How to check which diff ratio you have….

[peteracs]

Hi All

I have 3 gearboxes of unknown origin and trying to sort out what diff ratios I have in them.

I have read that it is marked on the body, but so far unable to find any markings at all relating to the ratio.

So I tried to put the box in gear and then interpret the number of revolutions input to output (these are not in a car).

Only one of the output shafts tuns when I do this and so far I have been unable to make sense of the results.

Any suggestions how I may work out what ratios I have would be appreciated!

Peter

[Nigel]

Hi Peter,

I hope the photo is clear enough. This reads 17/64.
As far as I know, all boxes were stamped just above the left side
output shaft.

[peteracs]

Hi Nigel

Perfect, after a bit of scraping found it on all 3 boxes, 2 off 1600 and 1 off 2l carb boxes as I suspected.

Hopefully the VX box I am collecting will be correct!

Peter

[Nigel]

Glad to hear Peter.

As you say, check that VX ratio is correct.
It should read 19/62.

Cheers
Nigel

[mangocrazy]

I checked both gearboxes I have for stamp marks, and found them easily (on the refurbished box that's fitted to my 2 litre engine) and with the aid of brake cleaner and a rag (on the box originally fitted to the carb 2 litre motor). Both boxes were stamped 14/53 and what I presume to be a serial number was also stamped - 84915 (no leading zeroes) on the refurbed box and 073971 (note leading zero) on the original box. It's tempting to read too much into this, but that adds weight to my suspicion that the refurbished box is a later one as fitted to the i.e. models.

Build date of my Spider has been confirmed as October 1979, and I don't think it was too long after that date that production of the i.e. models started, so I'm hopeful that it's a later box and crossing fingers that it might have the more relaxed 5th gear ratio.

If anyone knows otherwise feel free to disabuse me of these notions... 

[peteracs]

Hi Graham

I think that the 14/53 is the standard 2l box.

See the following which is posted elsewhere on the forum for list of ratios

Peter

[squiglyzigly]

I’m not sure where I got this from (somewhere on this forum maybe?) but it’s a little more simplistic in its info. No doubt its incomplete but it seems to show a majority of coupe/HPE/Berlina models only seem to have a handful of final drive ratios.
The smallest engines are missing from the list of course.

It seems to show there is one 2.0 carb ratio of 17/64 and two i.e. differential ratios. Early and late? 14/53 and 18/65. Or maybe the 14/53 wasn’t UK market? I’ve not got one and haven’t seen one that I can remember.

I don’t know how accurate this is but of the six 2.0 gearbox’s in my collection, mine are all carb 17/64,  i.e. 18/65 or VX 19/62 according to this chart.

[peteracs]

Hi

Interesting, so the lower of the IE and carb cars are pretty much the same, odd that the ie is lower than standard carb if only by a whisker, just the higher ratio IE which would be noticeable. Thanks for that, I had not seen the list.

Peter

[mangocrazy]

Hmmm - so both my gearboxes are the lowest diff ratios available for the 2000 motors. Bu99er. It's just my luck that the gearbox fitted to the donor i.e. engine that's in the Spider will have the more relaxed 18/65 ratio. I'll check when I go back to France in the next couple of weeks.