Change final drive sprocket
Thread Starter
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Tourer
Joined: Dec 2012
Posts: 262
Likes: 31
From: So-Cal, USA
Change final drive sprocket
I have a 2001 FXDX and I want to get my RPM's lower while I'm at highway speeds. I know there is the 6 speed kit but that's like $3k and my understanding of the gearing is the 6th gear isn't much of a difference from what I've got on my current 5th gear.
So if i change out the sprocket on the rear tire would that help me out?
I haven't gotten around to checking the gear count on there but the primary and the tire sprockets are both stock. should i change the primary side bigger, or should i change the wheel side smaller? how many teeth of change should i get and is there a calculator i can use to calculate this before i buy something?
Also changing the teeth would throw off my speedo, how do i change that on an old bike like mine that doesn't have a modern computer that can just change easily
So if i change out the sprocket on the rear tire would that help me out?
I haven't gotten around to checking the gear count on there but the primary and the tire sprockets are both stock. should i change the primary side bigger, or should i change the wheel side smaller? how many teeth of change should i get and is there a calculator i can use to calculate this before i buy something?
Also changing the teeth would throw off my speedo, how do i change that on an old bike like mine that doesn't have a modern computer that can just change easily
Seasoned HDF Member
Joined: Mar 2010
Posts: 21,091
Likes: 7,611
From: Poolville
Here's what I use..
https://www.rbracing-rsr.com/gearspeed.html
I don't know what you currently have but this will get you going in the right direction.. Because it's a 88" motor I really wouldn't go below 2600 at 60 mph in 5th gear...
https://www.rbracing-rsr.com/gearspeed.html
I don't know what you currently have but this will get you going in the right direction.. Because it's a 88" motor I really wouldn't go below 2600 at 60 mph in 5th gear...
Thread Starter
|
Tourer
Joined: Dec 2012
Posts: 262
Likes: 31
From: So-Cal, USA
Here's what I use..
https://www.rbracing-rsr.com/gearspeed.html
I don't know what you currently have but this will get you going in the right direction.. Because it's a 88" motor I really wouldn't go below 2600 at 60 mph in 5th gear...
https://www.rbracing-rsr.com/gearspeed.html
I don't know what you currently have but this will get you going in the right direction.. Because it's a 88" motor I really wouldn't go below 2600 at 60 mph in 5th gear...
But how would i correct my speedometer? I don't want to sit there and look at it being like 15 mph (or whatever it ends up being) off. I know in my old mustang i was able to pull out the speedo gear from the tranny and change it to a different sized one. is that something that i can do on a Harley?
Thread Starter
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Tourer
Joined: Dec 2012
Posts: 262
Likes: 31
From: So-Cal, USA
I found a 34T front pulley that seems like a good fit, but for the back I'm a bit uncertain about the thickness/width of the pulley. I have found a 66T and a 65T one but they say its 1 1/2" thick (link is example since the drag website wont link right). i am pretty sure mine is 1 1/8". would there be any issues with using a wider pulley? i mean smaller yeah obviously that would cause an issue because the belt wont fit, but a slight bit wider seems like it should be ok, can anyone confirm?
Road Master
Joined: Oct 2017
Posts: 815
Likes: 292
From: Uptown Bay Area, Cali
Your stock pulleys are 32T and 70T with a 1-1/8" wide 133T belt.
I do have to ask. At 75 mph, you are talking less than a 400 rpm difference if you changed radically to a 34T front and 66T rear. You would then be in the bad vibration zone at 75 mph of 2,800 rpm. Your bike is geared optimally right now. It would be a lot more sluggish with taller gearing, especially stock.
I had 32T and 66T gearing, and went to a chain drive and geared lower to get out of the vibration zone at 75 mph.
You might drop RPM, but end up going faster to get out of the vibration, and end up going at the same rpm as you are now. LOL
Dave
I do have to ask. At 75 mph, you are talking less than a 400 rpm difference if you changed radically to a 34T front and 66T rear. You would then be in the bad vibration zone at 75 mph of 2,800 rpm. Your bike is geared optimally right now. It would be a lot more sluggish with taller gearing, especially stock.
I had 32T and 66T gearing, and went to a chain drive and geared lower to get out of the vibration zone at 75 mph.
You might drop RPM, but end up going faster to get out of the vibration, and end up going at the same rpm as you are now. LOL
Dave
Last edited by TOE_CUTTER; Mar 9, 2021 at 06:28 PM.
I would be cautious with the 01 pulley replacement. There were changes to the size locator ring cast into the wheel hub, there are adaptors but that effects spacing. Plus, the 01 ran the 1-1/8 belt in order to fit the 150 tire, going to a 1-1/2 may limit you to a 140 like the 99. Honestly, toe & 98 are right, its a minor change that isnt really for the best: it puts your cruising speed at a less then ideal RPM for the engine and will make first too tall (ride a 6 spd bagger and see what Im talking about...).
There are only 2 real answers here, live with it, or spend the money for the 6 speed. Im running the baker DD6 in my 99 and that thing is amazing, the ratios are just right and cruises beautifully at 75-80.
There are only 2 real answers here, live with it, or spend the money for the 6 speed. Im running the baker DD6 in my 99 and that thing is amazing, the ratios are just right and cruises beautifully at 75-80.
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Seasoned HDF Member
Joined: Mar 2010
Posts: 21,091
Likes: 7,611
From: Poolville
Actually with your primary at 25/36 and a 34/66 secondary it will put you at 2.79:1 in fifth.. with the motor mods you say you have, you should be good. Just be careful with first, a 8.21:1 is pretty high.. higher then the old 4 speed shovels... with a 8.34:1 ratio in 1st..
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Joined: Feb 2019
Posts: 65
Likes: 23
From: alberta canada
On my 99 FXD with a 97 kit, cams etc I went with a 34 tooth front sprocket and the stock 70 tooth rear. Original belt fit and the bike cruises nice at 75 to 80. I do find in the 65 to 70 range there is more vibration than with the stock gearing, still have great passing power even in 5th.
For the Speedo error I got the Thunderheart programmable speed sensor.
For the Speedo error I got the Thunderheart programmable speed sensor.