what MC for hydraulic ebrake?

^^thx for that....only 13" long and 6" of throw with .625? that's a lot.....decision reversed, I should probably get the larger MC.

The ratio is 12-1, 12" handle. 3" pull to lockup on gravel, 4" on tarmac. Thats with VW front calipers on the rear. I don't know the master size. It was $130 new.

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Jon Burke
^^thx for that....only 13" long and 6" of throw with .625? that's a lot.....decision reversed, I should probably get the larger MC.

Well, that 6" was with a reeeeally hard pull, much harder than would be needed on dirt. So travel will typically be 4-5" in this car. The 4-5" pull is upwards from the tunnel rather than horzontal from the dash, which I like because it puts all the force through my rear-end (personal, not axle) and [edit] shoulder harness, and keeps force off of my feet while they are playing on the pedals.

The Starion pull end of the handle is just beyond the shifter in neutral position, so is very reachable.

If you go to the larger 0.7" dia cylinder vs .625, the throw will be 10% shorter at most (<1/2" change) but your pull force required will be 25% higher, as Sean has noted. With the .75% cylinder vs .625", the throw would go down by 15-20%, but force will go up 44%. So, you are on the 'wrong side of the curve' and paying a much higher force-needed-versus-throw-reduction-achieved when you move much off of the .625" cylinder. The 25 lb arm force that Paul cites is a comfortable number, and in the range where you can modulate it well.

And whoever does the math above will say that the numbers do not work that I stated; there should be an inverse % change relationship. But you have to keep in mind that part of the throw is just taking up the slack in the connections and in moving the aux MC piston past the cylinder's input port before ever moving any fluid to the rears; maybe only 1/2 to 2/3 of the throw movement actually results in any fluid moving. So the actual throw distance reduction works out much less than expected by just calculating the inverse of +% change in piston area. Force required, on the other hand, does work out directly as the +% change in piston area.

I would suggest going with what works......just IMO.


Regards,
Mark B.



Edited 2 time(s). Last edit at 04/01/2011 09:53PM by starion887.

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BJosephD

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starion887
0.625

Lever ratio should be large; 11:1 is OK but could be more. If you like, I can measure 1 or 2 here.

Lever length should be long, like 12" or more.....

Mark B.

Meaning the (vertical) lever if built to this spec would have hypothetically the clevis pin 1" above the pivot point at the base. with the lever extending 11" above the clevis point? Do i understand that correctly?

Yes .....maybe. This can be modified by setting the cylinder at an angle relative to the 'rest' and 'pulled' positions of the handle's axis, rather than at approx perpendicular angles like you are probaly imagining. Making a shallow angle between them and not putting the pin for the cylinder's piston shaft directly in the axis of the handle will give more leverage at the expense of more throw, but will make a nicer unit. I need to take a pix of the Starion setup, which was pretty well thought out. (Obviously not by me; I am just the student of other's good engineering!)

And like Pete wisely said, the mounting for all of this needs to be STRONG.

Regards,
Mark B.

John, dunno if this helps any, but I had the .75 that came with my k-sport style handbrake. VERY hard to get any lock. So I put a Wilwood .625 in and that is much much better/easier to have fun with.

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Brap Brap.

With all those things sticking up, how frequently do you go for forth 4th with the e-brake?
(Glad my shifter is right at the rim of the steering wheel where Gawd intended when he designed the Saab.)



Edited 1 time(s). Last edit at 04/03/2011 01:03PM by john vanlandingham.

Well I have one labeled "Rad Handle" (that's the handbrake) and the other labeled "Cog Jammer", I'm getting faster at reading them quickly and deciding which one to use for whatever kind of situation.

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Brap Brap.

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biggreen96
Well I have one labeled "Rad Handle" (that's the handbrake) and the other labeled "Cog Jammer", I'm getting faster at reading them quickly and deciding which one to use for whatever kind of situation.

I gotta brilliant ideer! Absofawkingtoootle-y brilliant idea: you could wire up some LEDs , like red for handbrake cause it stops you --get it,? and some other color for the shifter and duct-tape them to the shifter and hand brake respectively..
All you need now is some duck-tape:

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john vanlandingham
With all those things sticking up, how frequently do you go forth 4th with the e-brake?

I've done e-brake pulls in 4th at Sno*Drift. But that's about it.

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john vanlandingham

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biggreen96
Well I have one labeled "Rad Handle" (that's the handbrake) and the other labeled "Cog Jammer", I'm getting faster at reading them quickly and deciding which one to use for whatever kind of situation.

I gotta brilliant ideer! Absofawkingtoootle-y brilliant idea: you could wire up some LEDs , like red for handbrake cause it stops you --get it,? and some other color for the shifter and duct-tape them to the shifter and hand brake respectively..
All you need now is some duck-tape:

We can rig it up so that the codriver has a couple buttons that will turn on the LEDs so that it takes me completely out of the loop! But instead of duck tape lets use aluminum tape. It's shiny.

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Brap Brap.

alright....fancy hydraulic ebrake parts came in the mail today!

Now I need connectors and shit. There's no instructions/tech sheet with this thing, I guess they assume I know shit.

I don't....so if I want to use -3AN line with this thing, how do I know what the size/threads are in the MC and line prop valve? I have to get d'ap-ters, right? Or is this a standard thing I'm just asking a real rookie question here?

7/16-20 in and 3/8-16 out is usually what most are.
I'd recommend doing -3 to shit. What're those called. Gives lowest profile. Damn brain. Gotta go to watch soccer now.

Banjos!
Way easier to source than finding 7/16-20 tube nuts for 3/16 line. Although if you want to use tube nuts, here is the only place I could find to get 7/16 - 20 tube nuts for 3/16 line: http://store.fedhillusa.com/p263.aspx
But banjos make it more nicer.

Banjos? Did somebody say banjos?

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NoCoast
7/16-20 in and 3/8-16 out is usually what most are.
I'd recommend doing -3 to shit. What're those called. Gives lowest profile. Damn brain. Gotta go to watch soccer now.

which is in and which is out? I would think 'bigger' is out, no?

I had a 3/8-24 connector laying around, and that fit the prop valve fine, and one (input, I assume) of the fittings in the MC.

The other (output?) was a quite a bit bigger.

PHOTO:



smaller one (3/8 - 24) is open, the larger one is plugged. how do I figure out the stupid larger one? is it related to the MC size? (.625?)

the prop valve is small and bolts onto the side, so the line/fitting from the prop valve into the first MC fitting will be tight.


Kind of like this picture, except I'll have to have my on the oppposite side (brake will be mounted on the left/driver side of the tranny tunnel)





Edited 1 time(s). Last edit at 05/16/2011 11:26PM by Jon Burke.