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How many of you guys running 3.5" skinnys on the front are using a proportional valve to try and get more braking on the rear tires? I am having some braking issues with short shutdown tracks.
Thanks
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Proportional Valve
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we run a proportioning valve on ours
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what brake setup do you have? are you using the stock prop valve still?
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I have the aerospace 4 piston per caliper street brakes on all 4 corners. Yes I am using the stock proportioning valve. I have been running this setup for 3-4 years with no issues until now. I actually have other problems when braking. When I start braking the car gets unstable, pulls side to side. Bump steer is good. I have to slowly apply the brakes. As you could imagine this is not fun on short tracks. I got lucky once, I want to fix it before it kicks out again. If I have enough room to slow down I can ease the brakes on and manage to stop.
See video
http://www.turbochargedtimebomb.com/Videos/SethPowerSlide.wmv
Thanks
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153 Posts
well the first thing i usually do is toss the stock valve and get an adj for 35$. put it in the rear line and adj for apply. if youre unstable when braking you need to really look at the calipers ,wheel bearings and joints and tie rods to be sure theyre not bad.
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saw the vid,wow!!! that looks like shadyside nc, are you using braided brake lines, have you blead the sys real good? looks like the wheels on the right side of car locks up, maybe. make sure there are no bushings in the control arms loose front and rear. check the k-member mounting bolts make sure its not moving.
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138 Posts
Yeah that was shadyside. I am using braded brake lines on the front. I think I had all the air out of the lines. I had the car together for a while so I would think if air was in the line it would have worked its way out by then. In this video the wheels did lockup as the car bounced. I have run it at Rockingham since then and I made sure I did not hit the brakes to hard. I noticed that the car started swaying side to side as I applied the brakes and the tires did not lockup. I just let up on the pedal and gradually pressed it again. Luckily I was only running an 1/8 mile on a 1/4 mile track. It still wasn’t comfortable because I almost ran out of track there.
I am going back thru everything. I have rebuilt my front calipers and plan on doing the same to the rear. The control arms look ok and the K-member is tight. The front shocks seem to be set the same. I haven’t checked anything on the rear yet, but I will. The car drives fine up until the point I start braking. My brake lines are close to my drivers side header so I went back and installed some heat barrier.
Thanks, Seth
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138 Posts
I
I have heard that some people are proportioning the front. It looks like people are having good luck either way. My car weights about 3271 depending on gas & ballast and I have about 46.8 on the rear and 53.2 on the front. My thought was to put the valve on the rear and let the rear calipers get more pressure than they have right now. It has to help over the stock proportioning valve. Having more pressure to the rear can also help building boost on the foot brake since I have a turbo car. This raises another question. Most turbo cars have two sets of calipers on the rear. I wonder how they manage their pressure and keep the rear tires from locking up with twice the stopping power?
Thanks, Seth
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keep in mind pressure and volume are two different things. on the ford master cly we normally put the valve in the line that feeds the rear on the fox body stock sup 3000-3300lbs
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I am kinda leaning on installing it on the rear lines and just removing the stock PV all together.
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i have aerospace discs on the front and dual aerospace on back. where would i put the adjustable proportioning valve? im almost ready to start running the lines. thanks in advance!
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Yeah I hear ya, I just want to make sure I fix my main problem. If I dont fix it, it will come back.
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I talked to wilwood and they told me to remove the stock proportioning valve and install the new one on the front brakes. They said with the small tires up front and larger ones in the back is what's doing most of the stopping rather than the weight on the front tires.
Thanks,
Thanks,
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1,723 Posts
Along similar lines, my front Strange brakes seem to drag too much.I do use a prop. valve.If I jack the front of the car up and spin the skinny hard it will only continue to spin approx. 3-4 more revolutions.I've checked it without the caliper so I'm sure it's not the bearings too tight.Could the prop. valve be too biased toward the front ?
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153 Posts
alot of guys run 2 adj valves 1 for front and rear, along with brake gauges in the car you can get the perfect braking you need. total cost of the type setup is around 150$, not bad in my opinion.
as for the calipers draging, yeah generally stock prop valves act a 60/40 bias i believe and also act as pressure vales to maintain about 2lbs on the calipers or wheel cyl. , i forget all that stuff lol so i could be off a bit.
as for the calipers draging, yeah generally stock prop valves act a 60/40 bias i believe and also act as pressure vales to maintain about 2lbs on the calipers or wheel cyl. , i forget all that stuff lol so i could be off a bit.
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I meant to say I run use an adjustable prop. valve.
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