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Discussion Starter #1
When fitting my ATB diff :D the crown wheel it had fitted has more teeth than mine (70 compared to 64 iirc) and my current final drive is 3.55 (awaits correction on the std F20 final drive). This means the box I stipped had a final drive of 3.74 (correct rob 16v astra if this is wrong :p ).

Given the above my question is with a std F20 gear train using a final drive of 3.74 what would my in gear speeds be for a rev limit of 7800 rpm?

Also how hard is it to change the wee gear chappie that the crown wheel mates with?

Cheers


:)
 

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Discussion Starter #5
:confused: bugger

oh well if the 3.55 will make enough of an improvement I'll fit that but speeds in gear for both combo's might help me decide to go shopping.

:)
 

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so you have swapped the crown and kept your 3.42? explains why your cars slow then ;)
go shopping matey, the f16 is stamped ****w374 i think so you should be able to pick one up from a cav cdi or summat by inspection :cool:
 

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hangong though, so youve got the 70 teeth crown wheel from the new diff, and still have your old 19 teeth pinion ?

well that does make 3.73. but i thought you had to keep them matched, otherwise the teeth wont physically meet will they ?
 

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Discussion Starter #8
Its the extra cost and hassle mate of getting another box to stip.

I've told you before red ones are faster! :p
 

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Discussion Starter #9
0ddball said:
hangong though, so youve got the 70 teeth crown wheel from the new diff, and still have your old 19 teeth pinion ?

well that does make 3.73. but i thought you had to keep them matched, otherwise the teeth wont physically meet will they ?

I havent swaped them yet as your correct I need to keep the matched pairs but before going to the hassle of swaping pinions I need to see if its worthwhile.
 

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couldnt remember what wheels you have, so i guessed 205/50/15, 7800 limiter

3.55 diff

42.46785902
69.79671274
101.8654726
134.607946
169.3942691

3.42 diff

44.08213436
72.44980416
105.737552
139.7246223
175.8332326

3.74 diff

40.31040094
66.25089043
96.69048874
127.7695744
160.7886779
 

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Discussion Starter #11
:) cheers Oddball

there 195/50/15's but it makes little difference the 3.74 seems the only one worth while.

So anyone, how hard is it to change a pinion gear???
 

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the teeth from the 3.42 are different pitch to the 3.55 was different when I looked at them when I had both sets here to see if I could mix and match to get an alternative FD.

regards muppet.
 

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WeeKenny said:
:( sounds hard
its not that hard, justa bit fiddly and kinda long winded, take the gearset out, by removing the selector turret on top of the g/box, then undo all the bolts round the gearset sandwich plate, then pull out the cluster, then comes the fiddly bit,strip all the gears off one of the shafts and refit to the new shaft, unless ofcourse you can find the same cluster witht the different f/d on it, then just swap em, hope that helps
 

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Discussion Starter #16
yeah that helps, still sounds hard tho. lol.

I'll get a box with the final drive I want and practice on it.

:)
 

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Discussion Starter #18
So I could get a 4x4 GSI2000 box and just stick my diff in that???
 
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