On the outside of a 65 K/H Proportioning Valve, there is a machined groove which has a rubber grommet in it. What function does the rubber have?
Martin
Covers a hole in the machined surface that works as a bleeder/vent from the spring chamber on the bottom of the housing. The rubber band/gasket works as sort of a cheap one way valve design
(http://www.concoursmustang.com/forum/gallery/14/6-300520171753.jpeg)
Jeff
If the rubber band/gasket is really old and clearly cracked, assuming brake fluid would come out?
Thanks!
Hi Martin, looking at the drawing Jeff posted, no on brake fluid leaking out. The brake fluid will only leak if other seals have failed.
Take care
Cory
Will send it up to Jim C to waive his magic wand over.
Thanks
Am I correct that the proportioning valve only affects pressure to the rear drum brakes and has no effect on front calipers?
Quote from: mygt350 on May 30, 2020, 10:38:03 PM
Am I correct that the proportioning valve only affects pressure to the rear drum brakes and has no effect on front calipers?
Correct just like other years
Ive pulled apart many 65/66 GT350s that the rear metallic shoes had virtually no wear so most bias on the from t brakes
Quote from: acman63 on May 31, 2020, 11:21:31 AM
Ive pulled apart many 65/66 GT350s that the rear metallic shoes had virtually no wear so most bias on the from t brakes
Maybe that explains why 6S1757 still has the original drums, even with all the racing in the 70's. Had them turned when I did the brakes in the early 90's and there was still plenty left to turn again.
Quote from: acman63 on May 31, 2020, 11:21:31 AM
Ive pulled apart many 65/66 GT350s that the rear metallic shoes had virtually no wear so most bias on the from t brakes
And yet they needed cooling in 1966 ;)
Quote from: Helmantel on July 04, 2020, 02:50:00 PM
Quote from: acman63 on May 31, 2020, 11:21:31 AM
Ive pulled apart many 65/66 GT350s that the rear metallic shoes had virtually no wear so most bias on the from t brakes
And yet they needed cooling in 1966 ;)
Not really . If you think that the 66 scoops cooled anything I think you need to take a closer look . The air blows on the tires not the brakes . It was cosmetic ;)
I know. I had to laugh the first time I looked at a 66 Shelby and noticed the "tire coolers"
The valves were set to work with "hot" brakes. If you set the valve to make the brakes effective when cold , they will lock up FOR SURE if run at a competitive event where they see heat. "Street driving " is not enough.
In drag racing , I ride the brakes when smoking the tires before the starting line. The holding power on the starting line is far better with the rear brakes heated and stopping at the end in great too.
Quote from: gt350hr on July 08, 2020, 05:19:29 PM
The valves were set to work with "hot" brakes. If you set the valve to make the brakes effective when cold , they will lock up FOR SURE if run at a competitive event where they see heat. "Street driving " is not enough.
In drag racing , I ride the brakes when smoking the tires before the starting line. The holding power on the starting line is far better with the rear brakes heated and stopping at the end in great too.
Aren't the valves overkill on the street then? They should be R model only then?
No, they were used on every Mustang. Not Shelby installed or specific. Totally needed on any disc brake equipped car of any make or model if you have a disc / drum combination.
Quote from: shelbydoug on July 09, 2020, 07:22:13 AM
Quote from: gt350hr on July 08, 2020, 05:19:29 PM
The valves were set to work with "hot" brakes. If you set the valve to make the brakes effective when cold , they will lock up FOR SURE if run at a competitive event where they see heat. "Street driving " is not enough.
In drag racing , I ride the brakes when smoking the tires before the starting line. The holding power on the starting line is far better with the rear brakes heated and stopping at the end in great too.
Aren't the valves overkill on the street then? They should be R model only then?
Quote from: Royce Peterson on July 09, 2020, 09:03:14 AM
No, they were used on every Mustang. Not Shelby installed or specific. Totally needed on any disc brake equipped car of any make or model if you have a disc / drum combination.
Quote from: shelbydoug on July 09, 2020, 07:22:13 AM
Quote from: gt350hr on July 08, 2020, 05:19:29 PM
The valves were set to work with "hot" brakes. If you set the valve to make the brakes effective when cold , they will lock up FOR SURE if run at a competitive event where they see heat. "Street driving " is not enough.
