Drive line thrust washer

[Dune Country]

working on a '31,
finally got the diff set up, thanks guys.
Fitting the drive line bearing and speedo gear on I noticed that there were two thrust washers, I noticed this taking it apart but thought nothing of it.
With just one washer the speedo gear is off center, with two it is right.
The only problem I see is that the snap ring groove is gone, the snap ring was on before but came off easy. I drove the truck before the tear down and noticed no problems or noises, I have already rebuilt the tranny and didn't notice anything wrong with the rear main bearing.
I plan to test fit the trans and see if there is any binding.
Am I on the right track?

[Tom Endy]

There should only be one thrust washer, and it should have a series of holes around the circumference to allow grease pumped in at the grease fitting on the trans rear bearing retainer to migrate into the roller bearing in the torque tube. In most cases you will find a space between the speedo drive gear and the snap ring. I am not sure why there is a variation in the space. It may have something to do on how far up the taper the pinion gear sleeve traveled before it seated. People tend to worry about this space and want to add extra washers. When you install the little speedo housing the two gears will center themselves.

I am not sure what the purpose of the snap ring is. It may be for bottoming of the U-joint, or possibly Henry had the rear axle assemblys hanging on a rack with the torque tube pointing down. The snap ring would then have prevented the roller bearing, speedo drive gear, and thrust washer from falling out.

Tom Endy

[Dune Country]

thanks Tom, once again you saved me a bunch of work.
It makes sense that the speedo gear would float with the driven gear.
Yes both thrust washers have holes but with the space left between the bearing and gear where does the thrust come from?

[Barry B./ Ma.]

Hi Tom, I remember on a roadster I had I had to pull the rear end back and add another thrust washer because the speedometer gear would slip out of mesh with too much gap.

[1931 flamingo]

Try to find a thinner washer or make one and put holes in it to take up the slack??
Paul in CT

[Dune Country]

Sponsored Links (Register now to hide all advertisements)

thanks for the reply's
the two thrust washers that I have work to center the gear.
my concern is pressure on the trans and pinion bearings.
A test fit will tell.

[columbiA]

Some times without a second thrust washer, the speedo gear will not stay centered & speedo will quit working.If so,you could fish a piece of wire around D-S once or twice behind gear & twist tight & should keep gear centered--saves pulling rear end to fix it.

[Dune Country]

I assume that there is no real thrust and the washer(s) is just a spacer?
Can't see where the "thrust" comes from anyway.

[eystein]

I think that you should NEVER use more than one thrust washer. As Tom said, the holes in the washer are there to let grease passthrough back to the drive shaft bearing. Two washers will seldom be in alignment, hence the holes will be blocked, blocking the flow of grease.

I was worried that the slack was so much that the speedometer gear would slip out of mesh. Therefore I custom made a thicker washer, replicating the holes.

There should, however, always be some slack of the speedometer gear on the driveshaft, both backwards and forwards, to allow for axial shift in the driveshaft when the double taper bearings in the rear end become worn.

[columbiA]

Ive used 2 washers on my DS for over 75,000 miles and no problems.The grease always gets thru them.The 2 washers always move in relation to each other to let grease thru.The washers dont have any thrust on them at all.They are really just spacers.