48 Panhead sprocket shaft

[corpse]

A question that I cannot find an answer too.

Im rebuilding a 48 pan motor, what year did the tapered sprocket shaft on the left side flywheel change to spline?
Also, they accommodated the change with a different bore on the left case to accept the new style bearings correct? Therefore, Im assuming I can't run a spine sprocket shaft on my 48 left case if I wanted too..

Thanks!

[Dragstews]

1954 was the last year for the tapper shafts ..

The case race bore did grow in size for the 55-up Timken bearings ...
Not enough meat in the 54 and back cases to convert ...

[Tattooo]

Therefore, Im assuming I can't run a spine sprocket shaft on my 48 left case if I wanted too..

Thanks!

Yep you are correct, and like Drag said also you can't change it.........

[Dragstews]

Also you can't change it.........

Unless you buy a new left case ....

And break down the flywheels for installing the spline shaft.



Restamp your Vin numbers onto the new case ..

Done ....

[pan620]

I do not think that is legal, at least in my state

[DustyDave]

In some states it is illegal to even know that a number was altered or stamped anywhere but the factory. Had a friend spend a small fortune to keep from going to jail for telling an Oklahoma cop that the body shop that repainted his semi had removed and replaced the number plate to paint under it.
Dusty

[corpse]

Okay great, thank you for the info! I’ll be keeping it tapered, probably go with some new turrett & Osborn flywheels o

[JBinNC]

Okay great, thank you for the info! I’ll be keeping it tapered, probably go with some new turrett & Osborn flywheels o

No reason not to use your existing flywheels as long as the tapers are good. The factory flywheels can be rebuilt many times.

Jim

[Dragstews]

Here's a reason ... "STROKE"

[corpse]

Indeed! I just don’t have a set

[Dragstews]

Indeed! I just don’t have a set

If need be, I can build you a crank ..
A few needs would be needed in order to balance it ..
1) pistons
2) rings, wrist pin and clips
3) rods, bearings & cages and the crank-pin & nuts

New shafts would be nice to have, Jims or S&S

As far as the stroke, 4-1/2" is bout like having a stock stroke with engine life the same.
4-5/8" is also a good stroke to do, piston speed jumps a bit in turn shortens the life a tad ..

Anymore than that will hard on the pistons unless tall jugs are added to the soup ..

About the pinion and sprocket shafts bearings ... They may need to be serviced ..
That requires line lapping the case races to true them and remove trace ware ..
Oversize bearings are available ...



The cases and jugs may need to be notched for rod swing ..

[JBinNC]

Indeed! I just don’t have a set

For the straight bearing motors, you can use two right side flywheels. One must be '80 or earlier to accept the pinion shaft, but the other could be up to '86 (?) and of course they must have the same stroke, either 74 or 80 cu.in.You would have to add your own timing marks.

Jim

[Dragstews]

In the old days, Fellows use two right side U wheels ..
Those used a step crank pin, some Boys would off-set the tapper to allow the 41-up FL crank pin ..

All that work to up the stroke to 4-9/32" ..

[JBinNC]

Yes, two right side wheels was a quick way to a lighter bottom end, quicker revs. I think I've talked myself into it; I've got a set of 80 cu.in. wheels with bad (spun) sprocket shaft taper. One more right side wheel and I'm in business. Cheap pan stroker.

Jim

[flatman]

My experience with two right side (light) flywheels. Built a 80 inch flathead years ago with 2 right side flywheels. You always had to be on or off the throttle. It did not like to lope along. always had to accelerate or deaccelerate, Great around town rompety romp but not so fun on the highway. Seemed kinda strange as Indian chiefs basically have both flywheels the same and dont have that problem.