Brake Proportioning valve on awd spyder

[91laserrsnt]

I have an awd spyder, and I feel that my braking in the rear is inadequate. My car is non abs, and I was wondering if I should get an adjustable proportioning valve. The car is really really heavy in the rear now, and the stock setup just is not performing properly.

Anyone ever tune one of these or have any recommendations on what to do? I have early 95 vented rotor setup also.

 

[tsiboosted]

I have been looking into these myself in the past week or so and have been doing research on where to find and buy some of these valves. I found THIS website for the brake adjustable proportioning valves you may want to give a look at. My dads car has these on them and work great for him. Just be careful if you do go with something like this, that you know where the knob is set during installation to avoid trial and error settings later down the line. Reasonably priced as well I believe. Hope this helps you out some.

 

[91laserrsnt]

I have found a few products like that already. Just wondering if someone has some first hand experience with any of these items, and weather or not I should be adjusting the brake bias at all.

 

[tsiboosted]

I have found a few products like that already. Just wondering if someone has some first hand experience with any of these items, and weather or not I should be adjusting the brake bias at all.

I personally as of yet do not have it setup. My dads car however does but it is a rear wheel drive front engine car. We have tested his at the track and basically what you can do is control the amount of weight transfer during braking. If you have more 'Bias' dialed into the rear brakes, or out of the front brakes it will not allow the front of the car to brake as hard causing the weight to transfer at a slower rate. This will help if the car is diving forward too much during braking. I'm sure you would see a much more drastic display of this in our cars as the majority of the weight is towards the front of the car.

You were saying the rear brakes feel inadequate, but it may be there is too much brake in the front and the rear is just fine. The rear brakes in our cars (especially in a race prepared DSM where it is gutted) do not take that much abuse. Well not as much as the front anyway. When I am racing for a full 20 minutes, my rear brakes hardly get used at all. My tire pressures in the rear as well only go up about 4 degrees from the cold pressure checks prior to going out in the session.

What type of rotors and pads are you running now, front and rear? You mat be able to solve this issue just by trying different pads and not have to go as far as to put a brake bias setup in your car. Just something else to think about. I hope some of this helps.

 

[91laserrsnt]

Im running brembo slotted and dimpled rotors in the front and rear. Im running OEM pads in the front and ebc green stuff pads in the rear. Like I said, the rear rotors are the large early 95 vented rear rotors, and the front calipers are the awd dual piston.

I think green stuff pads are shit, and I am planning on switching back to oem on the rear soon. I had the car up to 120 the other day and was messing with the braking and it felt like a pos. Another problem im having is with the suspension being able to handle the extra weight. Im using awd springs in the front, and spyder springs in the rear. The spyder springs are visibly larger than the awd springs, and that is why I went with that setup. The car doesn't really feel that natural, and a lot more things need to be taken into consideration when doing the awd spyder swap.

Maybe the proper spring/brake setup would solve most of the problem? Who knows. Very few people have this same setup which makes it very hard to diagnose handling issues with the car.

 

[absolute_DSM]

I used to talk to jtmcinder about this, we should get him into this.

 

[tsiboosted]

Im running brembo slotted and dimpled rotors in the front and rear. Im running OEM pads in the front and ebc green stuff pads in the rear. Like I said, the rear rotors are the large early 95 vented rear rotors, and the front calipers are the awd dual piston.

I think green stuff pads are shit, and I am planning on switching back to oem on the rear soon. I had the car up to 120 the other day and was messing with the braking and it felt like a pos. Another problem im having is with the suspension being able to handle the extra weight. Im using awd springs in the front, and spyder springs in the rear. The spyder springs are visibly larger than the awd springs, and that is why I went with that setup. The car doesn't really feel that natural, and a lot more things need to be taken into consideration when doing the awd spyder swap.

Maybe the proper spring/brake setup would solve most of the problem? Who knows. Very few people have this same setup which makes it very hard to diagnose handling issues with the car.

Like you said, I have never seen anyone run the kind of setup you are running. I am not claiming to be any suspension expert by any means. But it may interest you more in the beginning to get a better overall suspension package on your car. Now if you want something I believe would be a good street setup and for some descent track suspension, try going with something around 350 in the front and 225 - 275 in the rear. That would give you still a good ride but at the same time be a little more aggressive (but not full blown race) suspension setup. Now some people may disagree with me on these numbers and maybe you could go a little more stiff if you wanted to, but at the same time you have to think if you are driving this car a lot on the streets. Or is it going to just be a track car. With the springs taken care of you will want to upgrade the struts as well. Konis, KYB, Tein whichever you want to choose is better than factory any day of the week to me. If it is your street car as well as a toy, you may want to go with a strut that is adjustable. That way you can go down when on the street and stiffen it up when you go to the track. Or you can go with a full coilover system, but they tend to get rather pricey. if you wanted to go in that direction, just get a good strut and go with the Ground Force coilover kit and you can get many different spring rates to play with. Just a preference I guess on which ones you want to go with. Your suspension has a lot to do with your braking performance as well. I think people tend to over look that when they are having braking issues.

