Clutch fork

rsk289 · #1 (**permalink**) 08-09-2014, 03:54 PM

Well, the best laid plans...
Planned to install the engine today, but have got hung up on the clutch fork. I have an early 289 (probably Mustang) style, but it's a cheap repro and the two fork fingers don't seem to be long enough to hold the springs on the release bearing, and it binds on depression. I have the correct 'C3' 5-bolt bellhousing, and I think all the clutch hydraulics and hardware should be the same as Sunbeam Tiger (MkI, which had the 5-bolt 260). I have the correct bracket for the slave cylinder mount - I bought a new casting for this from the US, which turns out to be exactly the same as the old Tiger one I had, and the slave cylinder is a common Girling one.
What I don't have is a Tiger clutch fork! This is C3AZ-7515-A, which takes a special pushrod with a curly spring to hold it to the fork. Rod and spring I can get, but does anyone know which fork will work with this? NPD and the Mustang outlets supply a fork for 65/66 6 cyl Mustang, 37515B, which I am told should work - anybody know if it will, or of an alternative?
Real pain - I hoped to get the motor in and check those angles. There's always something you don't foresee...

Roger

LMH · #2 (**permalink**) 08-09-2014, 07:15 PM

The C3AZ-7515-A is a 10" fork and pretty rare as far as I know. I read on a Tiger forum of a guy using a 9 1/4" fork, C5OZ-7515-A which made the clutch engage a little quicker.
Might be something to look into.
Larry

rsk289 · #3 (**permalink**) 08-10-2014, 12:47 AM

Thanks Larry, I'll investigate.
I'm guessing the C3AZ fork is the correct item for the Cobra, as it seems to me that the entire setup would be the same as for the 260 Tiger.

Dan Case · #4 (**permalink**) 08-10-2014, 03:07 AM

Quote:

Originally Posted by rsk289

Thanks Larry, I'll investigate.
I'm guessing the C3AZ fork is the correct item for the Cobra, as it seems to me that the entire setup would be the same as for the 260 Tiger.

Cobras came first.

The bracket (Cobra unique supplied by AC Cars), spring tab (fabricated in house by Shelby American), the chrome plated push rod (a Girling supplied part with its end cut off and rounded for a Triumph something), ball nut (Cobra unique), and spring are Cobra specific parts. The Girling supplied (complete with unified threads identification) jam nuts is just a Girling sundries type piece.

The Sunbeam Tiger bracket is not as strong as the one for a Cobra. The ones I have held are not as thick in cross section (significantly thinner with the long bolt shorter than the corresponding one in a Cobra) where the bolts fix it to the engine and the webbing is not exactly the same. The Cobra part is identified with the same foundry logo as the late Cobra alternator bracket which was also provided to Shelby American by AC Cars. Both the Cobra and Tiger brackets are cast steel.

The ball nut for a Tiger does the same job as the one on a Cobra but that is just about where the similarities end. Cobras use an extension type coil spring between the end of the clutch fork and a fabricated (from wrought black angle iron) tab fixed in place by one of the bolts securing the slave cylinder to the bracket. Tigers used a custom spring clip to hold their push rod ball nuts to the fork.

All the Cobra and Tiger pieces have been copied and sold commercially at one time or another; and get mixed in the secondary markets.

rsk289 · #5 (**permalink**) 08-10-2014, 05:21 AM

Aha. As ever, Dan to the rescue - thanks again.

Dan - do you know which clutch fork the Cobra used? Is it the C3AZ-7515-A?

My old Mustang has come to the rescue. I bought it 10 years ago, took out the motor and 3-spd t/l to fit a stroker and T5. Stashed the parts away and forgot about them, until yesterday. I dug out the b/h and sure enough, it still had the clutch lever in it, and it was the early type with the wire clip and the spring hole offset at the tip. No part number.
The interesting bit is the fork length, where the forks rest on the bearing. I have a NOS '68 lever, still with Ford sticker, rusty but unused. This is the later type with the riveted spring clip. Putting them side-by-side, the earlier lever is about 1/2" longer from the pressed-in pivot ridge to the tip of the two forks. This would explain why my release bearing was hanging up on the fork when I tested it. It seems that the 5-bolt bellhousing, or something else in the chain, is different. I'm really happy I didn't throw the old lever out 10 years ago!
Roger

Can't fit the motor yet, my engine crane won't reach so I've had to order a long-reach one. Didn't fancy trying to install from the side.

