What a PITA. Ok so I haven't cut any lines yet. But I really do want to try to get this thing by installed tomorrow. But at the same time, I don't want to have a problem that I can't fix before I have to leave Friday for the track.

The rear line is a single 1/4" line. So I need to cut the rear line that's under the car, add a fitting and flare it then connect another one to it, run it through the trans tunnel and mount it in the ash tray location. Obviously then back down again and connect to the rear of the brake line that runs to the rear.

I've rented a flare tool before and it took me a couple of tries but I got it to seal. I'm afraid of cutting the rear line clean enough and making a good flare. I feel like that could be a disaster. Also, will I have a hard time bleeding the brakes with the prop. valve being mounted up so high?

I might just scrap this for now since I have a track day coming up.

Any help will be appreciated!

Why are you putting a valve in it? Are you having rear brake bias issues? Run parts store pads on the rear, take a spare set and drive it.

Old brake lines get brittle. They like to crack when you flare them. The older they are, the worse the problem can be. If I had a paid for track day coming up in a day or two, I'd leave that project alone. If you are getting brake hop, put a much less aggressive pad on the rear and watch your downshifts. I suspect that will get you through, particularly after you get some heat in the brakes and the rears start fading a bit.

Yep, I have a bias valve but don't even use it any more.

Running xp10s in the front and ceramic in the back, no axle hop under braking.

I've found that running a more aggressive pad in the rear (like xp8) and dialing back rear bias led to me more likely to lock up the fronts

I've removed abs, that transfered way too much braking to the rear. I'm running XP20's front with C5 front brakes and stock LT1 rears with the cheapest pad I could find. I posted my axle hop videos last year and the conclusion was I just need to add a prop valve. With smooth application of brake and no downshift, I'm actually threshold braking the rear, not the front. Since removing ABS, I've never locked the front wheels. But my pedal feel is awesome. And it's so easy to bleed brakes now.

That was at Carolina Motorsports Park, one of the hardest tracks in the US on brakes. This weekend will be at Roebling Road, much easier on brakes. I'll leave this project for another day.


https://youtu.be/3fN0aUKiJus

Ah, I thought the ABS system was still in the car.

That's a double flare tool, right? These days you probably need one of those for the brake system. Don't mess with unless you have a double flare tool.

Have you done the necessary fixes to stop axle hop? I've been told a poly front ta bushing and dual rod end LCAs at a minimum...

I've got to fix the rear lock up first. I'm literally locking the rears.

Strange. I'm currently running XP10s up front, ceramics out back, full bias to the rear, and LCAs with poly on chassis side, rod end on axle side, with a poly TA bushing.

With 675F/225R I could only get it to hop under very hard downshifts with no heel toe. When I went up to 750/250 I feel like it was a little more worse on too aggressive downshifts but still can't get it to hop under hard braking.

Now that I think of it I run 4 piston superlites up front with the biggest pistons they offer. My lines are all replumbed to be 3/16" line with AN3 hose front and rear, so I wonder if that is why my brake bias is different than yours.

Anyways to answer your question, it is a "1/4" size line but usually it is metric bubble line on both ends. You can try use a regular double flare as this is how mine was setup originally (bias valve mounted in bay connected to stock line with remote wilwood cable). I'm not sure if having you valve up high in the ash tray (close to trans tunnel?) would be an issue for bleeding as long as it is lower than the master cylinder; usually a pressure bleeder would make quick work of that.

I don't recall the stock line being very easy to flare compared to aftermarket line you can buy when making your own lines.

To do it right, IMO, I would rip out the stock line and run it through the cabin as 3/16 line with adapters front/rear.

The OE line and the green coated line from the local parts houses are usually hard to flare. The flaring kit from Mastercool makes flaring ridiculously easy, buts its a bit pricey. The kit is kinda like a sawzall. Once you use it, you'll wonder how you ever got along without it. If you do as many brake/fuel lines as I do, it'll be well worth the money.
Mastercool p/n 71475PRC does 45 degree double flare, metric bubble flare, fuel line oring flare and A/C line o-ring flare.
http://www.ebay.com/itm/Mastercool-71475-P...r-/271530708754
I mounted my adjustable bias valve just behind the shifter and it will gravity bleed at the rear calipers. I have a knob that will go through the console to adjust it, but, once I set it with the stock pads, I don't have to mess with it.

So the consensus seems to be, don't install a prop valve if you don't already have one and instead tune brake bias with pad compound? I don't have brake hop, I just want the rears to actually do something. They don't really do much on a stock 3rd gen.

A proportioning valve can be a useful tool for tuning the brakes. This is particularly true on LS1 cars because they typically have too much rear brake from the factory due to the larger rear brake package. You can also try to correct this with pad compound.

If you have a car that has minimal rear braking, a proportioning valve is likely not going to help you much. In that case I'd add slightly more aggressive rear pads until things balance out a bit better.

One warning, running a mix of more and less aggressive pads can result in weird brake bias changes throughout an autocross run. I used to run XP10 fronts and XP8 rears. When cold, the rears worked "sooner" than the fronts. As the brakes heated up, the fronts got better and if I really beat on the brakes, the rears would start to fade a slight bit. So every corner had different brake bias and you never knew exactly what you were going to get at the next corner.

I just checked my rear brakes. The pads are gone. That was only two track days with cheap rear pads. I've never had that happen before. That's another indicator that I have too much rear brake.

Not necessarily. Also an indicator that the pad compound can't handle the heat. We have seen that issue when CMC cars went up to Stoptechs from LS calipers.

I installed a Wilwood dial BPV between the reservoir & ABS last year, and bought a brake pressure tester to see how much the pressure was dropping. With the BPV full open, max rear pressure was 1125-1150psi, and it dropped to 700psi at max restriction. It also didn't fall off during testing, which was probably 5-10s with the pedal hard to the floor. I haven't raced my car since 2009, but after installing the BPV I went through 3 or 4 rear compounds before settling on the Akebono ASP749's (DOT GG edge code). My goal was to creep up on the edge of rear brake lockup and then dial it out with the BPV. But the BPV is still wide open and I'm not aware of a slightly more aggressive compound which would meet my criteria. The Akebono has very little dust and no noise (neither matter in a race environment obviously), but just enough grip where drivers can feel the rear 'sit down' a bit. I've not been able to get the rears to lock up yet in daily driving, but obviously it's not driven in anger as it once was.

On a tangent, the front G-Loc R6's dust and squeal more than the DS-2500, stopping power is better though, and equally easy on the rotors. DTC-30's still have better stopping power, but gouge the rotors, squeal more often and dust slightly worse. The R6 dust comes off pretty well after numerous cycles of wet/dry (I still use Sonax wheel cleaner), there are some areas where the compound stubbornly clings to the wheel. But at least it doesn't melt into the wheel like the DTC-30 dust.

I also got rid of abs and put the proportioning valve from Wilwood.
Have Porsche big red in fronts w/ stock rears

This is exactly what I was thinking of doing....running the same pad F & R. You guys certainly have a lot more experience with this than me, but in my case, my '95 has LS1 front calipers with LT1 rear. Also non-ABS and have the Wilwood valve already. Would I still see the bias change throughout a AX run since there's going to be more heat created in the front? Are some pads better than others for NOT changing grip with increased heat?