I have done a search and can't seem to find the answer...most ask about going from a 5 speed to a 6 speed...

I have the following: 2008 Road Glide with the factory 6 speed transmission and I do not have the noise most complain about...

Does any one know if you can swap the transmission gear set for an 09 or later oem factory gear set without changing anything else?

I am only looking to swap for gear ratio purposes.

While the 08 has a 6 speed...to me it is not like the 09 or later that I have ridden...the later models seem to utilize 6 gear as more of an over drive..I could be wrong on this thought but based on the specs the ratios are different from an 08 to an 09 and later model.

Thanks in advance for your help and comments.

 

I think you will find the main difference between your bike and a later spec is that you have a 66T rear pulley and they have a 68T. That makes them slightly shorter geared than your bike, in other words less of an overdrive.

If you can post your trans ratios and confirm your primary and secondary gearing we can take a closer look. I think your bike has 34/46 primary, 32/66 rear. The details should be in your owners manual.

 

Thanks grbrown, you're correct with the info on my specs..this is what I have from the specs given by the MOCO in my service manual...not sure about the 2009. This info I have for that year is from the specs given on HD's website:

2008 Model
Primary Drive (compensating/clutch): 34/46 ratio
Secondary Drive (transmission/rear wheel sprocket): 32/66
Gear Ratio (overall)
1st - 9.312
2nd - 6.421
3rd - 4.774
4th - 3.926
5th - 3.279
6th - 2.790

2009 Model
Primary Drive: Chain, 34/46 ratio
Secondary Drive: ????
Gear Ratio (overall)
1st - 9.593
2nd - 6.650
3rd - 4.938
4th - 4.000
5th - 3.407
6th - 2.875

I was told that the rear wheel sprocket was different, thus the reason for the gear ratio difference...looking for confirmation. I believe the changes for the wider tire (2009) meant a difference in sprocket width, just was not sure about the drive ratio's....if the secondary ratios are different, then perhaps my original thought is incorrect.

 

Well that is a surprise! I've worked my way through those ratios and the trans internal ratios are very similar, but not the same:

2008 Model
Gear Ratio internal
1st - 9.312 3.337
2nd - 6.421 2.301 1.450
3rd - 4.774 1.711 1.334
4th - 3.926 1.407 1.216
5th - 3.279 1.175 1.197
6th - 2.790 1.000 1.175

2009 Model
Gear Ratio internal
1st - 9.593 3.336
2nd - 6.650 2.313 1.442
3rd - 4.938 1.717 1.662
4th - 4.000 1.391 1.234
5th - 3.407 1.185 1.173
6th - 2.875 1.000 1.185

The other difference is that final pulley, 68T whereas yours is 66T. However your rear wheel is a slightly different rolling diameter. Your MU is approx 25.37" in diameter, while a 2009 180 tyre is slightly smaller, at 25.21".

So what can we make of this?! In actual fact it looks as if the top gear of your own bike is slightly more of an overdrive than an 09. I would also observe that the gap between 5th and 6th on your bike is a slightly bigger step than on an 09. The figures in green are me messing with numbers, they show the step increase from one gear to the next one up. I prefer the look of your ratios to the 09, although the differences are not great.

There is not enough of a difference IMHO to make changing your trans ratios worthwhile, even if it is easy to do. I can only suggest you try a few more test rides, to see if your impression changes with more experience.

I haven't answered you original question, but I hope that has been helpful!

 

grbrown...your input has been very helpful and informative...I believe the gear sets are swapable, but given the calculations you came up with, I would have to agree that it would not be worth it...unless i came across a free set then perhaps I would swap for the sake of seeing what the difference would be...thanks for all your input.

 

It's a pleasure - you kept me off the streets for half an hour!

 

you can change the trans pulley from a 32 to a 30 tooth and get youll have a lot better bottom end with not a huge change on the top the 07 and 08 were different than latter models speedo would be off about 5mph

 

To answer the original question you can swap the gear sets. grbrown is correct that the 09 went to a 68 in the rear but only on the FL dressers, softails and dynas remained the same.