Hewland question?

[Stan Vann]

With a Hewland Mk8/9, how would you determine which final drive ratio you have, without taking the gearbox apart? Is there a number or plate on the exterior?
Thanks,
Stan

[Modo]

If your 4th gear is a 24:25, 25:25, or (25:24 or 26:25 forget the higher gear than 25:25) and it was not geared for autocross or tight course, then it is probably a 9:31 the earlier ratio used ........ don't know 4th gear ratio...then good question....can u see the pinion thru the filler plug on top, 10 teeth 10:31 or 9 teeth 9:31, probably not....I know you can see the crown wheel?? I would hate to turn the engine once and try and figure the ratio's and degree the rear axle turn

[supertiga2]

hi Stan
this is how i do it
remove rear cover so you can put a mark on pinion shaft nut --straight up
mark both rear tires straight up
turn both rear tires same direction and count and keep up with complete turns making sure you wind up straight up at the end of each revlution
count pinion reveloutions at same time
it helps to have 3 people to do this.
10 tire rev X 31pinion rev=10-31(this sounds backwards but aint)

hope this helps

David

[Dave Welsh]

The ring gear is not visible through the drain plug.

Like David says, pull the rear cover, etc.

One full turn of the wheels = 3.1 turns of the pinion shaft (the top shaft) = 10/31

One full trun of the wheels = 3.4 turns = 9/31

[Stan Vann]

Thanks, I appreciate that.
Stan