Author Topic: Clutch grind (reverse)  (Read 4275 times)

camaroman1969

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Clutch grind (reverse)
« on: July 14, 2012, 02:44:43 AM »
Hi Guys!  I own a 1969 Camaro SS 396/375 car with a 4-speed M-22.  Just finished a frame off restoration on it.  Ever since I statrted
driving it, when I try and use reverse, it grinds.  Adjusted clutch numerous times.  Last move is at 1/2' to 1' free play on pedal.  It also appears that when car get hot, grinding seems more apparent.   It's fine when car is cold.  Any advise would be helpful.
Don

bertfam

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Re: Clutch grind (reverse)
« Reply #1 on: July 14, 2012, 03:07:16 AM »
I'm assuming you mean it grinds when you try to shift into reverse. That's actually normal if you don't follow the "rules" (check out your owners manual for the procedure on shifing into reverse).

Note that reverse doesn't have a syncro, so you have to come to a complete stop before you can shift into reverse. It also helps if you momentarily engage a forward gear first, then go into reverse.

What weight gear oil did you put in there?

Ed
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BULLITT65

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Re: Clutch grind (reverse)
« Reply #2 on: July 14, 2012, 05:11:16 AM »
you may want to post this in the topic of "maintenance", you may get more responses that will help you out.
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JohnZ

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Re: Clutch grind (reverse)
« Reply #3 on: July 14, 2012, 02:45:22 PM »
Adjusted clutch numerous times.  Last move is at 1/2' to 1' free play on pedal. 

That's not adequate pedal free play; spec is 1-1/4" +/- 1/4".  As Ed noted, reverse is a plain spur gear with no synchro, and unless you push in the clutch and let the trans spin down or select a forward gear first, you'll get a clash going into reverse.
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mopar346

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Re: Clutch grind (reverse)
« Reply #4 on: July 14, 2012, 03:07:06 PM »
Reverse is not synchronized as mentioned if it is allowed to stay at idle in neutral the rolling resistance of the tranny will cause the gears to begin to tumble or spin even though they are not engaged. A synchro is nothing but a brake that allow the gear and the engagement/lock hub/collar to achieve the same speed. In order to stop this tumbling you need to place it in a forward synchroed gear first to stop everything and then shift smoothly and directly into reverse. As mentioned you cant shift into reverse while rolling. I think the play the adjustment is pretty close to right although and 1.25 wouldn't be bad either. The main thing is you have to make sure your throwout bearing is not in contact with the fingers of the pressure plate or you will eat up a bearing in short order. I tend to set the adjustment on the tighter side so I don't have to adjust it as often, again I make sure the throw bearing is free of the fingers.

I agree with the others though, sounds like normal operation if you are not stopping the tranny first. The reason it is better cold is the gear oil in thicker and works are a brake not allowing the gears to tumble as fast.

Hope this helps.

Mike S

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Re: Clutch grind (reverse)
« Reply #5 on: July 14, 2012, 03:50:17 PM »
 I use the forward first then shift into reverse method all the time especially in colder months.

   When I set the adjustment rod I do it with the return spring off and rock the bellhousing arm back and forth until I can hear a 'tap' which is the sound of the throwout bearing hitting the pressure plate fingers.
That way I know for sure there is some free play and no contact of the throwout bearing/pressure plate fingers under normal operation. This manual feel works for me instead of adjusting for pedal play which has led to premature throwout failure prior.

Mike
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L78 steve

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Re: Clutch grind (reverse)
« Reply #6 on: July 17, 2012, 05:48:46 PM »
I would also check the bell housing alignment with the Browell tool. A misalignment will cause the pilot bushing to drive the input shaft when the clutch is disengaged.
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