Guest Posted March 5, 2002 Share Posted March 5, 2002 I had to take the differential cover off to replace a broken bolt. While I still have the cover off, I'd like to learn as much as possible about the guts of this thing. I was told this was a posi and I think it is but is there an easy way to tell by looking inside? Also can you determine the ratio by counting the gears or something? I am pretty sure you can turn the drive shaft and count the rotation of the tires or something but thought there might be an easier/more accurate way while the cover is off. I'm sure it will be some time before I do this again... by the way, it has 12-bolts in the pan cover. Thanks in advance! ------------------ Dave '70 Monte Carlo smokecracker@hotmail.com http://www.zoominternet.net/~cotton3 Quote Link to comment Share on other sites More sharing options...
Andreas Posted March 5, 2002 Share Posted March 5, 2002 This had been answered here: http://www.firstgenmc.com/ubb/Forum4/HTML/000055.html You can count the number of teeth on the gears, but I think that you will not be able to count them on the pinion gear without removing the carrier. Hence, the rotating method is easier... If you see springs and/or clutch packs or other weird stuff inside the carrier, its a posi. If you only see four conical shaped spider gears, it is an open differential (no posi). ------------------ 71 Monte 383 "The Full Monte" 86 Monte LS ZZ4 "The Gray Mouse" FOR SALE! Andreas' Monte Carlo Site Member NMCOA, FGMCC (Event Coordinator) ------------------------------------------ ------------------------------------------ "It ain't a car if it's not a Monte" [This message has been edited by Andreas (edited 03-05-2002).] Quote Link to comment Share on other sites More sharing options...
Mr70Monte Posted March 5, 2002 Share Posted March 5, 2002 You can count the pinion teeth while the gears are still in the rearend, but it is a pain. Most all GM ring & pinions have the teeth count stamped in the ring gear, like 41:15 for 2.73, 46:14 for 3.31, 41:10 for 4.10's etc. Also stamped in the same location is the part number & a date code. just rotate the gear and wipe the oil off the edge & you should find it. Quote Link to comment Share on other sites More sharing options...
ejw71 Posted March 6, 2002 Share Posted March 6, 2002 The axle housings are code stamped for each ratio. Of course, unable to find decoding housing location book. When found will post. ------------------ Ed '71 Black 350/700R4 Mar. 31th completion date '71 Saddle SS454 orginial '71 Project, 2" chop planned Quote Link to comment Share on other sites More sharing options...
alex's72fgmc Posted March 6, 2002 Share Posted March 6, 2002 hey dave look under the general section on the topic of how to id rear end ratios it is made by me covering all years "this is only true if your ratio was not changed since it came out of the factory.... hope this helps alex ------------------ hmmmm the sound of wrenches turning and... slowly out from the garage emerges a luxury muscle car that is anything but... it is.. the monte carlo with a new edelbrock performer rpm power package and new 350 block stroked to 377 cid. Quote Link to comment Share on other sites More sharing options...
Guest Posted March 6, 2002 Share Posted March 6, 2002 thanks for all the feedback... I know there are only 2 gears - one small one that woudl be attached to the drive shaft if it continued through the housing and a larger one that the axle would run through the center of. Their is something that looks like an overgrown marshmellow oposite the larger gear (attached to the right rear axle). No other gears visible. I think I'll look for the numbers this weekend and post them here... Thanks again all! Dave ------------------ Dave '70 Monte Carlo smokecracker@hotmail.com http://www.zoominternet.net/~cotton3 Quote Link to comment Share on other sites More sharing options...
Andreas Posted March 6, 2002 Share Posted March 6, 2002 The "marshmellow" is what rear-end freaks call "carrier" . This would be the part which would contain all elements of the positraction unit in it... The carrier should have at least one opening, turn the wheels if you can not see it. Then, if you can not make out four smaller gears inside of the carrier, but all kinds of other stuff such as plates and springs, chances are that you have a positraction unit. ------------------ 71 Monte 383 "The Full Monte" 86 Monte LS ZZ4 "The Gray Mouse" FOR SALE! Andreas' Monte Carlo Site Member NMCOA, FGMCC (Event Coordinator) ------------------------------------------ ------------------------------------------ "It ain't a car if it's not a Monte" [This message has been edited by Andreas (edited 03-06-2002).] Quote Link to comment Share on other sites More sharing options...
Guest Posted March 10, 2002 Share Posted March 10, 2002 OK, i finally got under the car today and was not able to find any stamped markings on the gears. I did find, in white ink of some sort, a line with a cirle around it and the number 45 immediately following it. This sequence is written on both the small and large gears. I decided to count the teeth on the gears but seems strange... I found 43 teeth on the big one and 13 on the small one. Does this sound like 3.30 posi? Any idea what the (l)45 marking is? Quote Link to comment Share on other sites More sharing options...
Grease Posted March 11, 2002 Share Posted March 11, 2002 43 and 13 sounds like the ratio GM calls 3.31 the white line and # are probly a set up code for shims . mike Quote Link to comment Share on other sites More sharing options...
Guest Posted March 11, 2002 Share Posted March 11, 2002 Thanks Grease! Quote Link to comment Share on other sites More sharing options...
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