I'm not too familiar with differentials, so Im looking to be educated. As I look through the Summit Racing catalog, I see Auburn makes a posi rear for our cars. Will this come with the ring and pinion gears? If not, what does the 3.23 ratio refer to? Thanx guys.
Posi Rear for 7.5
- Thread starter buzz77
- Start date
- Status
No it will not come with the gear set, or the bearings for that matter, to install a posi PROPERLY you will need the posi unit, the outer bearing, and races, a carrier shim set to reset your lash. You can re-use your gears and leave the pinion in the housing that will leave your pinion depth intact, but if you change the gear set you will need pinion bearings and races pinion seal, and crush collar, and the knowledge and tools to rest your pinion depth ( or just re-use the shims and turn your radio up to drown out the whine from the rear end) The "3.24" is the axle ratio, the drive shaft spins 3.24 times for the axle to turn once. To make it simple say your car has 2.00 in it and at 55mph it turns 2,000rpms put in 4.50 gears and at the same speed it will now turn 4,500 rpms, the lower the number the lower the rpm the higher the number the higher the rpm at the same speed. ( I know these numbers are not exact for those of you that know the formula just giving an example)
That statement you see is referring to the housing itself, it has to do with the thickness of the ring gear, in relation to the centerline of the pinion. A ring gear spacer can be used to adapt the ring gear, but your better off buying the correct parts for your housing
It defines the series of the carrier. 2 series carriers will take 3.08 and numerically lower ratios, and the 3 series carriers will take 3.23 and numerically higher ratios. As you ratio goes up the pinion gets smaller and the ring gear has to be moved closer. So the 3 series carrier actually has a mounting ledge for the ring gear moved closer to the center.
However there are "thick" gears out there that are made to put 3.23 and numerically higher ratios and the 2 series carrier.
However there are "thick" gears out there that are made to put 3.23 and numerically higher ratios and the 2 series carrier.
Thanksguys. Im confused because of the series 2&3 carriers. Whether it takes 26 or 28 spline axles. Also the summit catalog seems to list 2 different model #'s one for 78-82 cars and another for the 83 and up cars. Whats the difference in 7.5 rears for those years???
Some of these guys might know for sure but I believe these cars are all 26 spline, I think the 28 spline option is for aftermarket axles. I don't think the year makes ant difference on the posi unit, it does for the outboard pinion bearing, but I'm pretty sure the posi units are all the same
Our cars with the 7.5 are 26 spline, The 8.5 used 28 spline. Most of the V6 cars came with 2.41 gears, that's a 2 series. In '89 ( I think) GM changed the 7.5 to 28 spline. You can go to 28 spline using the 8.5 axle if you wanted to. I'm pretty sure the carriers are the same from 78-87. Personally, I wouldn't spend $400-$500 for a new carrier. There's plenty of good used ones at the bone yards. Mine came from an old S10 pickup and can't beat the price.....FREE. LOL
I was going to mention the same thing about a used one, many many S-10s came with a posi unit, and a bunch if them trucks in the yards, could even get a gear set with the ratio you want as well, they used some of the more desirable ratios in them trucks
- Status
