Gear ratio

[tracy]

I have an 8 3/4 rearend in a 70 roadrunner. 489 case I got from a friend. Said it was I 391 suregrip. 11 teeth on the pinion, 43 teeth on ring gear. Only numbers I see on ring rear is 537. So what do I have here ???

 

[eldubb440]

43/11= 3.909....

 

[tracy]

So it is a 391

 

[tracy]

One more question. Its a clutch style. Not been in use for many years. Could the clutches be stuck. I have something binding ?

 

[eldubb440]

if it's difficult to turn rolling it around the yard on its own, that's probably a good sign

 

[tracy]

Ok. It is. Thank you

 

[khryslerkid]

With all of the pitting on the gear I'd have to wonder what the bearings look like. You'll find the pitting from the vehicle sitting for many years and the moisture gets to the top of the gear that's not submerged in gear lube.

 

[eldubb440]

With all of the pitting on the gear I'd have to wonder what the bearings look like. You'll find the pitting from the vehicle sitting for many years and the moisture gets to the top of the gear that's not submerged in gear lube.

I didn't look at the picture

 

[tracy]

Yeah ther is some pitting

 

[tracy]

Bearings seem to spin ok. But that's with no load

 

[33 IMP]

489 case usually has a cone style suregrip.
If the suregrip bolts together from the ring gear side, it's a cone
If it bolts together from the opposite side, it's a clutch.

 

[R413]

It is a cone type

 

[tracy]

Mine is a clutch type, I found out what was the problem. Side gears all busted, so now what ?

 

[dvw]

Mine is a clutch type, I found out what was the problem. Side gears all busted, so now what ?

Measure the back lash before any disassembly. Then the carrier can be removed repaired, and reinstalled w/o removing the pinion. When reinstalling the carrier return to the original back lash. If you've never done this type of work and don't have the special tools? Do yourself a favor and take to someone who does. This isn't a beginer job. I probably have parts.
Doug

 

[33 IMP]

You could try Dr Diff for parts. Other than him, I have no idea. Good luck!

 

[tracy]

Ok. Thanks

 

[R413]

With the pitting and broken spider gears when is it time to give up on this unit?

Hard to tell because the photo looks worse than and under the sea job from the 70's.

 

[33 IMP]

Gears and bearings might be bad..... but the 489 case is a good one, gears available In a variety of ratios, and the clutch suregrip is the preferred one, IF the repair parts are available.
It's not trash can filler.

 

[R413]

Can you take a better photo?

Does this look like a cone to anybody else? Picture is a challenger for sure.

 

[R/T Boy 67]

It is a lousy picture, but it does look like a cone type to me.