Doing a 3.37 primary gearing setup, DO NOT hesitate! Do it!

Reply Subscribe

Thread Tools

Search this Thread

May 7, 2007 | 03:45 PM

#41

xxxflhrci

Extreme HDF Member

Joined: Sep 2006

Posts: 10,033

Likes: 29

RE: Doing a 3.37 primary gearing setup, DO NOT hesitate! Do it!

Quote:

ORIGINAL: 77Tulsa

You guys think your getting better gas mileage with lower gearing?

I have the HD brochures for the 2001 and 2003 model years. HD rated the gas mileage the same for both model years. All of the FI Touring bikes were rated at 46/39. Those are about the numbers that my FI 3:37 geared bike has always gotten, also.

I agree with the others. I enjoy the 3:37 gearing much more than the 3:15. I ride a 2003 Electra Glide at work. It feels likea dog compared the my personal bike. With the 3:37 gearing, not only is acceleration a bit quicker, top gear roll on's are much stouter. Riding two up and loaded heavy, there is never any need to downshift once you get about about 50 mph. The bike just takes off. With the cams that I have, the sweetspot is at about 70 mph. The bike jumps hard when you crack the throttle. I'm sure the guys with 3:37 gearing and 100hp/100tq have some bikes that are a blast to ride.

Aug 29, 2007 | 08:36 AM

#42

akpauly

6th Gear

Joined: Jul 2007

Posts: 12

Likes: 0

From:

RE: Doing a 3.37 primary gearing setup, DO NOT hesitate! Do it!

Hi all,
This sounds like it might be a good mod, as I'm planning on doing the self adjusting tensioner soon. Anybody know if the '06 police bike also came with the 3.15 gearing, or were they geared lower?
My '06 FLHTPI runs 3000 rpm at 70 mph in fifth.

thanx, Pauly.

Aug 29, 2007 | 09:19 AM

#43

cwilks

Banned

Joined: Jun 2006

Posts: 2,145

Likes: 1

From: St.Louis, MO.

RE: Doing a 3.37 primary gearing setup, DO NOT hesitate! Do it!

My problem is that when I'm on the highway I'm running 80 not 70 so what's the rpm's at 80?

Aug 29, 2007 | 09:56 AM

#44

Harleypingman

Extreme HDF Member

Joined: Apr 2006

Posts: 10,449

Likes: 46

From: Roswell, GA

RE: Doing a 3.37 primary gearing setup, DO NOT hesitate! Do it!

'06 final drive is 3.15:1.

cwilks: see this for calculating rpm/mph relationship:

http://www.nightrider.com/biketech/calc_speed_rpm.htm

Aug 29, 2007 | 11:02 AM

#45

Bryan TTM

Banned

Joined: Mar 2006

Posts: 8,603

Likes: 10

RE: Doing a 3.37 primary gearing setup, DO NOT hesitate! Do it!

the 3.37 gearing has a 37 tooth basket and a 24 tooth motor sprocket....gearing is what moves you...remember the 85 Z28 with its paltry 165hp...remember how fast it moved, its bc that was the first year of the 4sp auto and the gearing made the difference....there are two ways to go with kdeitz's "best of both worlds".....do a 3.37 with an SE bc the SE 1-5 gears are the same spread as your stock gears...that will yeild big low end and give your bike the ability to cruise at low rpms in 6th....OR....a Baker DD6 with a 37 tooth basket....both give results very similar....you can cheap out and just buy the engine sprocket for 100 bucks...it will yeild a final ratio of close to 3.21 and you can feel that in the seat of your pants....we've done the research, we've tested several setups....save your figg'rn and use this info for the best results

and the self adjusting tensioner is $HIT....it will ratchet as tight as it goes right off giving you a too tight condition....i also know this from experience...best to use the stock tensioner and do it yourself periodically

Aug 29, 2007 | 11:43 AM

#46

Harleypingman

Extreme HDF Member

Joined: Apr 2006

Posts: 10,449

Likes: 46

From: Roswell, GA

RE: Doing a 3.37 primary gearing setup, DO NOT hesitate! Do it!

I am going to make the 24Tswap to the compensating sprocket resulting in a 3.25:1 final drivewhen I get back from Ireland in mid-Sept and will post pics and results on my '04 EG.

Aug 29, 2007 | 11:58 AM

#47

pkenyon1

Road Captain

Joined: May 2007

Posts: 654

Likes: 0

From: Manchester, England.

RE: Doing a 3.37 primary gearing setup, DO NOT hesitate! Do it!

I have no idea what you are talking about...

Please explain what is done and what 3.37 means to a fool like me...

That way least I can ask someone who does know to do it for me, without looking foolish twice (fool me once shame on you etc. etc.)

Please let me know how much this improvement cost to do.

Thanks

Aug 29, 2007 | 12:05 PM

#48

Bryan TTM

Banned

Joined: Mar 2006

Posts: 8,603

Likes: 10

RE: Doing a 3.37 primary gearing setup, DO NOT hesitate! Do it!

simply put....the 3.37 changes the speed of the primary....in turn that changes the output at the tranny shaft which will feed more power to the rear wheel by means of gears rather than pumpin up your engine...the primary connects the engine to the tranny....it is not a direct 1to1 relationship...on the crank end(in the primary) is a sprocket(25tooth stock)...change it to a 24 tooth and you'll get one more tooth of pull for each revolution...on the tranny shaft is a clutch basket...on the back of the basket is a ring gear(stock is 36)...change it to a 37 .... its just the two gears inside the primary being changed to alter the final gear ratio