shadejo

Clutch fork failure

115 posts in this topic

No need to guess, I have a low-ish mileage clutch arm right here. Now I can see the exact radius of curvature they used in both sockets, it isn't constant.

 

(Don't worry, eventually I'll stop posting shots of 3D scans and CAD files and start posting pics of actual machined parts, but since this is the start, this is what you see first!)

 

More to follow soon on this little fix. Could save all of you quite a bit of time and money fixing your smarties! By the way, if you are thinking of modifying your actuator, please wait!

 

Dave

ClutchArm.JPG

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Yes Dave,

Over time the actuator needs to be adjusted closer to the bellhousing, adding the acorn nut to the end of the actuator shaft moves the actuator outwards away from the engine but there is still room in the slots to accomidate the space required by the nut.

canman

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Tolsen: The cost of the fork is irrelevant in this case because of the cost of labor to change it, and the sad fact the new fork will have the same problems the old fork did. It is not a fix, just a consumable at that point. A consumable that is very time consuming to change.

 

Thanks CANMAN for confirmation of the adjustment. Adding the acorn isn't really a fix either because the problem is primarily the relative motion between the tip of the actuator and the fork itself. What really doesn't help things is how low the hole is for the actuator. If you ever go through a puddle or dusty conditions everything will be introduced to that point and just make the "grinding" even worse. 

 

The other pivot point doesn't see the wear and tear because of how shielded it is, because it has a spring to keep it fully engaged and lastly because it sees quite a bit less angular displacement due to it's location. 

 

Anyway, I spent far too long designing a little replacement tip for the actuator, the profile exactly matches the socket of the clutch arm so you can remove actuator, place tip on actuator, install and the problem is gone for good. The motion and friction is now between the special heat treated and coated insert and the tip of the actuator in a sealed environment with the appropriate grease. The arm only sees the pushing force of the actuator, not the "rubbing" as before:

 

 

 

 

Actuator Insert.JPG

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Socket in clutch fork gets punched through and holed due to owner neglecting to carry out required maintenance.

Applying grease to socket stops corrosion and reduces wear.

Clutch actuator should be preloaded hence there should be no axial play in way of contact between push rod and fork socket.  Any axial play there adds to the woodpecker effect with end result being punch through.

 

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Yes, can be used not matter how bad the fork is, unless you have made something else and totally messed up the fork. The typical hole left by the actuator is not a problem, this is one of the major advantages to the concept. 

 

Worst case: Fork gets hole in it and car is now immobile. Pull actuator, install tip and replace. Other than having to calibrate the actuator, you are good to go, forever (Until something else breaks) 

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Dave,

I would like to order 2 of your new actuator tips.

Please P.M. me with the details so I can E.F.T. Payment.

canman

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Several years ago I modified the actuator with a brass tip and have had no problems since but now I'm thinking that I haven't checked it lately! I am having difficulty following your fix Dave.  How does it still work if the fork becomes punched through?  I didn't see a drawing of your fix only the fork itself.  What am I not understanding about this?

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On 9/29/2016 at 2:44 AM, DesignerDave said:

Yes, can be used not matter how bad the fork is, unless you have made something else and totally messed up the fork. The typical hole left by the actuator is not a problem, this is one of the major advantages to the concept. 

 

Worst case: Fork gets hole in it and car is now immobile. Pull actuator, install tip and replace. Other than having to calibrate the actuator, you are good to go, forever (Until something else breaks) 

How can i buy one of these tips from you? PM me and i can send payment.

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Hello Dave; I need to order 2 or your fork actuator caps, please pm me with details asap.

 

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Little behind on this topic, but this happened to me this morning and I found this thread while on the side of the road. 

After removing the actuator I noticed the rod was stuck through the fork. I use my car as a traveling toolbox for work so I had all manner of bits to work with. I found a flat washer with a smaller inner diameter than the rod, placed it over the open end of a socket and hammered it concave. Placed some grease on the washer and stuck it to the actuator, reinstalled everything and it got me to work. Hopefully I can get home with it.

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should work fine for getting you home

 

i remember brazing a large nut on the end of mine years ago and then using a grinder to give it a smoother shape...worked well and is still in service afik

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What I've done as a preventative measure is to cut m10x1.5 threads on the rod and added a nylon acorn nut (with a dab of lucas red & tacky grease on installation). I haven't put very much mileage on it but so far it shifts fine. Will pull it off to check for wear and tear and if it's too much I have brass acorn nuts for back up. I'm actually looking for the nylon nut to wear and not the fork as the nut is easier to change. I may have to change it frequently but it beats having to change the fork.

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