Need an explanation of the early clutch linkage.

[John Fitzpatrick]

This is a a photo of an original type GT-40 bellhousing, and the box is a ZF –0, and I’m hoping someone can explain what sort of linkage would have been used with it. The case has a journal (1) opposite a welded on boss (2) which is bored in alignment with the journal. I first thought a Girling type slave cylinder bolted to the machined area (3) and a shaft extended from it down to the bowl on the end of the lever arm (5), but that doesn’t explain the purpose of journals and boss. The land (4) above 3 might have been a reinforcement to keep something, maybe a plate (?), bolted to 3 from moving forward under load, but I just don’t know. A drawing, a photo—even an educated guess—would be much appreciated.
John

[Jac Mac]

John, I dont think 1&2 have any connection with the clutch. I have not seen an installation that uses them either- could be for a wishbone forward link mount even. The boss-4- is a pad to prevent the girling type slave cyl ( they have a matching pad in this area ) from rocking under load.

Jac Mac

[John Shand]

Originally Posted by toy264

This is a a photo of an original type GT-40 bellhousing, and the box is a ZF –0, and I’m hoping someone can explain what sort of linkage would have been used with it. The case has a journal (1) opposite a welded on boss (2) which is bored in alignment with the journal. I first thought a Girling type slave cylinder bolted to the machined area (3) and a shaft extended from it down to the bowl on the end of the lever arm (5), but that doesn’t explain the purpose of journals and boss. The land (4) above 3 might have been a reinforcement to keep something, maybe a plate (?), bolted to 3 from moving forward under load, but I just don’t know. A drawing, a photo—even an educated guess—would be much appreciated.
John

1 and 2 are for trans mounting, there are 4 bolts round the housing and two ears, one on each side of the trans, only used on zf #0 and #1 I belive, there is a good photo in the parts book of clutch and parts

[Mike Drew]

Originally Posted by toy264

The case has a journal (1) opposite a welded on boss (2) which is bored in alignment with the journal. [snip] but that doesn’t explain the purpose of journals and boss.
John

The purpose for the journal and boss is much simpler than you'd think. A long bolt with a spacer/sleeve went there. Besides the bolts that are parallel to the input shaft and secure the transaxle to the bellhousing, there are a pair of long bolts (7/16 UNF x 3 5/8 inches) splayed out at a 45-degree angle, which pass through the bosses, then through spacer sleeves and finally thread into the journal.

BTW those bosses are not welded on; they are cast with the bellhousing, and then machined flat. And that journal is not part of the gearbox! Or rather, it's not part of the gearbox case. Instead, it's part of the cast iron flange that goes on the side of the gearbox case, through which the stub axles pass.

Curiously, the GT40 parts book shows a locking nut along with this bolt, but I don't know what function that might have had, since the bolt threads into the side flange. And it doesn't show the sleeve?

I tried to find some good photos of a De Tomaso Mangusta setup, but none showed this arrangement clearly. The view is completely blocked from below by a chassis crossmember, and from above by all sorts of junk including the spare tire.

The early Panteras equipped with a Dash-1 ZF used the same arrangement, even though the gearbox was inverted. Here's a link to an excellent drawing of a Dash-1 ZF Pantera bellhousing and associated parts:

Pantera Store

The bosses for the bolt are very clearly visible; the bolt and spacers etc. are parts #18-21 in the drawing (clicking on the number hotlinks you to a photo of each part).

Among the innumerable differences between a Dash-1 and Dash-2 ZF are the sideplates. The Dash-2 did away with this whole 45-degree splayed bolt arrangement, and the current production RBT gearbox follows suit. However, as many (MANY) Dash-1 gearboxes were scrapped (for no good reason) by Ford, most ZF specialists probably have some of these sideplates sitting around, and they will interchange with the later style. So if you really wanted to be authentic, you could get a genuine GT40 bellhousing, track down a set of ZF Dash-1 sideplates, and away you go.

Note that the current Safir bellhousing has the bosses cast in for the bolts, but the holes are not machined in them, so you would have to take care of that detail yourself....

None of this does a darn thing about explaining how the clutch linkage works though.

In your photo, the Girling clutch slave cylinder is mounted vertically, with the pushrod pointing at the ground. It bolts in using two bolts at (3), and the cast boss (4) supports the body of the slave cylinder. The pushrod extends down and pushes on (5), which translates that vertical motion into rotational motion. You can see that the other end of (5) is attached to a cross shaft with a pinch bolt arrangement. That shaft rides on bearings and runs the full width of the gearbox, and is located at the very front of it, on the outside of the oily bits with all the gears etc., right below where the input shaft extends from the front of the box.



Pushing down on the end of (5) causes that shaft to rotate; on the shaft is a clutch fork with two feet on it, which press against the throwout bearing, and etc. and so forth.

