Transmission fork - Chevelle Tech
Transmission & Driveline Transmissions and Differentials

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post #1 of 9 (permalink) Old Jun 17th, 19, 10:24 PM Thread Starter
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Angela
 
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Unhappy Transmission fork

Just about ready to fire up my newly restored Chevelle SS L78 396 4 SPD and there is no adjustment in the fork. Everything is brand new. My question is, Is there two different forks for these Chevelle's. If so, Can someone chime is here with the right part number I need and possibly where I can get the proper one for my application. Thanks for any help/
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post #2 of 9 (permalink) Old Jun 17th, 19, 10:42 PM
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Re: Transmission fork

#3892632. This is the original fork...https://www.4speedconversions.com/3892632-1.html

The clutch fork on the left is for 73 and later Chevelles and Chevy trucks. Also called the truck fork or heavyduty fork. It has "wings" and is longer. This is also the fork Lakewood sells as their heavy duty fork. It will cost you available clutch rod throw in the 67's thru 72 Chevelles.

The fork on the right is the correct 67-72 Chevelle and Camaro clutch fork. Go to this page to get the measurements of the 3892632. https://www.4speedconversions.com/3892632.html An original is preferred, but the reproduction are nearly identical and will work almost as well. They will both work better than that truck fork. This is the (R)#3892632 reproduction fork....https://www.4speedconversions.com/3892632_r1.html

Did you set up your clutch fork angle? Are you running a stock bell housing? Do you know what I'm talking about?
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post #3 of 9 (permalink) Old Jun 17th, 19, 10:52 PM Thread Starter
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Angela
 
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Re: Transmission fork

Thanks Dutch Max for your reply. I am certain I have the fork on the right but your right, I'm not sure what your talking about "clutch fork angle"
Any guidance would be greatly appreciated. Thanks
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post #4 of 9 (permalink) Old Jun 17th, 19, 11:02 PM
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Al
 
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Re: Transmission fork

Does your fork have wings? You should be able to tell from the outside, might have to pull the boot to see it.

Stock bell housing? or scatter shield with or without engine plate?

What year was your car? Was it originally a 4 speed? or is this a conversion using reproduction parts...like Bell crank?

I need to know this so we don't head down the wrong track.
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post #5 of 9 (permalink) Old Jun 17th, 19, 11:05 PM Thread Starter
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Re: Transmission fork

I currently have a scatter shield on now. I will be changing that out with a new heady duty stock bell housing if I have to drop the transmission.
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post #6 of 9 (permalink) Old Jun 17th, 19, 11:09 PM Thread Starter
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Re: Transmission fork

No wings on the fork, Scatter shield with plate, 1969 Chevelle original BBC 4 spd car
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post #7 of 9 (permalink) Old Jun 18th, 19, 12:10 AM
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Re: Transmission fork

Quote:
Originally Posted by MikAng View Post
No wings on the fork, Scatter shield with plate, 1969 Chevelle original BBC 4 spd car
Bummer. Pretty sure you'll need to pull the trans and set the pivot ball height with an adjustable pivotball or use and adjustable throwout bearing to achieve a proper clutch fork angle.

You may have the correct fork. You can measure it when it comes out.

When you install a scatter shield with block plate you need to make up for the difference in thickness of the new assembly. Even if you are using a stock bell housing this should be checked. Variances in flywheel thickness, disc thickness, and finger height often upset the tolerances GM gave us to work with. We have a finite amount of rod travel to work with to get proper clutch disengagement.

This video is a good primer of the process. The beginning info is good to know, setting the pivot ball height begins at 4:22. Basically we take measurements of the bell housing and flywheel and apply that to the known pivotball height for a stock bellhousing, flywheel and pivotball. Then we come up with an adjusted pivotball height to account for the variances we have due to the non stock parts. Before we slam the trans back in, we visually check the clutch fork angle. We want a 5-7 degree forward angle of the fork with throwout bearing installed and held against the fingers of the pressure plate. If you look at yours now, I'll bet it's well back of 90 degrees of the trans shaft.



https://www.summitracing.com/parts/m...ar/1970?page=2
https://www.summitracing.com/parts/lak-15501

Some more questions:

Which bell housing are you using?
Which clutch set up?
Is this a Muncie or???
Do you know what pilot bearing you are running? Have you checked to see that it is non magnetic and that you have an installed clearance to the shaft of .002-.003" We might have to install an extended pilot bushing since you are running a block plate. We'll have to do a measurement on the input shaft, then from the face of the bellhousing/transmount surface. We should have 5/8 inch of the shaft in the bushing. (BASICALLY, THE THICKNESS OF THE SHAFT.)

Has the bell housing been indexed or aligned? If not, I suggest you start here for a good shifting long lasting set up. Do parallel first, the concentric alignment. If it's off, your set up won't last long, you may have clutch disengagement issues, or shifting issues.

Have I scarred you off yet? Don't worry, it's not all that difficult and you'll be rewarded by a properly functioning clutch package.

Below is a picture of clutch fork angle. This one appears correct at 5-7 degrees forward. It gets a bit more difficult to check in the car, but it's dooable. You'll note the fork is very close to touching the front of this bellhousing. If you look at yours with the throwout bearing installed and held against the fingers of the P plate, it's probably pointed towards the rear of the car. There's no way you'll get enough throw to properly release your clutch like this. Thanks to Jody or whoever I stole this picture from. I have a whole stack and I forgot where it came from.
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post #8 of 9 (permalink) Old Jun 18th, 19, 12:19 AM
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Al
 
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Re: Transmission fork

Quote:
Originally Posted by MikAng View Post
I currently have a scatter shield on now. I will be changing that out with a new heady duty stock bell housing if I have to drop the transmission.
That's an option, but you'll still need to do the bellhousing alignment and set your pivotball height for proper clutch fork angle.

Personally, I love my feet, I would stay with the SFI scatter shield bellhousing.
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post #9 of 9 (permalink) Old Jun 18th, 19, 12:29 AM
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Al
 
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Re: Transmission fork

How to set and check pivotball heigth

And how to align bellhousing...Credit to Jody of Jody's transmissions.(if you have an issue with me posting this, I'll have it deleted)
Attached Files
File Type: pdf clutch fork angle measure method.pdf (648.8 KB, 11 views)
File Type: pdf Legend_Bellhousing_Alignment.pdf (263.8 KB, 7 views)

Last edited by DUTCH MAX HEADWORK; Jun 18th, 19 at 12:44 AM.
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