Ok,

I have been hearing alot about this IDS, but I am not quite sure what it is? How does it work?

 

Isolated Drive System. It's a comeback from a number of years ago that was discontinued and now a "new" item again. The system is a two piece rear pully/hub that is isolated by rubber to absorb some of the torque shocks of the V twin engine. Makes the ride a bit smoother...it's nice but a properly adjusted belt will do much the same job. Seems like tire noise is amplified through some of these hollow metal sub-assemblies.

 

OTHER SAY IT HELPS A LOT WITH THE 07 TOUR MODELS CLATTER CHATTER SOUNDS COMMING FROM SOME WHERE IN THE DRIVE TRAIN. THE SOUND IS A NORMAL SOUND THAT ALL THE TOURING MODELS MAKE SAYS H.D.

 

Thank you for the clear description.

I just put a 6 speed Accessories Unlimiited gear set in my 2003 Road King. It shifts through all of the gears very smoothly, however I get a lot of whine and chatter from 3rd gear on up. This happens at lower RPM's and/or when I downshift. First and Second gear, on the other hand, are relatively quiet.

My friend has a Baker 6 speedin his chopper and he says thatmy transmission is actually much quieter than his. Would an IDS help me with my problem?

 

Does anybody have any idea of why this whine and chatter is typical in 6 speed transmissions?

 

IDS only fits 2007's and comes stock on 2008's.

 

Aftermarket (and pre '07) gear boxes have straight cut gearteeth as Harleys always have. The straight cut teeth are 'whiney' as speed or load increases but are fine otherwise. Also, the backsides (coast side) of these gears are sometimes not as well 'dressed' or surface prepaired before hardening as the front (or drive side) so will whine from uneven contact during a coast or downshifting. An ideal gearset has total contact throughout the tooth engagement all the way through the involute and the next tooth will continue the load carrying. That is a major task for some gears in a gearbox because of the fact that the tooth contact is modified due to space. A gearbox gears are a mixture of pressure angles and diametral pitches to compensate for the ratios in a given space requirement. Those gears will very pleasently whine when they are transferring torque and load. As long as the shifter dogs are doing OK with slipping into eachother without a rake during a shift, the transmission is fine. Some heavier gearlube will silent some of the whine noise but the chatter is harder to quash or silent. Thats where the angular cut teeth and the IDS for the new Harleys came from - noise - from the bikes and customers that demand some quality. The '08 transmission whines in both first and fifth. Fifth is where the bike rides the most! The IDS will do nothing about the gear whine. Baker has a fix already for the '07 and '08 fifth gear whine.

 

Thanks for the explanation. I am still a bit confused though. If my stock gearset was straight cut, why didn't it whine and chatter?

If I understand what you are saying, it is because the tooth contact is NOT modified due to space. Also, you have said that the new Harley have angular cut teeth, however all I hear is that these bike whine and chatter also. I guess what you are saying is that this was Harleys attempt to fix the whine, but it did not work for 1st and 5th gears.

 

The new HD transmissions gears are angular cut except first and fifth which are still straight cut, and they whine. The rest do pretty good as far as whine goes. Some of the 'take-up' clatter is still there - it's the nature of this type of gearbox...And I'm not sure why they didn't follow through with fifth...

Now I'm not saying that some gears are cheaper than others in their manufacture but it stands to reason that a gear that has a better finish or even a ground finish will be much quieter running than a rough surfaced set. The 'rougher' set may be just as good and last just as well but you can tell the difference right away by their mesh sound. Some manufacturers even make wild modifications to the tooth shape to get the ratio that they want. Most of those will whine and clatter as the shape discontinues a constant mesh throughout a revolution. Most of this clatter is the total 'take-up' in a gearset where there are multiple junctions through dogs and splines in the change gears to make a final ratio. The take-up can be as much as a quarter turn of the rear wheel before the input is touched. That is a clatter that can only be taken out by a wise choice in a heavy lubrication with some EP additives - but not totally a hypoid lube.

Gears are a complex subject but the answers are pretty straight forward. The shape and center to center distance makes the mesh either a smooth transition or a whine. Too tight, they will whine - too loose, they will whine. Now add the tooth pressure angle and tooth shape and the problem gets much more complicated to the point of a compromise with the total expense of manufacture, or the noise. Harley is in the middle with these and I personally believe that they chose the cheaper route. Thus the IDS.