Rear end backlash

[SteveR]

I have noticed the backlash in my rear end needs tightening up. I believe that shims are needed but where do I get a supply of shims or am I going to need new gears? If I need new gears what ratio?

[keithb7]

 

Back lash between your crown and pinion is   Expected and required. You can slip out your 3rd member assembly. Using a dial indicator you measure your current backlash. Backlash between the crown and pinion is adjusted by moving the pinion forward or back in its mounting position. You can insert or remove shims to get it set to within spec. How thick of shims do you need to add?  Depends what you measure for your current lash.  For example spec may be. 0.006” to 0.010”. You measure and record 0.018”. You need to insert a .0010 shim. You can cut your own. Shims. You may also be able match some up with a shim you remove from the pinion. 
 

Some NOS pinion shim numbers include:

.010 688739

.0125 303856

.014 303857

.016 1403719

.018 688741

There are other area to check too, to ensure its not something else that needs adjustment. A list is provided in my ‘38 Service Manual. 
 

Edited October 29, 2022 by keithb7

[kencombs]

I've always used the pinion shims to set depth and/or preload only..  Then backlash was adjusted using the threaded adjusters on the carrier bearings.  Move both sides an equal amount to move the entire carrier in the desired location.

[keithb7]

Ken, Please tell us more. I’m always learning! The shims above are for bearing preload only?
 

Thanks. 

Edited October 29, 2022 by keithb7

[keithb7]

I dug into my manual a bit more. Both adjustments may be required to set up backlash and proper tooth contact. The carrier adjusters move the crown gear side to side. The pinion shims move thd pinion fore and aft. 
It is likely when one adjustment is made, the other will require a tweak as well.  Some verbiage in my manual:
 

 

Edited October 29, 2022 by keithb7

[Sniper]

Pinion shims adjust tooth depth, carrier bearing adjustments adjust backlash both are required to make proper tooth contact.

 

 

[SteveR]

Here is what happened. While I reinstalled my tranny and hooking up the drive shaft. I wanted to know what gear ratio I had. When I turned the drive shaft I noticed it would turn about 1/8 turn before the wheels would turn. I tried this several times in both directions. That was about a month ago. Yesterday when reversing I noticed a clunk coming from the rear end whenever I let the clutch out. It only happened when in reverse and not going forwards. I assumed it to be the gear backlash or am I missing something else?

[dpollo]

before you start messing with adjustments, excess backlash is often caused by the spider gear and axle gears.  Notice in the illustration the washer on the axle gear.

This is a non metallic material.  The washers on the spider gears are bronze.    Look there first.  .008 backlash is ideal on the crown gear/pinion  mesh.  you need not disassemble anything out of your comfort zone to check these points, but first, see that the pinion nut is tight.   Just tight..... and do not use an impact wrench on it.   

[SteveR]

7 hours ago, dpollo said:

Notice in the illustration the washer on the axle gear.

`I am assuming that you are referring to call-out numbers 41 & 44

I am assuming the "Crown Gear" is the 'Ring' gear # 46 and that you want a .008" backlash between #45 & 46

[dpollo]

you are incorrect.  I am referring to the axle gear and spider gear arrangement.