Dan Case · #6 (**permalink**) 08-10-2014, 06:11 AM

The 05/31/65 dated Shelby American "HIGH PERFORMANCE AUTOMOBILE PARTS" list identifies a C2OZ-7515-A Lever, Clutch as the service part.

cobrakiwi · #7 (**permalink**) 08-10-2014, 06:36 AM

Would just like to add a huge thanks To Dan as well, for his knowledge and his extensive picture library. It is a great resource when people like Dan offer to share there knowledge.
Dan, Thank you Sir.

No problem installing the engine from the side, I like to have the car on a lift as well.
Lift the car so the engine hoist legs will just clear under the lift, engine in over the side.
With the CSX, Kirkham, HiTech etc, you can install the engine with out removing the hood this way.
Here is a picture of the 427 engine about to go in Bill's HiTech.

rsk289 · #8 (**permalink**) 09-11-2014, 04:07 AM

Still trouble!
I have a new Carpenter clutch fork, C5OZ-7515-A which seems to be the closest I can get to original spec. But there's a problem. I have installed this into the 5-bolt bellhousing, and the fork ends are too short. It is correctly mounted to the pivot with the hairspring. I have measured the position it will sit in on the input bearing collar when in operation, and with the top retaining spring clip engaged the lower is not, or vice versa. The un-engaged clip prevents the clutch arm from moving back properly from the clutch diaphragm fingers and the release bearing binds. Photo in the correct working position:

I still have the old clutch fork from my Mustang, a '68 with 6-bolt 289, 3 speed toploader (original trans, can't verify clutch fork but likely original). This has a different rod spring mount, but has longer 'fingers'. Pic of the two together, with the pivot points aligned, new C5OZ on the left:

So, I guess I have to go with the longer Mustang fork. I don't have any part numbers for this. Anybody have any idea what's going on here? Something different about a 5-bolt bellhousing pivot point (but the Mustang one's from a 6-bolt)? Poor pattern parts - although the Carpenter piece has a Ford sticker on it with a Ford part number?
Really confused

Dan Case · #9 (**permalink**) 09-11-2014, 05:16 AM

I have not compared this with a part from any other original Cobra but this is the lever that was on CSX2551 when I bought it.

09/10/14 update. I consulted the foremost authority on 260/289 Ford production drivetrains and he advised me that the part shown came out for the 1965 SIX BOLT 289 Ford engine. He tells me that there are functional dimensional differences between it and the 1962-64 part specific to FIVE BOLT 260/289 engines. He recommended using the proper design with each engine design type.

A thing to think about is where do the fork tips ride on the bearing flange in use. The bearing doesn't move full length of the insert shaft cover's shank. It only moves out in the middle of the length somewhere.

rsk289 · #10 (**permalink**) 09-11-2014, 05:43 AM

Wow. That is the exact same fork (allowing for minor measurement variation) as the one that was on my '68 Mustang. I'm beginning to think it probably wasn't the original Mustang fork as it doesn't look like any in the catalogues. Thanks Dan - I will use this and lose no sleep over it now.

The dimension of the Daniel Carpenter C5OZ arm from pivot to fork tip bearing surface is a little less than 3 3/4", but the end tips of the fork are much shorter and the release bearing springs are not retained by this as shown in my first picture. With regard to your last comment regarding the point on the input bearing retainer where the release bearing sits when in action, my photo is taken with it in position judged by measuring how far the clutch fingers sit behind the rear block facing. It would move sightly closer to the engine when the clutch is depressed.
This arm is too short - I'm very happy I have the older one! If only Ford had stamped with a number, I could tell what it's original application really was.

Looking at your photo, Dan, the CSX2551 fork has the same tip arrangement as the Sunbeam Tiger, for the circular spring. Odd.

Dan Case · #11 (**permalink**) 09-11-2014, 06:20 AM

Quote:

Originally Posted by rsk289

Wow. That is the exact same fork (allowing for minor measurement variation) as the one that was on my '68 Mustang.

The dimension of the Daniel Carpenter C5OZ arm from pivot to fork tip bearing surface is a little less than 3 3/4", but the end tips of the fork are much shorter and the release bearing springs are not retained by this as shown in my first picture. With regard to your last comment regarding the point on the input bearing retainer where the release bearing sits when in action, my photo is taken with it in position judged by measuring how far the clutch fingers sit behind the rear block facing. It would move sightly closer to the engine when the clutch is depressed.

