• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Gear ratio

T

tracy

Well-Known Member
Local time
9:54 AM
Joined
Oct 14, 2010
Messages
436
Reaction score
98
Location
indiana
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 ???

17153923251997220910305237273450.jpg
 
One more question. Its a clutch style. Not been in use for many years. Could the clutches be stuck. I have something binding ?
 
if it's difficult to turn rolling it around the yard on its own, that's probably a good sign
 
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.
 
khryslerkid said:
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.
Click to expand...

I didn't look at the picture :rolleyes:
 
Bearings seem to spin ok. But that's with no load
 
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.
 
Mine is a clutch type, I found out what was the problem. Side gears all busted, so now what ?
 
tracy said:
Mine is a clutch type, I found out what was the problem. Side gears all busted, so now what ?
Click to expand...
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
 
Last edited:
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.
 
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.
 
Can you take a better photo?

Does this look like a cone to anybody else? Picture is a challenger for sure.
 
You must log in or register to reply here.

Similar threads

blue69runner
Noise coming from the rear of car.
Replies
9
Views
368
blue69runner
blue69runner
R
  • Locked
SOLD 8 3/4 489 Case 3.23 Posi
Replies
1
Views
732
RT6PK
RT6PK
Dave6T4
Help Me Identify 727 Trans
Replies
2
Views
510
qkcuda
qkcuda
LemonWedge
742 case 8-3/4 pinion bearing part #.
Replies
2
Views
760
LemonWedge
LemonWedge
old guys rule
8 and 3/4 yolk replacement
Replies
7
Views
1K
Cranky
Cranky
Auto Transport Service
Back
Top