Differential upgrade

[64plybelvwgn]

Having a '64 Belvedere, I have the weak '741 carrier and tapered axles. I want to upgrade to a 1965+ '742 or '489 carrier with a the clutch-type posi ( Sure Grip ), however am confused by the available swap info.

According to what I have read, B Bodies from 62-70 using the 8 3/4 diff have a spring pad to pad centerline of 44.00 in, and a backing plate to plate dimension of 59.20 inches. If this is the case and can be verified it would be a lot easier to locate a 67-70 diff than a 65-66. Much bigger range to choose from.

Any help and info would be appreciated.

Thank you.

 

[black64]

The rear width for b-body I have is drum to drum and goes like this

62-63 (64 max wedge) 58 1/2"
64 60 7/8"
65-67 59 1/2"
68-70 60 1/8"

spring perch all have 44"

Hope this helps

 

[etoyman]

Differential

I have '65 8-3/4 assembly powdercoated.. U would need the axles..I also have a 489 case ..sure grip c/w 4:10gears .. used but in great shape
let me know
shipping would be from canada
regards
Enzo

 

[64BEL]

I just swapped a '68 rear (supposedly from a GTX) into my '64 Belvedere. As stated, it's slightly narrower - but not by much. It went right in - no problem. I also installed super stock springs - which did create a few issues, but I have them ironed out now.

 

[Cranky]

As for the 741 being weak....how many broken ones have you seen?

 

[64plybelvwgn]

To 64 Belv:
Regarding issues with the installation of the SS springs, can you highlight some of the issues ? Did they give you any static lift ? I have a wagon and would like to get 2-3 inches of lift for tire clearance.

Thanks,

 

[64BEL]

To 64 Belv:
Regarding issues with the installation of the SS springs, can you highlight some of the issues ? Did they give you any static lift ? I have a wagon and would like to get 2-3 inches of lift for tire clearance.

Thanks,

Well, I put the 2" extended front spring hangers on as the front segment of the ss springs are shorter than the stock springs for a '64 B body (they're a one size fits all type of deal). An A body wouldn't need the extended hangers, from what I understand. So I got it all back together and had a nasty vibration starting at about 20mph. After looking at it and measuring, I realized that the rear was farther back than the stock location. This maxed out the driveshaft with no play left to the rear. I measured the total play in the driveshaft at about 1.5". I thought about going back to the stock front hangers, but the driveshaft would have been maxed out too far forward with no play that way - and it probably wouldn't have been able to bolt on anyway.

I measured the ss springs and the stock springs, and it turned out that my front segment was 1.25" shorter on the ss springs than the stock springs - not the 2" that the extended hangers were supposed to make up. So I figured if I had holes drilled 3/4" forward of the mounting holes in the extended hangers, it should put the driveshaft back in the happy medium of 3/4" of play both fore and aft. The extended hangers have two choices of mounting holes - verticle of each other. There really isn't enough material to drill a 5/8" hole only 3/4" forward of the original holes, so I had the new hole drilled in the middle of the two mounting holes - 3/4" forward. I had a friend do it because he had a better press and a steadier hand than me. LOL

After I buttoned it all back up, the vibration was gone - problem solved. Each car could be different individually, but this is how it shook out for me. Drilling the new mounting holes cost me an insignificant amount of height, but no sweat there. I'm happy with how it raised the rear up from before, but it is a bit of a rougher ride. No more problems with my 275s hitting the wheel wells with a back seat passenger now, so that's cool. I have pics of the operation - I'll try to get them posted.

Dave

 

[64BEL]

OK - let's try this. Sorry if they're really big. The first pic shows the car with the stock springs. The others show the comparisson between the stock and extended front hangers. The last pic shows the car with the SS springs and the vibration. Notice that I had them bolted through the lower hole - this is the highest option.

 

[64BEL]

Here is another pic that shows the mounting holes. I don't have a pic of the hangers with the new holes, but there's now a hole 3/4" forward and in the middle of the two holes they came with. This is the hole that the front eye is bolted to now.

The second pic shows how the 2" hanger studs didn't exactly match the factory studs. A little reaming of the body holes was necessary to get them to fit. The third pic shows the car as it is now. The torsion bars are cranked up a bit, and the pic has a shadow that obscures the view of the rear wheel somewhat. I don't have a better pic at the moment (too late to take one tonight yet!).

Dave

 

[5.7 hemi]

Just swap out the center and be done with it, unless you want to get rid of the tapered axles then use a 65 or later rear and problem is solved.

 

[64BEL]

Here's a pic of the new mounting hole.