Opinions/Options on Clutch Linkage Redesign

[Cazenave26]

Based upon year's of experience I know many of us with the mechanical clutch linkage have enjoyed tremendous reliability of the bell crank design that fails in just about every conceivable situation: Turning, turning at speed, chassis flexed, chassis not flexed, in town, on the highway, in low gear, in high gear, in 2wd, in 4wd. Most folks become experts and throwing the thing together again. I for many years carried a complete set of parts in the Jeep. Heim joint upgrades still don't fix the bell crank and a hydraulic conversion trades a certain mechanical failure with almost equally certain hydraulic failure, which can't be easily reassembled.

I found a guy that had modified the bell crank as I had built and show in the attached image. The redesign eliminated the pin for a machined shaft that bolts through the brackets and goes through the bell crank. Unfortunately, the flexing of the frame binds this system resulting in the entire unit rotating on the ends, not the bell crank around the shaft. I need to try something else. I'm okay with rotation on the end, but I'm not sure bearing mounted where the pins used to be for a rotating shaft to pass through, but frame flexing is an issue. I could replace the pins with Heim joints for the shaft to pass through, but they're not designed to have something rotating inside of them. I guess I could put Teflon bushings on the shafts passing through the Heim joints. It's all in the image. Anyone have any other ideas?

 

[Hedgehog]

I've been considering something similar using Heim joints removing the attachment point on the engine/transmission and going with the frame as the point for the bell crank.

 

[Cazenave26]

I thought about that too, mounting a bracket to the frame and eliminating the connection to the transmission housing, but I was worried about the bracket being in the way of the action to actuate the clutch.

 

[Torxhead]

I think the heim joints are a good plan to help with wear at that location. From what I have seen, the bellcrank should be perpendicular to the frame. I have seen them get offset by engine changes and worn out motor mounts. This seems to put too much load on the outer bellcrank mount and will cause it to break.

 

[Hedgehog]

Caz - Good point, but that could be worked around. For instance a dip in the bracket to allow the arm/lever to rotate through. Or have the base bracket rotate 90* at the engine side. Not as neat as it might be, but doable.

Torx - Isolating the belcrank completely away from the rotation of the engine would eliminate the issues you bring up. I'm not sure if the frame to drive train orientation would move enough to pop the linkage out of the clutch fork or not. It seems doable, maybe yes, maybe no. It would be fun to try and work out the problems.

 

[Cazenave26]

I think I'm going to go to the machine shop and see if the guys have any other ideas.

If not, I think that if the Heim joints are used you can keep the current frame to transmission bell housing mounts. If they cut and weld some moly tube to the mounts tabs, these could serve as the mount location for the Heim joints. I'm still a little worried about so much rotation in the joint, but Teflon should cover alleviate some of the rotation force allowing the joints to simply defect with the change in geometry between the two mount points. On the outside I have this thing drawn with an outer urethane bushing and a lock nut on the outsides. I think that a few Teflon washers would actual be better than bushings to allow the single piece bell crank to turn without working the nuts off the end. Teflon would eliminate the need for any lubrication.

A lot of the design challenge is driven by the binding that happens during driving. I just couldn't continue to drive around with the original design which essentially held everything in place with two paper clips.

 

[Cazenave26]

As I think about it, the Heim joints might allow for a slightly more robust outer diameter on the one-piece bellcrank.

 

[BusaDave9]

It may work out great but I went with a company that has a bolt on solution.
Rugged Ridge 16919.30 Heavy Duty Clutch Linkage Kit, 76-86 Jeep CJ Models

 

[hdgapeach]

Not trying to be the “glass half empty” guy, but I’d be worried about shearing the threaded ends of the solid shaft. You didn’t show a proposed diameter of those stud ends. I don’t know the force numbers exerted on the mechanism by the clutch fingers. I do know it’s enough force to pop the mounting bracket off the firewall. That has happened to me once on my first CJ5, back in the 80’s. I had to drill through the firewall and through bolt the bracket with a wide backing plate to stiffen up the area. My troubles were created by me by installing a body lift and NOT correcting the bell crank angle in relation to the frame.

A lot of engineering went into the design of the original design and has worked pretty well (IMHO) considering how old these rigs are. I don’t like the issues with the system either, especially when you perform modifications to the vehicles like we do. Anything that alters the perpendicular orientation of the bell crank will cause additional stress to the system (ie; body lift, drop skid plate spacers). Any mods that alter the position of the bell crank creates a need to remedy that angle. I had to fabricate a drop bracket for the firewall when I installed a 1” body lift to correct the induced angle on the CJ5 I have now. Along with that modification, I added an adjustable length clutch rod.

