Upgrading the trans
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Road Captain
Joined: Apr 2009
Posts: 501
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From: Jersey
Upgrading the trans
I recently found and purchased a Baker DD6 to replace the worn and whining 5 speed in my 1988 FLHS, which after 29 years of upgrades and changes doesn't even look like a sport any. Got a great deal on the DD6 kit, which also includes a new primary chain and comp sprocket. $1778 shipped! Haven't decided which way I'm gonna go with the gearing yet but now I'll have three choices: stock comp sprocket, when combined with the Baker's higher trans ratios will provide more grunt and acceleration potential with the same overall top ratio 1 to 1 in 6th as stock. The alternate comp sprocket that came with the kit is a 27 tooth, 2 teeth higher than stock and would provide an overdrive 6th, and a 1 tooth smaller comp sprocket that will also leave 6th close to the stock 5th. Think I'm gonna stick with the stock comp for now. I'll be posting pics as I go to document the swap.
One thing I had to do is swap out the stock clutch with a later model that will fit the splined output shaft of the new trans. The stock clutch, which I have broken a hub on once already is for the tapered shaft and key way style. Already have a complete clutch from a 2003 that was given to me, just needs a minor repair and a couple of pressure plate bolts. Won't be sorry to see that old clutch go.
One thing I had to do is swap out the stock clutch with a later model that will fit the splined output shaft of the new trans. The stock clutch, which I have broken a hub on once already is for the tapered shaft and key way style. Already have a complete clutch from a 2003 that was given to me, just needs a minor repair and a couple of pressure plate bolts. Won't be sorry to see that old clutch go.
Last edited by bentparts; Dec 21, 2017 at 01:08 PM. Reason: Add a pic
Club Member
Joined: Aug 2008
Posts: 22,861
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From: Lafayette, Louisiana
I vote for Stock ratios on 1-5 and overdrive 6, especially if you ride on the interstate or high speeds for long periods of time.
If most of your riding is in town, Red Light to Red light, then every fear lower with 6 providing direct drive would be the better choice.
What engine mods do you have? What cam? Is it Stock displacement? These things are also a factor.
If most of your riding is in town, Red Light to Red light, then every fear lower with 6 providing direct drive would be the better choice.
What engine mods do you have? What cam? Is it Stock displacement? These things are also a factor.
Club Member
Joined: Jun 2007
Posts: 45,429
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From: Bedford UK
I bought my DD6 direct from Baker, when they had one of their sales. I chose the 27T comp, instead of the stock 28T, partly because I now have a 160x17" rear tyre which is a little larger in OD than the stock tyre. I also fitted a 30T front pulley, so I will have a slightly lower first gear, to cope with Alpine hairpins, but still have a taller top - for chasing Porsches down autobahns!
Strictly speaking the OD6 is an overdrive trans, in which the output shaft is turning over slower than the input shaft, when in top gear. The attraction of a DD6 is that input and output shafts turn over at the same speed, when in top, when it should also be more efficient. With over 100HP/100TQ I expect Hyacinth to be able to routinely run in top gear.
Hope that helps!
Strictly speaking the OD6 is an overdrive trans, in which the output shaft is turning over slower than the input shaft, when in top gear. The attraction of a DD6 is that input and output shafts turn over at the same speed, when in top, when it should also be more efficient. With over 100HP/100TQ I expect Hyacinth to be able to routinely run in top gear.
Hope that helps!
Dirt don't hurt
Joined: Jan 2011
Posts: 21,065
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From: Haslet Texas
That's why Baker recommends you get a different compensating sprocket which turns 6th from 1-1 to .86-1.
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Road Captain
Joined: Apr 2009
Posts: 501
Likes: 150
From: Jersey
I vote for Stock ratios on 1-5 and overdrive 6, especially if you ride on the interstate or high speeds for long periods of time.
If most of your riding is in town, Red Light to Red light, then every fear lower with 6 providing direct drive would be the better choice.
What engine mods do you have? What cam? Is it Stock displacement? These things are also a factor.
If most of your riding is in town, Red Light to Red light, then every fear lower with 6 providing direct drive would be the better choice.
What engine mods do you have? What cam? Is it Stock displacement? These things are also a factor.
I do mixed riding, mostly out in the country on back roads where the speeds are 50 or less and touring where i'll take the expressway to get to the good back roads. Very little city driving. Bike has enough power to comfortably run 80 MPH on the highway with the gearing it has now and still return 40 + MPG. I'm a touring cruiser who also likes to drag the floor boards in corners and occasionally race my buddies on what ever they're riding.
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I bought my DD6 direct from Baker, when they had one of their sales. I chose the 27T comp, instead of the stock 28T, partly because I now have a 160x17" rear tyre which is a little larger in OD than the stock tyre. I also fitted a 30T front pulley, so I will have a slightly lower first gear, to cope with Alpine hairpins, but still have a taller top - for chasing Porsches down autobahns!
Strictly speaking the OD6 is an overdrive trans, in which the output shaft is turning over slower than the input shaft, when in top gear. The attraction of a DD6 is that input and output shafts turn over at the same speed, when in top, when it should also be more efficient. With over 100HP/100TQ I expect Hyacinth to be able to routinely run in top gear.
Hope that helps!
Strictly speaking the OD6 is an overdrive trans, in which the output shaft is turning over slower than the input shaft, when in top gear. The attraction of a DD6 is that input and output shafts turn over at the same speed, when in top, when it should also be more efficient. With over 100HP/100TQ I expect Hyacinth to be able to routinely run in top gear.
Hope that helps!
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Road Captain
Joined: Apr 2009
Posts: 501
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From: Jersey
Doesn't look good
So, I pulled my primary apart getting ready to pull the trans apart. Went up to my buddies shop to borrow a race puller and some other special tools and we got to comparing part numbers for a clutch replacement to match the splined main shaft on the Baker kit. Turns out it's not as simple as getting a 1990 clutch and replacing my 1988 clutch with that. Harley changed so much between 88- 89 to 90 that I'd have to replace my complete inner primary, primary cover, starter, probably the wiring to the starter since my old bike has a separately mounted solenoid and who knows what else. As much as I would love to have the quieter running and smoother shifting of a Baker 6 speed It looks like I'm gonna have to sell this kit and just fix my old 5 speed. I can't just go to a 90 clutch because the starter ring gear is different too. Anyone ever converted an early evo trans from the tapered shaft with key to the splined main shaft of a later model evo?
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Road Captain
Joined: Apr 2009
Posts: 501
Likes: 150
From: Jersey
Finally got this sorted out
I've finally got this trans thing sorted out: after talking with Baker I've ordered a DD6 kit for 90/93 FLH and just purchased a 92 clutch assembly which is compatible with all my current parts on my 1988 FLHS, like inner and outer primary, starter etc. Kit should be here maybe by the end of this week. In preparation I've begun the tear down of my bike by removing all the parts that would be in the way and got to the point of removing the inner primary. After studying the FSM I was looking at the starter gear and trying to figure out a way to hold the gear while loosening the nut when I gave the gear a little tug and this is what happened: Pic 1, the whole starter shaft just slid right out in my hand. Now, it doesn't look damaged but the FSM doesn't say anything about it coming right like this. Hmmm, much easier but can this be ok? I planned to reuse my starter after a good internal cleaning since it was working fine but now I'm a bit concerned. Any body else experienced this?
