MAYDAY!- Clutch Pedal Flopping, No Disengage

[FireFighterHill]

 

[70deuce]

Did you post pictures?

 

[USAFSS-ColdWarrior]

Pics added.... It was a "human error"... past my bedtime.

 

[EMD567]

I would still pull the plate off the bell housing, and look at the clutch. That is a pretty robust rod, and it snapped for a reason.

 

[USAFSS-ColdWarrior]

I would still pull the plate off the bell housing, and look at the clutch. That is a pretty robust rod, and it snapped for a reason.

Agreed, and in the plans.

At this point, I KNOW I will at least need to replace the rod.

Realizing the force(s) required to snap such a rod (1/2" Diameter??) I guess I can LEG-PRESS quite heavily for an old fart.

It appears to be a very clean, straight and FRESH break. I have no real idea of how it broke. There was NO change in clutch pedal resistance at all prior to the failure. If the fracture was gradual, and worsened with repeated "flexing", then I might suspect a misalignment or one of the pivoting ends might be binding.... I'll be looking into that as I disassemble the linkage and inspect inside the bell housing.

Preliminary findings are a relief. We definitely have found a failure OUTSIDE the bell housing.... just need to confirm it wasn't caused by a problem INSIDE.

 

[Atomic]

I had a simular issue happen whe I was ABOUT to drive a used oil truck (Ford L9000). Pressed on the clucth pedal and snap. Set me back on the route 3 days or more to the point a week and half of catching up. It wasn't high up on Penske's to do list.

Also had a clutch pedal rotate while doing 65mph comming off the interstate in a fully ladden oily/water tanker (Peterbuilt 37. The rotaion caused it to bind up and I couldn't depress it. Talk about your pucker factor. Luckily there were no cars around and I had enough room to brake (down shift fanatic) and rip it out of gear. Glad I had my multi tool to fix it.

Good luck with it and your optimism is fantastic!

 

[doghead]

Wow, hopefully that is your only issue! (I would have lost that bet)

As a temporary fix, you might consider laying a bolt(with the correct thread) on top or below the rod and weld it together. At least then you can immediately continue to determine if the broken rod is the problem or the result of a problem.

I'm glad it looks like a simple fix!

 

[DieselBob]

Well there's your problem I was wondering if you had been able to determine what had happened. I would not have guessed that. Now to determine what caused the failure. Binding lever shaft. Binding throwout on input shaft bearing cap. Or just 40 years of stress on the rod.

 

[rlwm211]

It was that speed shift from 4th to 5th that took out the relay rod for the clutch I am sure....



RL (Tongue firmly planted in my cheek)

 

[gringeltaube]

................... Now to determine what caused the failure................

Looking at the pics.... : besides having replaced the original clevis pin with a common 1/2" hex bolt which came out to short for a nylock nut...., it also looks like it was overtightened, that way compressing the rod's clevis and restricting lateral (horizontal) movement. The resulting binding does cause fatigue to the rod to the point where it may finally break in two. Not clear if the counternut was in place and had fallen off after breakage.

In any case, with this kind of linkage running between something fixed to the frame (pedal lever shaft/ support) and the engine/transmission assy. moving around, it is always better to have to much play than to little. If the original pin had to be replaced it would be safer to use a straight headed pin W/ cotter pin instead, IMHO.

G.

 

[USAFSS-ColdWarrior]

Looking at the pics.... : besides having replaced the original clevis pin with a common 1/2" hex bolt which came out to short for a nylock nut...., it also looks like it was overtightened, that way compressing the rod's clevis and restricting lateral (horizontal) movement. The resulting binding does cause fatigue to the rod to the point where it may finally break in two. Not clear if the counternut was in place and had fallen off after breakage.

In any case, with this kind of linkage running between something fixed to the frame (pedal lever shaft/ support) and the engine/transmission assy. moving around, it is always better to have to much play than to little. If the original pin had to be replaced it would be safer to use a straight headed pin W/ cotter pin instead, IMHO.

G.

Your thoughts on the cause of the failure seems right on. ....

I hadn't tried to wiggle anything as of last night's photo posting, but pondered the pics all night.

I'd noticed that while the rod had "dropped" upon separation, the yoke on the other end was still sticking out horizontally, it was NOT "flopping" downward like a LIMP DUCK.

Today, I slid back under the deuce and grabbed the short end.... it took considerable force to pull it down. The rotational friction factor was far more than a clevis pin would have permitted.... Hence, I believe we have found the culprit for the linkage rod failure. The mechanical advantage through the clutch pedal made that additional friction unnoticable.

I haven't yet loosened that jerry-rigged and overtightened bolt to see if the yoke will "unbind" from it's mating clutch lever. But I was able to actuate the throw-out / clutch disengagement with a little help from a short cheater bar for some leverage. Looks like the clutch internals are OK.

It is presently 105.1 degrees F outside.... I'm waiting for more favorable outdoor temeratures to continue this exercise.

 

[rlwm211]

I appreciate the follow up on this. I have replaced the pin that was in my linkage with a bolt and nylock nut. I did not overtighten the bolt however. I have been to that dance before and did not like how it ended up, although never as drastically as it did for you.

Then again, 105 degrees outside....maybe it failed due to "THERMAL STRESS"??????

RL

 

[USAFSS-ColdWarrior]

Then again, 105 degrees outside....maybe it failed due to "THERMAL STRESS"??????

LOL I suppose there could have been a thermal factor involved if we were to delve into the deepest of forensic studies on this particular failure.

Just for the record, at the time of the failure, as best I recall, it was a cooler afternoon than today... I'd say it was only 98-100F when the pedal hit the floor.

 

[Maverick1701]

glad to hear it wasnt anything too major.
They are saying triple digits for us west-texas-ites all week...woohoo!!!