Speedometer and Speedometer Cable Questions

[rozemab]

Hello,

Troubleshooting a speedometer problem, would not register mph or odometer distance.

The head will react fine if I twist the inner cable with my fingers. Tracing the problem back to the gearbox it appears the inner drive cable may have sheared off (broken?) inside the drive unit that is screwed into place externally to the box.

1) How long should the inner drive cable extend beyond the medal cup at the end? My cable looks to be 5/8 inch beyond the end of the cup. The inner cable end doesn't look clean and sharp and thus I suspect the inner cable broke off inside the drive assembly.

2) Using a caliper, I measured the square female socket to be just about 1/4 inch in depth. Obviously 5/8 - 1/4 = 3/8 and thus a problem.. ,,,,, I removed (uncrewed the cable from the drive assembly) so I suspect it broke inside the assembly.

3) Should the drive assembly pull straight out of the gear box after removing the screw? Mine is pretty tight to the box. I can rig up a device with a slide hammer to tap it out if I knew the thread size of the knurled nut used to tighten cable to the drive.

thanks, Brian

PS If the cable is bad I can cut it and use the nut to remove the drive assembly. I will need to get a new drive and cable anyhow.

[mbskeam]

pull the drive and use dental picks to get the broken cable out. if this dont work then a small drill bit may work

[rozemab]

mbskeam,

thanks for the reply, should the socket be at least 5/8in in depth? (in the drive assembly)

Brian

[rozemab]

I could not remove the old broken cable from the drive. I ordered a new drive and found the unit comes with a 'plastic' like material for the 11 tooth gear at the end. The one I pulled is metal. Curious if all the repo drives are this way?

Brian

[bibs]

I have a question about my speedo and what the speedo indicates in terms of MPH.I had my shovel(66 slabside) at a shop this winter and had a few things done that I couldnt do due to an accident.

At any rate here.....with out rambling on and on.....The speedo wasnt working at the time,the mech. told me that he seen no drive gear was in the trans Well,rather than argue with him I said to him....go ahead and do what you have to,he did....put a drive gear in it(it had one in there.....I know, I used it about 2 years ago before problems with it arose)After he "put one in there" the bike doing 50 registers 74 on the speedometer!!!!!the speedo is good,the cable was new and everything fit like it should....WHAT GIVES HERE!?

[RUBONE]

There are three distinct SETS of gears for speedo drives for 4 speed transmissions. If the drive gear is not the correct one for the spiral gear in the transmission it will not only read wrong, it is chewing itself apart. Find out what you have before you trash your gearbox!
Robbie

[bibs]

Thanks Robbie....do you know how many teeth the speedo drive is? or should I say how many different tooth counts....like say one will have 23 teeth on it what would the other 2 have?
I actually only put about 45 miles on 'er since I've had 'er back home so hopefully no real damage has been done.

[rozemab]

bibs,

The older models use a 11 tooth gear.

[bibs]

Mine is a 65-77 ratchet lid....I'll pull the drive out of it and count the teeth

[bibs]

Yup....the speedo drive unit was 13 teeth....no wunder she read 73 when I was actually doin only 50




Does anyone have an 11 tooth unit they can spare?....I'll buy it!!

[bibs]

I'm pretty much back where I started here.An 11 tooth doesnt work or mesh with what's in the trans....the 13 tooth is the correct unit after all.
Do speedos wear out?The trans is,from what I figure a 65-77 4 speed,it has ears for mounting to a cast inner primary(early shubbelhead)

[awander]

If you were supposed to have an 11 and you used a 13, you would read a LOWER speed on teh speedometer.

Doing 50, the speedo would read 50*11/13=42.3MPH.

[bibs]

Well Andy....that aint the case,Maybe it's the speedo...do speedometers wear out? If so it's the first time I ever heard of it.

[awander]

Well Andy....that aint the case,Maybe it's the speedo...do speedometers wear out? If so it's the first time I ever heard of it.

On the contrary-I think it IS the case-and it proves that you are not in the the "need an 11-tooth, but have a 13-tooth" situation.

I also wish there was more info avvailable on teh exact combinations of worm and gear that are supposed to be used in the transmisisons. I have never found a good reference. I know when they rebuilt the tranny on my '64, they installed the wrong worm inside, and I had to buy a new speedometer(there are 2 speedometer "ratios", 1:1 and 2:1(or is it 1:2?))

[fourthgear]

On the back of the speedo , it may have the ratio on it . May be stamped or just black lettering. You will get wrong readings with the wrong ratio/gear combo(s) . And yes they do wear out ,but it could just need a good cleaning and lubing & don't forget to lube the cable .