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location on clutch pedal for hydraulic throw-out pushrod connection?

Started by Dakota, September 01, 2020, 03:21:11 PM

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Dakota

If you have a Hydramax (American Powertrain) or similar hydraulic throw-out bearing, I would appreciate getting any details you can provide (include pictures) of where and how you attached the pushrod to the clutch pedal.   From what I can see under the dash, getting inside the 2" maximum from the pedal pivot point that American Powertrain recommends would be either a really tight squeeze or require some modifications to the pedal to work with the hardware provided.   Thanks.

JonH

Don't have hydromax, but when I did mine I knocked out the existing spud for the stock linkage, and used that spot. Everything I read said to use a pedal ratio of about 6 to 1. That put the connection at about the stock location. Just an FYI, I also had drilled a hole below that spot at first, and could hardly even push the pedal....

Just a caveat here...I have an external cylinder on the clutch fork not a hydraulic throw out bearing. Could make a difference...:dunno:

Chryco Psycho

 :iagree:
Unfortunately I am not familiar with the exact product you are using , pictures would help .
I have set up a number of hydraulic slaves inside the bellhousing & I doubt an external slave would make a significant difference


Dakota

Mine is currently mounted about 3/4" directly below the the stock connection point (as close as I could get without removing the stud or whatever it's called).  My wife was working the clutch while we bled the system.  It took her both feet.   She couldn't drive it that way.  Need to move it.

I'll add some pictures tomorrow. 

Gary

We are using the same set up you are I think.  We are working on a 61 Corvette with an LS and 6 speed.  Just got done mocking up the pedal and we used the stock location for the rod. Haven't mocked up the drive train yet but I don't see why there should be a problem. We have the same pedal ratio as before.  Biggest issue was just revamping the clutch cylinder to mount up to the slanted firewall.

Rich G.


Rich G.



Brads70


Rich G.

Plenty of threads inside. Been like that for years. Not much pedal effort either.

Dakota

Here are some pictures of my clutch pedal and also today's lesson.

There's a reference article on American Powertrain's website which provides more details (I came across this article way too late for me, but hopefully it may help someone else).  It can be found here:

https://americanpowertrain.com/pedal-pusher-how-to-measure-and-adjust-your-clutch-pedal-ratio/

Based on my measurements, the stock clutch configuration has a ratio of 4.5 vs. the 6.0 that American Powertrain recommends for their Hydramax set up.   The math:   12.5" pedal length / 2.75" distance to stud =4.5

My "close should be good enough"  :pullinghair: initial placement for the pushrod mount has a distance of 3.375", which results in a ratio of 3.8.   The math:   12.5/3.375 = 3.8

To hit the 6.0 target ratio for this clutch pedal, the pushrod mount would need to be about 2.1" from the center of the pedal pivot point.   The math:  12.5" pedal length/6.0 target ratio = 2.08"

I think this means I have to add a tab onto the pedal to get the right ratio.   I welcome corrections on this before I warm up the welder.

If it matters, I have a 3 finger clutch.





Chryco Psycho

I would remove the factory pin & move the location as high as possible & try that first . it should be enough , if you are going to be welding anyway you can fill the new hole if it doesn't work


Brads70

Instead of welding on a new tab , couldn't you simply drill a hole  your 2.08" below the fulcrum on the arm?

JonH

Went thru this a while back. As I stated previously I knocked out the original spud and used that hole. I had a hole similar to where you put yours and it took way too much effort to move. I am also using a 3 finger Ram clutch. You will need the over center spring as well to make the pedal comfortable. Should work for you.

Dakota

@Brads70  - there's an offset between the location of the stock stud and the arm.  I don't think it would line up well with the master cylinder for the bearing.

@JonH & @Chryco Psycho - I'll knock out the stud and try it there.  Adding back the over-center spring was the piece I was missing to make it work.   I'm not too worried about me working with a heavier clutch but it's got to be OK for my wife too. 

Thanks much for the comments. 

Dakota

I tried connecting the pushrod for the hydraulic bearing's master cylinder to the stock location.   With the over-center spring also installed, I could handle the clutch but my wife couldn't.   After looking at several options that all involved adding a bracket of some sort to the pedal, I ended up relocating the "arm" of the clutch pedal as shown in the pictures below.   This moved the stock mounting location to 2-1/8" from the pedal pivot which hits the 6:1 ratio with the pedal length as recommended by American Powertrain.  The reason the arm is "tipped" is to keep the mounting point for the over-center spring in its original position (the high tech pencil drawing in the background was my guide).   There was some minor clearance work that had to be done on the clutch/brake pedal bracket to keep things from rubbing, but otherwise it has worked well and easy.

One other note:  the shoulder bolt that comes with the Hyrdramax system is 5/16" diameter, which is just slightly smaller than the pin that's attached to the pedal for the stock clutch pushrod.   Just as I finished drilling the hole, the remnants of the stock pin popped out which left a hole a little too large for the shoulder bolt.   I had to weld the hole up and re-drill it. 

The bare metal on the first picture shows where the arm was originally located.   The 2nd picture just shows the pedal painted.   It's not perfect in appearance, but now it works.

The clutch pedal no longer reaches the rubber bumper in the pedal bracket, but it's not needed with the Hydramax anyways.   As an added bonus, the brake and clutch pedals are lined up now - that offset always bugged me.