Rear gear setup help

[Gliderider06]

So I go to setup my rear for the Impala and just couldn't get my backlash anywhere close. I'm using a non-P case, 3.55 gears and a Yukon posi unit.
When I bought the posi unit, I was going to run 3.73 gears, but changed my mind and bought 3.55s. Now the box for the posi says 3.73 and down and well, I'm now using 3.55 and that messes me up.
So, will I be ok with just putting the spacer between the ring gear and posi? Is there different thicknesses of the spacer or just one size?
Paul

 

[oldskydog]

3:73 was not available in 1955-1964 diffs. They were 3:70.

 

[La Hot Rods]

I wouldn't use a ring gear spacer. If it was a trailer queen you could get by with one.

 

[Gliderider06]

I wouldn't use a ring gear spacer. If it was a trailer queen you could get by with one.

What other options do I have besides a new gearset? Not too sure if I want to run 3.70 gears. I haven't found a thick 3.55 gear set online yet.

 

[MRHP]

Difference between 3.55 and 3.70 at 60 is probably 150-200 rpm. No big deal really.

 

[64ss409]

I have had a spacer with 4.11 gears on a series 3 posi since 1964. It is only a 340 hp, but it has been raced with slicks and no ring gear or spacer problems. I don't see why you would need a spacer on a series 3 posi with 3.55 gears.

 

[Gliderider06]

According to Yukon Gear, my posi unit is good for 3.08-3.73 gear sets.
I have almost. 070" in backlash which exceeds the books .003" and it binds at .060" as I rotate it. I think I need to pull it back apart and double check my pinion shim depth. Not sure what else it can be unless I got my end caps on the wrong sides.
I dunno

 

[MRHP]

Sum Ting wong.

 

[La Hot Rods]

Is this a P case? If not you need to make clearance for the posi unit.

 

[Gliderider06]

Is this a P case? If not you need to make clearance for the posi unit.

Not a P case and I clearance it already. I have about 1/4" between the case and posi unit.

 

[dakota tom]

Do you get a later 8.2 posi by mistake?

 

[Ishiftem]

Sum Ting wong.

I know that guy!

 

[Gliderider06]

So, I got it figured out and corrected. Anyone want to take a guess? A hint. It has to do with the pinion gear.

 

[La Hot Rods]

Didn't crush the crush sleeve?

 

[327]

That is what I thought.

 

[Gliderider06]

Didn't crush the crush sleeve?

Nope. It was. Not the problem. Oh, new bearings and races were installed, but was not the issue.

 

[327]

Ya Ok ...................... ???

 

[La Hot Rods]

Wrong pinion gear

 

[Gliderider06]

Wrong pinion gear

Yes!
So the pinion is from an early 1955. Yukon said early pinion gears will not work. The depth of the early gear to a 1959 gear was .150" shorter. This kept me from being able to get my backlash and caused the binding before getting to the factory specs.
My dad always said. Live and learn...

 

[327]

Not Posi ... But I am running a 3.70 rear in my Impala.