Anyone else doing brake proportioning valves? (Page 2/4)
tshark FEB 09, 02:34 PM
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[This message has been edited by tshark (edited 09-08-2018).]

Raydar FEB 09, 05:43 PM
Thanks for jumping in, Paul.

It's really easy for me to speak in generalizations. ("My back brakes suck.")
You can explain it so that it makes sense.

[This message has been edited by Raydar (edited 02-09-2015).]

doublec4 FEB 09, 06:27 PM
I plan on reproducing these. Right now I only have the 84-87 I've made drawings / models for. I'm getting them quoted right now.

I would need one of the 88's so I can do the same.
E.Furgal FEB 09, 06:38 PM

quote
Originally posted by Raydar:

My 88 has a very pronounced front-bias to the brakes. From talking with other folks, I understand that this is pretty typical.

This was aaron88's mall thread.
http://www.fiero.nl/forum/Forum4/HTML/064690.html
It would appear that he no longer is making these for whatever reason.

I was wondering if there is another solution for this situation, or if someone else might be inclined to produce these.

I would have posted this request in the mall, but there are obviously technical aspects to this that are more involved than simply posting a "want to buy" thread.

Thanks.




is this a stock car,??
weight change(per wheel have car scaled), spring rates, ride height, shock valving, all effect this.. as the stock settings "assume" the way the vehicles weight will be transferred from/to each wheel and how fast that weight moves,
so is the car seeming having to much front bias, from changes that upset the engineered weight transfer that the stock bias was ment for?

[This message has been edited by E.Furgal (edited 02-09-2015).]

Steven Snyder FEB 09, 07:58 PM
If aaron88 can't make one soon enough for you, this is another option:

JEGS Adjustable Proportioning Valve and Distribution Block

555-63025

It replaces the entire stock proportioning valve / distribution block with an adjustable unit. You will need to make up the lines from the master to the block and/or use some adapters for the rest. The only downside of this one is you lose the safety shuttle valve that blocks flow to one circuit (front or rear) if there's a big leak. The advantage is I think you can increase proportioning more than you can with aaron's setup.

I have had one on the shelf for a few years that I never ended up installing because I got one of aaron's direct-swap adjustable valves. If anyone is interested feel free to PM me, I'll let it go for cheap. They're almost $100 new.

[This message has been edited by Steven Snyder (edited 02-09-2015).]

Raydar FEB 11, 12:23 AM

quote
Originally posted by doublec4:

I plan on reproducing these. Right now I only have the 84-87 I've made drawings / models for. I'm getting them quoted right now.

I would need one of the 88's so I can do the same.



Cool. I'll keep an eye out for these, when you have them.

And thanks, Steven.
That is an option, but I don't have the capability to fabricate lines. Would like to explore the simpler option first, if it becomes available.


quote
Originally posted by E.Furgal:

is this a stock car,??
weight change(per wheel have car scaled), spring rates, ride height, shock valving, all effect this.. as the stock settings "assume" the way the vehicles weight will be transferred from/to each wheel and how fast that weight moves,
so is the car seeming having to much front bias, from changes that upset the engineered weight transfer that the stock bias was ment for?




It's far from stock, but I have attempted to not do anything that would upset the balance. All changes were... in proportion to one another.
It still was heavily biased towards the front, even before I made any changes, except that the stock Formula rubber was quite hard. I could lock up the fronts even more easily.
Raydar APR 18, 05:59 PM
I think I may have found a source for the 88 combi valves.
Well...three of them, anyway. If it works out, I'll publish the source for the other two.
olejoedad APR 18, 07:07 PM
Dumb question....
Has anyone investigated using a bias valve from a FWD car (pre ABS) on a Fiero?

Maybe there is an off the shelf solution available that we haven't thought of.....
pmbrunelle APR 18, 08:32 PM
Most FWD cars are diagonally split, so they'll have two proportioning valves; one per rear brake. That's probably not what you want for a Fiero, unless you plan on a diagonally split system.

The bigger issue is what junkyard parts are not normally adjustable.

Anything you'll find on Jegs/Summit will be "off-the-shelf", and adjustable, and thus recommended for a homebrew braking system. If I had to guess, I'd guess that the OEMs initially tuned a car with an adjustable valve, and then once they found the right setting, they had a fixed version built. But starting with something fixed strikes me as the wrong way of doing things.

For "cheap" and "off-the-shelf", at the expense of fast tuneability, why not try an assortment of springs to replace the stock spring? For small quantities, I have purchased from:
https://www.centuryspring.com
Raydar APR 19, 03:56 PM

quote
Originally posted by pmbrunelle:

....
For "cheap" and "off-the-shelf", at the expense of fast tuneability, why not try an assortment of springs to replace the stock spring? For small quantities, I have purchased from:
https://www.centuryspring.com



It's not just a matter of tuneability. I have a situation, now, where I think the combination valve is causing problems. When I nail my brakes, the left front wants to lock up long before the others.
I have replaced the lines, rotors, pads and calipers, and bled the system to a fare-thee-well, with exactly zero change.
I thought it might all be my imagination, until I bought another 88, and found that the brakes work much better - and relatively evenly. The combi valve is about all that's left.