REPRINT FROM OLD HTT: WHO HAS HAD 3.37 GEARING THEN BACK TO 3.15 GEARING

[ClassicRider2002]

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DISCLAIMER: THIS IS A REPRINT TOPIC FROM "OLD" HTT

I have saved many great topical discussions as "links" over the years and would hate to see these lost, so I am reprinting this TOPIC here, which may "perhaps" help some.

TOPIC:  WHO HAS HAD 3.37 GEARING THEN BACK TO 3.15 GEARING  06-26-2005

   
From: VDeuce  (Original Message) Sent: 6/26/2005 7:10 PM   Message 1 of 33 in Discussion
I'm interested in hearing from those of you guys that have had 3.37:1 gearing on their bike, and have since switched back to 3.15:1.

I have a Deuce that has 3.37:1 primary, Underground heads, HSR45, 10.5:1 CR, etc.. and I think that having the 3.37:1 winds out first and second gears so quickly that I'm considering going back.  I ride about 50% two-up, but not usually around major hills. I do like to get out to the black hills every year too.  I like to haul ass and like to average 75+ when conditions allow for it, usually more like 85 when doing the long hauls.  Thanks in advance!

[ClassicRider2002]

From: oldschool Sent: 6/26/2005 8:22 PM   Message 2 of 33 in Discussion
I've never considered going back and I run 3.37 gearing on both my bikes. I have a problem with speeeding around at 80-85 too and still wouldn't consider changing to get only 240 lower rpms with the 3.15. Most performance shops recommend running 3.37 gearing with 10.0 and up compression. Not hard to understand why either if you think about it. The best $85.00-$95.00 dollars I've spent to stay out of the rev limiter in 1st, 2nd & 3rd is an all in one shift light.   
   

From: ButDiesel Sent: 6/29/2005 1:38 AM   Message 3 of 33 in Discussion
I would love someone to explain to me,the difference in the gearing discussion ,and why would you change and what are the benefit's.I have a RKC 03 95'',86 HP & 97 TQ,and would like a bit more get up and go.....in a previous thread,it was suggested to me to change my gearing and that should suit me!!!!!.......but i'm lost,what do i change to and why....ride two up a lot.Any help would be great thks.
   

From: jmorton10 Sent: 6/29/2005 5:41 AM   Message 4 of 33 in Discussion
This is what you change:
37846-99a clutch shell(37T) $230.26
40269-85a compensating sprocket(24T) $38.08

this gives you quicker accelleration through the gears at the expense of slightly higher revs at cruising speeds.  Your rpm will be around 300 rpm's higher at 70 mph.  ~John


From: allredallthetime Sent: 6/29/2005 5:53 AM   Message 5 of 33 in Discussion
I went the other way with my Deuce. When I had the engine work done, I installed a Baker DD6. I have plenty of power and 85 on the highway is really relaxed. I always felt the engine was a bit out of its element at higher speeds with the stock gearing. 
 

From: DeuceMeister Sent: 6/29/2005 5:57 AM   Message 6 of 33 in Discussion
I changed to 3.37 gearing and wouldn't consider going back.  My Deuce is so much more responsive in all gears and is a joy to twist the wick.  I have a 95 incher running 37g's, KB flattops, HSR 45, DTT, reworked heads, etc.  Of course, if I ran 80-85 mph on a regular basis I probably wouldn't have changed.  When I'm on the road I like to cruise at 70-75mph and that's no problema.  The 3.37's really woke the beast up. 


From: RideWideGlide Sent: 6/29/2005 9:18 AM   Message 7 of 33 in Discussion
Isn't there a larger rear belt pulley available? It should cost a lot less and would certainly be easier to install.  Hardcore


From: Thunderslide Sent: 6/29/2005 9:49 AM   Message 8 of 33 in Discussion
and screws up you speedo reading the primary gearing change does not.
   

