Proportioning Valve photos Disassembled

[DougAustinTx]

I took my proportioning valve apart because the rear drum brakes were locking up before the front discs. After cleaning all the rusty looking sediment off the internals, and brushing the inside of the housing with a brass shotgun brush, the brakes are much more reliable. Still not sure how it actually functions, but it does. I did notice that the rubber boot on the shaft seemed to fit loosely but it looks like it was made that way. Also, the disassembly went more smoothly when I clamped the big nut in the vise and turned the valve housing with a big Crescent wrench. Since I had not been able to find a photo of the internals on this site, I thought someone else might like to know what is inside.

 

[Bear]

Thanks for taking the photos of the "guts." !

 

[roma042987]

thanks for the photos! im having the same issue here. may take mine apart this weekend. Did this fix your problem?

 

[DougAustinTx]

Thanks guys. Yes, cleaning the prop valve took care of the locking rear brakes problem. Now when I get up to 40mph and smash hard on the brake pedal for a panic stop, I get a fairly fast stop with all 4 tires lightly protesting. Before the proportioning valve cleanup, the backs would lock and I would slide in a nice straight line toward the car waiting at the stoplight. Whew! I was lucky there wasn't any real rust pitting in the cylinder of the valve. Mostly just stuck-on dark red crud. The rubber was in amazing condition for probably being original to my '79. I had already switched over to DOT5 synthetic a few months earlier, so I shouldn't get any more rust or crud. Good luck on your overhaul.

 

[lostmarbles]

I had already switched over to DOT5 synthetic a few months earlier.....

DOT 5.0 is silicone-based fluid isn't it?

If so, I changed my motorcycle fluids to that and it's made the seals swell so that my front disc calliper pistons are now reluctant to move freely.

(With the effect that if I hit the brakes coming into a corner, the front disc keeps braking even when I release the handle-bar lever! )

But perhaps you mean DOT 5.1? (Which a brief search on the Internet tells me is still the old-style glycol fluid.)

 

[roma042987]

Thanks for the reply I'll tear into mine asap.

 

[DougAustinTx]

DOT 5.0 is silicone-based fluid isn't it?

If so, I changed my motorcycle fluids to that and it's made the seals swell so that my front disc calliper pistons are now reluctant to move freely.

(With the effect that if I hit the brakes coming into a corner, the front disc keeps braking even when I release the handle-bar lever! )

But perhaps you mean DOT 5.1? (Which a brief search on the Internet tells me is still the old-style glycol fluid.)

Nope, I use DOT5 (the purple silicone stuff). I should have called it silicone rather than synthetic. I use it in all my collectable cars because it doesn't absorb moisture. I guess I have been using it for about 12 years now with no problems, but I would not be in a position to argue that it might cause some types of rubber to soften. It just hasn't happened on anything I have ...yet.

 

[Blue77FJ40]

Is that an aftermarket master cylinder? I don't see the large copper nut under where the brake lines attach. That is where the stock residual valves live (under the nut).

 

[DougAustinTx]

Yea, it's definitely not an Aisin master, but it's been on there for years.

 

[carreta]

Where can I find a proportioning valve like this or at least the parts.

Thanks

 

[carreta]

Will this valve work with rear disc conversion>

 

[71-CRUISER]

Will this valve work with rear disc conversion>

Not likely. Besides they are about $300 new from toyota. I never install Disk Brakes on the Rear of any FJ40s but when i install Front Disks on 40s we install the Wilwood adjustable prop valves.

 

[carreta]

Not likely. Besides they are about $300 new from toyota. I never install Disk Brakes on the Rear of any FJ40s but when i install Front Disks on 40s we install the Wilwood adjustable prop valves.

Is there a willwood model in particular that I should use?, will it fit with original brake line fittings, or I will to modify those lines.

Thanks

 

[DSRTRDR]

Wilwoods (and like models from other manufacturers) were developed for the US domestic market with domestic dimensions, so they will not fit with the original brake lines

you will either needs to flare new brake lines or use the strategy I posted in your other thread

 

[carreta]

Ok Claudia I'll take those parts numbers then, Thanks

 

[Racer65]

To those of you who have taken apart the stock proportioning valve, what would you say is the likelihood of causing some damage such as breaking a rubber piece or stripping the nut? I know I need to clean it out, but not sure if I want to mess with something that is irreplaceable.

 

[peteinjp]

Tilton does make a metric P-valve but I'm not sure if the seat is the same as the Toyota lines.

Pete

 

[DougAustinTx]

To those of you who have taken apart the stock proportioning valve, what would you say is the likelihood of causing some damage such as breaking a rubber piece or stripping the nut? I know I need to clean it out, but not sure if I want to mess with something that is irreplaceable.

If you can get the parts out, I would say it's unlikely you would ruin anything. You will not ruin the nut if you take it apart using the method I suggested. However, if your brakes are working ok now, why bother taking it apart? If the brakes aren't working properly, what do you stand to lose by trying to fix the prop valve? If it turns out to be un-repairable, just go to you car parts place and buy an adjustable prop valve. I have taken two of the original Aisin prop valves apart and cleaned them and they both had nice pliable rubbers and the internals just needed a good cleaning.

 

[Racer65]

Well, my brakes work under normal circumstances, and I've bled it without any trouble. However, whenever I have to stop in a hurry, I always hear skidding tires sound in the rear. I thought that was normal until I read about proportioning valves.

 

[DougAustinTx]

Yep, if the back brakes are locking up first, it's time to overhaul the proportioning valve. It makes a huge difference in stopping when everything is working as it should. The only other cause of this would be a malfunction in the master cylinder.