C1 Follow up axle shafts (posi vs nonposi)

**Gary Chesnut** · May 14, 2003, 11:07 AM

Re: C1 Follow up axle shafts (posi vs nonposi)

Researched posi axles, housings and according in all the yearly parts books and supplements for straight axles which are in my library that I can't get to right now due am living in temp apartment while constructing a new home and shop. Anyway, the posi axles shafts are in fact 1/8 inch shorter than standard axles. If a standard axle is used it should/will bind the posi unit up or at least that's what I remember from years past, if my memory serves me correctly and sometimes it doesn't.

The only difference in the bajo housing between posi and non-posi is the "doughnut" washers in the axle tubes right close to the weld point on the banjo and these were oil slingers designed to keep the posi fluid in the gear section and an oil dripper/slinger baffle that was welded at the 12 o'clock position over the ring gear.

Hope this helps. Sorry for not responding to your previous post but couldn't access my files. Good luck,

Gary #5895
....

**Kraig Bradtmiller** · May 14, 2003, 12:48 PM

Re: C1 Follow up axle shafts (posi vs nonposi)

Gary,
That's my point on using the longer nonposi axles. I agree that they would bind in the axle. BUT according to others that responded to my question, they will not bind -- what a dilemma! I seem to recall puchasing axle bearings years ago and you also received a spacer that was inserted between the axle bearing and the axle housing. I presume this offset the axle by 1/8". Maybe this is how a nonposi axle could be used with a posi carrier.

**James F.** · May 14, 2003, 01:08 PM

Re: C1 Follow up axle shafts (posi vs nonposi)

Kraig,
I remember the axle requirements exactly as Gary has stated. I believe the bearing spacer you are referring to is actually a retainer. There is a ring retainer that fits right BEHIND the bearing on the axle shaft (on the pumpkin side of the bearing). Its purpose is to (help) keep the shaft from sliding out and leaving the rear end housing! Some SCCA racers tack welded his spacer to the axle, Very old "Corvette News" suggested this. Regards,

**Mike E.** · May 14, 2003, 01:53 PM

Re: C1 Follow up axle shafts (posi vs nonposi)

There was also an axle bearing spacer. That was to remedy the difference in thicknes between the posi and non-posi bearing.

**Gary Chesnut** · May 14, 2003, 02:59 PM

Re: C1 Follow up axle shafts (posi vs nonposi)

Well such a delima. Starting with '59 Chevrolet included a large spacer due to a smaller rear wheel bearing width. This is as best I can recall (hard to do sometimes), but nevertheless I have verified the difference in the axle bearing widths due to having a large stock of 57-62 Corvette axles with bearings that have been collected over the last 30 years. When I moved the shop contents to storage and again into the new shop - I often wondered why I kept all that "heavy" stuff around. The parts books illustrates the different rear wheel bearing part no.s The '57 posi rear wheel bearings were roller bearings not ball bearings, sorry don't remember about the other C-1 posi years without my research notes. But I can assure you if you use the regular Corvette wheel bearings with non-posi axles in a posi pig it will bind up (been there done that in the earli 60's). Maybe the passenger car wheel bearings make a difference, have not compared the width, etc. Possible option to cutting 1/8 inch off the axle ends and by the way this doens't hurt anything unless you are going back to a non-posi some day, would be to use 1/8 in spacer shim between the axle end bearing retainer and the bearing. This would allow the bearing to fully seat in the axle housing. If 1/8 in spacer is insert as in '59 posi environment between the axle bearing and the housing, the bearing if it is 1 inch (think that is the width of the posi bearings)in width could protrude out of the axle housing. Good luck and best regard, Gary #5895

**Kraig Bradtmiller** · May 14, 2003, 03:04 PM

Re: C1 Follow up axle shafts (posi vs nonposi)

Mike,

That's the one I'm referring to and I bet it was an 1/8" thick!

**Kraig Bradtmiller** · May 14, 2003, 03:28 PM

Re: C1 Follow up axle shafts (posi vs nonposi)

Gary,

According to the my 1960 GM Parts Manual there were 3 different bearings used for 57-59 vettes and the parts book does not distinguish between posi and nonposi axles. In other words, all three bearings would interchange between posi and nonposi axles. So what is their differences. Keep in mind that all three bearings used the same axle bearing retainer (the stamped metal plate with 4 holes that retains the bearing to the axle housing). I also know there is a difference in thease retainers (I've seen shallow vs deep). Again, the parts manual doesn't distinguish between pos vs nonposi applications. Are you suggesting the width of the bearing varies between 7/8" and 1 inch? Do you know why there is a deep vs shallow bearing retainer and if so, which application are they for?

