Input shaft

Hi, can anyone advise. I have a ZF25/2 gearbox, a Safir bell-housing and a Roush 347 engine, but the input shaft hits the back of the crank before it tightens up on the block? was there different length input shafts on the original ZFs. I have considered grinding about 3 mm of the end. Has anybody else come across this problem. HELP

Short answer: yes

Longer answer: the original ZF gearbox had an input shaft of a certain length, as did the first evolution which was called the /1 version. When Ford and De Tomaso got together to produce the Pantera, the /2 version was created which superficially looks the same, but is improved and changed in numerous ways. The case is physically bigger, almost all internal parts are different, and (here is the answer to your question) the input shaft was longer.

The early Panteras used /1 gearboxes left over from the Mangusta program. They were partially dismantled and the ring and pinion were flipped, as the Pantera was designed to run the gearbox in an inverted orientation. The bellhousing was deeper, long enough that the input shaft was some distance from the back of the crankshaft, so an adapter was fitted that slipped over the snout of the input shaft and indexed inside the pilot bearing in the crankshaft.

The /2 version used a different bellhousing with the same depth as the /1 bellhousing, but larger in diameter and with a different bolt pattern. The /2 input shaft is longer and reaches the back of the crankshaft without need for an adapter.

If you have an original-style GT40 bellhousing, it will only fit an original or /1 gearbox. I think Safir makes a hybrid bellhousing with a larger diameter and different bolt pattern to bolt to a /2 gearbox, but if it's not also thicker, you would either have to shorten the input shaft or run a spacer between the bellhousing and block.

Or so it seems to me. I would speak to the Safir boys and Paul Fleming and see what they have to say....

BTW the BMW M1 gearbox input shaft is a LOT longer than a Ford /2 which is why it's not really practical to buy an M1 box for GT40 use...
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This thread was in the gearbox forum when I started writing the reply above, but somehow it got moved to the website comments forum. A goof, obviously. Can an admin move it back please? Feel free to delete this post once that's done....
Thank you Mike. First I have been a member for sometime but have not kneaded to post anything till now. I am just finding my way round so apologies if I post in the wrong place. I understand what you are saying so it OK to grind 3mm of the input shaft
Its going into a SPF GT40 p2340

Pat Buckley

GT40s Supporter
Mike -

I want to thank you for all the help you have been to me (and I am sure others) over the past number of years.

Your advice has always been on target.

A BMW M1 box has a shaft that is too long by a few MM....ask me how we know? And ask how long it takes to wipe out the thrust bearings in a Windsor engine!

This was done by a well known Ford engine shop who thought that when the bolts holding the bellhousing didn't tighten up to the block they just needed a "little more snugging!"

Some pre-emptive measuring with a plunge micrometer would have saved a lot of time and money.

Howard Jones

I does no good to state that "I did it another way" and leave it at that. With all kindness and respect either post the information or don't say anything at all. Should someone arrive at this thread via the search function in the future the "other way" doesn't help anybody.

Again with all respect and kindness.

Ian Anderson

Lifetime Supporter
I would presume by
A) drilling / machining the crank deeper to allow clearance
B) adding spacers between engine and bell, or bell to transaxle

But Frank I would also be interested to know how you did it!