8 3/4 Open 489 (2.71) to Sure-Grip 3.91

[mikepmcs]

yup if both wheels were up and you just got under 3 rev's on the driveshaft, you actually might have 2.73 sure grip rear.  a great highway/cruising gear.  If you had one wheel on the ground and were able to turn the other than i am confused now.  Sure grip I don't think would allow that.  I hope i misunderstood.  either way with your math it looks like you have a pretty high gear, like 2.7's or 3.2's.

v/r
Mike

[RD]

OR....

you could look on the passenger side front of the pumpkin and find your rearend ID tag which tells you what your gear ratio is hehehe

assuming its still there

[mikepmcs]

Jamey,
That's the funniest thing i've heard all night.  Little tag on the chunk, bahahaha! I think that is just a myth.

[RD]

Jamey,
That's the funniest thing i've heard all night.  Little tag on the chunk, bahahaha! I think that is just a myth.

i try.... i know i dont have the wit as bull or old moparz... but my vain attempts at humor do fall onto some listening ears sometime LOL

[SeattleCharger]

yup if both wheels were up and you just got under 3 rev's on the driveshaft, you actually might have 2.73 sure grip rear.  a great highway/cruising gear.  If you had one wheel on the ground and were able to turn the other than i am confused now.  Sure grip I don't think would allow that.  I hope i misunderstood.  either way with your math it looks like you have a pretty high gear, like 2.7's or 3.2's.

v/r
Mike

Hey Mike, both wheels were up in the air, and spinning the driver's side wheel, the other would spin same direction, if I spun one wheel forward, the other wheel would spin forward, almost like it was a locker, I don't know, if I spun one backwards, other would spin backwards.   I believe the rearend is not original,
   the car was originally a 318 column AT, but the previous owner I guess, put a 440 in it, got rid of the column shifter and shift indicator and put in a center console hurst ratchet shifter,   car was very basic on options originally, QQ1 blue, four wheel drums, has PS and PB at least.  So the previous owner hotroded up the car and must have put in the sure grip, THAT is GOOD,  hope I have the 3.2's and not the 2.7's.  Just guessing, knowing the car was all changed, with a hurst ratchet shifter, can't figure he would go with 2.7's, would make more sense that they were not so tall gears, I don't know, will have to count the driveshaft/wheel spin ratio like you guys said, thanks, Nate

[mikepmcs]

You are doing it right.  I just wanted to clarify you had both wheels up.  I hope you have 3.23's also although it needs to be over 3 turns.  2.7 are a great highway gear however and they will do ok for you too. 

I'm just changing my rear cause I want some snap and don't care about economy.  So i'm looking for 3.91 SG myself.  I don't do much highway driving so it really doesn't matter to me as long as my end result with my gear/tire combo can snap my neck when i hit the gas, i'm a happy man.

v/r
Mike

[SeattleCharger]

Thanks you guys.   Hey, if sure grips were made for performance cars, would't they more likely have 3.2 or lower gears instead of 2.9's?   If the previous owner put the sure grip on, maybe he just took it off some other car, and didn't change the gears, so would the odds be that it wasn't 2.9?    Were 2.9's ever original gears from the factory in any sure grips?

[mikepmcs]

I do think that their is a 2.94 or something out there.  Maybe you do have that one.  I'm sure someone will help us out on this one.

v/r
Mike

[sext7366]

Just thought you might want to know but there is a guy who sells mopar truck and van parts online who sells 8 3/4 pigs used for about $350 plus shipping which is a better deal than you will find most places, oh and he doesn't sell junk...if you want a rear with pitted gears and a suregrip he'll let you have it for 150-200 (depending on the gears), but then he wont make any guaruntees.  So that should tell you enough.

[mikepmcs]

Thanks, how about some info on where we can find this guy or contact him.


v/r
Mike

[daves68]

Just bought a 489 center from a boneyard NewYorker. Said 2.71 on the tag but the ring gear has 2.94 stamped on it. Go figure. Spin the ring around and look for some numbers. If it's factory, it will be on there somewhere. I have not changed one out to a suregrip yet but am looking to do it. Check with some of the advertisers in the Mopar magazines. I got some great info from Randys. Will probably get the parts soon and give it a shot. Just part of the experience.