8.75 Question about the axles

[BeepBeepRR]

I was doing the rear brakes today and went to pull the passenger side drum off and the axle adjuster was out of the retainer. And it was damaged and would not rethread into the retainer. I got 2 more axles and they were old but retainer was in good condition. But now I can not get enough adjustment to get the play out of both sides. Question is Are the axles supposed to touch each other inside the carrier. And is that how you get the adjustment for both sides at once with only one adjuster nut.

 

[Yatzee]

I was doing the rear brakes today and went to pull the passenger side drum off and the axle adjuster was out of the retainer. And it was damaged and would not rethread into the retainer. I got 2 more axles and they were old but retainer was in good condition. But now I can not get enough adjustment to get the play out of both sides. Question is Are the axles supposed to touch each other inside the carrier. And is that how you get the adjustment for both sides at once with only one adjuster nut.

The adjuster is there to adjust the axle end play which should be between .010 and .012 which you check with a dial gauge mounted to the backing plate with the tip touching the end of the axle. You don't pull on the axle, rather you push on one and measure the play on the other side. Do both in turn checking from either side. This is the procedure for a Sure Grip so you best know exactly what chunk you're working on. The axles do not touch each other - there is a pin between the inner ends of the axles in the differential that is meant to release the posi clutches when you turn a corner. One wheel turns at a different speed than the other so the clutch plates can't be engaged on turns.

 

[BeepBeepRR]

It isn't a sure grip wheels turn opposite directions. I never could get any of the driver side play to go away. The passenger side is good to go. But I will try again tomorrow.

 

[BeepBeepRR]

Ended up buying new axle setup. I was told that the 29 and 7/8 axles were from an e-body. B-bodies are supposed to be 29 and 3/16 is that correct?

 

[Glenwood]

here's a chart from https://www.bigblockmopar.nl/tech/mopar-rearaxle-dimensions/


8-3/4″ Axle Shaft lengths, from the splined end to outside flange end:
A BODY ’66-’72: 27-11/16″
B BODY ’65-’67: 28-7/8″
’68-’70: 29 3/16″
’71-’74: 30-5/8″
’71-’73 wagon: 31-21/64″
C BODY ’65-’69: 30″
’70-’71: 30 5/8″ (Chrysler & Fury)
’70-’73: 31-21/64″ (incl. ’69 wagon)
IMPERIAL (Large Bolt Pattern) ’65-’66: 30-1/8″
’67-’69: 30-5/16″
’70-’71: 29″
’72-’73: 31-7/16″
E BODY ’70-’74: 29-31/32″
A100 ’65-’70: 30″
D100 ’65-’71: 31-1/8″
’72-’74: 31-21/64

 

[BeepBeepRR]

here's a chart from https://www.bigblockmopar.nl/tech/mopar-rearaxle-dimensions/


8-3/4″ Axle Shaft lengths, from the splined end to outside flange end:
A BODY ’66-’72: 27-11/16″
B BODY ’65-’67: 28-7/8″
’68-’70: 29 3/16″
’71-’74: 30-5/8″
’71-’73 wagon: 31-21/64″
C BODY ’65-’69: 30″
’70-’71: 30 5/8″ (Chrysler & Fury)
’70-’73: 31-21/64″ (incl. ’69 wagon)
IMPERIAL (Large Bolt Pattern) ’65-’66: 30-1/8″
’67-’69: 30-5/16″
’70-’71: 29″
’72-’73: 31-7/16″
E BODY ’70-’74: 29-31/32″
A100 ’65-’70: 30″
D100 ’65-’71: 31-1/8″
’72-’74: 31-21/64

Thanks that helps. I guess the roadrunner has a e-body rear end. So my next question is when I get the new axles "which are cut to length" do I cut them for the e-body rear end or cut them for the b-body. Seems like I would match what came out right?

 

[Glenwood]

Thanks that helps. I guess the roadrunner has a e-body rear end. So my next question is when I get the new axles "which are cut to length" do I cut them for the e-body rear end or cut them for the b-body. Seems like I would match what came out right?

I'm sure experts like DVW, Miller, to name a couple will chime in, but if it were me, I'd want to be sure what housing I had first. B & E housings, perches and axles are different lengths. This is assuming that yours was never modified. The chart in the link I posted might help identify it for you.

 

[BeepBeepRR]

double post sorry.. read below.

 

[BeepBeepRR]

OK, I measured the housing and it was 54 7/8ish without pulling the drum back plate off to get an exact measurement from end of the housing to the other end, and the spring perches center to center was 44 inches. So I can assume the housing is OE. or atleast from a 68 to 70 b-body. So the axles should be cut at 29 and 3/16 to be right.
8-3/4″ Housing Widths, from one end to the other end:
’68-’70: 54-15/16″
Spring perch distance/widths (center-to-center)
B BODY ’62-’70: 44″
8-3/4″ Axle Shaft lengths, from the splined end to outside flange end:
68-’70: 29 3/16

The carrier in the rear end is a 741 Which by the guide i was reading says it was for low HP cars.. And this leads me to believe it is not the correct rear end for the roadrunner. Which should have a more durable carrier like a 489 Or at least the carrier has been swapped. Which might just be the case.

1-3/8" small stem pinion (aka. '741')>
Carrier casting numbers: 1820657 (1957-1964), 2070741 (1964-1972). This assembly was typically used in low weight/low horsepower applications through low weight/medium horsepower and high weight/low horsepower applications. Pinion depth and bearing preload is set with shims. Differential bearing setting (ie. backlash ) is set with threaded adjusters.

 

[Glenwood]

I haven't heard of too many 741's breaking. They seemed to hold up ok behind the mighty max wedges in their day.

 

[BeepBeepRR]

Thats good info. I did find a 489 here locally.. Maybe i can grab that on the cheap and set it up.

 

[Glenwood]

489s seemed to be the fav, particularly if they have a clutch type Sure Grip. I had a 741 open in my 64, but swapped out the entire rear end with a 1970 B-body rear which had a 489 SG cone style. Otherwise, I would have gladly kept it a 741 if I had a SG since my 64 is just a cruiser.