Hans3 Posted February 16, 2019 Share Posted February 16, 2019 Through what bolt hole is the posi tag supposed to be mounted? I can never see this on pictures of used (supposedly posi) rear-ends; thanks ! Link to comment Share on other sites More sharing options...
JZRIV Posted February 16, 2019 Share Posted February 16, 2019 What year? Link to comment Share on other sites More sharing options...
Hans3 Posted February 18, 2019 Author Share Posted February 18, 2019 On 2/16/2019 at 2:09 PM, JZRIV said: What year? Oops, sorry... it's for a 1965 diff. Link to comment Share on other sites More sharing options...
steelman Posted February 18, 2019 Share Posted February 18, 2019 This may not be true for the Riviera, but on early Corvettes the tag is attached to the fill hole. I could not find any good reference pictures. And Riviera may be different. Link to comment Share on other sites More sharing options...
telriv Posted February 18, 2019 Share Posted February 18, 2019 I know '61-'65 posi's are on the fill plug. Link to comment Share on other sites More sharing options...
RivNut Posted February 19, 2019 Share Posted February 19, 2019 (edited) Originally published in The Riview Volume 2 Issue 6 Sept./Oct. 1996 "On the bottom of the axle tube, there is an X inside a Circle denoting a positive traction rear end." I think I remember some one posting that the Posi rear's filler plug had a square drive that you inserted a 1/2" drive breaker bar into to remove the plug, and the non posi units used a head on the plug that you use a wrench on to remove the plug. Did I dream this or did anyone else read it? Edited February 19, 2019 by RivNut (see edit history) Link to comment Share on other sites More sharing options...
telriv Posted February 19, 2019 Share Posted February 19, 2019 The Posi fill plug has a 3/4" hex you use a wrench on. Non Posi uses a 3/8" drive square extension to remove. So you are remembering the opposite Ed. Link to comment Share on other sites More sharing options...
PullmeoverRED Posted February 21, 2019 Share Posted February 21, 2019 So 1963 had either or? What decided this? I'm currently experiencing some clunking noise coming from rear end and it seems my differential could be the culprit. Any thoughts? Link to comment Share on other sites More sharing options...
telriv Posted February 21, 2019 Share Posted February 21, 2019 Add 2 bottles of GM posi additive & go to a large parking lot & do a bunch of figures eights. AND IT IS NOT EITHER OR WHAT. IF IT HAS A 3/4" HEX IT'S A POSI. IF NOT AN OPEN REAR. CAN I be any more clear on this??? Link to comment Share on other sites More sharing options...
PullmeoverRED Posted March 21, 2019 Share Posted March 21, 2019 Relax telriv...appreciative of the info, however could do without the ATTITUDE. Thanks- Link to comment Share on other sites More sharing options...
first64riv Posted March 21, 2019 Share Posted March 21, 2019 Are the hex heads and square drive bolts interchangeable? My differential has a square drive bolt but I've been told by the PO it's a posi. I do have to get under it and look for markings. Link to comment Share on other sites More sharing options...
RivNut Posted March 21, 2019 Share Posted March 21, 2019 (edited) 8 hours ago, first64riv said: Are the hex heads and square drive bolts interchangeable? My differential has a square drive bolt but I've been told by the PO it's a posi. I do have to get under it and look for markings. Nope. Just pull out of the car wash with wet tires and "NAIL IT." Or find a dirt road, it's easier on the tires and the drivetrain. Markings are hard to find on a 50+ year old car. You didn't check out the Posi claim when you bought the car????? Edited March 21, 2019 by RivNut (see edit history) Link to comment Share on other sites More sharing options...
phoemsen Posted March 21, 2019 Share Posted March 21, 2019 It just so happens that mine is still up on jack stands. Here is a picture of the filler plug with 3/4" Hex head and tag ""Limited Slip Diff Lube Only " Or something close to that. 1 Link to comment Share on other sites More sharing options...
psychostang Posted March 21, 2019 Share Posted March 21, 2019 Ok people, if you have the car lifted, simply turn one of the rear wheels. IF the opposite follows, its a posi. If it rotates opposite, it's an open diff. 1 Link to comment Share on other sites More sharing options...
RivNut Posted March 21, 2019 Share Posted March 21, 2019 3 hours ago, phoemsen said: It just so happens that mine is still up on jack stands. Here is a picture of the filler plug with 3/4" Hex head and tag ""Limited Slip Diff Lube Only " Or something close to that. Tom, This doesn't jive with the description you posted earlier. ??? On 2/18/2019 at 7:39 PM, telriv said: Posi fill plug has a 3/4" hex you use a wrench on. Non Posi uses a 3/8" drive square extension to remove. Link to comment Share on other sites More sharing options...
1965rivgs Posted March 21, 2019 Share Posted March 21, 2019 1 hour ago, psychostang said: Ok people, if you have the car lifted, simply turn one of the rear wheels. IF the opposite follows, its a posi. If it rotates opposite, it's an open diff. ...or its a posi with worn clutches.... Tom 1 Link to comment Share on other sites More sharing options...
first64riv Posted March 21, 2019 Share Posted March 21, 2019 6 hours ago, RivNut said: Nope. Just pull out of the car wash with wet tires and "NAIL IT." Or find a dirt road, it's easier on the tires and the drivetrain. Markings are hard to find on a 50+ year old car. You didn't check out the Posi claim when you bought the car????? I did not test the posi claim, unfortunately. Link to comment Share on other sites More sharing options...
telriv Posted March 22, 2019 Share Posted March 22, 2019 Ed, That is a 3/4" square you use a 3/4" open end wrench on, NOT a 3/8ths. drive racket or extension which has a 3/8ths. square end. Link to comment Share on other sites More sharing options...
RivNut Posted March 22, 2019 Share Posted March 22, 2019 So were there both hex(oganal) and square heads on the posi filler plugs? Link to comment Share on other sites More sharing options...
telriv Posted March 22, 2019 Share Posted March 22, 2019 ED ALL POSI'S THAT I KNOW ABOUT HAVE THE 3/4" SQUARE dating back to 1960 at least, maybe further back. Now when the 9 3/8ths. went to having a rear cover is when the tag was placed on the cover. Tom T. Link to comment Share on other sites More sharing options...
RivNut Posted March 22, 2019 Share Posted March 22, 2019 Then where did the term "Hex" short for hexagon, a six sided parallelogram, come into the vernacular? Link to comment Share on other sites More sharing options...
1965rivgs Posted March 22, 2019 Share Posted March 22, 2019 32 minutes ago, RivNut said: Then where did the term "Hex" short for hexagon, a six sided parallelogram, come into the vernacular? Because one can use a "hex" or box wrench to remove it...standard "tech speak" and well understood in the field Tom Link to comment Share on other sites More sharing options...
first64riv Posted March 22, 2019 Share Posted March 22, 2019 So both are square type drives, but Posi's are males and open's are female. The dead on angle of the image is a bit deceiving but I will assume it's a "male" square drive bolt and confirms Tom's statements. Chris Link to comment Share on other sites More sharing options...
1965rivgs Posted March 22, 2019 Share Posted March 22, 2019 Chris, Yes, it is a male square. The open rear is a female square, Tom Mooney Link to comment Share on other sites More sharing options...
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