Rear axle question 65-70
 

Hello,

I have been toying with an idea and wanted to see if anyone has tried it. I was looking into the feasibility of putting a 78-96 B-body wagon 8.5 rear axle in my 66 Grand Prix. The width is close to the same and the bolt pattern is right. What got me thinking about this was the fact the rear sway bars from most mid 70's b body sedans and '78 and later wagons will fit on the 65-70. I would have to assume the lower control arms run in a similar plane across the various model years. Anybody have any info they could share?
Thanks

I'd be interested in hearing from anyone who has successfully used one, as I have one from a '94 caprice wagon with 3.23 posi. It is something like 4" wider than the standard b-body axle, if I remember right.

I like this line of thinking... all it takes is a measuring tape and a little trigonometry. Would have to assume that axle is pretty stout, too.

There is a guy in Smoke Signals with an original 3.42 Posi axle drum to drum for an outrageous price. Love the idea... but pass.

Good parts of this swap would be the axle still has 11" drums; a disc swap from an SS or a V57 trailer package car would be a no-brainer. The Imp SS guys are all up in it on durability mods for drag versions, and there are zillions in the fleet of ex-cop and taxi models. It'd be the shizznit to find this axle swap would also accomodate the 9C1 rear bar, but if I keep thinking about this, hair will grow on my palms ;);););););)

Yes, I have a 9c1 sedan w/rear disks and the stock braking feels significantly better in it than even the 11" rear drums in the standard b-body (which is fine).

Looking at my complete wide unit (out of the wagon and on the floor), it seems as if the perches are the same as the standard b-body, but the axle tubes are simply longer and extended out of the housing further. In other words, if they were pulled out, cut 2", and reinserted and welded straight, it'd go right up into a sedan like factory.

I'll try to upload pics in a few days, if this thread lives. Unfortunately, I do not have another rear end at the same location to put next to it for comparison.

longnlow66, is the 5x5 bolt pattern correct for your car? I know certain b-bodies through the years used it, including my buddy's '77 Delta 88.

I'd sell my 3.23 posi drum-drum for say $500 to anyone who cares to pick it up about 10 miles north of Providence RI. I think even the e-brake cables are intact. Remember it's the wide station wagon one.

I have been thinking about this swap for a while. I have a spare 8.2 out of a 68 Pontiac full size. I can take some measurements on this housing and we can compare it against the measurements from a newer wagon housing.

mechanic17, the 5x5 pattern is correct for my car.

Here is some info I pulled from the Impala SS forums about the B-body GM corporate 8.5 axles

Chevy
91-92 sedan
1566mm - narrow (all)

93-96 sedan
1566mm - narrow (9C1 - disc & drum & some other drum applications)
1598mm - wide (Impala SS - disc & B4U - drum)

Buick 91-96 & Fleetwood 93-96 sedans
1566mm - narrow (all)
NOTE: Fleetwood housing is unique to the application - 4-channel ABS provisions

91-96 wagon, all
1642.5mm

Sedan housings, in both widths, have the same lower control arm bracket location/spread distance, and will fit any other sedan frame. Wagons have a wider spread distance (approx. 2") between lower control arm brackets on housing, and corresponding wider frame lower control arm mounts.

I did some reading on the Impala SS forum about swapping disc brakes to the wagon rear axle. The wagon rear axle has larger diameter axle tubes as well as thicker hub flanges. These differences prevent the disc brakes from being a direct bolt on.

Does anybody have a flange to flange width for the 65-70 factory axle? I had written down 65.5 in my parts book for my 66, but I can't remember if I actually measured the housing, or got this off the net.

Rear Axle width
 

I have a 3.42 posi rear out of my 66 Bonneville at my shop.
I will be there later this morning, and will take smoe measurements
Ron

Wasn't J65 part of the Buick, ahem, "Trailering Package?"

A former client of mine was at Buick :old::old::old:when that was being cooked up. Turns out more than one engineer in Flint needed a new RWD tow car for a race car... and a better way to get the kids to soccer than the dustbuster minivan.

So, they basically stuffed the entire 9C1 Police Car into a Roadmonster, and had a car of supreme quiet and refinement that would scare holy hell out of anything south of a Corvette... in particular, the Marauder. :usa2::usa2::usa2:

Of course, Buick being the fuddy duddys they tend to be, would have nothing to do with a "performance" Roadmaster, and rather than kill all the good work, hid it in plain sight in the order guide under "V57 Trailering Suspension" or something similar.

Back to the first part, though: I was 99% sure the stawag came with 4-wheel discs and the better brake linings. Or is my memory permanently toasted:confused::confused:

Get in touch with Brad at Fab Craft Metal Works. He and I have been working on getting parts available for the 65-70 B body rears. He has 3.55 gears in stock now. I also just took delivery of some custom built axles for my rear end. Since I've gotten the 4500 lbs Bonneville down into the 10.80s at 125+mph, I was told to get some after market axles even though the stock 31 splines haven't even twisted. Brad and I have both been really astonished that they're still holding. Brad also has an idea about the rear sway bar from his 57 to 64 setup and adapting them to the 65-70s.

milt

What is the possiblity of a 3-series Posi for something less than a first born?

In the interim, would a 3-something posi fit a 3.23 open '65-70 housing? My goal would be to get 3.55s and a posi in my YH 421/TH400 combo.

BOB

The 3.55s were machined with an extra thick flange so that they would fit a series 2 differential without the use of an adpater plate. He also machined the ring gear to accept right hand threated bolts. The series 2 differiential are fairly common as opposed to the series 3s.

milt

Does the 3.55 still fall in the right place in a 3.23 housing? Does it work with a factory 2-series posi? Will both work in a regular 3.23 housing?

