G/Box ratios

[2LTR Rona]

Has anyone got a manual way of calculating the ratios in a manual box?

Have been flicked this but am uncertain of its accuracy

1. Count the splines at the output shaft of the box.
2. Put in gear, not 4th cos thats always 1:1, but one of the others. Do all of them in turn.
3. Mark the top of the input shaft and the top of the output shaft with a dot of twink/white-out
4. Slowly turn the input shaft one rotation and get a mate to watch the output shaft.
5. Count the number of splines on the output shaft after one turn.
6. work out the ratio as follows:

ie. 21 Spline out-put shaft,
3rd gear, 1 turn of the input = 15 splines at output shaft

15 divided by 21 = .71

1 divided by .71 = 1.41

So ratio of 3rd gear is 1.41:1

Cheers

[KE20]

or
put into gear and turn output shaft one full rvolution and count how many times the input turns
ie:
in 3rd gear
1 full turn of the output is 1.41 turns of the input.
easyr than calaulating stuff

[KinLoud]

That looks very similar (but slightly different) to one of my past posts or PMs to someone. I use the twink trick all the time.
Yep - it works for me.
If you are checking FWD ratios you will have to know the diff ratio as well.

Ken
Ham
021 408 863

[2LTR Rona]

Cheers for that guys.

Should have said in the OP that it's for working out ratio's on a RWD box

Ken - How dose it differ slightly to what you use?
If you are able to post or PM me your version it would be greatly appreciated


Cheers
Blair

[KinLoud]

I would just count how many turns of the input shaft gives one complete turn of the output shaft - same as KE20 says. Less brain power needed.
I always check it twice to reduce cockups especially with fwd boxes where 4th isn't always 1:1

Ken
Ham
021 408 863

[TrouserFxGt]

As Ken said not all boxes (rwd or fwd) are 1:1 in fourth.