HarleyTechTalk

I have a twin cam gear cluster. Can it be modified or used in a M8 transmission which is damaged? Perhaps just swapping out a few gears or shifter cam?

As a whole, no- there are some gears that interchange, tho. 35000198A is the part number for the 2017 and newer (M8 touring) cartridge, 35246-10B is the part number for 2007-2016 (TC touring) cartridge.
Some gears are interchangeable. Cross reference these two pages. 2022 vs 2016

I put a m8 gear set pn 35000198A into a 07 RK.  I changed shift drum to keep neutral light working.

Wonder if changing the shift drum would make the older gear set functional. Thanks

I bought what I thought was a gear set for TC.  I had dealer drop ship to my trans guy.  When I received it.  I stuck it in.  Test ride I found light not working but would flash between two gears.  After some research and talking to dealer I purchased from.  I found out they sold me a m8 trans.  I took it back apart and changes shift drum only.  He has rode it all season with no complaints.  Hard way to learn this on a pro charged bike.

Thank you, Sir! Good info.

tearing into the gear cluster change out now thanks for the info, I'll let ya'll know how bad i screw things up

FYI- After switching out shifter drum (M8 for TC) everything was good, neutral light functions properly but the gear indicator light on the dash seems to be reluctant to show the transmission is in 6th gear, no light. All other gears function flawlessly but 6th gear shows some times and sometimes not. Help?

Quote from: Gopher on March 07, 2023, 04:49:35 PMFYI- After switching out shifter drum (M8 for TC) everything was good, neutral light functions properly but the gear indicator light on the dash seems to be reluctant to show the transmission is in 6th gear, no light. All other gears function flawlessly but 6th gear shows some times and sometimes not. Help?

Does cruise work when the light fails to show?

Quote from: Gopher on March 07, 2023, 04:49:35 PMFYI- After switching out shifter drum (M8 for TC) everything was good, neutral light functions properly but the gear indicator light on the dash seems to be reluctant to show the transmission is in 6th gear, no light. All other gears function flawlessly but 6th gear shows some times and sometimes not. Help?

You have an M8 bike correct? Put an earlier gear set in a late bike?
what bike?
Just verifying.

Rushmore touring bikes on up have the indicator in the odometer, indicating every gear.
Some may get confused and think of the 6th gear light on the earlier bikes.
I'm admittedly unaware if they do that on the Softail line.

Either way in both cases they are "calculating" what gear the bike is in by comparing engine speed and trans output speed.
There is nothing mechanical to indicate gear except neutral.

Most of the 6th gear indicator issues on the earlier bikes with just a 6th gear light seem to stem from ratio changes and then not being corrected in the gear table in the tune.

There may be some conflict with maybe the neutral switch still?
It flicker any while in 6th?

KD- the 6th gear indicator light does not light while in 6th gear and the cruise control does not work, however the cruise does work in every other gear, and the gear indicator light also works for every other gear. 6th gear is the only gear with no light or cruise.

Cheech- the neutral light works fine no flicker. The bike in question is a 2019 M8 FLHTK Ultra. I changed out the shifter drum to allow the neutral indicator switch to function properly. The bike runs through all the gears with no issues except no cruise or 6th gear indicator light in the odometer display. I changed out the vehicle speed switch with no change with the cruise or indicator light for 6th gear. Quite frustrated. Curious if there is a difference between the 5th gears of Twin Cam and M8? I am under the impression the vehicle speed switch in the side of the transmission reads off of 5th gear and due to a difference this may be the problem.

I live in Arizona and it's hotter than heck here now. I'm waiting for cooler weather to tear into this trans issue and rebuild the M8 gear set. But your opinions are very welcome.

Quote from: Gopher on September 05, 2023, 04:34:46 PMCheech- the neutral light works fine no flicker. The bike in question is a 2019 M8 FLHTK Ultra. I changed out the shifter drum to allow the neutral indicator switch to function properly. The bike runs through all the gears with no issues except no cruise or 6th gear indicator light in the odometer display. I changed out the vehicle speed switch with no change with the cruise or indicator light for 6th gear. Quite frustrated. Curious if there is a difference between the 5th gears of Twin Cam and M8? I am under the impression the vehicle speed switch in the side of the transmission reads off of 5th gear and due to a difference this may be the problem.

Are the 5th gears in the TC transmission strait or helical? If straight cut they're not going to give the same input as the helical gears.

Quote from: Gopher on September 05, 2023, 04:34:46 PMCheech- the neutral light works fine no flicker. The bike in question is a 2019 M8 FLHTK Ultra. I changed out the shifter drum to allow the neutral indicator switch to function properly. The bike runs through all the gears with no issues except no cruise or 6th gear indicator light in the odometer display. I changed out the vehicle speed switch with no change with the cruise or indicator light for 6th gear. Quite frustrated. Curious if there is a difference between the 5th gears of Twin Cam and M8? I am under the impression the vehicle speed switch in the side of the transmission reads off of 5th gear and due to a difference this may be the problem.

Yes the speed sensor reads the main shaft 5th gear.

When you say no light you mean there is no numeral 6 on the odometer? Correct?
(we've had guys on here looking for the green 6th gear light IN the speedo before when there isn't one on the Rushmore bikes on up)
But there is numeral 1,2,3,4,5 when in those respective gears?

If the second is true that makes no sense as apparently it's reading correctly for those off the same gear and speed sensor regardless what gear the trans is in but then no 6 on the odometer when in 6th.
So seems to rule a mechanical issue out.
If there is one? 

You had this bike since new?
Did you break the original trans?
Has it been tuned?
Any chance the gear table is corrupted in the tune if it has been tuned and now its showing itself and there's a correlation since you've done trans work.

What I'm getting at is are YOU certain the 6th indicated correctly before the trans breakage issue.
Perhaps did you buy the bike broke, fixed it mechanically then now the 6th gear issue and now chasing your tail when it's not a mechanical issue at all.

Here is the part number comparison between the Twin Cam and the M8 you specified.
2015 Twin Cam
mainshaft        35467-06B
countershaft    35470-10
main 5th         35801-10

2019 M8
mainshaft        35467-06C
countershaft    35600094
main 5th         35000179