So I have GrandAm/Beretta setup on the front of my 86. Stock Fiero on the rear. In dry warm days I'm having problems with the fronts locking up, (right front) and the rears feeling not as powerful. I've heard about the 88 Fiero bias valve, anyone know where I can get one?
Also, I have a LOT of brake fade during the rain. I'm wondering if this is do to not having the rotor dust shields? It feels as if the disk needs to get warmed up and free of water before it starts to respond. Or maybe it just my cheap autozone pads?
I'm open for upgrade options, but I need to keep the ebrake. That has always been the setback for me. I know this subject has been done over and over...but I don't ever recall seeing an option to save or adapt the parking brake.
The condition you are describing is not brake fade. All brake rotors need to warm up to work effectively. In the wet the rotor takes longer to get up to temperature. Brake fade occurs when rotors get too hot. I have the willwood valve in your link installed on my car and it works for me. But the problem with these valves is they are designed for older cars where the problem is premature rear wheel lock up caused by too much braking force sent to the rears. So when installed on the rear brakes of a Fiero they make the front lock up problem worse.
The problem with the prop valve and the whole stock system is too little force going to the rear brakes. GM never factored in the rear weight bias of the Fiero. This is not a bad thing because the whole point of the prop valve is to keep the rear wheels spinning in a panic stop when you want the car to stop in a straight line.
The way I made the Willwood valve work is I disabled the stock prop valve, basically just turning it in to a fluid junction block. This should have turned it in to a 50/50 pressure split front to rear but still the fronts locked up early. So I put the Willwood valve on the front circuit only (and with the stock prop valve disabled it does nothing) and experimented with it until the fronts did not lock up until the car was nearly stopped and the rears did their share of braking without locking up at all.
I ran the car with this setup all summer and had it on the track and I finally can say my brakes work better than stock and since my rear brakes are stock I still have my parking brake.
I do not have a larger master cylinder and I use a stock brake booster. I have 11" lebaron brake rotors with Willwood GM metric 2 piston calipers on the front. The piston area of my front calipers is a lot less than the normal single 2.5" piston calipers commonly used in these setups.
Would I recommend using my setup to other people ? Absolutely not. Unless you have a ton of experience setting up and tuning brake systems and suspensions you could easily end up in a ditch somewhere.
Get an 88 prop valve and see how that works for you. From what I have read it certainly would not make things worse.
The 88 bias valve will make things worse. It is set up for equal volume piston displacement on all four corners. His current setup has larger displacement needs for front calipers.
I did the Seville calipers on the rear. They allow for use of the stock E-brake system. May have to change the cables ( I did) to slightly longer ones . Brake bias for me is not an issue. I did change the Booster to the larger booster, and also the MC, along with the Grand Am brakes in the front. Did you also change your rubber brake lines? They get weak over time, and will swell when the brakes are applied, reducing the pressure going to the calipers.
I started off with the full Lebaron kit from RCC (no longer in busines). It came with the Cadilac rear calipers but the brackets were so flimsy I never did get them to work. Braided lines all the way around and this is when I first encountered the right front lockup problem. And all the calipers had cast iron bodies and they weigh a ton compared to stock rear fiero calipers. The solution to the lockup problem is Aaron88's adjustable proportion valve. But he refuses to make them anymore and no one is willing to copy his nice little device. (see on going thread in the mall) .Supposedly if you use a single piston 2" diameter front caliper and the 88 prop valve with stock rear calipers you get a nice balance front to rear. But you can't do that with a grand am front kit because it has 2 1/4" piston calipers. Willwoods GM metric calipers come in that size but only fit the lebaron (Zettner) kit brackets and not stock brackets.
So that just leaves you a choice of getting rid of your grand am kit and starting over with a lebaron style kit. There is no easy or cheap way to get rid of the lockup problem.
I have the brackets, calipers, and hardware for the rear brake upgrade. This is the Cadillac Seville upgrade. This will work with the Fiero e-brake with some modification.
I have the brackets, calipers, and hardware for the rear brake upgrade. This is the Cadillac Seville upgrade. This will work with the Fiero e-brake with some modification.
Let me know if you are interested in them.
Do this, or just return the front brakes to stock.
I did the Seville calipers on the rear. They allow for use of the stock E-brake system. May have to change the cables ( I did) to slightly longer ones . Brake bias for me is not an issue. I did change the Booster to the larger booster, and also the MC, along with the Grand Am brakes in the front. Did you also change your rubber brake lines? They get weak over time, and will swell when the brakes are applied, reducing the pressure going to the calipers.
Seville calipers? huh. I havent heard of that option. Do you have a link to the exact one? And how do you keep the parking brake? Is there a bolt hole for the bracket?
I have Braided lines.
[This message has been edited by SP1200 (edited 04-19-2018).]
I have the brackets, calipers, and hardware for the rear brake upgrade. This is the Cadillac Seville upgrade. This will work with the Fiero e-brake with some modification.
They are an upgrade if used with compatible front calipers and larger diameter rotors. But not with the GA fronts. You would have an ebrake, but terrible bias f/r. To answer your question from a previous post.... A hydraulic ebrake will hold on a hill, but not pass many state inspections, and will not provide emergency stopping power in the event of a system hydraulic failure.
So if you had the Grand Am fronts with 9" rotors and single piston calipers with a diameter of 57mm combined with Seville calipers with 54mm pistons with 11" rear rotors and an 88 prop valve I think you would have a system with a sleight front bias. That is the type of setup I like.
It may sound strange to put a bigger rotor on the back but keep in mind that the Fiero has about 56% of its weight on the rear wheels and in most cases has bigger tires back there. If you have ever seen a 32 ford hot rod with way wider and taller rear tires in the back you will see huge brakes on the back compared to the fronts.
Makes me wonder if I have been looking at this problem from the wrong end.
Buy Rotrexfiero's fiero's rear Seville kit and get a stock 88 combination proportion valve and leave your front brakes as is. No guarantee that it would work though.
Fieroguru's 13" brake kit for 88's uses the stock 88 calipers and prop valve but he also uses Aaron88's adjuster on his personal car. So how well does that setup work without the additional adjustment ? It is all a big cr@p shoot without something that allows you to fine tune.
Buy Rotrexfiero's fiero's rear Seville kit and get a stock 88 combination proportion valve and leave your front brakes as is. No guarantee that it would work though.
Fieroguru's 13" brake kit for 88's uses the stock 88 calipers and prop valve but he also uses Aaron88's adjuster on his personal car. So how well does that setup work without the additional adjustment ? It is all a big cr@p shoot without something that allows you to fine tune.
The advice in your first paragraph will result in terrible braking performance.
Guru's 13" kit for the 88's works exceptionally well with no fine tuning.
Its not a 'crap shoot' if you know what you're talking about. Brakes are serious business.