Bearing (posi and nonposi)
57 vette 57 pass 904262 (STAMPED)
57-9 vette 57-8 pass HY JRN1542 WAB-23
58-9 vette 58-9 pass ND-RW607SY12

Bearing retainer (posi and nonposi)
#3708829 56vette 55-6pass
#3739104 57-60vette 57-8pass
#3755959 59-60pass

**Gary Chesnut** · May 14, 2003, 04:00 PM

Re: C1 Follow up axle shafts (posi vs nonposi)

Here's some background on Chevrolet parts books. The best resource for a given year is its respective yearly parts books, plus the monthly update supplements. Such as for '57 it was issued in Mar 57. There were monthly part no. deletes, add, changes, new parts, etc. added as supplements starting with Sep '56 through Feb '57 which were all incorporated into the Mar '57 parts manuals. Supplements were issued for '57 parts manual everyone month until Mar '58 (can't get to my books, but think it was Mar) which incorporated latest and greatest for '57 and the early '58 Corvettes.

Remember for sure the '57 and '58 Corvette rear axle bearings were roller for posi and ball bearing for non-posi and believe they were the same width of 1 inch (may not be exactly 1 inch as can't get to my notes and am recalling this from my poor memory). In '59 when the 1/8 inch shim was first used, this was used to compensate for a narrower bearing. These bearings superceded the '57 & '58 bearings and there may be a foot note in the parts manuals that state the 1/8 inch shim was to be used with the newer service replacement bearings, not sure on that.

This is all the data I can provide you with for now. If you can wait until Sep when I get my library out of storage and into new house, send me an e-mail and will scan/fax you the pages from the earlier parts books. gchesnut@flash.net Regards, Gary#5895....

**Kraig Bradtmiller** · May 14, 2003, 05:12 PM

Re: C1 Follow up axle shafts (posi vs nonposi)

Gary,

THe data I reference in the discussion thread came from the GM Parts and Accessories manual dated April 1, 1960. The supplements your are referring to I presume were issued throughout the year to GM dealerships as a supplment to this manual.

**Gary Chesnut** · May 14, 2003, 05:57 PM

Re: C1 Follow up axle shafts (posi vs nonposi)

C1 Chevrolet parts books are most valid for the current model year such as '60 parts manual would be for a '60. For a '57 as an example the '57 parts book with supplements will provide the most accurate information. If a '60 parts manual is used to reference parts for a '57 what is shown is the latest and greatest part that Chevrolet had available in '60, which is not necessarily same as the original part such as the bearings and might require an additional part such as the 1/8 inch shim. It's best to use a parts book for the year Corvette that parts are being researched for which will show the recommended part available on the date the parts manual was issued. If Corvette is earlier the original part may or may not be shown. Later parts will be included in the monthly supplements or maybe in the next year's parts book if it wasn't superceded. Hope this helps explain. Regards, Gary#5895....

**Kraig Bradtmiller** · May 14, 2003, 08:42 PM

Re: C1 Follow up axle shafts (posi vs nonposi)

Gary,
I understand and am aware of what you are saying. That's why in my first thread I pointed out my information came from a 1960 GM Parts Manual. Matter of fact, the parts book contains replacement part numbers (NORS) as is not a 100% accurate picture of what was installed on the assembly line. By the way, do you still have the 57-62 axles?

**roy braatz** · May 14, 2003, 10:44 PM

Re: C1 Follow up axle shafts (posi vs nonposi)

OK Here we go. I did a two page artical on this in 1991 same arguments by some.
1.The bearing retainers, that hold the axle in the bango
A.shallow retainer was non-posi
B. deep retainer was posi.
2.Non-posi axle used in a posi. bango used a spacer.
3.Non-posi used ball bearing.
4.posi used rollor bearings.
5.Eather bearing can be used in a posi bango, but a spacer may be needed.
6.Beside the baffles that are in a posi bango the end flanges are deeper calling for a wider bearing and deeper retainer.
7.Posi bearing are rollor because they are wider and take the load you hot roders take on curves.
8.The pumkin has a large "P" for posi.
Changes were always made from one year to another and that I think is were the arguments come in because many Corvettes were SREWED up over the many years of ownership.

**Gary Chesnut** · May 15, 2003, 09:29 AM

Re: C1 Follow up axle shafts (posi vs nonposi)

Kraig, send an e-mail to gchesnut@flash.net Guess I missed that on the first posting, sorry about that. Gary#5895....

C1 Follow up axle shafts (posi vs nonposi)

C1 Follow up axle shafts (posi vs nonposi)

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