A persistent Craigslist post in my area has a stack of 2-series posi axles for sale, would be great if one of those would pan out for my project. I'm thinking my born-with '66 3.23 housing, a rebuilt GM Pontiac 2.9-something posi unit and the fabcraft 3.55s ... unless there is a good reason to switch to the later model '92-96 B-Car axle.

My housing had a series 2 and 3.08. I bought a used 3.42 and ran it. When I got the 3.42s, the spacer plate came with it. The 3.55 bolts right on without the need for the spacer plate and falls right in. Give Brad a call at 800.208.8242. He'll set you with everything you need plus excellent customer service.

milt

I am still looking into this swap. I have located wagon axle with 2.93 gears for sale. I need to go take a look at it. If I can get it cheap I will post some side by side pics of it and the 68 axle with measurements.

Interesting thread. Seems no one has hit upon a cheap alternative to the old pontiac factory stuff. Going to kick myself if late model stuff is easy and cheap.

Myself, I have pursued "the great white whale" and have scored a used 66 3-series posi carrier with 3:42. So far I have 300 in the carrier and gears, and another 350 in bearing and rebuild kits. Been quoted around 500 to put it all together in my 68. I really like the idea of not having to worry about control arm locations, alignment, etc. Hope this will really pick the stop light performance over the open 2:73.

Anyone know of a good shop in or around Nashville to do the differential install?

viva la DarkSide!
 

This is a great thread!

I am really looking forward to both the elegance of anything that comes out of FabCraft for the '65-'70 P/8 cars AND the establishment of reliable alterations and deployment of the '90s Impala/Roadmaster rearend hardware into the '65-'70 P/8 cars.

Rustyrelic: sure wish I could repeat that score, am hoping something comes of the search for a good alternative for our old war wagons.

The 65-70 B body rear end is 65.50" drum to drum. Frame rails near the rear tires are about 51.50" at widest point. Wide Track Pontiac! Sure does make it difficult to find wider than stock wheels, because the backspacing\offsets are usually not deep enough. I am currently looking to stuff a pair of 20 x 9.5" wheels I got a killer deal on, but of course their 5" backspacing puts them 2" from the frame rail and zero inches from wheelwell lip, and thats even with it rolled up...not good. Only solution is a narrowed rearend.

Just did some math on the axle width: a '66 will be about 1664 mm so the b car axles will be too narrow or need spacers to get to the orig track

Finally got around to shooting some pix with my phone--sorry for the poor quality (dark garage). This one came out of a '92 or '93 Caprice wagon with 3.23 or 3.42 (I forget) posi. Hopefully this will confirm some of the measurements others have posted.

I am the owner of several b-bodies, so I'm probably gonna strip the internals out of this housing for use in the standard sedan--unless somebody offers to buy it first.

The axle housing dimensions are the same on all '77-'96 Chevrolet B-bodies (Chevrolet Caprice's and impala's) I've measured. Don't have any 90's era Hollander books to double ck, but are the '90"s B series wagon rears any wider than 90's B series sedan rears?
I've pulled quite a few 8.5 B series rears of this vintage & torn apart quite a few 8 7/8 in mid 80'sBuicks & Caddys & don't believe they are any wider, I in fact believe they are the same width rear. That would make them all too narrow to fit in a '65-70 B series Pontiac.

Once one starts comparing the below rears, they are basically the same axle flange to axle flange & as far as the geometry goes with the upper control arm perches. There are different styles of housing ends, 28 spline or 30 spline axles, different looking spring mounting tabs, Spicer 1310 & 3R pinion flanges & theyre were two different factory rear disc brake set-ups (the '77-78 LeSabre Sports Coupe version & the '90 Caprice version).

GM rears:

'73-77 A-body 8.5 c-clip
'73-77 A-body 8.5 bolt-in axle (one of my favorites)
'77-78? B-body 8.5 bolt-in axle (same as next above)
'77-78? B-body 8.5 c-clip (Palla cop cars of these years will have usually have 8.5's)
'77-mid 80's 7.5 c-clip B series (weak junk)
'77-84 B series 8 7/8" MP series c-clip
mid 80's- 96 B-Body 8.5 c-clip (30 spline '88 & later)

Another style of GM rear that is wider than the '73-77 A-body/'77-96 B-body rear AND the upper control arm perchs may be very close in geometry to the 65-70 B series PONTIAC is the '71-76 GM B series rears. Know these are not a direct bolt-in to '65-66 B series Pontiacs, as I've built them all, but could be something to ck out to see if upper control arm perchs have the same spread & same geometry. If they do, its as simple as removing lower control arm/shock perchs & correctly positioning & welding the the early Pontiac style on.

Of these GM 71-76 B series rears:
-'71+ 2 door & 4 door Chevy Impallas & Caprices typically had the 8.5 C-clip axle rear. Also were used in some low horse '71- (maybe) '72 Pontiac Catalina's
- 455 equipped '71- Pontiac B series & often Olds Delta 98's of these years had the 8 7/8 MP series rear (some manuals may refer to it as a 8.75).
-Biggest '71-73 Buicks with 455's typically had a 9 3/8 which is also very hard to find good ratio posi & gears for. 3.42's in this style are real tough!

Good luck, as I'm out yarding I will try & get some detailed pics. I have nothing anymore for '65-70 B series Pontiac rears in my racks. Just sold the last of my '65-70 P series axles (with new axle bearings installed).