I have a 66 Beaumont with the original 10 bolt non-posi rear end. I believe this would be an 8.2 inch. I would like to change it out to a posi and I mentioned this to a friend who waid he had a posi rear end for it. He dropped it off and it is a Chev 10 bolt rear end, but I am pretty sure it's out of a full size car - there are no ears for the upper control arms and the rear end is wider than mine.
Question. What's the interchangeability for the internals on these? Any chance I can just use the carrier, and pinion in my rear end?
If the bottom of the diff housing is squared off it's a 8.5 and the internals won't work with your 8.2. Sounds like a 70 ish nova 8.5. They are tuff and would make a good down payment on a 12 bolt.
I'll get some photos & numbers off the housing and post - see where it goes. I figure if it won't work for my beaumont, it will probably work for someone - it turns over smoothly, the back lash seems pretty good and it passes the "turn one wheel and the other turns the same direction" test though I know that's not definitive. It has the posi tag on the cover bolt.
Does the cover look like this? If so, that is good.
Sorry for the poor pic but it's the best I could find. What I was trying to show is the upside down rib that bulges out at the top and drops down each side.
If the cover is smooth on the outside it is not correct.
And now I see after I posted this that Carl beat me to it! Good illustration Carl
-- Edited by Carl Stevenson on Sunday 30th of May 2010 09:24:13 AM
-- Edited by Carl Stevenson on Sunday 30th of May 2010 09:25:37 AM
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
OK - I got some pictures. It definitely looks like an 8.2 Chev to me - based on the photos & links above.
The lack of ears on the top means it isn't a Chevelle/Beaumont, and it looks to me like whatever it is out of had coil springs that mated with the control arms.
Notice the Posi lube only tag - and it turns over easily - no grinding, and seems tight as far as back lash. Even if I can't use it, it seems to be a pretty good rear end. Form a simple rotation, it seems to be about 3.23:1 ratio - maybe 3.08?
The photos shoudl show the cast numbers off the pumpkin - as well as some stamped numbers off the axle tube on the passenger side. The cast numbers are: N 3894859
and the stamped numbers are: G U 11 09 K (not sure about the 'K') E
Any ideas as to what this is out of? My guess was a full size, 60-ish Chev - Impala or Biscayne or ??
Will the internals work in my 66 Beaumont with stock 10 bolt, non-posi?
Oh, I forgot. You can take the centre stuff out of there and put it into your diff. Are you happy with your current ratio? (I forget if you said what you have now)
If you like your current ratio, take the posi section out of the diff pictured and keep track of the shims that come out of each side. Make sure you keep the left shims with the left side, right shims with right side. Pull your crown gear off your current centre section, put it on this diff and install the posi centre (with your crown on it) along with the correct shims that went came along with the posi centre. 99 out of 100 times this will work fine and the gears will be set up correctly, nice and quiet.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
They confirm what you said and a little more regarding the origin:
1966 Full Size Chev GU confirms 3.36:1 posi, (apparently the GU code was 1966 only), Eaton Posi, GM of Canada Built November 9 (I assume that would be 1966).
Sure glad to hear that the internals will work. I just checked the codes on mine, and it's CA - which I believe translates to 3.08:1, non-posi. The 3.08 seems to work well enough that a posi will be a big help. If I nail it at anything less than about 25 mph, I get muchos spin before I get any real go. I have directional tires so wearing out one rear tire is a pain and the added bite will be welcome.
I am tempted to use the 3.36:1 gears - I still like to be able to break 'em loose (I know - I'm a hooligan at heart). Can I use the crown gear, carrier and pinion out of this donor rear end? If so, should I use the spacers out of my rear end, the donor rear end, or am I starting from scratch?
If you want to do the gears and all, I would strip the entire Impala diff and use all the shims etc from it. I have done it like that and again, it will usually work fine. Just make sure to keep it all sorted as to what came from where.
The one challenge with that is knocking the pinion races out of the Impala housing but that is sure do-able with the proper punch, preferably brass.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
And an added thought, the 3.36 is about a 10% difference from 3.08. Not to talk you out of it but are you willing to give up a bit of fuel economy because it will likely be a little bit noticeable.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
I'm running a 700R4, so I have the OD, which will help. Even with that, I am sure I'll lose a little mileage, but for the number of miles I put on it any more, I think I can live with it. I think I filled the tank 3 times last year - including the top up with fuel stabilizer in the fall...
Good point though. I'll also need to swap out the speedo gear - converting to kilometers per hour is bad enough - correcting the speedo reading before converting is too much math...
Anybody have a comment for how much, seat-of-the-pants difference I'll see between the 3.08's and the 3.36's?
Youve got an o.d. automatic? By all means swap the 3.08 for a 3.36. I would think the o.d. with a 3.08 would be too tall anyway.
Another thing that Im thinking is that the rear from the B-body (full size) line also used 11" drum brakes rather than 9.5". That is what the 1965 Z-16 Chevelles used. Im just thinking that you ever upgraded the brakes, you might consider them as part of an upgrade that also included front disk brakes & dual reservoir master cylinder. Those 11" drums can still be used even with the 14" wheels.
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67 Chevelle Malibu Sport Coupe, Oshawa-built 250 PG never disturbed.
In garage, 296 cid inline six & TH350...
Cam, Toronto.
I don't judge a man by how far he's fallen, but by how far back he bounces - Patton
Yes, if you have a 700 for sure go with the 3.36. I am guessing you will see no loss in fuel economy with an overdrive in front.
As far as seat of the pants feeling? Don't expect miracles but you will notice it.
I would normally not swap ratios unless I jumped 2 ranges (i.e. 3.08 to 3.55 or something like that) but in this case since you have it apart anyway, go for it.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
As you know Carl, tire height can have a lot to do with ratio. You can pretty much jump one ratio just by going taller or shorter on tires. What do you have on there now?
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
I tend to go a bit conservative on gears, especially since I like to push the speed limit on the highway.
My 66 GP 427 4 speed was 3.31 and I would have liked a touch more except when I was on the Interstate and wanted to drive 70 or more. Then that was enough gear.
If you do lots of short trips I'd agree with the 3.55 idea. Lots of longer runs, then 3.31 makes more sense.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
If you used your old ring gear on the posi unit and the posi unit pinion gear you would have a 3.63 ratio. Your 3.08 has a 13-40 tooth combination and the 3.36 has a 11-37 combination. Swap the ring gear and you have a 11-40 combination for a 3.63 ratio. Just dreaming. Time for bed.