With the brakes, I have heard both good and bad about EBC pads in the past. More good than bad though. But if you are not happy with them, I say go with something different. I personally run Hawk HP+ in the front and Hawk HPS in the rear. But you cannot go with what I have as my car is setup differently than yours. But if you want a less aggressive pad in the front and something that is better quality the OEM, than the Hawk HPS would be a good pad there I believe. It is not as "grabby" as say the HP+, but still gives you good stopping ability without being overly aggressive. Which I believe this is what you are looking for here. You may even want to go with a pretty aggressive pad in the rear to compensate for what you are experiencing in the front now. But this could also have something to do with your suspension setup you currently have as well. A lot to consider with something like this. I hope some of this helps you out here.

 

[91laserrsnt]

The car is meant to be a daily driver and by no means do I expect it to be a race car at all. I have fun doing some spirited driving once in a while, however all im looking for is a great feeling car that will take the city bumps and bruises and not feel like its going to rattle apart. I am pretty much against most aftermarket suspension equipment. I feel that most of it is junk, and that once you start to modify 1 area ie:shocks, it will require you to modify other things ie:springs.

IMO lowering, or changing rates of different things pounds the piss out of other factory components that are on the car. I do however feel that I am left in quite of a predicament as it seems that I may have to be a bit of a hypocrite and install 'Julio' parts on the car just to get it to where it should be (factory feel).

As far as the braking system is concerned, is it too sensitive to mess with, or should I just toy with it to see what results may surface?

 

[underradar92]

I've switched to an adjustable valve. I can't say it'll solve your brake issues but I'd wait until you have equivalent/fresh pads front and rear, and are sure all the calipers are functioning correctly before making a potentially unnecessary/P.I.T.A. mod such as this.

That said, if you go forward with this, it works well once it's dialed in. Problem I've found with that is, even when I thought it was pretty close, under REALLY hard braking (track day) it was still pretty far off.

I wouldn't recommend learning that in an emergency situation.

 

[turboglenn]

This is one of my fist cars i haven't put a valve on just to have fun with. I just get the real basic front to rear biasing setups and use them for launch control to "faux drifting" on FWD's. On FWD it's fun to put ALL of the brake in the rear, hit a turn in 2nd at about 45MPH and mash the gas and brake, the rear will fly out but you'll be able to drag it around and control it pretty well with practice in parking lots . It's one of the few ways i've found to have some real fun in a front wheel drive car. On RWD cars, they make a great way to power brake without burning the rear brakes at all too fot rolling LONG burnouts. I've always thought cars should be like motorcycles and come with independant braking as an option, but that's just me

They are also really nice to have for tehir intended purpose as well, but i get more use out of them for other means most of the time.

 

[JSpecEclipse]

justin

The added weight in the rear of the car is substantial I would have installed the awd springs or an aftermarket upgraded one for an awd. Just because the spring is bigger doesnt mean that it has the right springrate. personally I wouldnt mess with the rear brakes too much. reason being when you hit the brakes the weight of the car goes to the front . This takes away the load on the rear brakes. If you increase the braking power of the rear brakes you risk the chance of locking the rear tires. Which in my experience is bad at 120mph. If I were you I would look into different springs for the rear and a awd brake proportioning valve. And call it a day... I lost your # when got a new phone pm it to me or call me sometime to discuss this further. Maybe we can go for a spin to better diagnose this problem.

Later ,
Drew

 

[JSpecEclipse]

oops i thought you were someone else sorry
advice still applies but nothing else does!

 

[91laserrsnt]

You sure its not me? I sold a gsx conversion setup to someone in fairfax VA. Im 1fastgst on all the other boards.

 

[Todd TCE]

FWIW.

An adjustable proportioning valve won't promise returns on your car. In order to evaluate it's function you'll need to gut any stock valve to get full rear line pressure into the valve. Adding a valve after a valve won't do anything.

Reviewing function for a moment; a prop valve only LOWERS output pressure, it cannot raise it. The knob changes the 'knee point'- the line pressure reached where pressure REDUCTION begins.

Examples
100psi in = 100psi out
200psi in = 180psi out
300psi in = 200psi out
400psi in = 250psi out
500psi in = 250psi out

As you can see here things begin about 200 and finish up total reduction at 400. Despite the added 100psi at 500, the output is constant with that of 400 also.

An adj valve changes the point where reduction BEGINS. Perhaps you want it to stay equal up to 300. It will and then the reduction begins. Most good vavles top out a 50% reduction.

Adding a valve can be nice but also very complicated as your car likely has four channel brakes. Means you'll need to Tee the lines both in and out of the valve. Then you lose independent abs function here as the puter doesn't know what to do with line reduction and BOTH lines see the reduction because you teed them.

It's also a bit of a band aide for poor pad selection....putting in hard core race pads in the rear and then using pressure reduction to stop them from locking?? No thanks, pit a better pad.

In the end it's a great tool if you know what to do with it, how to tune it and want to spend the time to install it. But promises of big braking gains are likely well overblown.