Troubleshooting help please?
#171
09-23-2011, 12:13 AM
Ok I offered the one in my 78 in case all this 8 3/8 stuff is real. I too have never heard of a one or a press fit bearing for that matter. The reason for my offer Val was that there is no dispute that its a 8.5 and were close enough for him to drive down and pick it up.
#172
09-23-2011, 08:01 AM
Join Date: Jul 2011
Location: Northern Michigan
Posts: 992
I think I have this figured out as to why not.. The day after I got the Chevelle rearend home I checked the casting #s and was concerned on a previous post about it being datecoded to a 1970 Pontiac rearend. I found info on the yearone site about the differences between a 1970 gm 10bolt and the type "c" corporate 10bolt. If this is the case it would make sense. Again, going off the casting #s on the one I went and bought. If it was originally in a Pontiac that would make sense out of the pressed in bearings because Buick,Olds and Pontiac were pressed in. Also, the 1970 10 bolt had a shorter ring gear and pinion gear than the corporate rear end. The rear end was in a '72 Chevelle but I really don't think it was the original one. The talk of the rearend in my Camaro being an 8 3/8 was all speculation and I don't think that's true. Still think the one I bought is an 8.5", just a different type?
#173
09-23-2011, 09:04 AM
Join Date: Aug 2008
Location: Portland, Or
Posts: 9,097
Here's what I can clarify, in '74-'75 GM introduced the 8.5 10 bolt. by '78 that was the only 10 bolt that was used in the Camaro. They never made a 8.375. What is going on here is the chevelle rear end is an 8.2 and not worth putting into the car. That needs to be reassembled and sold off. I failed you on that, I missed the fact that you mentioned it was from a '72. GM did not offer the 8.5 then and nothing interchanges between the two. You were given sound advise which would have worked if they were both 8.5's, my apologies. That said, I've done countless rebuilds and have three Camaro diffs sitting in my driveway all 8.5's, if the one in your car is not an 8.5 I'll eat my hat. Now, I may possibly have a set of 3.73's from my Z28, if they are still good. I have no plans for them. You can PM me if interested.
Last edited by 1971BB427; 09-23-2011 at 09:28 AM.
#174
09-23-2011, 09:10 AM
Join Date: Aug 2008
Location: Portland, Or
Posts: 9,097
I think I have this figured out as to why not.. The day after I got the Chevelle rearend home I checked the casting #s and was concerned on a previous post about it being datecoded to a 1970 Pontiac rearend. I found info on the yearone site about the differences between a 1970 gm 10bolt and the type "c" corporate 10bolt. If this is the case it would make sense. Again, going off the casting #s on the one I went and bought. If it was originally in a Pontiac that would make sense out of the pressed in bearings because Buick,Olds and Pontiac were pressed in. Also, the 1970 10 bolt had a shorter ring gear and pinion gear than the corporate rear end. The rear end was in a '72 Chevelle but I really don't think it was the original one. The talk of the rearend in my Camaro being an 8 3/8 was all speculation and I don't think that's true. Still think the one I bought is an 8.5", just a different type?
The solution might still be to have perches welded on and drop it in, but only if you want to leave it as is, and not change anything later. If it's something really odd, then installing it and forever having to deal with an oddball rearend might not be a good idea. On the other hand you may like it with those gears and never change anything again once it's installed.
Because I can do the fab work myself in a few hours I leaned towards just mounting the Chevelle rearend in new perches, and still would go that route, but I understand your hesitance if it's going to cost big dollars to have it done.
Last edited by 1971BB427; 09-23-2011 at 09:31 AM.
#175
09-23-2011, 09:27 AM
Join Date: Aug 2008
Location: Portland, Or
Posts: 9,097
Take a look at this link to the Nova Froum. It shows the differences between the various 10 bolt GM rearends in post #2:
8.5" 10 bolt rear end identification vs 8.2" - Nova Tech
And here's a good article from Chevy Hi Performance about the GM 10 bolts:
Posi 10-Bolt Upgrade Install - Tech Article - Chevy High Performance Magazine
8.5" 10 bolt rear end identification vs 8.2" - Nova Tech
And here's a good article from Chevy Hi Performance about the GM 10 bolts:
Posi 10-Bolt Upgrade Install - Tech Article - Chevy High Performance Magazine
#176
09-23-2011, 10:19 AM
Join Date: Jul 2011
Location: Northern Michigan
Posts: 992
I still think the one I bought is a 8.5", but really think it's originally from a Pontiac. The casting # 9799100 was the same for all 1970 Pontiacs. That's the only thing I can figure on this one. That would also explain the comments about the ring and pinion gears being shorter also. The link I used to find this is Rear Axle Identification
that's where is says that the Olds/Buick/Pontiac rear ends were press fit bearings. The mechanic said that it was a beefier rear end than the one in the Camaro. Thanks for the links to the information I'll check them out. I would have the rearend housing changed today but was told that I would need a shorter driveshaft because the yolk is bigger on that one.
that's where is says that the Olds/Buick/Pontiac rear ends were press fit bearings. The mechanic said that it was a beefier rear end than the one in the Camaro. Thanks for the links to the information I'll check them out. I would have the rearend housing changed today but was told that I would need a shorter driveshaft because the yolk is bigger on that one.
#177
09-23-2011, 10:26 AM
Join Date: Aug 2008
Location: Portland, Or
Posts: 9,097
Bigger, or longer??? Bigger is not an issue. Numerous places carry U joints that are two sizes, so they fit the driveline, but the other half fits the rearend yoke. When I swapped to the larger late style 10 bolt in mine it was frrom a '78 TA and I simply pressed in a $16 U joint that was small by large and bolted the driveline right in.
#178
09-23-2011, 10:29 AM
Jeez, what we have here gentlemen is a clusterf*ck. As it were. I can't remember what you paid for the Chevelle rear but I would dump it and start over. Sell it. Pick up something that is known to work.
#179
09-23-2011, 10:31 AM
Will these work anyone? I'm not a rearend guy. I go for the **** really. http://muskegon.craigslist.org/pts/2563285186.html
#180
09-23-2011, 10:53 AM
Join Date: Jul 2011
Location: Northern Michigan
Posts: 992
Can I get an Amen! The yolk is longer BB427. I realize that it's not gonna work... Just trying to figure out the "why's." That craigslist link looks like what I will have to do, already sent him a message. That's all I would need then? What is a gov-loc posi?