Your longer lever and the one from CSX2551 are different designs. The neck of yours is a tighter cross section and is probably stronger.

Your shorter lever is like what I see offered for sale for Ford I6s and small V8s some places and Ford I6s in others. The V8 claim doesn’t seem correct as all the I6 engine clutch parts and ancillaries are different any V8 application that I have worked on. The fingers are clearly too short for the V8 transmission input you show.

The position comment wasn't directed at you but a general audience information one. Lots of people read this forum and they might not all realize that the bearing collar doesn't stroke the full length of the bearing support shank when used with the original Ford "Long style" pressure plate design. I try to craft answers to problems with enough information to cover associated aspects.

rsk289 · #12 (**permalink**) 09-11-2014, 06:33 AM

Correct as ever, Dan - my eye for detail must have been temporarily clouded by excitement!
The shorter lever is the same as two others I have which are sold as pre-'73 Mustang V8 levers. In my opinion it could be dangerous to use these as I think it could be possible for the release bearing to hang up on the shorter fork fingers. At best it could disengage from the fork and a teardown would be needed to fix it.
Interesting your point regarding the original 'long finger' clutch cover design - it could well be that the release bearing sits in a different position.
Thanks again for the information - I have installed the longer fork and everything seems to work very smoothly. Going by your photo it will also look as it should apart from the narrower neck, which will be really hard to spot in situ.

Dan Case · #13 (**permalink**) 09-11-2014, 06:35 AM

If you use a Mustang lever dust boot much of the lever is hidden. If you use the Fairlane dust boot (as Cobras did) then more of the lever is exposed.

Dan Case · #14 (**permalink**) 09-11-2014, 01:11 PM

Post #9 revised.

cobrakiwi · #15 (**permalink**) 09-11-2014, 01:48 PM

Quote:

Originally Posted by Dan Case

Post #9 revised.

Dan
Would the clutch fork for the Cobra be the same as my 1964 HiPo Fairlane?
This car has the 5 bolt 289 HiPo, and is a late 1963 K code build.

Dan Case · #16 (**permalink**) 09-11-2014, 01:54 PM

Quote:

Originally Posted by cobrakiwi

Dan
Would the clutch fork for the Cobra be the same as my 1964 HiPo Fairlane?
This car has the 5 bolt 289 HiPo, and is a late 1963 K code build.

Based on today's contacts, yes. Six bolt engines went into production in late summer 1964.

cobrakiwi · #17 (**permalink**) 09-11-2014, 02:03 PM

Thanks, I was guessing that would be the one.
Cheers

rsk289 · #18 (**permalink**) 09-11-2014, 03:11 PM

Dan, I'm not clear about the revision to post #9 - do you mean that your photo, the fork from CSX2551, is for a 6-bolt?
It seems from other contacts that there is a definite difference between 5-bolt and 6-bolt clutch forks. This is a hard area to research as it is pre-Mustang.
I've asked JD Larson but no stock of any 5-bolt forks. I think I have another lead and will let you know!
Building this thing with a 5-bolt block has lead to a lot of unforeseen problems which, uh, I guess I should have foreseen. For the sake of simplicity it's ending up with more Tiger parts around the trans area. In any case, I've spent this month's salary cheque on one pair of seat runners!

Dan Case · #19 (**permalink**) 09-11-2014, 03:22 PM

Quote:

Originally Posted by rsk289

Dan, I'm not clear about the revision to post #9 - do you mean that your photo, the fork from CSX2551, is for a 6-bolt?
It seems from other contacts that there is a definite difference between 5-bolt and 6-bolt clutch forks. This is a hard area to research as it is pre-Mustang.
I've asked JD Larson but no stock of any 5-bolt forks. I think I have another lead and will let you know!
Building this thing with a 5-bolt block has lead to a lot of unforeseen problems which, uh, I guess I should have foreseen. For the sake of simplicity it's ending up with more Tiger parts around the trans area. In any case, I've spent this month's salary cheque on one pair of seat runners!

Yes, the picture in Post #9 is the 1965 design.

I have contacted everybody I can think of today and so far haven't come up with a 1962-64 part for sale that isn't worn out. I am told you must use the 1965 boot with the 1965 lever.

1962-64 design parts are very tough to find. Salvage operators usually didn't save much drivetrain wise that didn't apply to six bolt engines for 1965 and later Mustangs. Every early part I hunt becomes an ordeal.