Length of 915 tranny?

[klatinn]

Hi,

For my application I need to know the total length of a 915 transmission measured from the mating surface with the engine to the front cover. Excluding the length of the shift coupler nose.
I'm trying to decide if it will fit in my application instead of the current (strengthend) 4 speed VW bus tranny. The application will be in a 68 VW bus (currently 80 CIS, but changing to EFI/turbo).

Thanks in advance.

[cowtown]

I think there are some diagrams in Frere's book if you have it. If not, I've got a 915 on the floor of my garage I can measure tonight - PM me if you need me to do it.

[H20911]

appox 23 1/2- 23 9/16 inches from the back of the engine to the front bump on the nose.

[beepbeep]

Why not use 930 tranny instead? 915 are no wonders of reliability and their torque rating isn't so good.

[klatinn]

Thanx H20911,

appox 23 1/2- 23 9/16 inches from the back of the engine to the front bump on the nose.

Is this incl. the shift coupling nose?

Why not use 930 tranny instead? 915 are no wonders of reliability and their torque rating isn't so good.

Hi beepbeep,

As I understand, the 930 is even longer than the 915 and it might no longer fit. There is limited space in the drivetrain cavity in the bus between torsion tube and rear hatch. With the VW bus tranny it's already a very tight fit. As I want to get shorter gears and R/P for the 915, the torque issue might not be that much of a problem. The VW tranny's current gearing (in 4th) is optimized for the heavy camper (lots of drag) with the 80 CIS:
0.82 4th gear with 4.53 R/P. I would like something like that in 5th on the 915, like a 7:31 R/P which works out to 4.42. I have to see what's available for 5th. Ideally it would be a 0.84 ratio. I don't plan on dragging the bus, those launches put many times the load on the tranny than what's possible with steady load.

The VW tranny held up so far fine even when towing a 2-horse trailer. (Get's funny looks when you tow a horse-trailer with a VW camper and pull away from F350's with trailers on uphill freeway stretches )

Regards,
Klaus

[H20911]

klaus, you can cut a 930 long box to the 75-77 size (remove 30mm) and that is the same length as a 915 box. the 4 speed 930 (short) is the same as the 915 they just made the gears bigger and wider in the 930 box compared to the 915 so they could only put 4 gears in the same space.
sorry this is a spare trans and in a cabinet but you can get the idea.

here is where the 23.5 came from



I would not recommend the 930 box due to its gearing. you have to have a strong motor to pull. here is the stock gears avail for the 915 box. this is the 8:31 r&p but you can do the math for the 7:31 the rpm will be 14-15% higher with the 7:31 R&P and these gears.

[klatinn]

Thanx H20911,

That's exactly the info I was looking for.

[cowtown]

Hello Klaus,

Looks like you are squared away, but here are my measurements:

23.25" from the mounting surface to the cover.

Then there is an additional 2.25" of the "snout" of the case protruding where the shift rod is mounted.

This is from a '75 915 (magnesium case).

Colin

[Geary]

A Bus Box with adapted 4.57 R&P would be far more durable than a 915, and could be geared any way you wish. With the extra horsepower that you say you have, 5 gears are not required.... and no special fabrication when staying with your original transmission type.