74 220 Speedo not reading correctly.

[Warbike39]

Hey there, hope this subject has not been covered already, I looked but found nothing. I have 1974 Travco 220, new to me last year and almost nothing on it has not been touched, fixed repaired or replaced by me. The first time I drove my Travco I noticed the Speedometer was not working. This winter I got around to ordering a new replacement cable(old one was broken where it went into the tranny and clip on back of speedometer was broken. Anyhow, after replacing the cable my speed now reads quite high in comparison to what it should read, i used the speedo on my samsung tablet to track it and at about 35 mph the travco gauge said i was doing 50 to 55 mooch.
The rear tires are brand new and are 23585/16 compared to 7.50-16 That came on her when new. My question is can the Speedo drive gear wear out and cause this discrepancy or would it be the tire size difference? Tranny is a 727 torqueflite and 440 engine.. couldmit be the speedometer itself?
Thanks for the input gang!
Dave

[KB2CRK]

I doubt it is the tires as they are only 1/10 of an inch different in outside diameter and only 1/2 inch different in circumference.
It would read a little faster but not that much. It is possible the gear for the speedometer cable could be wrong or the differential was changed sometime in its past.

[Warbike39]

I do not believe the rear diff was changed,mit appears to be the original dan70 he with 4.56 gears.the speedometer cable couldnnbe wrongmmi guess but both ends fit nicely into their matching fittings?
Thanks for the replykb2crk

[KB2CRK]

It could be a plastic gear in the trans. If the transmission was changed in the past the gear could be the wrong one for the rear ratio. The gears were made in different colors for the different ratios and tire sizes.

[Warbike39]

I was reading about that. I will remove the gear tomorrow and do an inspection on it. Appreciate the help. The previous owner was an old friend of mine and a ham radio guy, is that what KB2CRK is?

[KB2CRK]

From the chart below it looks like you would need a 38 tooth gear. The gears are color coded. A 38 tooth gear should be Blue.
Now a 25 tooth gear is also blue and that might throw the speedometer of by 20 to 25 mph.


https://www.google.com/url?sa=i&source= ... 2991564100
source for number of te

[Warbike39]

Okay great appreciate the info.
Dave

[KB2CRK]

I was reading about that. I will remove the gear tomorrow and do an inspection on it. Appreciate the help. The previous owner was an old friend of mine and a ham radio guy, is that what KB2CRK is?

Believe it or not Yes I am a ham radio guy and my user name is my Callsign. While you were typing I was looking also. I need a new cable for my Mahal. What was the part number for the direct cable. My 76 had two cables, one from the trans to the cruise and then one from there to the speedometer. The cruise was missing most of its parts so a direct cable would work well for me.

[Warbike39]

I will find that Speedo cable part number for you..it is a 100 inch cable to reach and I believe I bought it at autozone...I also just climbed underneath my Travco and removed the Speedo gear from the tranny. It is an orange 40 tooth gear.
Dave

[Warbike39]

The 100 inch dodge Speedo cable that fits my 74 Travco and I believe goes up through 1981 was $17.99 from Autozone and their part number is CA-3050.