4 wheel disc brake conversion proportioning valve (1 Viewer)

JDNs78FJ40

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I purchased the non-abs MC for an 80 series and new booster and wildwood pvalve from another MUD member.. I was always planning on installing the pvalve. I read somewhere the non-abs MC made the pvalve not necessary and was setup to run 4 wheel discs? Anyone running their 4 wheel discs without the pvalve and the 80 series MC without rear lock up? Just curious..
 
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Dec 13, 2012
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I've got the setup and not having rear wheel lockup. I also have a Wilwood P-valve but have not installed it as never felt it was needed. Part of this might be the driving style and driving surfaces. Don't know if it matters but I built my setup with Wilwood 4 piston calipers at all 4 corners but have different piston sizes front to back. It's also been long ago enough that I can't recall if I put larger pistons in rear or front.
 

Purpleaction

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@1911 was key in guiding me through the process. We both have 4 wheel discs. He has a valve on his set up and recommended.
I think the low cost of the valve makes it worthwhile and it’s a small step in the process. I would get it in inline before you bleed brakes but If you decided to try without you could always add the P-valve next time you change out your brake fluid.
 
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@1911 was key in guiding me through the process. We both have 4 wheel discs. He has a valve on his set up and recommended.
I think the low cost of the valve makes it worthwhile and it’s a small step in the process. I would get it in inline before you bleed brakes but If you decided to try without you could always add the P-valve next time you change out your brake fluid.
I’d agree with this. In terms of the cost and technical needs of the pvalve, its really minor to rest of the upgrade. Not sure i needed one, but it’s in there. I don’t think i had any lock up on the rear, but maybe it had some initial setting that fixed it when i did the rear disc swap.
 
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Louisville, KY
I have the same setup. I put the valve inline and set it wide open for the first time out. The rear locked up and was very sensitive. I closed the valve quite a bit to the point where it felt comfortable. Just my $0.02.
 
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I recently added an FJ80 nonABS MC and booster, along with Monte Carlo rear discs and proportioning valve to my Willwood 4piston front disc brakes. I would not feel good about not having a proportioning valve. The brakes work amazingly well now, but without the valve adjusted, the rears are way too strong, and could possibly be unsafe in slippery conditions. At least with my setup.. I started a thread and made a list of all the parts I used, if it helps you. Check my post history
 

JDNs78FJ40

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Getting ready to start plumbing this all together and was bench bleeding the 80 series MC. Is there supposed to be a gasket here where it connects to the booster?
4ED8113A-0D28-4E8D-B0C4-69CA750A926B.jpeg
 
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Getting ready to start plumbing this all together and was bench bleeding the 80 series MC. Is there supposed to be a gasket here where it connects to the booster?View attachment 2507956

I have seen a gasket between the master and booster in some applications. It is in no way needed. There should be no fluid in the space between the two, and there’s even a slot at the bottom of the mounting surface to ensure there isn’t a seal between them.
 
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Even with an 80 series booster, a proportioning valve is still important. In some rare cases, the balance is correct front to rear. However, I know from personal experience, how quickly a 40 can spin around if the rear brakes lock on wet roads after a few dry weeks in the summer.
It’s not something to skimp out on.
 

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