MonteNH Posted September 22, 2011 Share Posted September 22, 2011 Sorry for all the questions. Im getting ready to do the gears in my Monte. Im going to add a Posi unit and 3:73 gears. When I called the speed shop today they asked if it was 8.2 or 8.5 ....Is there a quick easy way to determine what 10 bolt my Monte has ? Thanks in advance, Phil Quote Link to comment Share on other sites More sharing options...
robs70monte Posted September 22, 2011 Share Posted September 22, 2011 the 8.5 10 bolt will have 2 ears on the bottom of the center section the 8.2 is rounded Quote Link to comment Share on other sites More sharing options...
Mr70Monte Posted September 22, 2011 Share Posted September 22, 2011 either check the pinion nut or the ring gear bolts. 8.2" has 1 1/8 pinion nut and 3/8 ring gear bolts with 9/16 heads. 8.5" has 1 1/4 pinion nut and 7/16 ring gear bolts with 3/4 heads. Quote Link to comment Share on other sites More sharing options...
MonteNH Posted September 22, 2011 Author Share Posted September 22, 2011 either check the pinion nut or the ring gear bolts. How do I do that ? Is it easy to get at ? Mine looks like the 8.2 Is a 8.2 worth adding a posi to and some gears ? Quote Link to comment Share on other sites More sharing options...
cbolt Posted September 22, 2011 Share Posted September 22, 2011 either check the pinion nut or the ring gear bolts. 8.2" has 1 1/8 pinion nut and 3/8 ring gear bolts with 9/16 heads. 8.5" has 1 1/4 pinion nut and 7/16 ring gear bolts with 3/4 heads. Surest way to tell for sure. Doing mine this afternoon and had the exact same question so I would be sure to order the correct parts. Just take the driveshaft off at the rear and pop a socket on the pinion nut. Quote Link to comment Share on other sites More sharing options...
vacavillebob Posted September 22, 2011 Share Posted September 22, 2011 I am always amazed at all the great information the members like Rob have and share on this site. Its like calling the factory and getting the info you need. Its great to have such a talented group of people that go out of their way to share what they know with others. I just love this site. Bob Quote Link to comment Share on other sites More sharing options...
MonteNH Posted September 22, 2011 Author Share Posted September 22, 2011 I am always amazed at all the great information the members like Rob have and share on this site. Its like calling the factory and getting the info you need. Its great to have such a talented group of people that go out of their way to share what they know with others. I just love this site. Bob So true Now that im looking at mine it does not have the tabs that both pictures with red arrows show. Mine must be the 8.2 Quote Link to comment Share on other sites More sharing options...
cbolt Posted September 22, 2011 Share Posted September 22, 2011 Oh, and yes, it is worth adding the gears and the posi unit to the 8.2. Super Chevy mag just did an article either this month or last which described the entire process, with photos, for the 10 bolt. People will tell you the 12 bolt is stronger so if you are thinking about, or making, high horsepower you may want to consider the 12 bolt. I have found lots of parts for the 8.2 10 bolt, including axles, and I am not planning to making any more than 400hp, ever. Quote Link to comment Share on other sites More sharing options...
cbolt Posted September 22, 2011 Share Posted September 22, 2011 I would check the pinion nut anyway, just to be on the safe side. Quote Link to comment Share on other sites More sharing options...
MonteNH Posted September 22, 2011 Author Share Posted September 22, 2011 Oh, and yes, it is worth adding the gears and the posi unit to the 8.2. Super Chevy mag just did an article either this month or last which described the entire process, with photos, for the 10 bolt. People will tell you the 12 bolt is stronger so if you are thinking about, or making, high horsepower you may want to consider the 12 bolt. I have found lots of parts for the 8.2 10 bolt, including axles, and I am not planning to making any more than 400hp, ever. Thanks a bunch. Same for me , I plan on being right around 400 HP myself. I wont be drag racing the car which Is why I was considering just building this rear end as long as its an 8.2 Quote Link to comment Share on other sites More sharing options...
Chris Posted September 24, 2011 Share Posted September 24, 2011 Phil, Give me a call after lunch Saturday and we can put the car up on my lift so you can actually look at what's installed without laying on the ground. Quote Link to comment Share on other sites More sharing options...
MonteNH Posted September 24, 2011 Author Share Posted September 24, 2011 Thanks so much Chris , I will call You this afternoon. Quote Link to comment Share on other sites More sharing options...
MGD72Monte Posted September 24, 2011 Share Posted September 24, 2011 Great info on this post, I'm about to open up the diff on mine and was wondering how to determine if I have 8.2 or 8.5. Looks like it should be easy. Thanks all!!! Quote Link to comment Share on other sites More sharing options...
robs70monte Posted September 24, 2011 Share Posted September 24, 2011 you can tell with out taking the apart 8.5s have the ears and the 8.2s don't, its pretty cut and run Quote Link to comment Share on other sites More sharing options...
VE3HZZ Posted September 29, 2011 Share Posted September 29, 2011 Thanks for the info and pics will make it easy to check mine for future reference. I have often been to some swap meet or ??? and seen an item for a car etc and now with some extra info will know if that diff (for example) will fit have parts I may want..I need to read up more as I can..... I knew joining here would be a wealth of information. Thanks again. Scott Quote Link to comment Share on other sites More sharing options...
