final drive diff gears - teeth count

[jimbob-mcgrew]

im looking into switching diffs.

does anyone have a pic, or a link, of some sort of chart, with the tooth count of both gears of each ratio ?

:thumb:

[jimbob-mcgrew]

oh and one more thing, ive not done it before, but i understand you can do with the box still in the car.
pop both shafts out, remove the cover plate, undo the securing latch clip, and then unscrew the big beast castlated nut, then the whole thing comes out ? is that right ?

what else will i need, just fresh oil and a gasket kit ?

[Southie]

I'm sure this will come in handy at one point as you've not mentioned which gearboxes you've looked at.

http://i345.photobucket.com/albums/p379/SOUTHIE01/Nova%20Rally%20build%20manual/Vauxhall%20gearbox%20ratios/2VauxhallGearboxRatios.gif

[Edd]

Nice little chart that mate +Rep

[Southie]

I think I got it off Stuarts Gearbox site a long time ago, cheers though lol

[jimbob-mcgrew]

thats handy southie :thumb:

i was going to put a 4.18 into my f10

you got any info on tooth count of the diff gears ?

just so i know what ive got and what im buying, they all look the same

[pete17]

thats handy southie :thumb:

i was going to put a 4.18 into my f10

you got any info on tooth count of the diff gears ?

just so i know what ive got and what im buying, they all look the same

just count both input gears teeth and output gears teeth and divide it and thats where the figures in the table are from:thumb:

[jimbob-mcgrew]

can you explain that a bit more simple for me please pete, i know bugger all about gearboxes.

the extent of my knowledge is theres 2 gears in the diff that effect the ratio - 1 large and 1 small :(

[meritlover]

oh and one more thing, ive not done it before, but i understand you can do with the box still in the car.
pop both shafts out, remove the cover plate, undo the securing latch clip, and then unscrew the big beast castlated nut, then the whole thing comes out ? is that right ?

what else will i need, just fresh oil and a gasket kit ?

you will be able to change the crown wheel, but i cant remember if you can get to the pinion without pulling the gear cassette out.
someone here will know.

[pete17]

can you explain that a bit more simple for me please pete, i know bugger all about gearboxes.

the extent of my knowledge is theres 2 gears in the diff that effect the ratio - 1 large and 1 small :(

Hi mate , the diff consists of two gears, a large one and a small on the end of your output shaft ,(ignore the planet gears 3xall the same size) count the amount of teeth on the big gear and divide it by the amount on the little gear! this also works on finding the ratios on your gears in the rest of your gearbox I.E. first gear has a input gear (on the input shaft) and a output gear (on the output shaft) count teeth of both gears divide the highest number of teeth with the lowest and the number given is the ratio:thumb::thumb::thumb::thumb:

hope this makes sense :):):)

[pete17]

you will be able to change the crown wheel, but i cant remember if you can get to the pinion without pulling the gear cassette out.
someone here will know.

you have too pull the gear cassette out

[meritlover]

i thought so but i couldnt remember.

the castleated nuts can be pigs to unscrew if the o-rings have galled up. you should really set up the backlash and build it up properly. You cant really just tighten them back up again and drive off.

gasket sets are cheap enough though.

[jimbob-mcgrew]

yeah makes a bit more sense pete :)

my box is stamped 418 but i doubt thats whats in there as the accelerations pants, ive driven smaller engines with even longer diffs 394, which were quicker.
the owner before was abit of a cowboy, and has changed alot of things himself around the car, it wouldnt suprise me if he's chucked a 374 in there for better motorway miles or something

need to check it out.. leaking from the casing too, suspect.

whats 'backlash' lover boy ?

[garyc]

Somewhere on here there is a list of the cwp ratio with the notch count and I think the teeth count. It may have even got copied over to the guides. Try a search.

[meritlover]

its the take up of 'slack' between the crown wheel and pinion, you need a clock gauge to setup the pre-load on the bearings ( i think there are shims for this). but you 'might' get away with nipping it up like you would a wheel bearing. But, the pitch of the nuts is so fine, and the resistance so great on the threads and o-rings that you cant actually feel how tight youve got it.

[pete17]

its the take up of 'slack' between the crown wheel and pinion, you need a clock gauge to setup the pre-load on the bearings ( i think there are shims for this). but you 'might' get away with nipping it up like you would a wheel bearing. But, the pitch of the nuts is so fine, and the resistance so great on the threads and o-rings that you cant actually feel how tight youve got it.

yea thats right or if you are just changing the crown gear to your diff/bearings , mark it before you remove it and try to put it back in the same place, thats what always used to do :thumb:

[garyc]

Also forgot to say, drop the diff plate and count the notches in the teeth. Iirc there are no notches then it is a 4.18