'65-'67 Olds rears

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'65-'67 Olds rears

Post by WMACHINE »

I understand you're "the man" when it comes to Olds rears.
I'm interested in learning as much as I can about the evolution of the performance rears from about '65-'75. Both in what came original, and what works now as a "good" rear.
I understand that just prior to the "O" Oldsmobile rear introduced in '67 (very late '66 I believe), the performance rears were the "P" style Pontiac rear.
Anyway, I'd like to first get your opinion on the 10 bolt posi that just preceded the Olds O rears. I have a Q5 code P rear from a '67 W-30. I know it was supposed to have a 4-pinion posi, and it has what I think I've identified as a 4-pinion Borg Warner posi carrier. There is nothing in the shop manuals/Product Information Manuals about these 4-pinion units. I have a May '66 built '66 442 with a 3.90 posi P rear, and a May '67 built '67 442 P rear stamped TH but with 4.11s that I presume were dealer installed. I've yet to open them up to see what carrier they have.
Your comments?
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monzaz
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Re: '65-'67 Olds rears

Post by monzaz »

Wmachine, Ok will start with the olds evolution...

The first integral rear that super seeded all were the 1961-1963 f85 and skylark. This rear was all by itself and this is where we first find our drum backing plates that are still used on all muscle car brakes through to 1980. and was even used all the way to the last s-10 used in 2003. GOOD RUN for brakes....:)

The posi units used in the 61-63 were POWER LOCK units a very good design BUT these rears were so small it did not matter. The PL units used 4 spider gear design giving more surface area to deliver power to the axles shaft and side gears on the unit.

The axle shaft were terribly small in diameter and only 23 spline .... NOT much power is going to be delivered through these rears.

reference pictures below:
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f85 skylark 1961-1963.jpg
f-85 power lock dated at 1962 on the case.jpg
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Re: '65-'67 Olds rears

Post by monzaz »

Next we have the Pontiac and Buick/olds era of rears:

1964 the A-body muscle cars were born and the Pontiac Tempest, Lemans, GTO, Oldsmobile F85 and Buick Skylark were sharing the rear differentials.

1964-1966 were all bolt on springs to the rear differential perch area and the upper control arms were longer then the 1968 -1972 a-body chassis.

Pontiac rear had a distinctive extra diagonal webbing cast from the upper control arm ear mounts top of the center section casting and ran to the pinion area of the housing. These rears were considered The heavy duty 10 bolt castings of their day. Pontiac main carrier caps were very beefy wider and thicker with more material over the carrier bearing area.

Buick skylark and Olds F85 shared the same B type rear this rear was cast with only one lower webbing found on the Pontiac housing and NO upper webbing at all. The caps were thinner in width and metal over the carrier bearing area.

every thing else on the rears were identical... spring perch center line backing plate width brakes used axle bearing, wheel bolt pattern 5 lugs on 4 3/4" circle... all the same.

Only exception to the A-body rears were WAGON Differentials which used larger axle bearing diameter where the bearing is pressed on and wider brake options which also changed to different backing plates.

Next installment tomorrow...JIm :)
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buick one web support and u-bolt example.jpg
pontiac housing casting.JPG
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Re: '65-'67 Olds rears

Post by WMACHINE »

Thanks Jim. On to the carriers!
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Re: '65-'67 Olds rears

Post by monzaz »

Ok, Well according to mostinfo we have the 4 pinion/ spider gear HD units were only in the firebird rears. BUT this is very gray area of muscle car area. If your car was an american built 442 car it should have gotten the 12 bolt olds in that 1967 year.
The olds F85 will have received the 10 bolt 8.2 rear B or P

As I stated NO MATTER how original you think your car is stuff happens over 40-45 years.

I have a TH code in 1966 as 3.91 anti spin rear...NOT in 67 but the books have been wrong before too. THis is why physical inspection is a MUST

It appears that TH was dropped in the 67 year and then it came back in the 1968 model year as a c-clip 12 bolt chevy rerar and it is NOW 2.56. Go figure that???

