Do you shift without the clutch?
Seasoned HDF Member
Joined: Mar 2007
Posts: 66,948
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From: TOAK western branch
Because you have to be very fast at going through the shift to avoid the teeth getting damaged, the dog rings allow for there to be no syncromesh but the shift has to be very fast to be smooth, if you have any play in your shifter which most Harleys do then the shift is likely to be less than clean which will result in the gear teeth getting chipped and the surface being shaved. This will ultimately lead to a sloppy gearbox with lash in the gears and gears jumping where teeth are missing. These teeth can also result in seized boxes.
On the other hand if the shift mechanism is tight and you are familiar with clutch less changes then the gearbox layout is actually designed for it.
The ideal solution in my mind is dog rings with helical cut gears as helical cut gears are inherently stronger and the arrangement makes some allowance for less fluid changes, as the helical gear will take up with less mesh then straight cut gears and then self align the gears as load is applied.
On the other hand if the shift mechanism is tight and you are familiar with clutch less changes then the gearbox layout is actually designed for it.
The ideal solution in my mind is dog rings with helical cut gears as helical cut gears are inherently stronger and the arrangement makes some allowance for less fluid changes, as the helical gear will take up with less mesh then straight cut gears and then self align the gears as load is applied.
Outstanding HDF Member
Joined: Apr 2012
Posts: 2,938
Likes: 30
From: North Florida
One last thing that I should have put on my list.
I would never, ever try to talk anyone else into doing this. If you have a clutch and you can pull it in, use it.
That wont hurt my feelings.
OP ask if anyone did, I said yes.
I would never, ever try to talk anyone else into doing this. If you have a clutch and you can pull it in, use it.
That wont hurt my feelings.
OP ask if anyone did, I said yes.
Last edited by Harleycruiser; Oct 28, 2012 at 08:41 PM.
Thread Starter
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Cruiser
Joined: Aug 2012
Posts: 159
Likes: 0
From: Saluda SC
I have over 40 years of time in the saddle of different types on bikes. Everything from dirt to touring. I have never had to go into the trans on any of them. Just lucky I guess. I have torn apart and rebuilt all types of engines and transmissions, auto, truck tractor and even farm tractors. I was just curious if the Harley trans would stand up to shifting without the clutch. I have shifted gears on some of the other bikes without the clutch and some shift well and sone do not like it. So far I have always used the clutch on my 08 ultra classic but just in case I have a brain fart and forget to use it I don't want a catastrophic failure. I would hope a random shift doesn't trash the gearbox.
Stellar HDF Member
Joined: Mar 2012
Posts: 2,616
Likes: 10
From: Scotland
So engineering told me.
Club Member
Joined: Mar 2009
Posts: 66,136
Likes: 51,475
From: Niles Canyon Ca.
Randoms won't hurt you , guy with skills it's easy to do , just isn't good for the box that's all . That little video ? take a look at the outside edges of the highlighted yellow gears as they move , see those big big square teeth ? those are what engages under pressure into the sides of other gears moving a bit slower to drive them and shifting without the clutch those gear dogs are under pressure , blipping the throttle lessens the load but doesn't disengage it like the clutch is designed to do and you accelerate the rounding off of the engagement edges , surfaces and the pockets the engage into which in time leads to popping out of gear under loads or you find your missing shifts more often . In a tight gear box like the 5 & 6 speeds when they start doing that gear teeth failure is the next step because the teeth are taking the hit instead of the bigger beefier dogs and the puny bearing harley has been having big issue with go away taking shafts with them .
The shift arms are thin cast material & ground to a precise fit & size . Speed or no clutch shifting those thin arms are under serious constant side loading pressure as you put a little nudge on the shift lever to preload them and you are doing that whether you know it or not way outside their design specs and they heat up , wear very fast , bend or break . The thing is in the new 6 speed boxes their is very little clearance or slop for all that shifting and movement to take place . Fried & bent shifting arms are the most common tranny failure I see on the 5 & 6 speeds and the owners always fess up the " getting on it ..... " which means no clutch shifting . One a heavy bike like a fat *** bagger the problem is accelerated because torsional & loading stresses go way up and the big beefed up motors and that poor gear box is being pounded .
That's the mechanics of it guys , your bikes you bought them ride as you want that's all I'll say about it . Outa here
The shift arms are thin cast material & ground to a precise fit & size . Speed or no clutch shifting those thin arms are under serious constant side loading pressure as you put a little nudge on the shift lever to preload them and you are doing that whether you know it or not way outside their design specs and they heat up , wear very fast , bend or break . The thing is in the new 6 speed boxes their is very little clearance or slop for all that shifting and movement to take place . Fried & bent shifting arms are the most common tranny failure I see on the 5 & 6 speeds and the owners always fess up the " getting on it ..... " which means no clutch shifting . One a heavy bike like a fat *** bagger the problem is accelerated because torsional & loading stresses go way up and the big beefed up motors and that poor gear box is being pounded .
That's the mechanics of it guys , your bikes you bought them ride as you want that's all I'll say about it . Outa here
Last edited by TwiZted Biker; Oct 28, 2012 at 01:53 PM.
Road Master
Joined: May 2012
Posts: 1,081
Likes: 7
From: Canada
Helical gears are stronger than straight cut gears of the same size, regardless of any myths you may subscribe to, this is simply because they have more teeth and as a result to loads are spread out more. The reason straight cut race boxes are strong is because they use physically larger gears, also they are not prone to thrust load which is why helical cut gear boxes have to have stronger and heavier transmission cases. In a motorcycle this is less of an issue until you start doing some serious tuning.
So engineering told me.
So engineering told me.
Also with helical gears you have more side loading (the gears wanting to push themselves apart) which put more pressure on the end bearings, thrust washers, and other internal parts on the shaft. Not good for high performance or heavy duty applications.
cheers
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Stellar HDF Member
Joined: Mar 2012
Posts: 2,616
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From: Scotland
The reason for helical gears is for noise reduction, period. They are actually weaker than straight cut because during rotation only a percentage of the drive gear tooth is in contact with the driven gear. Hence the old school "rock crusher" M-22 Muncie compared to the M-21. The M-22 had staright cut gears, the M-21 doesn't. The M-22 was designed to handle more power (like the LS-6 454). If the helical gears were indeed stronger (which they are not) the engineers at GM would not have bothered.
cheers
cheers
You kind of said this with the rest of your post but your initial reasoning is flawed.
Road Master
Joined: May 2012
Posts: 1,081
Likes: 7
From: Canada
You are incorrect, the gears size for size are actually stronger in helical cut gears but the thrust loading leads to the requirement of stronger casings and it is the casing limitations that limit the use of helical gears to lower power applications.
You kind of said this with the rest of your post but your initial reasoning is flawed.
You kind of said this with the rest of your post but your initial reasoning is flawed.
That's right, it's not the contact of the teeth, but the side loading that makes using helical gears a bad idea in high performance applications.
A few more beers down range and I'll be all good
cheers