I would like to put a portioning valve in between the front brake line coming out of the master cylinder and into the stock portioning valve, but the inlet for the wilwood portioning valve is too small? I amusing you can get adapters? Does anyone know what the threading and attachment sizes for the tubing for the front line out of the brake master cylinder? I believe the inlet size for the wilwood portioning valve 1/8-27 i would need something to adapt to that?

anyone?

If you get an answer please let the rest of us know. I have a portioning valve sitting on my shelf I need to install on my car.

if you are using an aftermarket proportioning valve then why would you want ot keep the stock one? the valve restricts pressure to the line it is connected to - you will be restricting flow to both the front and the rear, adding un-needed pedal resistance..

better to remove the spring from the stock valve, and put the proportioning valve in the rear line

quote Originally posted by Kohburn: if you are using an aftermarket proportioning valve then why would you want ot keep the stock one? the valve restricts pressure to the line it is connected to - you will be restricting flow to both the front and the rear, adding un-needed pedal resistance.. better to remove the spring from the stock valve, and put the proportioning valve in the rear line

The stock system doesn't restrict pressure is just slows the rate of pressure buildup to the rear.

I should clarify a little, I have wilwood 12" brakes on the front of my car and 88 stock brakes on the rear, and there is way too much braking up front, that is why i want to reduce the pressure. I am in the try and see what works phase right now, because as far as I know, no one else has this same setup.

quote Originally posted by Madess: I should clarify a little, I have wilwood 12" brakes on the front of my car and 88 stock brakes on the rear, and there is way too much braking up front, that is why i want to reduce the pressure. I am in the try and see what works phase right now, because as far as I know, no one else has this same setup.

that makes more sense now... look for threaded fittings at www.mcmaster.com

I found this page

http://www.amstreetrod.com/989545ERL.php4

but I don't know which fitting? Anyone know what standard range of AN means?

i dont know how much help this is but heres a picture of the one on my car.I dont know what sizes they are because it was on the car when i got it

Just try taking the spring out of the stock Fiero unit and see how that works.

I took out the spring, and still way to much front brake - the four piston calipers just have too much clamping force compared to the stock brakes.

do a 12" covette rotor upgrade to the rear of the 88.. its easy and cheap and will give you more even braking - it keeps the ebrake because it uses the stock fiero caliper just a rotor thats 2" larger in diameter

quote Originally posted by Kohburn: do a 12" covette rotor upgrade to the rear of the 88.. its easy and cheap and will give you more even braking - it keeps the ebrake because it uses the stock fiero caliper just a rotor thats 2" larger in diameter

WOW, yeah that sounds great, because definitely the perfect option would be to upgrade the braking performace on the rear brakes.

now please define "easy" and "cheap" and is there a write up on this anywhere?

Wilwood 4 piston brakes upfront and stock out back? LOL

And then you want to bandaid it with a 50 part? LMAO

Do it right and upgrade the rears or die in a firey horrific braking accident.

your choice!

The 12" corvette upgrade on a 88 IS cheap and easy. Might get your hands dirty though! eeek!

[This message has been edited by DOHC_SWAPPER (edited 01-24-2006).]

WCF makes a kit to add OEM C4 12" rotors to a Fiero, using the stock Fiero calipers. It consists of redrilled rotors, adapters to relocate the calipers and hub centering rings for the rotors. I think it's around $300, including rotors. You can buy just the mounts for about $216, and a few members on here have also made them for sale, but I forget who.

A search in the Mall will probably turn up a few different options. It's a great upgrade if you already have larger wheels.

https://www.fiero.nl/forum/Forum1/HTML/047271.html

quote Originally posted by DOHC_SWAPPER: Wilwood 4 piston brakes upfront and stock out back? LOL And then you want to bandaid it with a 50 part? LMAO Do it right and upgrade the rears or die in a firey horrific braking accident. your choice! The 12" corvette upgrade on a 88 IS cheap and easy. Might get your hands dirty though! eeek!

well to rebut I actually got off quite cheap on the fronts, the wilwood upgrade cost me about 250$, because a friend and I fabricated the parts. So it is not like I spent a massive amount on the fronts and then cheaped out on the rears. I would like to do wilwoods in the back, but that would be some more fabricating, adjusting and testing and that took while. As for getting my hands dirty, we did fab the parts.

ok, I am bringing this thread back to life.
I now have 12" front rotors with 4 piston calipers and now
I installed 12" rear rotors with stock 88 calipers, and the spring removed from the stock portioning valve.

and now, STILL too much front brakes.

so we are back to the portioning valve. now this is probably a stupid question, but since i have too much frount brake do I want the portioning valve in between the master cylinder and the front brakes or like the picture above, in between the master cylinder and the rear brakes?

