byron Posted July 28, 2011 Report Share Posted July 28, 2011 Hi I,m asking for a friend of mine. He recently bought a small Nissan pick up and is doing maintenance on it. He wants to change the rear end lube. Question is how does he tell if it has a positrac or a regular rear end in it. Will jacking it up and spinning one tire and watching the other tell him anything, will there be a tag on the third member with info or anything in the vin or serial number that will tell him. I don't know anything else about the truck, if more info is needed I'll have to ask. thanks Byron. Link to comment Share on other sites More sharing options...
4cylfordz Posted July 28, 2011 Report Share Posted July 28, 2011 the best way is to just look at the carrier when you drain the fluid. most posi tracks will have a s- shaped spring and a stack of clutches next to one side where a open diff will only have spider gears. however if I remember correctly most of the little Nissan trucks are drop out third members so looking at it may not be an option. jacking the truck up and spinning the rear tires with the truck in neutral will tell you if it's got one, either they'll both turn ( as well as the driveshaft) or one will turn in rev rather than driveshaft spin(open diff). when in doubt just put the modifier in it.... it won't hurt a non- posi! Link to comment Share on other sites More sharing options...
byron Posted July 29, 2011 Author Report Share Posted July 29, 2011 Thank you 4cylfordz This information is exactly what my friend was looking for. Rotating one tire and seeing what the other did is how he wanted to determine what he had but no one he asked could give him this answer. I'll pass this along to him and again thanks for the information. thanks, Byron Link to comment Share on other sites More sharing options...
4cylfordz Posted July 29, 2011 Report Share Posted July 29, 2011 anytime, glad to help Link to comment Share on other sites More sharing options...
jwmbishop Posted July 29, 2011 Report Share Posted July 29, 2011 Okay so what if other side does nothing and driveshaft turns? Link to comment Share on other sites More sharing options...
4cylfordz Posted July 29, 2011 Report Share Posted July 29, 2011 than a brake is dragging on the side not spinning (or some other form of load on that axle, wheel bearing tight seal ect.. open diffs will always choose the tire that takes the least amount of effort to turn. in this case its requiring less effort to turn the differential and driveshaft in a over drive fashion, what was 4.10:1 is now 1:4.10 than it is to turn the other wheel so there is a problem that should be adressed on the side with the load during a zero load situation (tires off the ground). on a further note, a limited slip operates using a mixture of locked rear end and open diff, most commonly use clutches or cones to lock the two axle shafts together in order to create a more balanced torque to tire distribution, think a fishing reel drag... though in order to avoid extreme wear to the clutches during slippage ( like parking or turning) you have to put in a modifier similar to that that's found in automatic transmission fluid. Link to comment Share on other sites More sharing options...
jwmbishop Posted July 30, 2011 Report Share Posted July 30, 2011 Good answer - you obviously know whats happening in the rear. from an old suspicious guy though the answer is someone welded it locked and broke something, lol Link to comment Share on other sites More sharing options...
4cylfordz Posted July 30, 2011 Report Share Posted July 30, 2011 went to school to get certified to do this stuff, came out as a suspension steering and drivetrain specialist/ auto body refinishing tech and somehow ended up running a small shop as an engine builder/machinist... figure that one out lol but I appreciate the complement. but I can tell you this, the key to being the best of the best in the automotive field is not to be able to figure out which parts fail or how to replace parts but if you can understand why things work, meaning the physics that makes them tick than you can take that knowledge and apply it to anything because underneath it all every part in every car works exactly the same. Link to comment Share on other sites More sharing options...
jwmbishop Posted July 30, 2011 Report Share Posted July 30, 2011 Thats kinda the way it worked for me - after years of hands on I got the certs rather easy (certs help in getting a higher $$ job), then after more years (and experiences in all auto trades body, upholstery the whole shebang) I found myself unemployed when ferrari NA sued the company I was working for as a coach-crafter at the time. So I went back to school again. Those NIASE\ASE certs got me some course credit so I was able to get the Associates Auto Design Engineering in three years. Then spent the next 6 years building engines so the degree never brought any money back. I will say this though - after school my failure analysis skills went WAY up and THAT brought me money back (more precisely client loyalty - and job offers from which to negotiate wage/bonus structure). Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.