hi i have a 1989 flhs which has the tapered main shaft and i kept breaking clutch hubs not even doing burnouts or anything so i found a stronger one with the press on ring for the outside which worked the clutch hub no longer split but now i have sheared the key and ruined the whole shaft and i know this will continue to happen if i just replace the parts to how they were and i want to know how to change it to a 1990 or 91 or whatever year splined shaft, i have read that its as simple as changing the clutch basket and the shaft and iv heard i could have to replace the transmission case, jack shaft, inner primary, and all that. so i really need some help and want to know the easiest and cheapest way to fix this i dont want to be out a bike all summer, thanks

 

I found this in my notes. I had copied from some where years ago. It may help.

So off I go, "This ain't never breaking again!" I'm gonna switch to the
splined shaft, so to save you all some time and research I'll detail what it
took to make the modification. The only parts that need to be changed are
the mainshaft, the clutch assy and nut, I was mislead by some in that I
would also need to update the starter and the inner primary. Luckily I spoke
with another rider who has an older cousin of the Bastard who had the
change-over done by a savvy 81 wrench. Although the rider had no clue what
had been done to his FXR he was certain he had the splined clutch mainshaft.
I looked at his bike closely to see what I could see, and externally I could
see no difference, original starter and inner primary. Doing more research I
discovered that the 90 -93 clutch assy has the same starter gear and
location as the earlier model.

You need the shaft and clutch assembly from a 91.
The splined shaft will swap with the the tapered in the transmission, but you need the clutch setup for the splined shaft.

 

and thats all i need? going by the harley parts book it says i need to change alot more than that. i just want to be sure before i start anything, thanks for your reply

 

No, a 91 splined shaft will not swap with a tapered mainshaft.

If you are only swapping mainshafts, and keeping the original gearset, you must use a `90 mainshaft.

Here`s the whole story:

The tapered shaft was used through the `89 model year.

In `90 a splined shaft was introduced, that part number was only used one year.

The `90 mainshaft can be swapped out with a tapered shaft in an `89 or earlier 5 speed transmission, it is the only splined mainshaft that will work with `89 and earlier gearsets.

The `91 and later mainshafts have a different outside diameter than the earlier mainshafts, at the area where the shaft is supported by the needle bearings inside the main drive gear (the main drive gear inside diameter changed for `91 also).

The best way to change over to a splined mainshaft is to find an entire gearset, they can be found for 100-200 bucks, with low mileage.

Don`t mix gears between gearsets. When you remove your gearset from the transmission, you must also remove the main drive gear (it is the gear that will be left in the case after you pull the gearset out).

Use the latest model year gearset you can find (I put a `99 gearset into my `89 case).

`90-`93 clutch will have the same primary gearing and starter ring gear as `89 and earlier, but if you don`t mind a different starter or primary gearing, you can use a later model clutch than a `93.

The most expensive part of this job is the clutch, if you buy these parts at dealer prices they will be out of this world, so look for a `90-`93 outer clutch shell on ebay, and a `90-`97 inner clutch hub.

It may sound like a lot of stuff, but this is really a very simple straightforward job.

 

Thank you!!!
Dan89FLSTC
This info is just what I was looking for...

 

Ok well I saw someone new posted and I did the switch a while ago now and works great, here is a picture of my work order with prices and part numbers, you'll need to replace the bearings, make sure you get the correct ones for a 91 mainshaft, we ran into a problem where the old bearing was a couple thousandths difference, hope this helps, any questions email me gauthier6916@gmail.com

 

Another thing to consider:

If the bike has not been upgraded to the latest front pulley configuration, now is the time do do it. The upgraded parts are the pulley, pulley spacer, oil seal, nut, lock plate and bolts.

 

Hello. I wpo;d like to do this conversion on my 1989 FLTC. Can I use just the mainshaft from a 1990 and will the inner clutch hub from a 1990 fit my clutch assembly? I know I need to press them apart. Thanks

 

a 1990 spline shaft goes right in..just need new clutch hub