Trans Ratio Question?

[grassost]

Does anyone know if a final drive gear and pinion from an automatic beta transmission can be installed on a '81 5sp transmission to lower the final ratio? I'm looking to lower my rpms on the highway and I'm wondering if a swap of final gears from a '79 automatic beta could solve this problem?

[Wallace]

Hmmm .. . no idea - but they are CERTAINLY swappable from a manual box .. . . done it with a vx one into a monte box .. .

[A1.6HPE]

Hello,
The Beta automatic transmission is a completely different (unique) design so the final drive is different fron manual transmission - ie will not fit.
As far as I know (Wallace feel free to correct me) the pinion and crown wheels need to be matched and as the pinion is an integral part of the output shaft which includes the gears then (obviously) the auto box would not have a suitable pinion shaft.
In practical terms the only transmission that will give a worthwhile reduction in revs on a motorway is the VX type of box from a Coupe or an HPE - the Trevi ratio is a bit lower.


Leo

[Wallace]

Lordy - forgotten how I did it now - yes, the main shaft from the gearbox has a pinion machined on it - - but it is possible to change the ratio as the big cog somehow unbolts . . . . going to have to take some photos. Give me a few days. .. .

[Wallace]

Had a look at my box of gearbox bits last week - and as usual, I was talking rot (again).

Leo's right - the pinion is machined into the output gear shaft - the bit which IS bolted to the big pinion is one of the output shafts - it was this I swapped when I converted the monte box to a vx one. (it was about 4 years ago - .. . )

So unless you want to convert from an automatic to a maual box, I think you're stuck with it.

Alternative idea - fit larger wheels !