In drag racing , I ride the brakes when smoking the tires before the starting line. The holding power on the starting line is far better with the rear brakes heated and stopping at the end in great too.
Aren't the valves overkill on the street then? They should be R model only then?
Every Mustang had a non-adjustable valve. The 65-6 Shelby's had a version of the Corvette adjustable valve. It had it's own S1MS part number.
The only use I can think of for it would be as Randy stated, "for race use".
Even today typically the rear brakes don't need to be done often. Every 75,000 miles or so. Fronts every 30,000. It's about a 2 to 1 ratio.
Lots of things were done on the '65s apparently with the presumption that they were all race cars
Quote from: Royce Peterson on July 09, 2020, 09:03:14 AM
No, they were used on every Mustang. Not Shelby installed or specific. Totally needed on any disc brake equipped car of any make or model if you have a disc / drum combination.
The proportioning valves that were used on the 65 and 66 GT350's were different in that they were adjusted to compensate for the larger 2 1/2 inch drums and the more pressure needed to activate them in proper relation. Those special proportioning valves adjusted differently had a different Ford engineering number consequently Kelsey Hays identified them by painting them black instead of the typical battleship gray. That was most likely so that they could be told apart by assemblyline workers from the regular valves given that there was no other distinguishing features.
Doug ,
NOT the same valve as a Corvette. They had bigger fitting/tubing sizes. True both versions were made by K/H and used the same raw casting.
Royce , YES same valve as C5ZZ "except" the S1MS version was "preadjusted" for use with 2-1/2" metallic rear lining. The C5ZZ valve was set for 1-3/4" organic lining. If you had an original C5ZZ and S1MS side by side , the difference in adjustment is obvious. This is also noted in the partial blueprint Jeff S posted earlier in this thread.
For '67 and later , metallic shoes were dropped and standard inline , non adjustable prop valves were used.
Right, the 67 and later Shelbys had the standard size rear drums. I did not know the prop valves for Shelby were readjusted for the 2 1/2" rear drums but it sure makes sense. Those would lock up big time without a proportioning valve.
Thanks for straightening me out!
Quote from: gt350hr on July 09, 2020, 11:12:01 AM
Doug ,
NOT the same valve as a Corvette. They had bigger fitting/tubing sizes. True both versions were made by K/H and used the same raw casting.
Royce , YES same valve as C5ZZ "except" the S1MS version was "preadjusted" for use with 2-1/2" metallic rear lining. The C5ZZ valve was set for 1-3/4" organic lining. If you had an original C5ZZ and S1MS side by side , the difference in adjustment is obvious. This is also noted in the partial blueprint Jeff S posted earlier in this thread.
For '67 and later , metallic shoes were dropped and standard inline , non adjustable prop valves were used.
Quote from: Royce Peterson on July 09, 2020, 06:35:37 PM
Right, the 67 and later Shelbys had the standard size rear drums. I did not know the prop valves for Shelby were readjusted for the 2 1/2" rear drums but it sure makes sense. Those would lock up big time without a proportioning valve.
Thanks for straightening me out!
Quote from: gt350hr on July 09, 2020, 11:12:01 AM
Doug ,
NOT the same valve as a Corvette. They had bigger fitting/tubing sizes. True both versions were made by K/H and used the same raw casting.
Royce , YES same valve as C5ZZ "except" the S1MS version was "preadjusted" for use with 2-1/2" metallic rear lining. The C5ZZ valve was set for 1-3/4" organic lining. If you had an original C5ZZ and S1MS side by side , the difference in adjustment is obvious. This is also noted in the partial blueprint Jeff S posted earlier in this thread.
For '67 and later , metallic shoes were dropped and standard inline , non adjustable prop valves were used.
Royce,actually 67 had 2 1/2 inch rear drums too. 68-70 had the smaller regular Mustang drums.
