transaxle-speedo question

[Jim Rosenthal]

Can anyone tell me (and would they please do so if they are able) what kind of speedo cable connects the ZF transaxle to a Smith's mechanical speedometer? Are there particular ends, is this any kind of standard part, etc?

Additional information: my ZF is a -2 unit which was a BMW NOS spare. It has a 4.22 ring and pinion.

Any information would be appreciated. Thanks, in advance.

 

[Julian]

This depends to some extent which speedo angle drive you have in the ZF,

For the Pantera there were actually two manufacturers used VDO and Veglia Borletti with each one having two ratios depending whether the speedo was km/h or mph (ratios are 1.1:1 or 1:1). Well they also came with differing cable ends one flat the other a square. Depending what you have and what your speedo drive is (usually square) you might find a cable that works from a Pantera vendor or you can probably get one custom made.

If you end up with a km/h drive and mph speedo indicated speed will be off.

 

[Jim Rosenthal]

This is very helpful. My ZF was intended for a BMW M1 (wish I had the car, too!), so it is probably a mph drive as it was a spare for an American-spec car. So the cable I will need will have a BMW end on the transaxle, and a drive end to fit the Smiths speedo...

 

[Jack Houpe]

Jimbo, you will have to use a adator as I think the smiths gauges are set up for a 3.77 ring and pinion, I did away with the speedo and went with a programable unit. But Olthoff has the gear unit you will need. I also have the same transaxle as you which have a slightly different 2-3-4 gear ratos as the pantera units. I think you will be happy with that but I wish I had 3.77 ring and pinion and plan on changing soon.

 

[John Fitzpatrick]

These folks can probably help you out. Nisonger Instruments :: the exclusive Smiths U.S. Warranty & Service Center since 1949
They repaired my tach many years ago and did a very good job.

 

[Jim Rosenthal]

Thanks to all, this is very helpful. Jack, any particular reason you wish you had a 3.77 final drive ratio? Just curious. My engine will max out at around 6000 revs; with a 4.22 final drive it may be kind of busy at high speeds. Then again, a GT40 is noisy even with the engine shut off....

 

[Julian]

I think you will be happy with that but I wish I had 3.77 ring and pinion and plan on changing soon.

Agreed, a 3.77 is best for the GT40 (same can be said for the Pantera, although I have a tall 5th gear which helps keep highway cruising rpm reasonable). The disadvantage is cost of R&P's for the ZF, in fact I have spare ZF that I was going to drop into my GT40 to replace the current Porsche transaxle, truth is by the time I pay to have it flipped for GT40 use, new cover etc. I can sell it and get one of the new ZFQ's ready to drop in and they come std with a 3.75 final drive.

Does the later BMW ZF require a flip to use in a GT40?

 

[Jack Houpe]

Thanks to all, this is very helpful. Jack, any particular reason you wish you had a 3.77 final drive ratio? Just curious. My engine will max out at around 6000 revs; with a 4.22 final drive it may be kind of busy at high speeds. Then again, a GT40 is noisy even with the engine shut off....

At 150 mph my tach was reading 6200, when I do an open road race (TEXAS NEVADA) and dial in 135 mph it will be to high of an rpm for my taste for that extended length of time. Besides if you are over zealous with the pedal in first and second the tires just lite up, I have tire spin at 60 mph in third, so the 3.77 will help this a lot.

The M1 is in the correct position BUT the shift rod must be pulled and replaced with the pantera unit which is on the right side of the transaxle, the M1 was shifted on the left. You will have to replace the top cover or waterjet out a mount and attach it to the old cover like I did. Also the input shaft is slightly larger and shorter due to it being metric. So you will have to use a bronze bushing to go from metric to standard for the pilot bearing.