From: wideglide4jesus Sent: 6/29/2005 9:50 AM   Message 9 of 33 in Discussion
I could live with a screwed up speedo just for the fact of how easy a pully swap would be!  Rick 


From: willyshd Sent: 6/29/2005 10:00 AM   Message 10 of 33 in Discussion
If I'm not mistaken the late model bikes come with a 70 tooth pulley. There may be one larger but I have'nt seen one. If your bike is an earley one they they had a 65 tooth, but I don't think this is the case. It won't be that easy and cheap when you have to change the belt to fit the new larger pulley.  Roger


From: blk-betty Sent: 6/29/2005 12:47 PM   Message 11 of 33 in Discussion 
Not just the dynas, my softail has a 70 tooth pully as well and I think all the newer TCs have 70 tooth too.

I wonder if you mean changing the font belt pully, don't remember the stock one's size but I know they make a larger one that changes the final gearing to something like 3.36.  It does make the speedo off and I consider this option before goint with the 3.37 swap using the compensating sprocket and clutch sprocket.

The problem with the front belt pulley change is you have to remove both the outer an the inner primary covers to get to it.  To remove the inner, you have to remove the clutch assembly and compensating sprocket along with the primary chain, starter jackshaft etc, etc,.  So the way I figured it, it was easier to just swap the compensator and clutch sproket from an remove and replace standpoint, plus the speedo is still accurate.

One advantage of changing the front belt pulley is it doesn't effect your starter, so if you have a high comp build and don't have compression releases, that may be the way to go.  Since swapping to the 3.37, I burned up my stock starter, but only because I was a dumba** and didn't consistenly use the releases, I do now however.


From: willyshd Sent: 6/29/2005 12:54 PM   Message 12 of 33 in Discussion
If you change the front pulley you have to go to a smaller one to get the results that you are looking for. If you change the rear pulley then you go to a larger one for the same results. It is an easier job to change the primary ratio. Roger


From: willyshd Sent: 6/29/2005 12:56 PM   Message 13 of 33 in Discussion
That is if you want to go from the 3.15 to the 3.37 side of ratio change.  You probably not be able to get it right on.  Roger
   

From: blk-betty Sent: 6/29/2005 1:15 PM   Message 14 of 33 in Discussion
Thanks Roger.  Couldn't remember if it was smaller or larger.  Basic rithmetic is not my stong point.


From: ButDiesel Sent: 6/30/2005 1:35 AM   Message 15 of 33 in Discussion
Thanks for your reply John.
Are those part #'s all i need to change to 3.37 gearing,doe's that include everything i need? ? ?  Dave


From: lugnuts09 Sent: 6/30/2005 6:38 AM   Message 16 of 33 in Discussion
I was considering going to 3:37, but after my buildup I stayed with the 3:15 and am glad that I have. I got plenty of torque [103] using Andrews 37 cam and I also have a great top end speed using the stock gears. In my opinion it wouldn't of been a cost effective gain for the amount it would of cost me on the top end speed.


From: ederdelyi Sent: 6/30/2005 7:03 AM   Message 17 of 33 in Discussion
>>I was considering going to 3:37, but after my buildup I stayed with the 3:15 and am glad that I have. I got plenty of torque [103] using Andrews 37 cam and I also have a great top end speed using the stock gears. In my opinion it wouldn't of been a cost effective gain for the amount it would of cost me on the top end speed<<

"Nit picker patrol" at work:

Actually, if you do the math and some real world testing you would find that you would actually have a higher *measured* top speed in 5th gear with the lower final drive ratio. Even a modified HD will have little likelyhood of revving to redline  with a 3.15 final ratio ... the final drive ratio has to be high on a low revving motor if it is to have a reasonable cruise RPM. Unless you are making *lots* of HP beyond 5500 RPM  you won't be able to pull the gear and will likely go faster in 4th than in 5th.

A motor with a wider RPM range can use lower gearing to greater effectiveness. That's *one* of the reasons why a 1000 cc sportbike with *only* 75 - 80 ft/lbs TQ can kick most HD's butts in both a top gear rollon and top speed.

