Proper downshifting will not net you any more wear then driving forward. Clutch, add a few rpms and release clutch for a smooth downshift. Now just pulling the clutch in and dropping a gear and dropping the clutch and you get that sudden jerk. That is were you see problems. It puts a huge shock load on the driveline as well as the crankshaft in the engine.

 

[quote=Faast Ed;5831256]The cranks are press fit. Parts assembled with no welding.
A good yank in the wrong direction is all it takes.
For example if you accidentally drop one too many gears during downshift.

Lots of (hard) early shifts with a torquey cam can have the same effect during acceleration.

I am shocked that more folks on this board are not aware of this!
It's fairly common knowledge elsewhere.

Sorry if I offended anyone by mentioning it.

No offense taken. In case you haven't figured it out, I'm new to HD, not riding. Like I said, it just seems strange to me that the big, tough, V-Twin would not be willing to take more abuse. At least I'm not the only one that's unfamilliar with this. Wonder if the "B" motor is better about this. In theory, I'm thinking the balance shafts would slow down the rate of deceleration as they do accel.

 

I had no idea these engines were so fragile? I use engine braking almost all the time and couldn't imagine riding down a curvy mountain road and *not* using the engine for braking.

 

Our history shows there is no damage done from properly shifting up or down.
Burnouts, wheelies, and otherwise beating the crap out of the engine can cause damage. Period.
As mentioned by many here there is nothing wrong with downshifting and we've yet to see a flywheel shift from downshifting IF the flywheels were true in the first place.

Abuse is the sure way to twist stock flywheels from our experiences.
We've seen plenty shifted flywheels from abuse and we've seen a few out-of-true flywheels from the factory.

IME, if a flywheel is defective from the factory it will either be out of true from the get-go or if the flywheels are not assembled properly they can shift on their own even if ridden like an old lady.

Having to ride your Harley like a little old lady because you are worried about twisting your flywheels is, well....just not necessary.
Anyone had a flywheel assy twist from normal riding, including up and downshifting?
Bob

 

Like everything else, it depends on HOW you do it.
Done properly, it's not a problem at all.

 

From what I've heard I sure don't want it to happen to me but, on hard acelleration the weight is shifted to the rear wheel, giving more traction. Why on decellertion when the weight transfers to the front would there be a problem. I've downshifted umteen times and chirped the rear tire, I would think the tire would give up before the crank.

 

In many cases the tire will give first, but you are still giving your crank an unnecassary "yank". Why test your fate?

How many here think that chirping the rear tire on downshift, is "proper & safe"?

I ain't even gonna say what I think. I'll get clobbered for it (again).

Searching "crank runout issues" has a couple of threads with unhappy customers, same words on Google likely has a world of info.

You folks carry on with your debate. I'm stepping out of this one.
My words have been twisted to say things that I did not say.
I hate threads like that. Read my posts if you wanna know what I said.
Then don't come back here saying I said something different.
Example: (post #74) I never said anything about "riding like a lil old lady to protect my crank",...... I clearly said that I take care to not over do it. I had a crank shift before, remember?
Truly pathetic what some people will do to bait somebody.

I ain't gonna list all the other examples.
Go ahead, "Ride 'em like you stole 'em"! Bwaha! I give a chit.



.

 

When you get use to a bike you (I) can tell if engine breaking is going to make the engine rev to high. It comes natural for me with out even thinking When i am coming up on a stop i will automatically do one or the other without having to think.

 

X2

I've never heard anyone complain that when they were engine braking and were in the right gear when they needed it they had shortened the life of their tranny by .0002%

 

If I am coming in hot and heavy then I hold the clutch and down shift all the way. Normal stops I engine brake.