Are your 4.11 4.10 gears original GM gears or aftermarket? You can look on the edge of the ring gear outer diameter it will have a GM part number and tooth count of the pinion and the ring gear and some letter suffix codes.

Richmond will have a richmond double diamond and there part number.

As for the type of unit used Borg warner /Auburn on in the same now.

That is a CONE typr unit that uses a conical surface area to create the friction needed to lock the rear up. Please reference pictures. Jim
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10 bolt 8.2  2 spider gear posi.jpg
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Re: '65-'67 Olds rears

Post by monzaz »

Ok, Well according to most info we have the 4 pinion/ spider gear HD units were only in the firebird rears. BUT this is very gray area of muscle car area. If your car was an American built 442 car it should have gotten the 12 bolt olds in that 1967 year.
The olds F85 will have received the 10 bolt 8.2 rear B or P

As I stated NO MATTER how original you think your car is stuff happens over 40-45 years.

I have a TH code in 1966 as 3.91 anti spin rear...NOT in 67 but the books have been wrong before too. THis is why physical inspection is a MUST

It appears that TH was dropped in the 67 year and then it came back in the 1968 model year as a c-clip 12 bolt chevy rear and it is NOW 2.56. Go figure that???

Are your 4.11 4.10 gears original GM gears or aftermarket? You can look on the edge of the ring gear outer diameter it will have a GM part number and tooth count of the pinion and the ring gear and some letter suffix codes.

Richmond will have a Richmond double diamond and there part number.

As for the type of unit used Borg Warner /Auburn on in the same now.

That is a CONE type unit that uses a conical surface area to create the friction needed to lock the rear up. Please reference pictures. Jim
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4 spider gear posi 3.64 gears heavy duty posi.jpg
10 bolt 8.2  2 spider gear posi.jpg
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Re: '65-'67 Olds rears

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Okay, let's start with what I know (as such) and then back to the gray. Though '67 was the first year for the Olds "O" 12-bolt, the Pontiac 10-bolt was still used in '67. In fact, not too many "O" rears were put under the F-85s in '67. (The "O" type is actually a 10-bolt carrier with a 12 boly cover). Olds was having trouble with their new O-rear in '67, though information about this "trouble" is sketchy. In fact, the '67 W-30 used the P rear. The W-30 P rear was spec'd as having a 4-pinion case that was bolted together with 8 bolts, as opposed to the usual 2-pinion case with 6 bolts. The standard gears for the '67 W-30 was 4.33 with a Q5 code.
The performance (posi) P rear gears and codes through '67 are:
3.55 SJ
3.90 TH
The performance (posi) O rear gears and codes for '67 are:
3.42 TM
3.90 TO
Now on to the gray. I'd post pics, but I can't figure out how. The carrier I have in the Q5 rear looks just like the 3.64 one you show in the housing. Except the Q5 caps look beefier and have a ">" in them.
What do you mean by Borg Warner and Auburn are now all the same?
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Re: '65-'67 Olds rears

Post by monzaz »

OK I love good info. Please keep the info you know coming also. All this info help everyone out. All the stuff we know is PHYSICAL. Books show code and such which i like to also know to match up with the physical info. Please anyone out there that has any disagreements or things to add, ALWAYS do so. This is how we find out the correct info.

Picture posting. Just scroll down the screen before you submit and you will see the browse button...click it and then find your picture. Now you much click the add file rectangle button this will load it to the page. you will see at the upper left a load bar...once that finishes it will be post when you hit the submit button. Ok? Good luck and please keep trying. If you shrink the picture it will load up much faster. Put your camera on 640-480 pixel and that will be great for most web site posting.

Now If you have arrows on your caps you have a PONTIAC 10 bolt 8.2 under your Olds car. That is good because in that 1967 year the PONTIAC was a better rear design on the caps and housing casting. This rear was taken right to the end of the Muscle car era of 1972 WITH NO major changes. (only axle seals were changed in 1968-69 and ring gear bolts went from 3/8" to 7/16" in late 60-early 70 rears.

Your carrier caps have a < on the driver side cap and a > on the passenger cap, correct?

You will also have the diagonal upper cast webbing on your housing too. Yes?

