Re: OD transmissions on ZA MG

["David F. Darby" <darby@tri-lakes.net>]

Subject: Re: OD transmissions on ZA MG and rear axle ratios

> Bullwinkle wrote:
> >
> > CR:
> >
> > They also state that the 4.55/1 car did 85.8 MPH at 5250 RPM and the OD
car did
> > 90 MPH at 4400 RPM.  Does that still work out at ~25% reduction?
-------------------------
> CR asked
>   However, the non-OD final drive ratio in this example (4.55:1) is
> different than in  the former one (4.87:1).  Did they test more than one
> car?
-------------------------
The ZA utilized a 4.875:1 rear axle ratio. After a whopping 10% horsepower
boost in the ZB, the 4.55:1 was introduced. While the factory might have
played around with OD, I've never seen it listed as an option for the car.

Regards,

David F. Darby
http://www.mgb.bc.ca/mgz