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heavy85

Tips for installing brake bias valve?

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It's obvious with the transmission out but is there some magic way to cut / extend / route through tunnel with the transmission still installed? Seems like there is not enough room and I dont want to have to pull the massive T56 just to install a bias valve. So does anyone have tips how to install a bias valve without pulling the transmission?

 

Thanks

Cameron

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I ran a new brake line to the rear of the car. I came into the passengers compartment through the firewall and ran the line under the center console. The valve is in the tunnel pocket where the ashtray sat. Then the line goes out the back of the ashtray pocket back under the car and to the rear splitter.

 

86586587_UiNvy-O.jpg

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It's obvious with the transmission out but is there some magic way to cut / extend / route through tunnel with the transmission still installed? Seems like there is not enough room and I dont want to have to pull the massive T56 just to install a bias valve. So does anyone have tips how to install a bias valve without pulling the transmission?

Put it under the hood or in the back under the car. You're really not going to be adjusting it very often once it is set.

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One time when I had the intake manifold off I mounted the prop valve under the dash as part of a "while I'm at it" project. The bracket is just some aluminum bar from Lowes that I bent using the bench vise. First I formed the tubing for the "under dash" part leaving the part for the engine compartment straight. That was then inserted through the two holes I drilled in the firewall. The intake manifold on the L6 needs to be off for the tubing to have a place to go until you can route it to the distribution block. I don't know about clearance for a V8.

 

Originally I had the prop valve mounted on the front fender inside the engine compartment, but it was a hassle to fine tune it on track days. Plus, as the day progressed I found that the optimum setting changed. Obviously it's easier if the valve is accessible inside the cabin. Also, while I don't usually drive the car in the rain, now and then I get caught out unexpectedly and on those drives I turn the valve out 1/2 turn to be sure that I'm not doing pirouettes on public streets. To Jon's point, I could have done this with the valve in the engine compartment, but it's a lot easier to do without having to pull over and raise the hood, especially when raining.

 

Edit 1: I had originally wanted to mount it the way cygnusx1 did, but like you, didn't want to pull the tranny. When I converted to FI and had the intake manifold off, this was the easier path.

 

Edit 2: Like most "while I'm at it" projects, this one took a lot more time than the pictures suggest. Finding the metric unions here in CO was a pain, and let's just say that the brake lines in the pictures weren't the first ones I tried :)

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I didnt have to pull the tranny to do what I did. I find it extremely nice to be able to adjust the prop valve on the fly. I can feel the changes in real time. In the rain, I can go several turns to increase rear brake pressure because the weight transfer to the front tires is MUCH less.

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We installed ours on the passenger inside wheel well. Very easy to run short lines through the floor into the OEM T-fitting directly below. Still can adjust from the drivers seat but not while driving of course. Agree with Jon, it's pretty much set it and forget it on the street. Also this location keeps passengers hands off the valve.

 

HPIM0837.JPG

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When I installed this prop valve, I wasn't prepared for any significant down time, nor did I care much about appearances. I wanted quick, dirty, and easy...

 

 

Pro2.jpg

 

 

 

 

Pro1.jpg

 

 

 

I *much* prefer double-flaring on the bench. One of the advantages of this mounting/routing was the short, easily accessible/removable lines... much of the reason I chose to do it this way.

 

Of course, don't forget to null the stock valve.

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The factory brake lines are M10-1.25 inverted flare. All of the proportioning valves that I have seen have 1/8" NPT threads and come with 1/8" NPT to 3/16 SAE inverted flare adapters. SAE 3/16 I.F fittings have a 3/8-24 female threads. Ideally, you would buy 1/8" NPT to M10-1.25 I.F adapters and be done. Unfortunately, I have yet to find such an animal. What I have been able to find are brake line assemblies that have a M10-1.25 fitting on one end and 3/8-24 fittings on the other. I have also been able to find M10-1.25 to 3/16 SAE adapters. Both of these items are made by Dorman and are available through most auto parts stores. I got mine at NAPA.

 

So what you end up with is one of the special brake line assemblies (M10-1.25 / 3/8-24) from the master cylinder or brake splitter going to the rear wheels. Then you have the proportioning valve with 3/8-24/NPT inlet and outlet fittings. From there, I run a long line that has SAE fittings on both ends. The long line runs from the outlet of the proportioning valve to the inlet of the Tee above the differential. The inlet of the tee has an SAE to M10-1.25 adapter installed.

 

I hope this helps.

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Don't use compression fittings in a brake system! You can however use Inverted flare couplers like Zmanco. If you look at his image here you will see that he replaced the factory proportioning valve with two couplers:

 

http://forums.hybridz.org/attachment.php?attachmentid=11342&d=1231570198

 

One of the couplers (upper) just connects the line going to the passenger side front brake. The other coupler is the one of interest. What he has done is take the line from the brake splitter that would normally go to the rear brakes and has routed it through the firewall to a proportioning valve mounted inside the car. He then runs the tube from the outlet of the proportioning valve back out through the firewall to the lower coupler which is in the line that normally goes to the rear brakes.

 

This is not a bad way to get the job done if you don't wish to remove the transmission. I had mine installed in a similar fashion for a long time. Later, when I had the transmission out for a clutch replacement, I cleaned up the installation.

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The adapter for the miata is for a 10/1 fitting.

I was told and hence always thought that our cars also used 10/1 but I see that you said it is 10/1.25. If so, then I would be in error about the miata kit fitting our brake lines directly (I have not checked myself and was about the get the adapter from flying miata, so I can't confirm).

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Don't use compression fittings in a brake system! You can however use Inverted flare couplers like Zmanco. If you look at his image here you will see that he replaced the factory proportioning valve with two couplers:

 

http://forums.hybridz.org/attachment.php?attachmentid=11342&d=1231570198

 

One of the couplers (upper) just connects the line going to the passenger side front brake. The other coupler is the one of interest. What he has done is take the line from the brake splitter that would normally go to the rear brakes and has routed it through the firewall to a proportioning valve mounted inside the car. He then runs the tube from the outlet of the proportioning valve back out through the firewall to the lower coupler which is in the line that normally goes to the rear brakes.

 

This is not a bad way to get the job done if you don't wish to remove the transmission. I had mine installed in a similar fashion for a long time. Later, when I had the transmission out for a clutch replacement, I cleaned up the installation.

 

I dont have a break in the line at the firewall - that must be a 260 or 280 set-up. I guess I could remove the safety switch manifold down under the master but then I would have to come up with a tee for the front brakes. I took off the shifter boot and the brake line is right there if I could splice in but I dont think I could get a flair tool in there. Why not compression fittings? I've used them in stainless rated to 6000+ PSI.

 

Cameron

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