I don't understand why you would put the valve in the line with rear brakes, because I need more rear brake to balance things out.
can anyone explain this or is there a good website to read about it?

Generally the front brakes are doing about 80% of the work to begin with. Why do you think the front brakes are doing to much work? You may have a problem with the rear brakes hydraulics, have you tried bleeding out the system to see if there is air in it? When you did the brakes, you should have started bleeding from the rear. Does the parking brake work? If not that could be the issue.

I've never seen an issue where someone wanted to reduce front braking capability, the porportioning valve is to reduce rear braking so the rears don't lockup before the fronts.

What master cylinder are you running?

quote Originally posted by Phil: Just try taking the spring out of the stock Fiero unit and see how that works.

I did this. It helps a little, but I am noticing problems with it. the rears are inconsistant now. my brake pedal is sometimes harder than other times, and my handbrake sometimes comes up high, and sometimes barely 2 clicks. I agree with whoever said the spring is part of a delay. I dont think there is a proportioning valve stock. I think the existing brake bias is due to the master cyl piston size & caliper piston size.

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1985 Fiero SE - Plain Red V6 Coupe
3.1 Crane272 MSD 4.10-4spd DarthChip Borla
D.A.M.M. - Drunks Against Mad Mothers

I know there is where to much front brake because I can lock up the front brakes at any speed. I am assuming it is because there is too much clamping force from the 4 piston calipers.

I have bleed the brakes and tested, no air, and the rears clamp fine, just not nearly as much as the front.

I am using a blaser master cylinder, I considered converting back to the fiero master cylinder, but I didn't think that would make much of a difference.

ok, I was reading on this site that he removed the spring and the rear seal...

http://www.terranexus.com/fieroman/brakes/brakes.htm

could B (in this picture) be the seal he is talking about?

http://www.webelectricproducts.com/99/4/shifted.htm

it would appear this would allow full brake pressure to the rear brakes, and then use the after market portioning valve to control it...

When I did mine the Held instructions said:

Remove the plug from the rear of the original Fiero combination valve, remove the plunger and spring and either braze or weld closed, the small hole that is under the small plastic cap in the center of the plug.



Here's a pic of the wilwood prop valve installed, can't recall what size the fittings are though.

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Dave E

www.ltlfrari.com

I too did a WCF 12" upgrade and put on a adjustable proportioning valve while retaining the stock unit (with spring removed). I left the stock unit in to retain the brake warning light. Chris West (WCF) confirmed that on a corvette based upgrade, the proportioning should be on the front (weight differences, and front engine vs rear engine etc). I currently have the front set up on about 50% but under hard braking, only the front locks up. For track use, I am trying to get more equal braking. I first tried to remove the plunger too, but brake fluid will leak out the plug. I think the Held solution of sealing the hole in the plug and removing the spring AND plunger may be required. A loose plunger (no spring) must block some of the flow to the rear.? I don't have an answer to the original question, but I got a metric valve (I think non-metic might have been better). I went to the auto parts store (had to go to 2-3) and browsed through their fittings to find all the adapters. Sometimes you can also get short pre-made lines with different ends. I also change the master cylinder to a corvette, so I needed some extra lines which made it harder. I may try to remove the original valve body after all.

has anyone confirmed the spring & plunger is actually a proportioning valve, or is it a valve to maintain slight pressure on the rears, or is it a slight delay for the rears? I cant see how with 2 completely seperate hydraulic systems you would need a proportioning valve? the only link betweent the front & rear hydraulic system is the brake light switch - which still keeps the 2 system seperated, and the master cyl.

bump

I think that "proportioning" refers to the proportion of pressure output (to brake pads) based on the pressure of the input (how hard you press the pedal). Like you said, I don't think it really has anything to do with front/rear, since they are separate. Maybe they could have used a less confusing term. The "proportioning" part is only on the rear in a stock setup. Under normal driving full pressure is applied to both front and rear. Under hard braking, full pressure to front and maybe 80% to rear. If you slam on the brakes really hard, you would get full pressure to front and maybe 60% to rear. Someone correct me if I'm wrong.