We now return you to regular programming ...
*sticks fingers in ears*
"Na Na Na ... I can't hear you!"
   

From: munkeywithlobo Sent: 6/30/2005 10:57 AM   Message 18 of 33 in Discussion
I got a better idea, block out 5th gear and cruise around in 4th all the time.
It like having 3.87 gearing. Must be better than 3.37.  Bruce
 

From: YogibearRK Sent: 6/30/2005 1:13 PM   Message 19 of 33 in Discussion
Well here where it's a hunnert miles to town and I have the power to pull the 3:15's ( S&S 106 ,S&S 577's, SBC's prepaired heads, roller rockers , race tuner, ect ) I'll just stick to them and ride in 4th when I am in town !!!                                               Just my .02 Yogi


From: AO147 Sent: 6/30/2005 8:29 PM   Message 20 of 33 in Discussion
Ed,
If the tranny sprocket is changed from say a 32T to a 31T, does it throw the speedo reading off?
Shipey


From: dselko Sent: 6/30/2005 8:32 PM   Message 21 of 33 in Discussion
If you change the sprocket after the transmission, yes.  If you change the gearing in the primary, then this is happening before the transmission so the speedo is still accurate.


From: ederdelyi Sent: 6/30/2005 8:56 PM   Message 22 of 33 in Discussion
>>If the tranny sprocket is changed from say a 32T to a 31T, does it throw the speedo reading off?<<

Yes, but it's easy to correct the speedo with a re-calibration box. SnS and Dakota Digital (my preference) both make one.


From: lugnuts09 Sent: 6/30/2005 9:08 PM   Message 23 of 33 in Discussion
I thought the trnny ratios would not throw off the speedo. Just the final drive ratio would chage speedo reading. Kinda like putting a Super T-10 in your muscle car with a lower first,2nd 3rd gears does not affect final drive ratio; which therefore does not change speedo reading. 
 

From: ederdelyi Sent: 6/30/2005 10:10 PM   Message 24 of 33 in Discussion
>>I thought the trnny ratios would not throw off the speedo. Just the final drive ratio would chage speedo reading. Kinda like putting a Super T-10 in your muscle car with a lower first,2nd 3rd gears does not affect final drive ratio; which therefore does not change speedo reading.<<

Depends on where the speedo sensor is getting it's data from. On a HD, the speedo sensor counts gear tooth pulses from 4th gear on the mainshaft. Changing final drive ratios (as in the front trans sprocket from 32 to 31 or rear wheel sprocket from 70 to 71) will alter the pulse count as will changing the tooth shape of 4th gear. Trannies like JIMS 5/6spd and others with full contact gears require the re-calibrator even though the tooth count on 4th gear is the same. Changing engine primary ratios has no effect on the 4th gear mainshaft pulse count relationship and no re-cal is required.


From: joek86 Sent: 7/1/2005 7:22 AM   Message 25 of 33 in Discussion
I, and two of my friends have changed back  to 3.15 gearing.  We have 100/100 - 115/111 performance figures.  We all agree that it is better at 3.15!  We now have a first and second gear which was almost non existent with 3.37.  We are no longer on the rev limiter all the time and when cruising at high speed, the engine is more relaxed and not vibrating as much........... Joe


From: ederdelyi Sent: 7/1/2005 7:59 AM   Message 26 of 33 in Discussion
It all depends on one's perspective and riding habits/focus.

For the guy on a heavy bagger who likes to putt down the road at 50 -55 MPH in 5th gear and has the occasional need to accelerate to pass without (dare I say it?) downshifting, or pull a grade at that speed without (I'm gonna do it *again*)downshifting, it works well. It also works well for the guy who wants just a little better acceleration and isn't concerned about the 225 to 250 RPM difference at 70 to 75 MPH cruise speed.