Hetman Posted December 31, 2011 Share Posted December 31, 2011 the 8.5 10 bolt will have 2 ears on the bottom of the center section the 8.2 is rounded This is an excellent topic, about which I know embarrassingly little. But they say the only stupid question is the one left unasked, so I'd like to ask you experts some similar questions I have about the rear axle on my 1970 (April build date) Monte Carlo which is equipped with a 350 c.i., 2-barrel engine. I can't identify the differential on my Monte (shown below) despite looking at the above photo and description. To be fair, I haven't gotten a chance yet to get under the car and take a good look at it, but from what I see, it's none of the differentials listed in the pictures here. I know it's not a 7.5" but it doesn't seem to be the 8.5" either, which have very noticeable ears (lugs) coming out on either side on the bottom, as indicated in the middle picture. I have the 8.5" on every 2nd generation Monte I've ever had, but one of them (a 1973) had the strange ridge on the cover just like the one shown on the 8.2" in the picture. Is that what they refer to as the "irregular" cover? Anyway, as you can see in my pictures, my differential also has two-pointed ears in that same location, as well as very noticeable C-shaped indentations at 9:00 and 3:00 on the cover, neither of which is shown for the 8.2" 10 bolt in the left picture. So what gives?! What kind of axle do I have in my Monte? The car seems to be 100% original, with only 91,000 miles, so what kind of differential do I have, and why isn't it the 8.2"? I know this isn't of earth-shattering importance, but I'm very curious. Thanks for all the help! Quote Link to comment Share on other sites More sharing options...
Ian Posted December 31, 2011 Share Posted December 31, 2011 I think that is the BOP 8.2 10 bolt. I had one in my 72 many years ago. See here http://www.jdrace.com/Rear_ID/10bBOP_Pontiac.htm Quote Link to comment Share on other sites More sharing options...
Hetman Posted December 31, 2011 Share Posted December 31, 2011 Yes!! That's the one. Thank you so much, sir! Quote Link to comment Share on other sites More sharing options...
AL M Posted January 3, 2012 Share Posted January 3, 2012 Dont be afraid to build up that BOP...There are a few of us that have these rears. A lil more $$ to do but real strong. From what I understand back in the day they did a lot of part swapin' on the assembly lines. Mines on my build sheet w/ a 278 gear. Its now a 411 w/ a new eaton posi and doing fine behind my stout 427 sb with close to 600 hp. Quote Link to comment Share on other sites More sharing options...
Clever Idiot Posted January 3, 2012 Share Posted January 3, 2012 I was just about to ask whether or not anyone knew if the BOP was 8.2 or 8.5, because I also have a BOP. Thanks, Ian. Quote Link to comment Share on other sites More sharing options...
dave m Posted January 5, 2012 Share Posted January 5, 2012 ok I just checked the one I bought it also looks like a bop I hate to sound foolish but what is bop buick or pontiac ??? this rear came out of a 68 chevelle 4 dr and he showed me all the doc build sheet and protect o plate. I was factory to the car It was also an inline six. thanks Quote Link to comment Share on other sites More sharing options...
AL M Posted January 5, 2012 Share Posted January 5, 2012 Buick, Olds, Pontiac....came in all even ours...so really it should be called a BOMP... Buick, Olds, Monte, Pontiac..lol Quote Link to comment Share on other sites More sharing options...
Hetman Posted January 6, 2012 Share Posted January 6, 2012 It's good to hear that the BOP 8.2 is strong enough to handle big HP. I like the idea that it has bolt-in axles and no C-clips (though I've never had a C-clip failure; I've heard of them). Incidentally, I have had no problems with the 8.5" 10-bolts behind a souped up 454 in my white 73, and the factory 454 in my 74. I wasn't aware of the reputation of the BOP axle, but wondered why GM put 12 bolts in so many cars in those days if the 8.2 was good enough. Quote Link to comment Share on other sites More sharing options...
dave m Posted January 8, 2012 Share Posted January 8, 2012 one more question I do have the 8.2 with the shape line on the cover. I wAS PLANNING ON DOING NEW AXLE SEALS are they c clip axles or bolt in. under the pic itsays c clip but hetman above says bot in axles am I now talking about something diffrent??? also in either case do I need to have bearing pressed on and off to change the seals?? are the bearings pressed on the axles or someting diffrent, also if I decide to do the pinion seal, Is it safe to just pull the yoke off and replace the seal then re=torque the nut. sorry but I have never gotten into a rear alwasy just changed out the whole housing. thanks again dave Quote Link to comment Share on other sites More sharing options...
70 Iron Posted January 12, 2012 Share Posted January 12, 2012 Dave you should have the "C" clip type,also the bearings are in the axle tubes behind the seals,(won't need to touch the bearings to remove the seals)you'll need a slide like hammer to pull the bearings.Pull the rear cover and you'll see the pin that holds the axles against the C clips ,it will be between the axle ends and it will have a 3/8 or 7/16 bolt (head) in the one end that screws thru the side of the casting that will have to come out to slide the pin out so you can push the axles in far enough to pull the C clips ,some times the clips just fall out (Use a extension magnet )but caution that you don't turn the Assembly after the pin is removed and axles are out,the side gears and/or the washers that the axle spline goes thru may drop out and sometimes are a B --- to get back in place. Check the axles where the bearings ride for a wear grove when you have them out and replace the axle with a doner maybe from your other rear,maybe you can practice on it first . I would punch mark the yoke ,nut /with the housing even count the threads before you begin just to be safe and return everything back as it was. Please chime in guys if I gave Dave any bad advise, I'm to old to be insulted and working from memory Terry Quote Link to comment Share on other sites More sharing options...
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