Ottawa Fiero Club Forum

I designed an add-on to make the proportioning part of the combination valve adjustable.

I’m wondering how many people would be interested in one.  It’s fairly simple design so it shouldn’t cost much to have made.  I'm re-using the spring and rubber seals, so I’m thinking somewhere around $50.  I’ll have a better idea after I test the prototype to see if it needs a re-design.

I’m not going to eat the cost of having them made since I’m not going to mark up the price, so don’t answer unless you are absolutely sure of your answer.

If all goes well I may make them available for general sale.


Aaron

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What will be adjustable--the "delay" in rear brake application when one mashes the pedal quickly, the overall front/rear balance, or both?

The adjustability is for the front to rear bias.  Assuming that you will be increasing the rear bias the delay would be reduced (slightly) to the rear brakes (increasing the controllability while braking into corners).  This used in conjunction with a 2 lb residual brake pressure valve (Willwood) would be ideal for autocross and overall control.

However I don't personally plan on using a residual pressure valve.

Aaron

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UPDATE  xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Reducing the delay timing on the rear brakes, which is about a tenth of a second due to the extra passages and length of line is much too complicated to achieve inside the desired sail price.  So that issue has not been addressed.

Alternately you could use a residual pressure valve in line with the rear line after the proportioning valve.  This would decrease the rear brake piston travel, thereby achieving the desired result.

Aaron

Sounds good!  I would be interested in one.

What ^^^ said.

I suppose this thread should be in mods?

Here is a preview.

I can't seem to find that motor trend video that showed all the model years and more importantly the stoping distance for the 88 model. 128' I think and from some speed, I can't remember.

anyone?...anyone?....Bueller?...Bueller?

Bueller?.....Bueller?....Bueller?

update

Tested and working!

Constructing second prototype.

88 and pre-88 are different springs and spring rates.

But of course!

BTW I think we have two or three of the pre-88 combination valves if you need one for any reason.

Couldn't hurt to check them for tolerancing.  No rush though.

Aaron

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Managed to dig up three of them, each with a different casting number FWIW.

Pick a time & place....

Sweet...

Probably lot numbers (casting run numbers) so they know which ones to chuck if there's a bad run.

I'm in the middle of a move right now, I'll be at it for just over a week to come (painting and all that other stuff).  But I do think I can manage to get over to see Kitten at work this week if that's not too much to ask?

Aaron

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No problem at all.  She has them with her as of this morning.

Sorry about the delay!  I have been a little more busy than I had originally anticipated.

Aaron

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No prob, they're still waiting for you.  Just give us a day's warning before you want to pick them up.

They're in the back o f the Beetle at the moment and ifyou happen to drop by on a day we take the bikes to work, they'll be where you are not.  :)

Poke poke poke...  Aaron, how are you making out with these things?

We're probably going to install the "Zettner" brakes on the 84 some time this season; would be nice to be able to fine-tune the bias.

Everything was done last year.  New prototype installed and working fantastic.

Unfortunately I haven't had any access to tools to make any more.

I might be able to work something out with a friend of mine if need be.  In my opinion it works so well that everyone with a Fiero shold get one even just to adjust the old weakened factory spring.

Best value brake upgrade for anyone that knows what they are doing.

Most dangerous brake upgrade for all those that don't know what they are doing (still worth it though).


Aaron

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My favourite category.   ;)

I will be making 6 adapters a week from now.  If someone want's one, please measure the nut on the rear of your combination valve (19mm or 21mm?).

Also, I would like to test the operation of this valve on a car (84-87) that has a large front brake upgrade combined with stock rear brakes and rotors.  The voluteer must be in resonable driving range of me, have time for and be willing to allow testing.  This volunteer will also receive a free valve (go figure).

Aaron

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Aaron,

I'll take one, (19 mm).

Let me know when available.

Gord

We're in for two.  I'll measure the valves tomorrow and let you know the nut sizes.


I'll quite happily be your guinea pig, assuming that no one else has stepped forward yet.

Done.

I'll be gone till latter in the week.

P.S. By the way everyone.  The 19mm nut allows adjustment of the rear brakes to higher pressures.  More on that latter.

Aaron

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One of each, please.  Both cars currently have valves with 21mm nuts, but one of our spares is a 19mm.  Give me a shout when you're back & ready to test, and I'm all yours.

Put me down for one as well.  I'll have to get you the nut size later though...

If anyone is wondering what the delay is...I'm waiting for the o-rings to come in.  Because of the fluid in the braking system rubber o-rings can't be used, and there seems to be a delay on my EPDM order.

Thanks for waiting.

Aaron

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O-rings are in!

Your lab rat is ready when you are.   ;)

I have posted an installation video on youtube.

http://www.youtube.com/watch?v=HdkKM9o9b9k


Regards,

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