Proportioning Valves

McCracken

McCracken

Logan Can't See This
Joined
Jul 9, 2005
Location
With your mom at a nice seafood dinner
Any recommendations from the group? I looked at some adjustable ones from Wilwood on Summit's site but I really have no clue which one to get. I'm still using the original Jeep one from 1975 and I've often thought I need to fix this. I figure it's a quick bolt in since I'm having to rerun some new lines anyway.

Here's the one I was looking at:

www.summitracing.com

Summit Racing SUM-G3906 Summit Racing™ Adjustable Brake Proportioning Valves | Summit Racing

Free Shipping - Summit Racing™ Adjustable Brake Proportioning Valves with qualifying orders of $109. Shop Brake Proportioning Valves and Distribution Blocks at Summit Racing.
www.summitracing.com www.summitracing.com
 
McCracken said:
I feel like the front takes the lion's share of the load.
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That's because the front takes the....
Front engine vehicles are usually always front heavy, and that increases a lot with dynamic weight transfer under braking. If you only ever go slow enough for weight transfer to not matter, you can add more rear bias. If you do that, you may need to beef up the rear brakes though, else you'll just overwork the rears. And no matter what, your brakes will only work as well as the weight on the tire, so if you're still highly front heavy, there's only so much rear brake you can actually use.
 
Fabrik8 said:
That's because the front takes the....
Front engine vehicles are usually always front heavy, and that increases a lot with dynamic weight transfer under braking. If you only ever go slow enough for weight transfer to not matter, you can add more rear bias. If you do that, you may need to beef up the rear brakes though, else you'll just overwork the rears. And no matter what, your brakes will only work as well as the weight on the tire, so if you're still highly front heavy, there's only so much rear brake you can actually use.
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That makes sense. I guess I was thinking for $60 I can have adjustability and possibly give myself a little more stopping "feel" from the rear.

I've got discs all the way around. I also upgraded the MC to the Ford E350 model that @Jody Treadway likes to run. I'm not sure what else I'd really want to go upgrading at this point.
 
In Samurais this is a problem.
the oem vavle goes out and the replacement is 300 bucks.
The alternative is a Wilwood (I think) kit from Low Range that includes fitting and a couple of pieces of line for way less than half that.
You like the price, plus you can adjust it as needed.
A couples hours worth of work and you're good ... AND you have the added benefit of adjustability.
You set it according to instructions .....
Drive it.....
Tweak it a bit....
Never touch it again.
 
McCracken said:
I've got discs all the way around. I also upgraded the MC to the Ford E350 model that @Jody Treadway likes to run. I'm not sure what else I'd really want to go upgrading at this point.
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The mc displacement front/rear needs to be matched to the caliper bore front/rear. Unfortunately, once you start swapping axles, the caliper size tends to get set by other factors unrelated to brake balance. If you're pushing too much fluid to the fronts relative to the rears, a proportioning valve can help account for that.

A good test IMHO is to panic stop from a reasonable speed and confirm that you can threshold brake the rears. You want them to participate, not lock up too much before the fronts, have some dive, etc. Basically, you want it to feel balanced. To Jody's point, it's tough to tell on the trail if the brakes are balanced (unless they're way off).

Also, make sure all components are in good shape. If the rear rotors sat out in the yard for a year before going under your rig, they're never going to stop well, no matter what you do with the fluid.
 
shawn said:
The mc displacement front/rear needs to be matched to the caliper bore front/rear. Unfortunately, once you start swapping axles, the caliper size tends to get set by other factors unrelated to brake balance. If you're pushing too much fluid to the fronts relative to the rears, a proportioning valve can help account for that.

A good test IMHO is to panic stop from a reasonable speed and confirm that you can threshold brake the rears. You want them to participate, not lock up too much before the fronts, have some dive, etc. Basically, you want it to feel balanced. To Jody's point, it's tough to tell on the trail if the brakes are balanced (unless they're way off).

Also, make sure all components are in good shape. If the rear rotors sat out in the yard for a year before going under your rig, they're never going to stop well, no matter what you do with the fluid.
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Well, the good news is that I got it in my shop and that's where it's been. I had been running the stock MC for years with the one tons. I'm assuming this will be more balanced since I upgraded to a larger MC and the one tons are indeed larger.
 
McCracken said:
I'm assuming this will be more balanced since I upgraded to a larger MC and the one tons are indeed larger.
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If you're running the 80s/90s Ford master cylinder, it was designed for rear drums and doesn't send a lot of fluid back there as compared to the front. If you have smallish front calipers and big rear calipers, it could still be unbalanced.
 
you can get an inline needle valve and do the same thing. put one in front and one on the rear and perfectly adjust your brake bias.
 
shawn said:
If you're running the 80s/90s Ford master cylinder, it was designed for rear drums and doesn't send a lot of fluid back there as compared to the front. If you have smallish front calipers and big rear calipers, it could still be unbalanced.
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You'd have to ask he guru on that one. He recommended it and I just went with it. The rear should be almost identical to the front. I use Chevy model calipers and discs. I think the kit I got was for Caddy calipers so you could use the e-brake but I opted for the cheaper option.
 
McCracken said:
You'd have to ask he guru on that one. He recommended it and I just went with it. The rear should be almost identical to the front. I use Chevy model calipers and discs. I think the kit I got was for Caddy calipers so you could use the e-brake but I opted for the cheaper option.
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The guru is right.
That master cylinder is the magic combo for OEM Single piston calipers front and back.
 
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