6 Speed DDS 6 vs 5 speed and chain drive

[David Jackson]

Hi Mike;

I am having my BAKER DDS 6 sent back to BAKER because of some shifting problems under hard acceleration. BAKER folks say there may be an improved shifting drum which I am thinking they will supply. They seem to be very helpful, at least so far, so I am not faulting them at all.

Question though, we have talked about hp and tq losses with the DDS 6 gearset because of the added leverage needed with the larger engine sprocket used in that application. If I use the DDS 6 again is there any way to avoid that loss? I think a stock engine sprocket would lower the top gear ratio to stock 5 speed.

I could also sell the BAKER gearset and use the SE 6 speed; what experience do you have with those?

I like having the higher gear for flat freeway riding. With my 113" engine I am wondering if I really need to have 6 speeds! I used to think of so many speeds as being something one needs for a peaky motor with a narrow powerband; not the case with most HDs.

I have been thinking of having my stock transmission gears put back in and finding some other way to get the high cruising gear.

What about chain drive with the option of different sprockets, especially for the rear wheel? Way back in the good old days I had a CH with a KR rear wheel and a stack of sprockets. I do have a (never used) chain drive conversion kit and wonder about using it with some different rear wheel gearing to lower rpms at cruising speeds.

I was talked out of using the chain kit last year by those who reminded me of the weight of the chain and those who told me more energy would be used up moving a chain around than is used up moving a belt around. Are those factors which make much difference?

Regards;

David Jackson

[Mike]

Baker has had some shifting problems and have been correcting them. Reports are that the corrections work extremely well. The S.E. trans does not exhibit the hp losses of the DD6 (about 4 hp vs 6) and we believe this to be a function of the primary reduction used in the DD6. That reduction is required to achieve overdrive in the DD6. This diff. between the two may be negligable on the street and I would not recommend trading one in favour of the other. Again, it goes back to the reason for installing the 6 speed in the first place and what we are trying to accomplish. Big high torque motors can get away with 5speeds and reduced (numerically) final drives (typ. front pulley changes) to accomplish an overdrive. These motors often end up in touring bikes and so may carry a much greater load or pull trailers. In these cases, regearing the final drive may not be desireable because you still want a deep drive first gear to get things moving. Changing the final drive changes all ratios, so now the 6 spd makes sense. Oddly, the guys with lighter bikes often want a reduced (numerically) gear set because these big motors accelerate so quickly you find yourself shifting immediately after letting the clutch out. As you can see it's kinda all over the map as to what people are asking for.
A high quality new chain will have about the same effeciancy as a belt, but as it wears that effeciancy deteriorates. That wear begins as soon as the rear wheel turns. The maintainance and mess that comes with chains and sprockets just does not seem to be worth the change.
Thanks, Mike

[David Jackson]

Hi Mike;

As always thank you for your most comprehensive reply to my post. I have been singing your praises as the major HD guru to anyone who will listen!

I gather an SE 6 speed may cost approximately 4 hp and the DD 6 may cost about 6 hp. As you say the difference seems hardly worth making such an expensive change.

Chain efficiency deteriorates as soon as the rear wheel turns ... I can understand what that means and also the maintainance mess and hassles.

Is there any source for alteration of final drives with belt drives? ie different sprockets, different length belts, any kits to alter belt lengths and so on?

Regards;

David Jackson

[Mike]

My head is starting to swell!!! Thank for the praise, it's greatly apprecciated. Rear sprocket selections are somewhat limited but front pulley's have a few more options (basically limited to primary/swingarm clearances). A wide variety of belts/lengths are available from BDL, Gates and Panther (Drag Specialties catalog) to pretty much fit any application that sprocket choices would allow. There are some belt repair kits that would, in theory, allow belt lengths to be modified but the strength would be highly questionable. They are designed as a temporary fix to get you to a shop for full repair (just like new car spare tires).
Thank you for using this forum, I hope others are enjoying these conversations as well! Mike