Speedo drive ratio

Chassis, frame, instruments, fenders etc.
Forum rules
Please do not start new topics here, but here: New Panhead and Flathead topics
Post Reply
zanny1
Posts: 6
Joined: Fri Jul 13, 2007 1:44 pm

Speedo drive ratio

#1

Post by zanny1 » Tue Feb 20, 2007 1:38 pm

My 60 FL reads 2 x the correct speed on the speedomoter. I believe the tranny is a 1956 and has a hand shift - foot clutch arrangment. Can I correct the reading with a different drive unit, or must I replace the speedo? Checked the forums but could not find anything on the subject. Thanks.



Cotten
Posts: 6791
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: Speedo drive ratio

#2

Post by Cotten » Tue Feb 20, 2007 3:07 pm

Zanny1!

You have two options:
Replace the speedo, or disassemble the transmission and install a different ring gear on the countershaft clustergear, along with a mated drive gear.
There are three different sets, so be careful.

Perhaps a speedo's ratio can be changed internally as well, I do not know.

....Cotten

zanny1
Posts: 6
Joined: Fri Jul 13, 2007 1:44 pm

Re: Speedo drive ratio

#3

Post by zanny1 » Tue Feb 20, 2007 11:23 pm

Post by zanny1 on Feb 20, 2007, 11:23pm

Thanks, Cotton. Looks like I need to locate a 1:1 ratio speedo. The box is in good shape, so no sense in taking it apart.

VPH-D
Posts: 804
Joined: Tue Feb 01, 2005 1:00 am

Re: Speedo drive ratio

#4

Post by VPH-D » Wed Feb 21, 2007 8:53 pm

The speedo drive ratio up thru 61 is 2:1. Perhaps you have the wrong speedo?
VPH-D

zanny1
Posts: 6
Joined: Fri Jul 13, 2007 1:44 pm

Re: Speedo drive ratio

#5

Post by zanny1 » Wed Feb 21, 2007 9:40 pm

Well living here in Venezuela there's no telling what is inside the box. But it would appear that if my current speedo reads twice as fast, I either have a 2:1 ratio in the box and a 1:1 ratio speedo, or visa versa. The speedo isn't marked, so is there anyway to tell what's in the box?

Cotten
Posts: 6791
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: Speedo drive ratio

#6

Post by Cotten » Thu Feb 22, 2007 3:17 am

Zanny!

I think the only clue would be to pull the drive gear and count teeth, and then consult Palmer's.

(My biggest confusion is the short run of wierd ones for early '61.)

If it has coarse teeth, its probably the common early drive.
If it has fine teeth, it is possible you have a late drive with an early ratio speedo. My feeble memory seems to make me think I got half speed with a late ratio on an early drive. But I gots CRS already.

If you have a reversible screwgun of a known RPM to drive the speedo with, then maybe we certain that the speedo is reading correctly, before tearing deeper.

...Cotten

FlatHeadSix
Moderator
Posts: 2682
Joined: Sun Jun 06, 2004 5:14 pm
Bikes: '31 VL, '34 VD, '45 WLA, '47 WL, '49 FL, '51 WL, '58 ST (Hummer), '71 GE (Servi)
Location: Lonoke, Arkansas

Re: Speedo drive ratio

#7

Post by FlatHeadSix » Thu Feb 22, 2007 4:56 am

Zanny
I had the same problem with a "rebuilt" OEM Stewart Warner unit. Turned out it had Kilometer gearing and a MPH face. Like you said, you are in Venezuala and anything is possible. I agree with some of the other advice you got, try another speedo with the correct ratio.
motorhead mike

Kuda
Posts: 342
Joined: Tue Aug 01, 2006 5:41 pm
Location: Maryland

Re: Speedo drive ratio

#8

Post by Kuda » Thu Feb 22, 2007 2:03 pm

Zanny1,

I've got good aftermarket 1:1 ratio speedo you can try if you like. Nothin' fancy, just a plain 1-120 black and white speedo, but it's yours for the cost of shipping if it'll help...

-Kuda
'49 FL

VPH-D
Posts: 804
Joined: Tue Feb 01, 2005 1:00 am

Re: Speedo drive ratio

#9

Post by VPH-D » Thu Feb 22, 2007 6:25 pm

Does the speedo have the gold and green face? This type was used from 56 thru 61. Look on the underside of the speedo for numbers like '509 ABC', these will indicate the year and type of speedo.
VPH-D

zanny1
Posts: 6
Joined: Fri Jul 13, 2007 1:44 pm

Re: Speedo drive ratio

#10

Post by zanny1 » Tue Feb 27, 2007 5:40 pm

You guys are great. Thanks, Kuda, for the offer. I am in south america, so I can't get anything shipped here. The guy I bought the used speedo from says he used it on a late model softail. I believe they are 2:1 ratio off the front wheel? My transmission has the numbers 121.85 stamped into it, with a raised boss and some numbers cast into the boss that i cannot read.

VPH-D
Posts: 804
Joined: Tue Feb 01, 2005 1:00 am

Re: Speedo drive ratio

#11

Post by VPH-D » Tue Feb 27, 2007 7:06 pm

A speedo from a Softtail will not read correctly on a 60 FL. If you were able to install this speedo on your Pan, you must have the wrong cable also. A 60 used a speedo with a female cable fitting, and a male fitting on the cable. The correct cable and speedo are available from antique guys. If you don't want to spend about $1000. usd, then H-D may still sell the eagle iron speedo in 2:1 for about @150.00 that uses a 62 & later cable.
VPH-D

zanny1
Posts: 6
Joined: Fri Jul 13, 2007 1:44 pm

Re: Speedo drive ratio

#12

Post by zanny1 » Tue Mar 06, 2007 8:23 pm

Did a little lookin on the internet. 2000 RPM on the cable is supposed to equal 60 MPH with a 2:1 speedo. Using my cordless drill, which maxes out at 1100 RPM, I got a reading of 69 MPH on a speedo that apparently reads twice actual speed on my scoot. 1.8182 x 69 MPH = 125 MPH at 2000 RPM. This would indicate that my box has a speedo drive of 1:1 and I need a 1:1 speedo. Hope this may help others who don't want to get into the box.

Post Reply

Return to “Chassis, Frame & Instruments”