The posi that is in your car if it looks like the Buick one is a super duty. It will have 4 spider gears and 2 side gears. The extra spider gears give the unit its extra strength.

Borg Warner and Auburn- They us to be separate companies and then they were bought out back in the day. BOTH are CONE type posi units reference picture of a dissembled cone type standard duty posi. All the yellow areas are worn parts. This was not a good posi unit...lol. Jim
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posi rears 004.jpg
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Re: '65-'67 Olds rears

Post by WMACHINE »

Okay, I think I've got the posting pics down now.
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Re: '65-'67 Olds rears

Post by WMACHINE »

Housing shots
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Re: '65-'67 Olds rears

Post by WMACHINE »

The gears not doubt has been changed, they're 355s. Stamped "39 11 GM 9 6710"
How do you like the brackets welded to the bottom of the tubes? To bolt on traction bars, I presume?
Anyway, there's the Q5 stamp, exclusive to the P-type '67 W-30 with 4.33 gears.Also attaching scans of the factory brochure on the '67 W-30.
I believe it is this carrier that Olds lists in the June '67 parts book as:
1967 F85, 5200 A/Spin "B" or "P" Axles CASE (w/lube -3.55, 3.90, 4.11, 4.33) (4 pinion type) 1396975.
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DSI Guide 1.jpg
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Re: '65-'67 Olds rears

Post by WMACHINE »

One more scan, from the "Specifications, Parts and Tune-up Information....." published 3/22/67.
Interesting that the next few pages show just the "standard" 2-pinion Anti-Spin that is in the regular Chassis Service Manual.
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'67 W-30 Q5 .3 001.jpg
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Re: '65-'67 Olds rears

Post by monzaz »

Ok...I like that info. So that is pretty neat. Even I learn new stuff with the options in 67... I would have figure the 12 bolt olds would have been optioned on a w30. So maybe the 12 bolt OLDS came out in the later part of the year of 67??? Olds used the pontiac rear until the introduction of the Olds heavy duty rear. Can you get any date of month and day off the rear in the webbing? I think all they did was give the day like 1-365.

CRAZY brackets I'll say...

I did notice something else in the rear with the posi shot. YOUr caps ar on backwards. The arrows point outward not inward. They should look like this < > NOT > < Ok.
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3.55 N pontiac.jpg
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Re: '65-'67 Olds rears

Post by WMACHINE »

I'll get you that casting info.
Yes, it would *seem* that '67 W-30s would go with the new heavy duty "O" rears, but they had initial problems with their new rear, and they went with the 4-pinion "P" rear. There is very little known about what exactly the problems were were. But surprisingly few "O" axles made it into '67 F-85s.
Here's what transpired according to the best info I've been able to gather:
This 4-pinion carrier we've been discussing was indentified as a Buick designed Series 3 carrier with 8 bolt halves and 4 pinions, p/n 1396975. The series 3 was in late production of '66 and all through '67 production.
First production on the '67 W-30 was Jan, '67. The O-axle was going to be available, but as of 12/9/66 was dropped. Note that's just before production started. An Olds racer involved at the time said they were "shucking the teeth" of the gear and pinions of the initial O-axles. Thus the continued use of the P-axles.
Whatever problems there were must have been ironed out by mid-'67, because when they rolled out in '68, they didn't appear to have any glaring problems.
Oh, and there was also mention of special (high strength?) axles used in the '66 and possibly W-30 rears, p/n 397375 instead of the standard p/n 393906.

So what is your opinion of the strength of the P-axle 10 bolt with the 4-pinion cone posi?
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Re: '65-'67 Olds rears

Post by monzaz »

Oh I think they are pretty good rears. They are definitely the strongest of the 10 bolt 8.2 rear by far. The Buick 68-70 rears were pretty good BUT the caps were inferior to the Pontiac. I think Pontiac caps were the biggest caps available on any 10 bolt rear even the 8.5 included. They were just wide and thick. You have to keep the carrier stable in the housings and there is no other way then to beef up the bearing caps. Just about every high torque failure started with a caps shift or failure in some way or another. Jim
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