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Thread: Sportster gearing revs and differentials.

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  1. #11 Re: Sportster gearing revs and differentials. 
    frequent forum contributor Club Member stevepritch's Avatar
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    Quote Originally Posted by copperleaves11 View Post
    Hi Steve . As Alan says, mine is a 3.38 and I still find 1st gear all but redundant.I hasten to add we are talking about Ford units, if yours is a BMW item, there is probably a greater choice. You could explore a later gearbox, even 6 speed , bearing in mind that more recent units are at 20 degree incline rather than the 10 degree of the M20. Interested to see what you come up with.
    Hi Dave, thanks, I had a look at 6 speed but the final ratio is no different to the 5, so the 1st 2nd, 3rd will be lower ratio. I cant help thinking that it will be a diff change, as it will give the lower gears longer legs.
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  2. #12 Re: Sportster gearing revs and differentials. 
    frequent forum contributor Club Member stevepritch's Avatar
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    Quote Originally Posted by Mike View Post
    Hi Steve

    As has been said above, I tried a 3.14 diff (after a 3.38 diff) and found it too tall for cruising on a motorway inclines - I felt it necessary to change down a gear. I find the 3.38 is a better drive overall.

    That said, I have the later M50B25 engine, which delivers its power higher up the rev range, so you may find a 3.14 or BMW's nearest equivalent, will work for you with the M20B25 engine?

    With regard to gearboxes, be careful to check all the gear ratios: I have a 6 speed manual gearbox lined up for my Cabrio from a Z4 (to go with the more modern M54B30 engine), but it's top gear is the same as my current 5 speed.

    I have had it suggested to me that a 5 speed box is better than the 6 speed to drive as you don't need to change gear as often due to the close ratios in the lower gears in a 6 speed box.

    A possible solution for your scenario would be to go for a 6 speed and a low ratio diff, and then regard 6th gear as an overdrive for high speed cruising?
    Thanks Mike
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