best choice for 5 speed gear ratio change

Discussion in 'Touring Models' started by oldscoolz, Oct 5, 2014.

  1. oldscoolz

    oldscoolz Member

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    I'm lookin at changing either the transmission pulley or rear wheel pulley on 2002 FLHRI 5 speed to run at lower RPMs at highway speed. I'd like to be doing about 2500 to 2600 RPMs rather than almost 3000 PRM at 70 mph. Stock tranny pulley is 32 tooth and rear wheel pulley is 70. (I think that's right.) I've looked at going to either a 34 tooth tranny pulley or maybe a 68 rear pulley. I'm doing the work myself so labor is free but it would be a lot easier to change the rear wheel pulley. The catch is that the rear wheel pulley is a lot more expensive. Looks like maybe $500 for the rear pulley versus $135 for the tranny pulley. I'd appreciate any advice from those of you have made this conversion. I'd like to do it without having to get a new belt. From what I've heard, this change shouldn't require a new belt, but it would be nice to know that for sure from someone who's done it already. Thanks.
     
  2. dbmg

    dbmg Experienced Member

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  3. Dr. Dolittle

    Dr. Dolittle Experienced Member Staff Member Moderator Contributor

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    I'm just curious - why don't you want to be turning "almost 3000 RPM" at 70 MPH? Seems like a lot of trouble and expense to drop your RPM's by 400 at most. And you'll have better roll on capability if you need to pass if you're already turning the higher RPM's.
     
  4. Jennmarr

    Jennmarr Junior Member

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    I'm with the good Dr. on this. What are you hoping to achieve by lowering the cruise rpm?
     
  5. dolt

    dolt Senior Member Contributor

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    A couple of things to consider:

    1. You will never get 2500-2600 rpms by changing the secondary drive ratio to 34/70 or 32/68; the best you can do is about 2850. The ony way you get to 2600 rpms at a decent cruising speed is with a six speed.
    2. A two tooth change to the trans or rear wheel pulley, normally will require a belt change; the OEM belt will be too long to allow proper adjustment. Every bike is different but the general rule is that the OEM belt will work with a one tooth change but two, not so much.
    3. When you drop the secondary drive ratio for lower cruise rpms (I join the chorus of why??) you also drop the final drive ratio on the other four gears which, if the motor is a stock 88" motor, will result in sluggish performance in the lower four gears. The H-D vtwin motor likes to spin.

    So, if you just have to have that lower cruise rpm, start saving for a Baker OD six speed.:D
     
  6. 03HD883R

    03HD883R Active Member

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    I changed the front pulley on my XL from a 27 tooth to a 29 tooth. Dropped it about ~400 RPM. I notice my cruising vibration is a lot less, I get better fuel mileage, and I get smoother, less jerky downshifts.

    No problems passing either. Then again, I usually ride it conservatively, I got all my road rage out when I was younger... lol If you want to pass me, go ahead, I'm usually in no rush. But when I am.. watch out!! lol
     
  7. dbmg

    dbmg Experienced Member

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    Or a newer Glide with the 6 speed trans......:s
     
  8. dolt

    dolt Senior Member Contributor

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    There ya go! Another fix; just a tad bit more expensive.:D
     
  9. oldscoolz

    oldscoolz Member

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    thanks for the comments. to those asking why, for the same reason HD went from a 5 speed to a 6 speed. i do longdistance runs. i like the feel of the bike at about 2500 rpms but would like to be coverin a little more ground. call it personal preference from long hauls. its a poor man's compromise for puttin a six speed in. i appreciate the comments about having to put a new belt on. is it really true that a two tooth change in a pulley means you have to change the belt size? that surprises me. is that your personal experience or what you've heard. thanks for all the comments. i'm most interested in hearing from those of you who have actually done this mod.
     
  10. dolt

    dolt Senior Member Contributor

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    I have not made the swap from a 32T to 30T pulley but those that I know have made the swap (mostly on later models) the 137T belt had to be changed to the 136T belt. Some have overcome the belt change by welding a "spacer" to the swing arm in front of the cam adjustor or elongating the axle slot to allow more rearward movement of the axle to adjust the belt to the proper tension.

    Of course, if you want to take the chance that you can drop two teeth on the trans pulley and use the OEM belt; please, be my guest.:D There is a formula one can apply to calculate the how much movement, rearward or forward, will result from a single tooth change in belt length. If I can find it, I will post it.:hii