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Discussion Starter · #1 ·
Does anyone have a Jims six speed transmission installed?

I’m looking at a six speed and I like the gear ratio of the Jims better than the Screaming Eagle. The Jims 1st gear is 2.94 compared to the SE of 3.21. This is supposed to provide about 5MPH more of useable 1st gear. Also the Jims overdrive is .86 compared to the SE of .89. This will provide a little lower RPM for highway cruising and after all this is why I’m looking at a six speed. Jims appears to be a little more bang for the buck. But since any 6 speed is expensive, I’d like to hear from some one who has a Jims six speed installed and if you bought the gear kit or the complete tranny.

Also I’ve heard the Screaming Eagle is made by Jims. Does any one know if this is true?
 

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Geno said:
Does anyone have a Jims six speed transmission installed?

I’m looking at a six speed and I like the gear ratio of the Jims better than the Screaming Eagle. The Jims 1st gear is 2.94 compared to the SE of 3.21. This is supposed to provide about 5MPH more of useable 1st gear. Also the Jims overdrive is .86 compared to the SE of .89. This will provide a little lower RPM for highway cruising and after all this is why I’m looking at a six speed. Jims appears to be a little more bang for the buck. But since any 6 speed is expensive, I’d like to hear from some one who has a Jims six speed installed and if you bought the gear kit or the complete tranny.

Also I’ve heard the Screaming Eagle is made by Jims. Does any one know if this is true?
Geno,

You don't say what model HD you have so I tried looking at post you've made and I believe you have a Dyna model. You will probably be alright with a 2.94 ratio 1st gear but depending on if you ride 2up a lot or not or had a Bagger then you might want to stay with the 3.21/3.24 1st gear unless you have a bulk cubed bagger, then the 2.94 should be ok. Reason I'm saying this is I have a bagger with a 2.94 ratio 1st gear, an if I wasn't a bulk cube bagger I would not have opted for that option. It work great for me but then again I'm running 3.37 5th gear overall final drive ratio to help make up some of the mechanical advantage I lost in 1st and because I also have effective .86 ratio 6th gear. I choose the 3.37 ratio to try and make 6th gear work for me at 75 & up mph instead of 80/85 & up.

At 70 I just stay in 5th unless I'm cruising long flat stretches of road as RPM drops down to around 2650 rpm and my engine only pulls hard from 3000 rpm & up in 5th gear so I wanted to at least get 80 MPH in the 3000+ rpm range and 75 in 2840 rpm range. By comparsion if I had gone with 3.15 overall 5th gear final drive ratio with .86 6th gear my 70 mph rpm in 6th would have been in the 2475 range, 75 mph in the 2650 rpm range and 80 mph in 2830 rpm range. On the type terrain around where I live might as well not have a 6sp even with a 124" bagger. The .89 SE 6sp would have been just if not more useful to me with 3.37 overal 5th drive ratio.

With 3.15 overall 5th gear final drive ratio will give you a 2.7 over all 6th gear final drive ratio with .86 6th and 3.37 5th final drive ratio and .86 6th gear ratio will give you a 2.9 6th gear. By comparsion the .89 6th gear ratio will give you a 2.8 ratio with 3.15 and 3.0 ratio. Based on what rpm your engine will pull hard from in 5th gear you could find 6th gear with either .86 or .89 just about useless for all but about 1-3%of the time.

Bottom line to make a 6th speed as useful as possible make sure your primary and secondary drive ratios will give 6th gear enough mechanical advantage to make it as useful as possible for you. I would have liked to been a 3100 rpm in 6th gear and that would still have been 400 rpms less than 5th gear at the same speed with 3.37 over all final drive ratio.
 

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Discussion Starter · #3 ·
TURBOTC, thanks for the info. Yes, I have a 2004 dyna low rider. I weight about 150 and normally don’t ride 2 up so it appears the 2.94 1st gear will be just fine. Besides I always thought 1st gear on my bike was a little to short.

You didn’t mention the manufacture of your 6 speed.

Is it a Jims?

Do you buy the complete tranny or just the gear set?

You replied with a lot of info about the final drive ratio. I believe my current five speed final drive ratio is…

(Clutch / Engine) * (Rear Wheel / Transmission)

(36/25) * (70/32) = 3.15 to 1

So if I understand a 3.15 final drive ratio with a .86 is not such a good idea and this is why you are running a 3.37 final drive ratio. What did you change to get a 3.37 final drive ratio?
 

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Geno said:
TURBOTC, thanks for the info. Yes, I have a 2004 dyna low rider. I weight about 150 and normally don’t ride 2 up so it appears the 2.94 1st gear will be just fine. Besides I always thought 1st gear on my bike was a little to short.

You didn’t mention the manufacture of your 6 speed.

Is it a Jims?
I'm running a Baker 6sp. Baker has 2.94 first gear option for both his OD6 .86 6th gear ratio and his DD6. Baker also offers "R" ratio 1st & 2nd gear for his OD 6 only which is a 2.82 ratio 1st gear & 2.08 ratio 2nd gear. He also offers a deep .80 overdrive. I'm running the DD6 which Bakers refers to as having an effective .86 6th gear ratio. 6th is 1:1 but with 28/37 primary and 32/70 secondary drives 6th gear rpms are also identical to his OD .86 6th using 24/37 primary gearing.

Do you buy the complete tranny or just the gear set?
I bought the builders kit.

You replied with a lot of info about the final drive ratio. I believe my current five speed final drive ratio is…

(Clutch / Engine) * (Rear Wheel / Transmission)

(36/25) * (70/32) = 3.15 to 1

So if I understand a 3.15 final drive ratio with a .86 is not such a good idea and this is why you are running a 3.37 final drive ratio.
What I'm trying to do is make you understand for a 6sp to be most effective you need to consider more than just rpm in 6th gear. The engine needs to be able to pull the gear and based on where you engine pulls hard from in 5th gear and the terrain in you area, 6th gear might be useless for the most part. I'm useing an S&S 124 to spin the tranny. I got lucky as I did not know where it's power came on as I did everything at one time. I guessed and hoped for 3100-3200 rpm based on some dynos I'd seen with different pipes, so I tried to get 80 mph rpm between 3050 and 3200 to try and be able to pull most to the grades I encounter in my area without having to downshift to much. 4th gear works from 50 to 60 mph, 5th 65-75 and 6th 80 & up although I can run at 75 MPH in 6th too. While 70 is possible in 6ht gear, I perfer to dwonshift to 5th as I'm back at around 3000 rpm and in the engines power band again. I do not have to downshift out of 6th gear for the most part from 80 mph and up as I'm within the engine's power band. If I want to pass quickly an in 6th at around 80 mph then I downshift to 5th. You would called the terrain "Foot Hills" in my area. Not many long flat straights.

What did you change to get a 3.37 final drive ratio?
Since I went with with the DD6 that has a 1.15:1 ratio 5th gear and I had not converted to chain my 5th gear ratio would have been 3.23 or 3.32 depending on if I used a 36 or 37 tooth clutch sprocket with 32/70 secondary. With 28/37 primary & 23/51 chain secondary drive I have 3.37 5th gear overall drive ratio and 2.9 6th gear overall drive ratio.

You would change your primary sprockets from 25/36 to 24/37 to get 3.37 with an OD 6sp as 5th gear is 1:1. Using the 24/37 primary gets you a 2.9 6th gear dirve ratio. That's the same 6th gear final drive ratio I'm running.
 
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