I believe many of the issues are brought on by us not performing needed maintenance on the stock setup. There’s a reason the original hollow tube has a grease fitting. Along with that comes the need to clean that system every now and then, replace worn parts and re-grease with new lube. The bushings eventually wear and need replacing. I’ve never had to replace the “paper clips”. The only job for those clips is to keep the bushing studs from coming out of the tube. There isn’t a whole lot of stress exerted on those clips until you modify the system and create the stress by not correcting induced bell crank angles.

You figure out how to make a system using grease-able tie rod ends on each end of the bell crank, I think you’d be headed in the right direction! Until then, either the system BusaDave9 uses, or a hydraulic clutch, is the way to go. I installed the same system BusaDave9 did and have had no problems (so far, after correcting the bell crank angle).

Good luck, and I admire your thinking on this. And apologies for the "dissertation"!

 

[Lumpy Grits]

It may work out great but I went with a company that has a bolt on solution.
Rugged Ridge 16919.30 Heavy Duty Clutch Linkage Kit, 76-86 Jeep CJ Models

Go with this kit.
I've used one since they first came out. I was selected as a field tester for this it, and still use it today.
LG

 

[Lumpy Grits]

Not trying to be the “glass half empty” guy, but I’d be worried about shearing the threaded ends of the solid shaft. You didn’t show a proposed diameter of those stud ends. I don’t know the force numbers exerted on the mechanism by the clutch fingers. I do know it’s enough force to pop the mounting bracket off the firewall. That has happened to me once on my first CJ5, back in the 80’s. I had to drill through the firewall and through bolt the bracket with a wide backing plate to stiffen up the area. My troubles were created by me by installing a body lift and NOT correcting the bell crank angle in relation to the frame.

A lot of engineering went into the design of the original design and has worked pretty well (IMHO) considering how old these rigs are. I don’t like the issues with the system either, especially when you perform modifications to the vehicles like we do. Anything that alters the perpendicular orientation of the bell crank will cause additional stress to the system (ie; body lift, drop skid plate spacers). Any mods that alter the position of the bell crank creates a need to remedy that angle. I had to fabricate a drop bracket for the firewall when I installed a 1” body lift to correct the induced angle on the CJ5 I have now. Along with that modification, I added an adjustable length clutch rod.

I believe many of the issues are brought on by us not performing needed maintenance on the stock setup. There’s a reason the original hollow tube has a grease fitting. Along with that comes the need to clean that system every now and then, replace worn parts and re-grease with new lube. The bushings eventually wear and need replacing. I’ve never had to replace the “paper clips”. The only job for those clips is to keep the bushing studs from coming out of the tube. There isn’t a whole lot of stress exerted on those clips until you modify the system and create the stress by not correcting induced bell crank angles.

You figure out how to make a system using grease-able tie rod ends on each end of the bell crank, I think you’d be headed in the right direction! Until then, either the system BusaDave9 uses, or a hydraulic clutch, is the way to go. I installed the same system BusaDave9 did and have had no problems (so far, after correcting the bell crank angle).

Good luck, and I admire your thinking on this. And apologies for the "dissertation"!

The OEM clutch linkage was designed by AMC 'bean-counters'. Made as cheap as could be from inferior steel that was soft and wore quickly. Would wear even faster when the pivot points became coated with desert dirt.
On the bellcrank. I lathe turned a full tube length silicon bronze bushing to replace the 2 nylon/plastic OEM bushings.
LG

 

[hdgapeach]

That's why I said "worked pretty well considering...". It's amazing the complicated design and price point materials work and last as long as they do. And you can make the original stuff last quite a bit longer if you do some hands on preventative maintenance every now and then.

I can only imagine how the sand blasting in the desert quickly erodes the metal. I'm only familiar with the swamp mud and clay over here in the south east!

Biggest wear location on my rig was the pedal rod where it attaches to the bell crank. The end was worn over half way through when I switched over to the heim setup. That would've been a good place for AMC to spend another dollar or two.

Can't complain too much, though. The original lasted since '76!

 

[Lumpy Grits]

Same major wear point on mine. Mine almost wore through in 3 yrs. I play in the sand a lot.
I swear, the whole OEM assembly was made from mild hot-roll steel.
LG

 

[w7geejeep]

My 78 CJ5 has a chain setup and it has a 5.0 ford motor when I leveled the motor in the frame it won't release the clutch the rod attached to the pedal bends a lot and it's very hard to push , result no clutch at all! Any ideas on the best and least expensive hydraulic assembly? Please!

 

[Turbogus]

A BIG X2, that kit is the bomb!

 

[Turbogus]

A BIG X2 on that kit, it is rock solid!