I've found that most all "A" motor TC's get "happy" at 3000 and above, 250 -300 RPM difference or even more in cruise RPM is no big deal, my 125+ HP motor can "pull" the 3.15 gear as well as anyone's elses can, and even though my peak HP is at 7100 RPM, it won't pull to redline in 5th ( around 175 -180 MPH) but it will in 4th,  so like most others, it will actually go faster WOT in 4th than 5th. 5th gear with the stock final drive ratio is a cruising gear on an HD, not a performance gear.

Since I have the close ratio setup on my trans, my first gear is more usable even with lower final ratios. If you are one of the bulk cube crowd with a bigger TQ than HP setup, you could likely benefit with something similar to the Baker "R" ratio setup for a more usable 1st and 2nd gear ratio spread even with a 3.15 final drive ratio.

I find the "B" motors to be "buzzier" than an "A" motor, frankly, I don't care for 'em. But, each and every one of us have different perceptions. Some people are more sensitive to low frequency vibes, others to high frequency vibes. I've been around long enough to know that what we have today is far better than what we had in the past and *all* motors and motorcycles vibrate at some point.

If you are running in the 3000 - 4500 RPM range for extended periods of time, 300 RPM +/- has very little impact on wear or fuel economy. The numbers and my real world data don't lie ... so, shoot me, 'cuz I think differently than the rest of the "pack"!  I now have to run out and fall on my sword 'cuz I used the "D" word

ALTHOUGH I (ClassicRider2002) TOOK THIS POST* FROM A DIFFERENT THREAD, I THOUGHT THIS WAS A GREAT STATEMENT AND OFTEN TIMES FORGOTTEN AND IT FITS PERFECTLY WITHIN THIS THREAD AND AFTER ED'S POST ABOVE:

*From: L-Bar Sent: 12/5/2006 5:02 PM
I suppose if you ride a lot at sea level keeping your 3.15 gearing is fine,  but if you are at 7500 feet and ride to 10,500 feet, loaded, pulling 6% grades at times with a passenger and a heavy bike the 6.5% difference make a nice difference.  Actually at sea level and the little time I spend there I don't mind 3.37.


From: munkeywithlobo Sent: 7/1/2005 8:21 AM   Message 27 of 33 in Discussion
Ed
I pretty much agree with all that you say so I guess you find that there is more one that don't follow the pack.  The 3.37 gearing is probably OK but IMO and incomplete setup. Going to 3.37 turns first gear into a granny gear which is almost useless unless you are pilling a hack or a trailer. When going to 3.37,  I'd go to a 2.91 first which puts it back in the range of the first with on a 3.15 and 3.24 first gear. BTW still running 3.15 and like it.  Bruce
 

From: ederdelyi Sent: 7/1/2005 8:31 AM   Message 28 of 33 in Discussion
Bruce,
Yup. That's why I have the 2.91 1st in mine. With a Dyna or any of the "lighter" bikes, the 2.91 gear works better with 3.15. 3.37. 3.42, 3.74 ... almost any *usable* final drive ratio. The heavy bikes can use the 3.24 1st, it would work much better if the motor had a wider rev range, but HD's don't need to be revved over 4500 RPM, so that kills that idea!


From: blk-betty Sent: 7/1/2005 8:59 AM   Message 29 of 33 in Discussion
I was under the impression that the earlier EFI TCs came with 3.37 final gearing and all of the oler Evo style Big Twins.  Am I wrong?  If I'm right, did the MoCo change the transmission ratios from the Evos to the Big Twins or did the older bikes have the "granny" first gear and everyone just put up with it.

I swapped the gears on my softail and although I do like it better this way, if I did a lot of high speed driving, like to stick with the back roads and see the countryside, I'd probably go back to the 3.15.  Ed's right, the B motor is quite buzzy above 3500 rpm. 

Didn't really realize how much so unitl we got my wife a dyna and I rode her bike.  First Harley was a 1200S, didn't think it vibrated all that much until I got the softail, what a difference.  Actually rode a Evo Fatboy after I bought my TC and thought the Evo softail vibrated almost as much as the sporty.  Didn't think my 02 was that bad until rode my wife's dyna and bro-in-law's RK. 


