Dana 20 Speedometer Drive Gear

Hi, My speedometer has been far off since I own this Jeep. (It reads way down). Got a new cable, a new speedo. It was still down and worked for a while. Now it barely working so I decided to look on the Transfer case side of it.

Th Driven gear is perfect. Full steel and 16 teeth
The drive Gear is plastic, Yellow. Does not look worn from the outside. Maybe 6-7 teeth (See picture)

The yellow plastic drive Gear almost turns freely. Sometimes turn with the driving shaft, skips aften and completely stops turning when a light pressure is applied on it wit a finger. So the drive Gear is loose.

1- What keeps the Drive Gear tight with the output shaft other than pressure?
2- Is the Drive Gear still available on the market?
3- Is it easily replaceable on the car? Do we need special equipment? New seals? New Shims, etc.

Thanks for helping

2-

 

The rest of the items to complete the puzzle are the SW 448856 driven Gear. Preliminary researches on internet says that the internal gear (Drive Gear) should be 447537. How come The driven gear is full metal. Info says it was used until 71 on Dana 18 TC and I have 1 1974 with Dana 20? Thanks for helping

 

Speedometer “gear sets”were manufactured as a single drive gear with various associated driven gears.
In other words the driven gears of various ratios must be mated to a specific drive gear.

The earliest gear sets prior to 1964 had limited ratios available.
Some drive gear sets are more versatile than other drive gear sets.
All speedo gear sets used in Jeeps prior to 1970’s were steel gears made by Stewart Warner.
It is best to identify them by the SW number.
During the 1970’s nylon gear sets came into production.
I’m old school and prefer the steel gear sets.

You cannot mix match earlier series of drive gear sets with later series of drive gear sets.
You can use any matched gear sets in most any transfer case you want. Except.....
You cannot mix IH speed gear sets with Jeep gear sets unless you also change the rear bearing cap.
IH gear sets run in reverse direction as compared to Jeep gear sets.

Matching a speedo gear set to your Jeep is mainly dependent on differential ratio and tire diameter.

 

The speedometer bounced on my Jeep also. My speedometer gear did that same issue yours has on my 74. The plastic portion could spin on the metal sleeve. I removed it, and it is a plastic gear bonded to a metal splined sleeve. The glue from the factory broke loose. I could not find a readily available aftermarket gear, let alone a replacement period even used online at the time. My father and I removed the gear cleaned all the oil off and cruised to the hardware store and bought strongest plastic safe glue they had. We glued the plastic gear back into place and let it dry over night. It was some sturdy stuff, it's been holding for 8years or so. Bouncing speedometer solved.

My gear is yellow just like yours.

 

Thanks, Makes a lot of sense. Will take it off and report. YH

 

Same here Speedometer bounced, and I foune the yellow gear just slipping. But I had a 2nd D20, so I swapped the tail shaft housing. I'll have to try your glue fix, so I can have a spare.

 

Can you quantify this? I’ve torn apart hundreds of Scout and Jeep 20’s, used speedo gears from both and never seen any cut reverse one from the others.

 

Nick thanks for your reply.
That statement was based on the only IH transfer case that I’ve ever dealt with a couple years back. So sorry if it’s was misleading.

The transfer case in question was an IH Dana 20, factory twin transfer case from the late 60’s Scout 800
It had a steel SW speedo gear set.

I should have a pic of two in my imgur account but I can’t get into that account.
So I’m going on old memory here but I seem to recall the SW gear set had a reverse cut and the Speedo cable entered into the rear bearing cap from the top instead of bottom as typical on a D20.

Here : luckily I just found a scout 800 rear bearing cap on eBay: Scout II 800 Dana 20 Rear Output Shaft Housing Bearing Retainer Transfer Case | eBay

 

I didn’t look at the pics but intuition makes me think maybe you are thinking of where the speedo drive is located on the housing? Both the 18 and 20 IH Scout speedo drive is roughly 180 degrees from the Jeep versions. The gears have the same directional cuts that I’ve dealt with. As you intimated (andothers have) the tooth direction and count must match for the various axle ratio and tire size.
We used to take 20 rear output’s and rob the yokes, speedo gears, and setup shims and toss the rest in scrap as no one wanted those parts. We would save a few housings and shafts and they would sit on the shelf for years.
We wanted the shims before they were being reproduced. The .003” were especially needed as they were almost always damaged during disassembly.

 

my 74 did the same. then started working again but speed is still off. I left it alone after searching for gears not found.

 

Solved! The Drive Gear was loose on it's shaft. Disassembled the rear output housing, Got everything apart and Epoxyed the Gear. Works like a charm for now. Just wait to see if the Epoxy can last. Thanks to all the contributors. Put some pictures of the project.

 

Great! Mine has been glued for 10 years or so. Not a ton of miles, but a while.

 

Hi, what´s the size of the socket you used to remove the speedometer sleeve? I tried to remove it with a 7/8" but i couldn´t because the thickness of the socket

 

It's 7/8". But you may have to sacrifice one on the bench grinder to get it to fit.