given track. Now days easily adjustable after market valves are mounted in the passenger compartment of race/track cars  for easy access and fine tuning by the driver in real time. Just my perception based on the facts as I see them others may have different opinion. 

[texas swede]

Thanks Bob,
So I need to paint my original valve black, It's dated 39-5.
Texas Swede

[Bob Gaines]

Thanks Bob,
So I need to paint my original valve black, It's dated 39-5.
Texas Swede

My guess is the only GT350 valves that were NOT painted black were the ones on very early built 65 GT350's that SA changed out the stock Mustang brakes to the GT350 spec 2 1/2 inch units. I think the black ones were used on the cars that SA had gotten Ford to install the big rear brakes on the rear end housings in 65 and all of 66 saving SA time and money. There is a Ford Memo talking about KH pre adjusting the proportioning valve for the bigger brakes to solve a problem they were having early on.

[mygt350]

My car has natural color valve with 8 threads showing.

[6s1640]

Hi All,

Here it is from the Ford MPC.  The 1965-66 GT350 had a unique part number for the proportioning valve C5ZX-2B091-A.  The ZX combo of letters was commonly used with SAI programs, according to Bob Gaines from a prior post.   Bob said "I thought I would mention that the ZX  is most commonly associated with Shelby as in C5ZX,C6ZX,C7ZX,C8 etc.  The ZX parts are only serviced for shortest periods of time it seems." This piece was also not serviced (at least in 1975), based on the below comment "Not replaced".

Hope this helps.

Cory