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Where to adjust clutch free play on a mopar?

AR67GTX

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I have a friend with a 69 Hemi Roadrunner 4 speed and another with a 70 440 Challenger 4 speed. They both have this strange (to me) two stage clutch pedal release action. There's an over-center assist spring that I guess is supposed to bring the pedal all the way back to rest - only it usually doesn't on either car. If you ease the clutch out it will just rest at the top to the first stage, about even with the brake pedal (power brakes). If you stick you foot under the pedal and give it a slight nudge, or release the clutch suddenly it will pop all the way up to rest on the pedal bumper stop and well above the brake pedal. So where do you adjust the free play on these? At the top of the last stage in the pedal coming up? Or at the top of the first stage in the pedal coming up? I've only owned GM and Ford 4 speeds so this clutch action is strange to me.

I was helping the guy with the Challenger sort out a few issues on his car and it was grinding on upshifts and downshifts to second. I knew it had nothing to do with this but I adjusted his Hurst shifter linkage (out of alignment) and put some shim washers under the shift rod G-clips to tighten up the linkage. But I was afraid to adjust his clutch as it seemed like his free play was beginning right at the top of the first stage of pedal release and if I tried to reduce free play to be sure he was getting full clutch disengagement and in that strange 2nd stage area where sometimes in pops all the way up and sometimes it doesn't. But he wasn't having any trouble getting into reverse so I figure the clutch is not his problem. Looks like he is going to need a gearbox rebuild as linkage adjustment made zero difference.
 
I just adjusted mine after a parade this last weekend (in-out-in-out-in-out repeat ad nauseum)….

You're not really "adjusting the clutch" - you actually are adjusting the pedal end free play, the
point where the pedal is when clutch actuation begins/ends.
From the Factory Service Manual:
"Adjust fork rod by turning self-locking adjusting nut (Fig. 5) to provide 5/32 inch free
movement at end of fork. This movement will provide prescribed one-inch free play at pedal."
clutch.jpg


In regards to the pedal "sticking", do you know if either car has a diaphragm type clutch (versus the factory
type Borg & Beck)? If so, the over-center spring (heavy spring usually on the pedal under the dash) should
already be disconnected - and the pedal won't necessarily come all the way up when released with those.

I have a B & B style on mine (over-center spring installed as factory) and mine was doing that slight
"sticking" as well, which was easily overcome by my big toe under the pedal lifting up.
Interestingly, once I adjusted the clutch as the FSM says to above, that went away and the pedal comes
all the way up by itself now - and clutch action feels much more PROPER now, even though I didn't quite
bring actuation all the way up to the 1" free play prescribed (more like 1 1/2" - 2").
Gotta be CAREFUL and not over-do the adjustment, or you'll risk closing the gap between throwout bearing
and pressure plate.
 
I've adjusted many a GM and Ford clutch, replaced numerous clutches and rebuilt a few gearboxes but these things have the oddest clutch feel I've run into. I think the RR has a B&B that was rebuilt by a rebuilder - but I'm not 100% sure. Neither I or the current owner knows what the Challenger has - I suspect a diaphragm as it has a real light pedal pressure. I can easily push it with finger tips to the floor.

So it sounds like the point of TO bearing contact with the clutch fingers probably needs to be above the first stage of clutch pedal release and maybe the clutch plate pressure on the bearing helps with pushing the pedal back up past that intermediate point where it otherwise wants to stick. I was kind of hesitant to adjust it for more clutch disengagement in case it continued to hang at that intermediate point and the bearing was still in contact with the clutch fingers unless the pedal was nudged up.

Thanks
 
The throwout bearing clearance from the fingers of the clutch is a "set" thing - it's supposed to be an
independent thing of any linkage connected to it/not connected to it.
It's only supposed to be affected by the components used (clutch and bearing, bellhousing, flywheel).
It doesn't change with pedal adjustment and has its' own minimum and maximum tolerance specifications.
That gap is maintained (when the clutch is in the pedal up/"relaxed" position) by the fork return spring
(refer to pic above), which keeps the clutch fork (and therefore bearing) off the clutch all together when
released (clutch fully engaged).

Any adjustment to the fork rod adjusting nut is to adjust pedal height at point of clutch engagement/
disengagement only.
Once I finally understood all this, I saw the beauty of the engineering. Ma Mopar always did have the
best engineering in those days. :)
 
Don't forget that over center spring works in both directions. If the clutch rod adjustment is set so the spring is not at the point it pulls the pedal up, it's pulling the pedal down. If that be the case you are likely continually running the release bearing on the plate fingers. It can cause undue wear on the bearing and possible clutch slippage.
 
Don't forget that over center spring works in both directions. If the clutch rod adjustment is set so the spring is not at the point it pulls the pedal up, it's pulling the pedal down. If that be the case you are likely continually running the release bearing on the plate fingers. It can cause undue wear on the bearing and possible clutch slippage.
Aye.
Until you get a chance to adjust it properly, just remember to do the toe flick under the pedal to keep it up!
 
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