Input shaft above or below pinion shaft?

[Ryan L]

Is it better to have the Input shaft above or below the pinion output shaft on a transaxle?

Guess it will depend on
- Sump depth,
- Transaxle height
- Height of output shafts
- Plunge depth on CV’s
- Ground effects, venturi and diffuser considerations

I’m thinking that from a handling point of view the input shaft should be above the output shaft, as this would give the lowest centre of gravity.
Is there anything else that needs to be considered assuming that it is possible to flip the ring in a box.

 

[Russ Noble]

Well Ryan,

Given that the output shafts dictate the height that every thing sits at, then from a handling point of view you want the input shaft BELOW the output shaft.

This lowers the motor which is the major weight at the rear of the car. Thus giving the lowest C.o.G. In practice the lowest part of the car is usually the bellhousing anyway. The sump is not usually an issue. Suspension links etc are more likely to influence diffusers etc than will transaxle orientation. IMHO.

Cheers

 

[Ryan L]

Thanks or the response Russ, I read it last night but decided to sleep on it and clarify my thoughts.

I’m currently doing the research for the transaxle question? As you rightly point out that you need to know the details of this part before you position anything else, I knew about the requirements of drive shafts from a plan view, but had completely overlooked, or not fully comprehended the requirements from a side profile.

Having the transaxle output shafts centrically aligned with the input shafts of the wheel hub at static ride height would simplify the force calculations a lot and reduce the load on the CV Joints.

Ideally with the correct upright design, and transaxle correctly located we would have both the drive shaft and the lower wishbone/suspension link level, for a normal suspension design resting at static ride height. Does that sound right?

Also it is interesting to think about how some the transaxle options are used in there donor cars. A lot have a requirement to position a drive shaft running the length of the car under the floor or transmission tunnel.

Regards Ryan