64-65 Clutch Fork

[Joe L.]

Does anyone out there have a known-original clutch fork from a 1964 or 65 Corvette? In other words, a clutch fork that came out of 1964 or 1965 and is reasonably believed to be the original. I would like to obtain one either on loan or purchased. I don't care about condition or whether the fork is serviceable. I do not want it to use on a car, but rather, for research purposes only. Namely, I want to determine just what the difference is from the 67-81 fork which also replaced the earlier for SERVICE. Obviously, I'll post whatever information I come up with.

[Michael H.]

Re: 64-65 Clutch Fork

Does anyone out there have a known-original clutch fork from a 1964 or 65 Corvette? In other words, a clutch fork that came out of 1964 or 1965 and is reasonably believed to be the original. I would like to obtain one either on loan or purchased. I don't care about condition or whether the fork is serviceable. I do not want it to use on a car, but rather, for research purposes only. Namely, I want to determine just what the difference is from the 67-81 fork which also replaced the earlier for SERVICE. Obviously, I'll post whatever information I come up with.

Interesting that you should request that information/part. I asked just about the same question here two years ago and only one person replied. His reply was that the 64-65 part was exactly the same as 66 and later.
I know that's not the case though.

Near start of production of the 66 MY, all of the clutch linkage components changed, at least for small block. We know the clutch fork had to change dimensionally along with the rest of the components but we don't know exactly what the change was.

Over the years, this change brought about massive confusion, especially in the way these parts were listed in their various groups in the parts books.

Some of the later components work with the 64-65 setup but others create problems with clutch adjustment.

The ONLY part that I've never been able to verify the dimensions on is the 64-65 fork.

Hope you get some response on this and a KNOWN original part to inspect/measure.

[Wayne M.]

Re: 64-65 Clutch Fork

... Over the years, this change brought about massive confusion, especially in the way these parts were listed in their various groups in the parts books.

Some of the later components work with the 64-65 setup but others create problems with clutch adjustment...

Joe, Michael -- sorry I can't contribute any hardware, but I checked the part # changes over the C2- early C3 years [you two may already know this stuff ]. The history is certainly interesting. BTW, I have no chassis books prior to the first one, listed below.

July '65 Rev. P&A30: '64-5 Corvette (Gr 0.795) # 3844493

Oct '65 (1st '66 issue) '66 P&A30: '64-6 (327 & 427-L72) takes 3844493
__________same catalog _____ '66 L36 takes #3887177

Oct '66 (1st issue) '67 P&A30: '64-5 #3844493; '66-7 # 3887177 (no disp. or hp differences)

In service, part 3844493 replaced by 3887177 on 2-67

Oct '67 (1st issue) '68 P&A30: # 3887177 for all Corvette '64-8

Jul '69 (Rev) P&A30: 3887177 for all (still same on Oct 1, per P&A30B Rev),
and also in Jan '70 (Rev) P&A30B.

Somewhere I recall (TSB ?) mention of the spring on the clutch fork being revised, but a quick search of my documents drew a blank.

[Michael H.]

Re: 64-65 Clutch Fork

Wayne,

That's close to the way it actually occured. The glitch is the 66 425 HP but that's a long and confusing story that I'll get into some other time.
Basically, the 64-65 arm was replaced for service for all engines around the time you mentioned, Oct 1966.
In addition to the arm, almost all of the other components of the clutch linkage were replaced with a new design at the same time. It was a package, so to speak.
I think even the throw out bearing number/length changed but I don't remember for sure. Pretty sure the change also included the throwout arm pivot ball.

The problems started when people started mixing late parts with early parts on 64-65 cars.

If Joe Lucia can come up with a known original 64-65 T.O. arm to measure dimensions, I'll bet we'll see a nice report on the entire linkage system change between 65 and 66.

This topic has been a mess in the parts books for decades.

[John H.]

Re: 64-65 Clutch Fork

I've been tracking the clutch linkage question(s) for a long time, and I keep updating my notes from other boards and this one (most recently here about six months ago or so), as follows - but with no notes on clutch forks:

1963-E1966 SMALL-BLOCK:

3832857 Cross-shaft - 135





3819152 Pedal Bracket


1965-1966E BIG-BLOCK:

3872962 Cross-shaft - 155





3872963 Pedal Bracket


L1966-1967 ALL:

3888279 Cross-Shaft - 155-158





3872963 Pedal Bracket (1966 only)

[Mike B.]

Re: 64-65 Clutch Fork

John,

If you could post that same information for C-1s I believe it would be most appreciated by many. I in particular want to check the degress of separation on the cross shaft on my '61. I have a suspicion that it is from a passenger car.

Thanks,
Mike

[Wayne M.]