From: jmorton10 Sent: 7/1/2005 10:31 AM   Message 30 of 33 in Discussion
You most definitely DO NOT need a six speed tranny to make use of 3.37 gearing, these motors will run happily all day long at 3500-4000 rpm's.  I have had 3.37 gearing in my last two bikes & never felt I needed another gear.
~John


From: RideWideGlide Sent: 7/1/2005 10:37 AM   Message 31 of 33 in Discussion
I'm sure I've asked this before, but, being old, I forget...

My SERT setup information defaults primary drive ratio at 1.440 and secondary drive ratio at 2.188. How does that equate to the primary ratio of 3.15 or 3.37?


From: bcnasty Sent: 7/1/2005 10:49 AM   Message 32 of 33 in Discussion
I love my 3/37 gears in the 05 deluxe with a B motor I was worried about vibration after going from a FLHT to the deluxe but at 70 I am ok after 78 it's a little much . I am equally glad the deluxe has a chrome rear fender trim . I use it like a skid plate and have replaced it for the 3rd time due to syn air in the front tire making the tire rise off the ground.I will say if you are the type to hit the rev limit on every shift its not for you but the few times a day I do and expect to rev quick I shift past that point and flat out love the quickness. I actually beat my sons RC Honda thru 3 gears then he walked me badly. But for three gears the old guy had him.  bcnasty


From: ederdelyi Sent: 7/1/2005 11:02 AM   Message 33 of 33 in Discussion
>>My SERT setup information defaults primary drive ratio at 1.440 and secondary drive ratio at 2.188. How does that equate to the primary ratio of 3.15 or 3.37?<<

Primary ratio  X final or secondary ratio = true final ratio

25/36 primary = 1.44:1
24/37 primary = 1.54:1
32/70 seconadry = 2.1875:1

1.44 X 2.1875 = 3.15:1
1.54 X 2.1875 = 3.36875 (3.37):1

[ClassicRider2002]

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Anything added beyond this point is new information.

Regards,

"Classic"

[ClassicRider2002]

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I actually have a excel spread sheet that was provided within a THREAD here at HTT by:
From: Fuzznut5197 Sent: 6/13/2008 7:01 PM
Anyone have any use for this driveline spreadsheet? It was posted here back in 2003, and I thought is was saved somewhere in HTT, but I can't find where.

Hopefully all will be able to down load the EXCEL PROGRAM below next to the "paper clip"

If you plug in your actual gearing (comp sprocket "T"ooth size, clutch shell basket/ring gear "T"ooth size, rear wheel sprocket "T"ooth size, transmission "T"ooth size as well as rear wheel diameter then it will factor RPMS and such which would aid you in determining what level of gearing you might benefit most from........then if you wish to ponder some other options for your comp gear or your clutch shell basket gear or perhaps your secondary gearing which might require a different belt you can see what might create the biggest bang for your buck.....

[NOTE: Please remember that putting your cursor next to the paper clip icon below will allow you to open this EXCEL PROGRAM, if you desire simply choose to save the program to your computer as well]

[attachment removed after 60 days by system]

[ClassicRider2002]

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Hello Everyone~~~

Through out all of the "old" THREADS that deal with the 3.37 Gearing Modifcation to our TWIN CAM BIKES I really enjoyed reading them....and after all of the valuable input from everyone whom posted, I eventually did the MODIFCATION to my 2002 RKC.  Like many before me have stated and I must concur, this MODIFICATION has to be ONE OF THE ABSOLUTELY BEST MODIFICATIONS I have done to my "BAGGER", it's such a wonderful "bang" for the buck invested....

Thus I put together a detailed THREAD about the modification, if you are interested in reading about such Simply CLICK, VIEW, & READ the Attached "LINK" below:

3.37 MODIFICATION GEARING INSTRUCTIONS FOR 2002-2006 TWIN CAMS 

I happen to be "ClassicRider" @ V~TWIN FORUM.

Regards,

"Classic"