Chain drive question we all should have been asked earlier.

Chain drive shaft you need is Andrews Part #296800

 

Let me rephrase that - I should have known of an ' 84 FLT it was chain drive and given you the correct part number a while back.

 

The 296800 shaft is a replacement for the 35042-79 shaft, but... the late `84 uses a 35042-84 shaft.

Andrews does not show a replacement for the late `84 mainshaft, it is an oddball shaft that was only used for half a model year.

 

Yes, late '84 uses the number you listed but the "early" 5 speeds all used the same shaft since 1980, 35042-79 which is Andrews 296800.

296850 is for 5 speed belt drive.

 

The early 5 speeds that used the 35042-79 shaft were chain drive, with the old dry shovelhead type clutch.

The OP`s late `84 has a 5 speed, chain drive, diaphragm clutch.

 

Not that it matters to the OP but I did some more digging.

The Early '84 FLT (only) used the '81-'84 mainshaft 35042-79 and the earlier main drive 35029-79 (for chain) but did use the diaphragm clutch according to an HD parts catalog.

Late '84 used a 35029-84 mainshaft and a 35029-84 main drive gear for the belt.

So, (on paper) all that somewhat confirms something I've suspected but never had parts to prove - The 84-89 wet clutch hub has the same taper as the dry clutch.

 

Early `84 was the old shovelhead style dry clutch.

Late `84 was the diaphragm clutch.

That`s why they changed the mainshaft from the -79 shaft to the -84 shaft.

 

Confirmed...as I have at least one each in the Shop right Now.. in fact...far as I can tell the only difference in Early vs Late '84 was in fact that shitty late '84 Clutch..
Edit; BTW from all I have seen...this applies to All Big Twin Models...as well as the Sportsters...Very Un-Mo-Co Like!!!

 

I think I may have found the shaft Dan labeled oddball. It's a 35042-84.

It wasn't an oddball to HD because it was used to '90 on certain cop bikes, mostly FXRP. That's right - chain drive with the early wet clutch. It was also used in that combo on the '84 FLTC DBLE.

 

The online HD parts microfiche shows that shaft as used on the FXR Police bikes, but it shows late `84 only, just like other models that used this shaft.

We know it was not used in `90, because all 5 speed transmissions were belt drive and splined clutch.