Packaging and heavy clutch wouldn't allow me to run mechanical linkage so I used master and slave cylinders with a standard TOB. I bled the cylinders but it takes a significant amount of pedal movement to begin clutch disengagement (maybe 3" out of 7" total travel". The clutch fully engages re-engages about halfway up on pedal release. I'd like re-engagement to be closer to the top of pedal travel. Check out this video and let me know what you think is going. on: https://www.facebook.com/brian.fulw...ZLu5i6AomrmTdKkXLhofBdvpCi2R3Vzk3MhVZD1H2biFl Specs Wilwood 7/8 bore master, Speedway 7/8 bore slave, both with 1.25" travel. Upper pedal length is 9", lower is 1.4", ratio is 6.4:1. total upper pedal travel is 7" Clutch fork and pedals both have return springs Slave pushrod has little slack and is almost snug I started with a little slack on the master pushrod and have adjusted it from 1/2 to 2 turns tighter but it didn't have much affect on the release/apply point
In the video it looks like the pedal return spring is actually unseating the push rod in the master cylinder. However your description sounds about right for where in the pedal stroke things should happen you don’t want the release bearing under load and you don’t want to over extend the clutch.
Are you getting full stroke on the master cylinder? If not you need a longer arm from the pedal going to the rod that works the master cylinder.
I don't think it's unseating since I have the rod adjusted 1 turn longer than snug with pedal fully released - unless the cylinder piston is dragging. I may have to remove the boot to investigate.
I'll have to measure it but the clutch works fine on the road. It's just that re-engagement before the pedal is up that's getting me. I have a pedal stop for the fully released position. I set the adjustable rod length by turning it close to snug and then past snug so the rod length should be close. It makes me wonder if something funky isn't going on with the first bit of master cylinder piston travel.
Does that mean you’ve removed the free play from the pedal to MC? If so that’s going to cause you issues such as not releasing the clutch at some point. It could also cause your issue I think as you’ve now got a closed system so the slave can not return to a natural rest point.
That clutch fork is designed to use a return spring in that outside hole. That won't help the pedal travel point at release thing but will keep the contact between pushrod and fork tight and pull the release bearing back off the clutch. It doesn't have to be a very stout spring though. As long as you are getting the stroke you need pushing the piston in the master cylinder to actuate the slave and have the clutch release right and then have the necessary clearance between release bearing and clutch fingers static it is probably more about pedal ratio. Somewhere in the Wildwood archives there is probably mention of the pedal ratio it works best with.
When you watch the video look at the master cylinder pushrod, when the pedal is almost fully released it seems to me to have a funny vertical movement, that’s why I thought it maybe getting pulled away from the master cylinder.
I removed freeplay as a test. It didn't make much difference so I'll adjust back to nearly snug. Agree that you don't want pressure on the clutch fingers with pedal at rest.
It has a return spring now but it didn't when I shot the video. I'll have to look up what Wilwood recommends on ratio but this one feels right on stroke and effort.
The magic number for a master bore with a 7/8" slave is 3/4". Also, how much movement do you have at the fork? Mine is close to 1", you will never use all of the 1.25" of the reported slave travel. Look for any slop in the linkage, etc. That eats up travel potential.
Is the slot in the clevis bottoming out against the pivoting arm when released? Are you just wanting to change the engagement/disengagement location, or do you feel you simply have too much overall pedal travel?
The clutch fork is moving right at 3/4". Nearly all the slop is out. I guess I'm just expecting the hydraulics to start and finish working nearer to the top of pedal travel. You now, kinda like mechanical linkage
There's 1/8" or more of clearance between the lower arm and the clevis. Typical clutch design is 1"pedal freeplay at the top of travel. That's what I'd like: begin disengagement at 1" pedal deflection and end re-engagement at the same spot. That's all occurring around 2"+. https://www.facebook.com/video.php?v=2168405116826766
Mine works great, we tried to get fancy with making a lot of parts that did not work. Finally once the close to 1" travel at the fork was achieved, I was very happy with it. Initially I moved the pedal pivot down lower out of convenience to the plate I made up (that holds the brake and clutch masters). Well... that needed 2 people to push the pedal. I moved it up to the stock location, made up a new plate. I'm thinking, do you have any flex at the firewall? That can eat up travel.
I think if you extended the pivoting arm enough to move the pivot hole maybe 1/2" further from the pivot axis, it would bring you closer to your goal. That would probably mean lowering the master cylinder 1/2" as well. If you have the tools to make another of the pivoting brackets, you could just swap them and see just how much difference it made.
Yep, a 1/2" longer lower arm would decrease pedal travel by about 3/4" and would increase pedal force from 30 lbs to 40 lbs. Or I could shorten the upper pedal to achieve the same effect.
I don’t know if it would make a difference, but I think that the clutch fork is not at the right angle, or you are using the wrong throw out bearing. The fork should be more toward the front of the engine, by using a longer throw out bearing the fork would be more toward the front of the vehicle. I am talking about the piece that the bearing is pressed on to I think it is called the sleeve. I also think you can change the pivot ball that screws into the bell housing. Thanks Ron.
I cant really see it well in your videos but is the fork back from center at rest? Is the throw out bearing short or do you need and adjustable pivot to give it more mechanical advantage? Edit .. I just read Rons Post I think thats the problem.
I cut an inch off the tops of the brake and clutch pedals. They are the same height. It seems to be a decent compromise between stroke and pedal effort.
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