Re: 64-65 Clutch Fork (clutch pedal rods)

I realize I'm a little off Joe's clutch fork topic, but I have the occasion to measure three different clutch push rods together; '63-5 small block (orig, from a '64); '65 L78 rod (probably original, from my car -- note white paint dab to right of first pic); and a service # 3888213 (NOS). Also might help to compare with John H's table data.

3 thumbnails: first shows threaded ends with rods aligned at 2nd and 3rd step-down bevels. Note length differences.

2nd pic shows thread ends with pedal bracket holes aligned (shows variance in overall length).

3rd pic shows pedal bracket end (note transistion from flat at hole to full diameter rod -- differs [longer] on the '213' from the other two).

Lengths: measured from pedal bracket hole centerline to end of threaded rod; also along the rod which turns slightly at the bend. The 3888213 is 19_1/4", with threaded length 4_9/16".
The 'L78' rod is 18_13/16" long, and has 3_5/16" thread length.
The '63-5 small block is 17_5/8" long, and also has 3_5/16" of thread.

[John H.]

Re: 64-65 Clutch Fork

John,

If you could post that same information for C-1s I believe it would be most appreciated by many. I in particular want to check the degress of separation on the cross shaft on my '61. I have a suspicion that it is from a passenger car.

Thanks,
Mike

Mike -

The last C1 I did ('57) was 12 years ago, and I didn't make any notes on the clutch linkage; maybe one of the current C1 guys have some measurements.

[Tom D.]

Re: 64-65 Clutch Fork

Trophy Blue 1966E number 2999 (from on or about 10/13/1965) still had the short pedal rod. It's got 300 horses (SB). Adjusting nuts were at the very end (tip) of the rod back when it had four wheel opening flares and I was driving it.

The other clutch push rod was worn, same as shown above.

Paragon's reproduction (pedal rod 1746) has a conical tapered area at base of the threads, not same as the "steps" seen in Wayne's photos.

Also, Paragon part 1746 has slightly less "bend" as does the service replacement, number 3888213.

[Clem Z.]

Re: 64-65 Clutch Fork

could it had somthing to do with the fact on some years you could change the position of the rod on the clutch pedal arm to get a quick action clutch action ?

[Joe L.]

Re: 64-65 Clutch Fork

could it had somthing to do with the fact on some years you could change the position of the rod on the clutch pedal arm to get a quick action clutch action ?

clem-----


That's a possibility. However, somewhere I seem to vaguely recall that the "adjustment" for this was done somewhere else in the clutch system. It could have been at the fork, though. I do know that the L66-81 fork, the 63-0nly fork, and the 57-62 forks don't have provisions for pedal throw adjustment. So, if the 64-E66 did have such a feature, it was unique to that fork.

[Keith H.]

Re: 64-65 Clutch Fork

Hi Joe,

I removed the clutch fork from 1964 s/n 15027 this summer. The car has original engine and bellhousing but not the original transmission. The history of the car is unknown before 1971, so it do not know if the clutch fork is original. However, it appears to have been in the car for a very long time and is worn out.

I would be glad to take more photos and/or send you the fork itself. The attached photo is the only one I currently have on hand. I also removed two clutch linkage rods and can take pictures or send these if you'd like.

Kind regards,
Keith

[Clem Z.]

Re: 64-65 Clutch Fork

clem-----


That's a possibility. However, somewhere I seem to vaguely recall that the "adjustment" for this was done somewhere else in the clutch system. It could have been at the fork, though. I do know that the L66-81 fork, the 63-0nly fork, and the 57-62 forks don't have provisions for pedal throw adjustment. So, if the 64-E66 did have such a feature, it was unique to that fork.

if i remember (CRS has set in) you moved the clutch rod down lower on the clutch pedal arm to a different hole so you did not have to move the clutch pedal so far to disengage the clutch.

[Michael H.]

Re: 64-65 Clutch Fork

if i remember (CRS has set in) you moved the clutch rod down lower on the clutch pedal arm to a different hole so you did not have to move the clutch pedal so far to disengage the clutch.

Correct Clem. The adjustment was made at the clutch pedal. All 63-66 cars had this feature.

[Joe L.]

Re: 64-65 Clutch Fork

Hi Joe,

I removed the clutch fork from 1964 s/n 15027 this summer. The car has original engine and bellhousing but not the original transmission. The history of the car is unknown before 1971, so it do not know if the clutch fork is original. However, it appears to have been in the car for a very long time and is worn out.

I would be glad to take more photos and/or send you the fork itself. The attached photo is the only one I currently have on hand. I also removed two clutch linkage rods and can take pictures or send these if you'd like.

Kind regards,
Keith

Keith------


I would LOVE to have it to carefully examine. If you would send it to me, I'll return it to you and pay the postage/shipping both ways.