+1 Metallic lining is the KEY. "Cold" metallic brakes stop poorly . Once they get some heat they work well. The average driver doesn't get enough heat in them to utilize them as intended by SAI. Renters of Hertz cars complained about poor brakes to the point where SAI had a "brake test group" which sent cars to San Francisco and LAX for monitoring. My Hertz was one of those "test cars" where organic (2-1/2) linings were substituted at some point. When I reinstalled the original metallic linings , I had WAAAAY too much front brake apply and had to readjust my prop valve.
Randy
Quote from: Bob Gaines on July 09, 2020, 06:49:49 PM
Quote from: Royce Peterson on July 09, 2020, 06:35:37 PM
Right, the 67 and later Shelbys had the standard size rear drums. I did not know the prop valves for Shelby were readjusted for the 2 1/2" rear drums but it sure makes sense. Those would lock up big time without a proportioning valve.
Thanks for straightening me out!
Quote from: gt350hr on July 09, 2020, 11:12:01 AM
Doug ,
NOT the same valve as a Corvette. They had bigger fitting/tubing sizes. True both versions were made by K/H and used the same raw casting.
Royce , YES same valve as C5ZZ "except" the S1MS version was "preadjusted" for use with 2-1/2" metallic rear lining. The C5ZZ valve was set for 1-3/4" organic lining. If you had an original C5ZZ and S1MS side by side , the difference in adjustment is obvious. This is also noted in the partial blueprint Jeff S posted earlier in this thread.
For '67 and later , metallic shoes were dropped and standard inline , non adjustable prop valves were used.
Royce,actually 67 had 2 1/2 inch rear drums too. 68-70 had the smaller regular Mustang drums.
I seem to recall that the 428 CJ cars got the rear drums upgraded to 2,25". Is that correct and does that apply to Shelbys too?
Not correct.
Quote from: Helmantel on July 12, 2020, 05:23:00 AM
Quote from: Bob Gaines on July 09, 2020, 06:49:49 PM
Quote from: Royce Peterson on July 09, 2020, 06:35:37 PM
Right, the 67 and later Shelbys had the standard size rear drums. I did not know the prop valves for Shelby were readjusted for the 2 1/2" rear drums but it sure makes sense. Those would lock up big time without a proportioning valve.
Thanks for straightening me out!
Quote from: gt350hr on July 09, 2020, 11:12:01 AM
Doug ,
NOT the same valve as a Corvette. They had bigger fitting/tubing sizes. True both versions were made by K/H and used the same raw casting.
Royce , YES same valve as C5ZZ "except" the S1MS version was "preadjusted" for use with 2-1/2" metallic rear lining. The C5ZZ valve was set for 1-3/4" organic lining. If you had an original C5ZZ and S1MS side by side , the difference in adjustment is obvious. This is also noted in the partial blueprint Jeff S posted earlier in this thread.
For '67 and later , metallic shoes were dropped and standard inline , non adjustable prop valves were used.
Royce,actually 67 had 2 1/2 inch rear drums too. 68-70 had the smaller regular Mustang drums.
I seem to recall that the 428 CJ cars got the rear drums upgraded to 2,25". Is that correct and does that apply to Shelbys too?
I've used stock 1-3/4" rear drums with organic lining, Velevet-touch mettalic, and 2-1/2" rear drums with metallic linings.
In my experience, those metallic linings are so hard, they hardly seat and you can't lock the suckers up at all either with the 65 "add on" proportioning valve or the stock (in my case '68) proportioning valve so to me, the adjustable is unnecessary on the street no matter how hard that you drive it.
As a matter of fact, the stock proportioning valve is just right for the Lincoln rear discs as well.
"68 GT350 Lives Matter!"
My "regular Mustang" 68.5CJ has 1-3/4 rear shoes.These were never used on SA vehicles , 350 or 500s.
Quote from: gt350hr on July 13, 2020, 11:25:12 AM
My "regular Mustang" 68.5CJ has 1-3/4 rear shoes.These were never used on SA vehicles , 350 or 500s.
Randy
PM sent.
Looks like I was "off" on my statement about 68.5 brakes on SA vehicles. I apologize to those I misled. I was going off of the last one I changed a diff in. Probably changed by a PO. My bad.
I could have easily suffered a bite from a coralsnake if left uncorrected. LOL