Technical 55-64 Chevy posi question

Hey guys, I have a quandary about a posi unit. . . I recently got a pile of 3rd member parts including a 3:36 posi. I also got another 3rd member with 4:11 non posi. So, smarty pants decided to make a 4:11 posi out of these.
Let me first state that none of the cases were the 'P' case.
I pulled the ring gears off and swapped them then put posi unit into case with 4:11 pinion/ ring set. This created a massive gap between them. I moved the adjusters all the way over but it's just not enough. A friend says he remembers a spacer between the ring gear and flange. . . Any thoughts?

 

Yes, the differential carrier has to match the gears. I think the split is at 3.70. Ring gear spacer is the cheesy way to go. Might be able to find thick gears, maybe not.

 

Yes you need a spacer. I'm not sure about a non "P" case it's been 50 years since I fooled with the 55-64 rears.

Pat

 

To hijack the thread, did you happen to get a 3.08 chunk??

 

I used the spacer and had no problem shearing off the bolts ( twice ) with a big block and a little traction. Went Ford nine inch after that.

 

Once you use a spacer, you will have to make clearance for the carrier.

 

Thanks guys for the quick response. I will have to dig out what else I have to see if I have a 3.08 set

 

I already paid the tuition (to the college of hard knocks) on this one.

The early ones, 55-early 56 carriers used a thinner ring gear. If you use a 57, for example, carrier, you must use the thicker ring gear and pinion set. There are aftermarket suppliers who sell these...but that doesn't help you with your stockpile of parts.

 

Question is how hard you planning on beating on it

 

Yes, I have a (New) couple spacers. I will give you a call latter

 

If you decide to go with thee spacer, make sure you get longer ring gear bolts to compensate for the thickness of the spacer. You'll have less of a chance of shearing off the bolts. Or, see if you can find a 4-series posi carrier.

 

^^And be sure the bolts aren't too long. Lastly drill the bolt heads for lock wire and tie them together. If you don't they will back out.

 

You can always "Lincoln locker" the one legger setup.....

 

Here You go Ron

 

This is a 5:13 ring with a spacer for a future oval track project.

Yes, I have 4:11 Posi in a non P case.

 

This is correct to the best of my knowledge. ^^^ the 3.7 should be the split and a ring gear spacer is your easiest option especially if you want to use gears that you already have.

You can make one, or you can probably still find them for sale. They are nothing special as far as materials go with the exception of the bolts.

 

So, my original post stated that I took a posi unit from a 3.36 carrier. I had a 4.11 carrier non posi.
I swapped the ring gears and installed the posi with 4.11 ring gear BACK into 4.11 carrier
So.. . . Why would I need a spacer? Is there a way to tell the difference between the carriers?

 

I just recieved this from Robert Palmer
Pretty incredible that you had this, in stock, in the original wrapper! Thanks again Robert!

 

I recall but it's been many years that the axles are a bit different lengths too posi vs non-posi can't recall amount thought--it's not much

 

Your welcome, I have one more in the wrapper but I am keeping that one for a future project.

 

The carriers aren't different, the "spindle" that the ring gear bolts to is. Look closely at the flange the ring gear bolts to and you will see.

 

I still have a5.38 gear for a 55-64 set up from my frt engine dragster but I used it to try to teach my wife how to drive a stick years ago.It is a single track

 

Did you take the “ posi” unit apart! It looks kinda strange to me. It appears the two halves are not completely “ seated” in the pics. It’s been a while since I’ve had one of those apart. But might want to check that. It could be just the way it “ looks”, too. But in the original picture, I swear I can see clearance in between the two halves on the carrier.








Bones

 

^^^^^ I see it as well. Looks about a 1/16" gap.

 

Nice catch there, thanks. I will check it ot

 

These factory Dana Steel Positraction cases are bolted together using REVERSE thread bolts, that are no longer available. Just one of the many oddities with these rear ends. I am Butch/56sedandelivery.