need some instruction with putting 3+R in a 4 speed case thanks
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3 speed with reverse
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What year of transmission, meaning tin primary, 65-69 or 70 up? There are a couple of reverse gear sets that are not interchangeable, so make sure the gear sets match. Also if your case is not machined for the reverse idler gear, it will need to be machined.
I run a 1969 flh sidecar bike with a 3R transmission that I built and installed. I am going to put the 4 speed back into the bike because I put a lot of miles on it and the 4 speed would be the better choice for an over the road transmission. So what are you going to use the bike for, daily runner or very seldom ridden, it makes a difference?
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I wouldn't do it unless necessary.
The 3-spd 2.71:1 first gear is substantially worse (lower number) than the 4-spd at 3.00:1, which is the opposite of what you want for more weight. The 3-spd's 1-2 shift falls off a cliff with 45% RPM loss (4-spd is 39%), the 2-3 is very bad at 33% ( 4-spd is 19%). This means you have no downshift at higher speeds - you can't reach second without buzzing the motor.
These work as OEM gearing because the engine (and transmission?) sprocket is smaller.
4-spd: 3.00, 1.82, 1.23, 1.00
3-spd. 2.71, 1.50, 1.00Last edited by kitabel; 10-26-2022, 11:31 AM.
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I run a 21 tooth engine sprocket with a 23 tooth trans sprocket with my 3R trans, I cannot downshift from 3rd gear down to 2nd gear until I go down to 20-25 mph, this makes it a pain once in a while like going up a hill behind a slower driving car or in a hilly area in general. As far as power is concerned, It is not an issue and you get use to riding with the 3r trans over time. The 3R trans is also a sliding gear trans that grinds once in awhile, like a Model A or a tractor. I had a couple of issues with my trans that ended being a clutch issue, the clutch has to be adjusted almost perfectly.
My bike pushes very easily and I only have one leg, so the 3R is coming out of my bike, mainly because of the 3-2 downshift. I get 35 mpg without a passenger, 30 mpg with my wife in the sidecar and 25 loaded down with camping gear for 2 separate people and my 200 lb nephew.
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Big engine, low speeds,good low RPM power: fewer gears, farther apart (truck, cars 70 years ago)
Small engine, big cam, high speed, bad low RPM power: more and closer gears
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I built my 44UL specifically for sidecar use 45 years ago and used a 3&R transmission. It is still in the same configuration and still my favorite bike. It has been on thousand mile trips with a passenger over high mountain passes (for example Red Mountain Pass, 11018 ft) here in the Rockies. At times a 4 speed may have been nice but it has always performed just fine within its limitations and I would never change it.Robbie Knight Amca #2736
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Originally posted by shovelheadstan View PostThanks all for your help. Putting together a trike with a shovel motor. I think I would like the idea of having reverse but am almost talked out of it. This bike would be used on occasion for small trips and most likely ridden on back roads. Have put together many rachet top four speeds.
ps: Have you thought about a 5 speed because reverse gear can be added without effecting the forward gears?
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Originally posted by Rubone View PostLook at the Shovelhead forum on here, member Ryan just bought a pile of parts with a 3&R in it.Last edited by ryan; 10-28-2022, 01:38 AM.
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