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Remote vacuum brake booster for a hydraulic clutch???

13K views 22 replies 13 participants last post by  elcam84 
#1 ·
I've been wrestling with my clutch for a while now. My knee is getting more sensitive to clutching these days. I need to lighten the clutch or my day is coming. I stumbled onto these remote brake boosters that can be installed anywhere on the car.


There are kits made from these - they are used in some english cars and Australian Holdens and Fairlanes. Seems simple enough to plumb in, it has its own slave cylinder so it is activated by the mastercylinder and adds boost so you plumb it in series e.g. master out to booster in - booster out to clutch slave in my case...

I posted on the Group Two Facebook as there are lots of Ausies on that page.

Thoughts???
 
#2 ·
In the process of putting my 69 Coupe back together I used a Modern Driveline hydraulic clutch system. I fabbed a bracket out of sheet metal & mounted it & the reservoir to the lip/seam of the cowl & the firewall just to the side of the hood hinge above the power brake booster.
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#3 ·
Do you have a hydraulic clutch now? One good thing about hydraulic systems is that you can tailor the clutch action to your personal preference by using a larger or small master. A small difference in master cylinder diameter cam make a world of difference.
 
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#12 ·
Do you have a hydraulic clutch now? One good thing about hydraulic systems is that you can tailor the clutch action to your personal preference by using a larger or small master. A small difference in master cylinder diameter cam make a world of difference.
I started out with a 3/4" master and 1" Slave, dropped to a 5/8" master and the pedal got easier. The issue is that its hard to get much more than 1.4" stroke on the master so going smaller won't disengage the clutch fully

Sorry, I forgot to mention the clutch. I have a Centerforce clutch with the little weights on it. So this probably goes towards a light pedal feel as well. The only thing I don't like about the clutch is the little weights can rattle slightly at idle. As soon as you dab the throttle, it stops. The rattling was louder when the clutch was new, and it seems to have quietened down somewhat after about 1000 miles.
Yes, Centerforce is a trade off. A heavy clutch adds rotational mass which slows acceleration of the motor, the opposite of a lightweight flywheel. So I don't use Centerforce.

Something like this? Centerforce Dual Friction Clutch Kits DF920830 I put this in last winter and it works awesome with as light of a pedal as the MDL "huge failure" King Cobra clutch kit but without the slip. The downside is the Centerforce setup is 5 pounds I think heavier than most performance clutch/pressure plate setups. I did an aluminum flywheel at the same time so I still lost some weight overall. I have the MDL hydro clutch setup that I could never work well or completely disengage without plastering the pedal to the floor regardless of clutch pressure plate setup. What finally made my happy was eventually working my way up to a 0.81 master cylinder and going from the MDL -4 line to a -3 line as recommended by Wilwood. Works like it should now.
Interesting, is -4 larger or smaller than -3? I wonder how I can tell which one I have? Do you have teh MDL Rube goldberg setup?
 
#4 ·
I have this type of hydraulic clutch. The pedal effort is so light you can press it with your hand with ease. This is used with an external slave cylinder. And I have joint problems as well and I need a light clutch to make driving my car enjoyable. The only thing I changed was the fluid reservoir which I did not like and I used something different.

 
#6 ·
The MDL hydraulic clutch conversion is really nice, however the actual pressure plat and clutch design is a real game changer. I have a high torque rated clutch in my diesel land cruiser (hydraulic clutch system) and its really light compared to a mate who has a different Brand unit rated to a similar level. Only difference is the brand and design.
So its worth talking to a clutch specialist about what will deliver what you need.
 
#11 ·
Thoughts???
Looks a lot like the remote brake booster in a Tiger. I'd be concerned that it would be too much boost and not enough pedal feel.
FWIW, my pedal is really easy with an 11" diaphragm clutch (MDL) and a full bearing Z-bar system.
 
#15 ·
When I build mine I plan to weld a bracket to the side of the clutch pedal pushing the pushrod location out to wherever in the engine bay allows optimal placement of the clutch master cylinder. The modern driveline firewall bellcrank demonstrates how you use the bellcrank to change the length and angle of the pushrod throw(though in that picture it looks like the pushrod angle is very poor). Anyway, building a bracket to attach to the side of your clutch pedal(by welding or bolting...preferably welding) will allow you to position the slave cylinder so it clears any brake booster....of course if your car was a manual to begin with then you have an open clutch linkage hole to plug and re-drill. There are other ways to solve it as well:



These guys solved it with an angled mounting bracket that I will bet clears a power booster just fine, though I am not sure how their pushrod angle ended up. The first thing to realize is that there a TON of different master cylinders out there...many of them that are of sufficient diameter to do what you want. The first thing to do is find one that is shaped to your advantage(for example, the one above is a poor choice because the mounting holes are vertically oriented....it would be far more ideal to find one with a diagonal mounting pattern, upper right lower left to provide maximum booster clearance)



this one as an example is for a late model Camaro or Corvette and the shape is pretty close to ideal for maximum clearance...the push rod angle looks pretty extreme...but that can be solved with an appropriate bell-crank



This is a firewall bracket for a Holden Torana....these are all solutions designed to get you thinking more about master cylinder mounting as a solution to the problem as opposed to a remote power booster...which just seems impractical and probably not the prettiest thing. There are also other options such as hydroboost if you are running conventional hydraulic power steering...or even electric power brake setups meant for hot rods.

P.S. Another advantage to an angle master cylinder is that it reduces pressure on the weakest plane of the firewall, so less reinforcement is needed(though I am sure some is still required.)
 
#16 ·


Yet another solution...mounting the cylinder under-dash and using a remote resevoir to fill it. In this case, he uses a bell-crank to reverse the direction of the throw. You could also use the bell crank to change the throw 90 degrees instead of 180....or even 2 bell cranks to change 90 degrees, then back the original direction...allowing engine bay placement of the master cylinder under the hood hinge.
 
#18 ·
Yet another solution...mounting the cylinder under-dash and using a remote resevoir to fill it. In this case, he uses a bell-crank to reverse the direction of the throw. You could also use the bell crank to change the throw 90 degrees instead of 180....or even 2 bell cranks to change 90 degrees, then back the original direction...allowing engine bay placement of the master cylinder under the hood hinge.
So I'm actually thinking of using a small remote booster for the clutch, not the brake. Its a cool design that can be put anywhere the hydraulic lines can reach, it senses input and uses the vacuum to boost the output remote from the slave. They use them on small English and Ausi cars, don't see them on american cars.
 
#17 ·
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#19 ·
One of the things I've never cared for about power assisted brakes is that it is more difficult to modulate them as precisely as I sometimes would like. Or at least it is to me. I have a feeling I would NOT like a power assisted clutch pedal. At the least I suspect it would have a tendency to be an on/off switch. But I don't actually know, you're clearing a brand new path here as far as I am aware.
 
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