[Paul Thompson 'Hooligan']

Another pic..

[John Fitzpatrick]

Paul-
Thanks for the detailed explanation. I misidentified the location of the threaded boss-- I looked again and it is in the side plate, not the case. It appears to be aluminum instead of cast iron, but I'll check it with a magnet tonight.

If the Panteras have the same clutch actuation arm, I could use the same slave cylinder, which would make life much simpler! Do you know if the shaft from the slave cylinder just had a hemisphere on the end going into the arm, held in place by the cylinder's spring force, or was it somehow more positively secured?

Thanks,
John

[Mike Drew]

Originally Posted by toy264

Paul-
Thanks for the detailed explanation. I misidentified the location of the threaded boss-- I looked again and it is in the side plate, not the case. It appears to be aluminum instead of cast iron, but I'll check it with a magnet tonight.

That was Mike, the Pantera Dork, with the detailed explanation.

I forgot to mention that the first-gen (Dash zero) ZF used aluminum side plates; the Mangusta/Pantera sideplates were changed to cast iron, supposedly due to cracking of the aluminum versions.

Originally Posted by toy264

If the Panteras have the same clutch actuation arm, I could use the same slave cylinder, which would make life much simpler! Do you know if the shaft from the slave cylinder just had a hemisphere on the end going into the arm, held in place by the cylinder's spring force, or was it somehow more positively secured?

Thanks,
John

I don't know if there was any retention mechanism. The Pantera slave cylinder and clutch actuation arm setup is totally different from the GT40, and I must confess I don't know how the Mangusta was laid out. I'll find out and let you know.

The Pantera parts are readily available, and in fact many/most CAV GT40s fitted with ZF gearboxes are using Pantera bits to actuate them. A bracket is cobbled together to mount the slave cylinder horizontally to the gearbox/bellhousing, instead of vertically as on the original.

PI Motorsports was a CAV dealer for a short time, and they tooled up to produce bellhousings and various other clutch actuation bits. They can be seen on this page, buried among scads of glitzy Pantera parts:

PI MotorSPORTS New Pantera Products

Mike (not Paul)

[GooseMeister]

Donut recall an early Mangusta bellhousing being different from a later one, in terms of LH clutch slave mounting and any extra ears at a 45 on either side. DeT Goose versions used a vertical pattern Fiat Multipla (and more) slave with a 45 degree angled mounting pattern. Piston travel completely vertical. No 45 bosses cast into the bellhousings like the pic's posted. (For some reason that returned with the early Pantera versions-with the trans "upside-down".)

I believe that the shaft springs on the throw-out bearing shaft act to push the slave piston back up the bore. Two springs, either side on my -1 box serve to do this quite nicely. Box mounts to bellhousing with 4 studs/nuts. Crazy glue after that....

My cylinder feeds via standard Girling-esque rod, and a simple threaded hex head ball with a lock nut. Look for 67+ Maseratti, to (perhaps early) Fiat X19 parts and you will find the balls somewhere. I'm sure that the cylinders are an off the shelf Girling part based upon the early Girling catalog (CD) that I bought from some guy way out east...across the pond the other way.... Search eBAY for "clutch slave +Girling" titles and descriptions and I think you'll hit gold.

Rebuild kit for my .750" bore was found under X1/9 and others.... Later X1/9 kits may require that you replace your old 1 seal piston with 2-3 seal X1/9 version, but hey, when kits are $9, what's the problem with changing to a more modern piston and seal design? I carry two in my tool box.....

I had my original cylinder bronze sleeved by a very competent machinist that speciallizes in that sort of thing, up here in the Sierras. You can find him at the bigger swap meets out here too. Good work, good prices.

Ciao! ooops! I mean, cheers!
Steve

[GooseMeister]

Found this auction for a -1 Pantera ZF and bellhousing for sale by a wannabeGooseowner..... Look thru the pics and you'll find an overhead/rear shot of the side plate that Mike spoke of, the spacer, etc. Keep in mind that slave was on the RH side in this app.

Great platform he has in his other auctions for a Goose race car, partially set up for Pantera suspension.....not a bad thing!

eBay Motors: Series I ZF Transmission-Mangusta, Pantera, GT40 (item 330226923604 end time Apr-19-08 09:32:33 PDT)


Steve

[John Fitzpatrick]

Jac Mac-
Looks like I tried to make this more complicated than it is. Occam's Razor.

Mike (not Paul), Paul (not Mike), and Steve-
Thanks for the information-- I think I have enough now to find a workable clutch cylinder and rig up an actuation rod. Very much appreciated, since I've fretted off and on about this since the cylinder got lost in a machine shop many years ago.


John (Not very good with names!)