rear end and tranny ?

[lukedukem]

so i wanted to find out what rear end gears i have under my car. so i jacked it up and marked the drive shaft and spun the tire. for every 1 tire turn i got 3 and a quarter turns on the drive shaft. tells me i got 3.23 gears and the housing is a 8 3/4. now when i spun the wheel the other spun in the same direction... what does this mean exactly. that its a suregrip? either way i turned it the other tire turned the same way.
and another thing i need to figure out... when my speedo says 60 mph i'm acctually going 50mph. so my tranny would need a speedo gear to match rear end, correct?
any help would be appriciated. i hope i did all this right.

luke

[randy73]

Could be, but my open spun also, but slower. If they spin the same speed, I would think it is a SG.

[John_Kunkel]

To determine the speedo pinion gear needed you need to know the exact diameter of the tire in addition to the axle ratio.

I would check the accuracy of the odometer over a known distance, in some cases the odometer is correct but the speedo isn't...in this case the pinion isn't the problem.

[lukedukem]

To determine the speedo pinion gear needed you need to know the exact diameter of the tire in addition to the axle ratio.

I would check the accuracy of the odometer over a known distance, in some cases the odometer is correct but the speedo isn't...in this case the pinion isn't the problem.

I realize that. But is it a sure grip.
And the odometer doesn't work but the speedo does. It says 60mph and I was clock at 50mph. That tells me the tranny speedo does not match the rear end. But I just want to know it the rear end is a sure grip. And who's to find out what I need to do to determine how to match speedo in car to actual speed car is going. I hope I'm confusing anyone.

Luke

[Back N Black]

For the speedo, i used my GPS and the speedo was exact with the GPS.

[Sublime/Sixpack]

With both rear tires off the ground and if both wheels rotate in the same direction you more than likely have Limited Slip. To be sure I'd chock the front tire, put the trans in neutral, jack up just one rear tire, then try rotating it. If it's difficult to rotate you have Limited Slip and it's probably in good working order. If it rotates easily it could be a Limited Slip but in poor condition, or an open diff.

On a side note, I once bought a diff. that was supposed to be Limited Slip. When one side was rotated the other side turned in the same direction. BUT before putting it into service I removed the cover and found the case full of saw dust! And it wasn't Limited Slip after all. It was simply an open diff. that was gunked up inside with gear oil and saw dust.

[lukedukem]

 

[firefighter3931]

Luke, you have a 3.23 sure grip in that 8.75 centersection. 

What tire are you running out back ? The speedo gear is definately incorrect.


Ron

[Cooter]

Luke, you could have a Sure Grip, and you could NOT have one. only way to tell FOR SURE is jack up ONE SIDE of car in rear, turn THAT wheel with car in Neutral and see if it moves. If it Moves, it is NOT a Sure Grip...If it won't Move without considerable force, it is a Sure Grip.

[lukedukem]

Luke, you have a 3.23 sure grip in that 8.75 centersection. 

What tire are you running out back ? The speedo gear is definately incorrect.


Ron

i'm running 275/60/r15

[lukedukem]

Luke, you could have a Sure Grip, and you could NOT have one. only way to tell FOR SURE is jack up ONE SIDE of car in rear, trun THAT wheel with car in Neutral and see if it moves. If it Moves, it is NOT a Sure Grip...If it won't Move without considerable force, it is a Sure Grip.

yeha, i'm gonna try that as soon as i get home from work

luke

[Cooter]

  Just to be good and sure.

[firefighter3931]

Luke, you have a 3.23 sure grip in that 8.75 centersection. 

What tire are you running out back ? The speedo gear is definately incorrect.


Ron

i'm running 275/60/r15

You need a green 31 tooth speedo pinion gear

Ron

[branded]

I'd like to jump in and ask if you can swap the gears in a 4.10 dana sure grip with 3.23 gears?  I'm looking to get my Charger on the road this summer and would like to have a higher geared rear end.  If this isn't possible, does anyone know where to look for a 3.23 rear end? 

[RallyeMike]

All these old timers responding on "how to determine if it's a sure grip" and nobody yet has provided the best way to check: Power brake, floor it, and see how many stripes you lay.  

I'd like to jump in and ask if you can swap the gears in a 4.10 dana sure grip with 3.23 gears?  I'm looking to get my Charger on the road this summer and would like to have a higher geared rear end.  If this isn't possible, does anyone know where to look for a 3.23 rear end?  

3.55 Dana 60 gears are widely available. I don't know that 3.23 exist.

[Cooter]

All these old timers responding on "how to determine if it's a sure grip" and nobody yet has provided the best way to check: Power brake, floor it, and see how many stripes you lay.  

That would work, cept I have an open 8 3/4 that Religiously lays TWO black marks. (Yes, I set it up that way with proper preload and hooks as hard as any "posi-trac" unit). As long as both wheels are unloaded, an open will spin both wheels.

[lukedukem]

Luke, you could have a Sure Grip, and you could NOT have one. only way to tell FOR SURE is jack up ONE SIDE of car in rear, turn THAT wheel with car in Neutral and see if it moves. If it Moves, it is NOT a Sure Grip...If it won't Move without considerable force, it is a Sure Grip.

I just tried this cooter, and yeah your right. It wouldn't turn. I'm pretty sure now. But I'll really test it like rallyemike said. Just got to put motor back together.

Luke

[Sublime/Sixpack]

All these old timers responding on "how to determine if it's a sure grip" and nobody yet has provided the best way to check: Power brake, floor it, and see how many stripes you lay.  

Yeah, that will work if the car has an engine, and it produces enough power to burn rubber.

[BrianShaughnessy]

I'd like to jump in and ask if you can swap the gears in a 4.10 dana sure grip with 3.23 gears?  I'm looking to get my Charger on the road this summer and would like to have a higher geared rear end.  If this isn't possible, does anyone know where to look for a 3.23 rear end? 

3.54 is as low .... err  high as you can go with Dana 60.

  There was a oddball Dana 61 out there that had 3.08's and a few other sizes but it's not common,  nor are the parts.


     

[5hunert]

 

All these old timers responding on "how to determine if it's a sure grip" and nobody yet has provided the best way to check: Power brake, floor it, and see how many stripes you lay.  

I'd like to jump in and ask if you can swap the gears in a 4.10 dana sure grip with 3.23 gears?  I'm looking to get my Charger on the road this summer and would like to have a higher geared rear end.  If this isn't possible, does anyone know where to look for a 3.23 rear end?  

3.55 Dana 60 gears are widely available. I don't know that 3.23 exist.