i was planning on going to the junkyard with my friend and diggin around for a posi for the GS. Are most GM 10bolts diffs. going to work. My secind question is how can i tell wether or not a diff is posi or not without taking it out maybe or maybe a trick to tell without taking the diff cover off.
In that link to George's "sight", I don't read anything about the easiest way to tell if a car has a limited slip dif or not..... o No: The easiest way to tell if it's a limited slip dif is to jack up both rear wheels and turn one wheel. If the other one turns in the same direction it's a posi. If it turns in the opposite direction it's not a posi. While you have the rear lifted from the ground, you can turn one wheel one revolution and count the number of times the driveshaft turns, which will give you a general idea of the ratio. And I don't agree with George that you shouldn't look for low numbers, it's so much more fun when you're cruizing down the motorway with speeds over 200 km/h and low revs on the old V8 engine.
Well, Erik, it certainly gives information for where to start looking. As opposed to going to every car in the junkyard so he can "jack up both rear wheels and turn one wheel". Your answer certainly can help answer his second question, but he would be there all day jacking up cars that probably do not have a posi, and that would not be the EASIEST way. And, BTW, the site does say the easiest way to tell if a car has a posi, and that is looking for the metal tag that says "USE LIMITED SLIP DIFF. LUBE ONLY". I would have to agree with George on the ratios. I don't know how many people out there besides yourself are cruising the streets at over 124 MPH. Highway gears certainly have a plus as far as how many RPMs we turn on the engine, but I am sure most people out there looking to put a posi in their car are looking for a better ratio for performance, not driving at over 124 MPH. o No: Finally Erik, thanks for pointing out my incorrect use of the word 'sight' instead of the correct 'site'...I really love it when someone mocks me for a typing error. It really takes a big person to point out other people's errors. I guess you are just smarter than me and have to point it out, thanks.
Jarrod,good read--you are right about people who put a posi in wanting ANOTHER gear ratio---I recently went from the 256 non posi to a 342 posi and I love it--- I turn 2600RPM @60 mph but I didnt buy my 455 for gas mileage---I leave that too my 3.8L SC V6 Regal @29 mpg hwy! And NOONE should be driving 124MPH on the "street"- :rant: - if you are-- you get what you deserve in addition to poor gas mileage. Pete
Nobody needs to get real uptight here, I think that Erik wanted to point out that a highway gear isn't "A waste of time" I have a posi and 2.93's and would never think about changing it, It might be different with a 350, or if you do a lot of racing, but it is a personal thing. Also, Erik wasn't stating that he would drive at 200 kph on the street, something that Pete and Jarrod took quite literally. All he's saying is that there is a trade off with going with a 3.42 or higher, that is really high RPMs at highway speed. Even George was looking to grab the realitively tame 3.08 ratio. True, that jacking up every car in a junkyard and spinning a tire isn't practical, but you can't really do what George is saying either, and all that info, while good does a person no good if they don't want to take it out or take the cover off. If you don't want to take the cover off look for the tag, it is easiest, but you will miss some where the tag was removed earlier in the cars life or just rotted away, Erik's way while harder is works everytime. Erik may have come across as a little harsh on the "site" and "sight" comment, but that's just Erik, no need to get real upset about it.
now children.... btw,if you notice erik lives in europe where you can drive those speeds :3gears: probably pretty nice in a riv :TU:
On the later model station wagons, 1980-87 which used the 28 spline axles, 88-up went to 30 spline axles, flip up the storage hatch/cover/lid on the very back of the wagon. On the bottom side you will see a GM option code sheet taped/glued to it (same as found on the trunk lid of the 78-87 G-body models such as Regal, Cutlass, Monte Carlo, Grand Prix) What you want to see is the G80 code which indicates limited slip rear (posi unit) Next you want to verify gear codes. I do this which saves a lot of time. GU1 2.56 GU2 2.73 GU3 3.08 GU4 3.23 GU5 3.42 GU6 3.73 GU7 4.10 Now, this info does not guarantee what left the factory is still in the car. I have only found 2-3 cars that had G80 and did not have a posi unit. Rear axles were swapped out. So, the sure-fire way is to remove the cover. Some full size models will have the 8.5" rears with posi are the Olds 98, Pontiac Parisienne and some Buick Electras. Good Luck!
