I just replaced the pinion gear, I removed a 11 tooth and replaced it with a new 10 tooth gear, I didn't change anything else and now the diff is locked up, the wheels won't turn? what would I need to look for.?

Thanks
Rick

You most likely need to adjust your thrust washers to get proper gear mesh. Or, reset the depth of your pinion.

Anytime you change a pinion gear you have to check and possibly reset the gear clearance.

I was doing a barnyard repair, take one off put another back on like in the old days, I will do some adjusting.
Thanks for the replies.

Rick

Rick -- The solution could be as simple as adding some more paper gaskets at the spool to get more clearance between the ring gear and new pinion. I don't see how the thrust washers would be at fault if the rear end was working before the pinion change.

Mike, thanks that is what I am planning, I didn't put one on so it will probably be ok with one or two.

Rick

If it won't turn at all, it might need 4 or 5. Just keep adding them until it turns freely and you can't feel each tooth as it rotates.

Won't a 10-tooth pinion require less clearance than an 11-tooth? 10-tooth pitch circle radius < 11-tooth? Just asking, jb

You must have changed something else when you did this.

Before you take it apart, can you feel any backlash in the gears when you try to turn the driveshaft? If you can, the gears aren't locked. Is it possible that you have a pinion spool bolt that's a bit too long and maybe it's going in too deep and hitting the ring gear?

Also, just backing out the pinion till you get backlash is no solution. Pinion depth and ring gear side-to-side adjustment does 2 different things with respect to bevel gear mesh. You really need to start from scratch.

I would encourage you to pull one of the housings, bolt up the torque tube to the installed half and check both the pinon depth and the gear backlash. It will take some time but is a small price to pay. I broke a pinon on a downhill approach to a red light and threw it through a riveted housing.

Additionally if you are doing it you might check to make sure the radius rods are adjusted correctly. Murray Fahnestock has a really comprehensive write up on how to do both.

When you do all this adjustment, be sure to use some prussian blue on the teeth to see the contact pattern. It could be as simple as adjustment of the pinion spool. If you have a good contact pattern, that is all you need to do. However, read on.

What you are trying to do is match a new gear with another worn gear. It is quite possible that at sometime in the past, the gears had been adjusted for wear, and now one gear is new so the clearance would be too tight.

You might need a combination of adjustment of the thrust washers and moving the pinion gear. You need to order new thrust washers and fit the one on the left side first to get the proper gear mesh then the one on the right to eliminate end play in the axles.

Norm

Norman,

Totally, 100% agree with you!

James, the optional 10 tooth pinion was created by Ford to be directly replaceable with the standard 11 tooth pinion, using the same distance and the same 40 tooth ring gear. Now, with 90+ year old parts that have been restored, the parts may need some tinkering before they fit..

I loosened the six bolts and everything is free and working just fine, I will put the gasket in place and re-check it, I am not building a Swiss watch so the very fine tuning is lost on something that may be driven two or three times a year.
Thanks for all of the great information and taking the time to respond.

Rick

Thanks, Roger. jb

Rick, you really need to pull the rear end and set the clearances correctly. It's not something that is very hard or very involved. One afternoon, tops.

I get what you're saying about it not being a Swiss watch, but if you'll take just a little bit of time and care and interest you'll avoid ruining it AND it'll last another 100 years for the people who have it after you.

(Message edited by Wreckrod9 on February 16, 2017)

I was comparing a 10 tooth and 11 tooth pinion and they are the identical diameter. When removing a tooth the difference in diameter is made up in the thickness and design of the teeth. If the 10 tooth pinion is too far forward it will bind, as the fatter portion of the tooth will clash and bind with the crown gear teeth. Therefore be sure the new pinion gear is as far on the shaft as it can be. Check for burrs and any foreign matter. I would not recommend any shims. Also check for any burrs on the crown gear that may cause binding.