E34 Gearbox conversions. Good or bad?

[e.dayanan]

In my still continuing search for my UDM, I've recently been hobbled by the issue of 4 or 5 speed gearboxes. The GM 4 speed has a final ratio of 0.74 and a final drive of 3.15. The VERY rare 5 speeder ZF boxes have a final ratio of 0.72 and coupled to a final drive ratio of 3.15. The Jatco boxes use the same ratio as well? My question basically means, is the Jatco box worth it? Mathematically there seems to be very small difference between the GM and ZF boxes. Does this apply to the Jatco box too? If I do go for a Jatco...what do ineed and how much will it cost? Is it worth it? Any comments? Smike....u use a Jatco. Any input to share? Thanks everyone!DMann

 

[anakin]

Any updates?

 

[LaVegax]

I do not understand exactly the question ...
GM = General Motors?
I know that BMW uses only Getrag and ZF.
What do you want exactly?
high speed?
higher torque ?

Read here about some ratios :

http://www.bokchoys.com/differential/GearRatios.htm

 

[fabianyee]

The jap spec E34 used the JATCO 5 speed gearbox... JATCO = Japan Transmission Co...

Ppl used to say that the E34 JATCO gearbox is 'disposable' gearbox, can't repair the valvebody if faulty. If it develops problems, means throw away... Not sure about now.

 

[anakin]

The jap spec E34 used the JATCO 5 speed gearbox... JATCO = Japan Transmission Co...

Ppl used to say that the E34 JATCO gearbox is 'disposable' gearbox, can't repair the valvebody if faulty. If it develops problems, means throw away... Not sure about now.

Thanks Fab...any other thot?...

 

[gypsyqueen]

Looking for a 5 speed manual gearbox for e34 1990 520i M20 if anyone has any clever ideas?

I have found a second gearbox which I can hopefully recondition with my current gearbox 'campur'. I'm a bit nervous about doing this, has anyone done this before and know where I can find the measurements to help with a successful recon?