Rear dif swap?

swisherred

swisherred

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I have a 2.76 rear end that has had the bearings replaced with green bearings. I also have a 2.76 sure grip rear end removed from another car with unknown miles. I know the brake lines on it are jacked up...but work...I already replaced all of my brakes on mine...trying to decide if I should swap all the new stuff over to the other rear end or keep mine and just swap the diff.

Ive never swapped a diff and have no idea what I would be getting into...special tools? problems? is it really just removing the bolts and axles and swapping the diffs?

I am considering getting a 3.23 gear set too...never changed those either. both are 742 cases.
 
Yup it's pretty simple swap....hardest part is probably getting those old U-bolt loose and wrestling it up over the springs...unless you drop the rear portion of the spring and then roll it into place. Make sure to buy new U-bots. ;)
 
Assuming this is an 8 3/4 rear, it's pretty easy to just swap the center section. Since you have "green" bearings, you don't have to adjust the end play.

Pull the drums, then unbolt the retainer for the axles and pull the axles out about a foot. Unbolt the driveshaft and now unbolt the center section. Scrape the gasket and replace with new. Reverse procedure to assemble.

Much easier than pulling the entire rear. Hardest part is wrestling the center section into place. Most guys use a floor jack, although I've known some strong guys that just pick them up and toss them in.
 
I would also suggest just doing the 3rd member swap. As noted replace the gasket. Green bearings are considerably less sturdy than tapered rollers. A lot will depend on how hard you intend to drive the car. If this is a pleasure use auto, you can probably get away with the green bearings. If you drive it hard or intend to pull a trailer, tapered rollers are a much stronger choice. Some of the green bearings are now being imported from China and I would not trust those under any circumstances. If you are going to go back to tapered rollers, you will need to replace the inner axle seals. Check the donor rear end, if it has good tapered rollers, USA made, it would be a cheap fix for your own piece of mind to just swap the axles. FSM gives the end play adjustment procedure, it is not that difficult. With a sure grip, be sure to install the proper amount of sure grip additive to the gear oil. This is also a good time to check the u-joints and replace them if necessary.

Dave.
 
I'm going to be swapping the springs too...any reason i cannot use the original U bolts?
I didn't install the bearings...previous owner stated they had been changed. I didnt realize they weren't as good as the tapered bearings. I do drive sort of hard, and MAY do a trailer some day, but probably not. I liked the idea it had new bearings...but maybe since I'm swapping the springs too, I should just swap the entire rear and move the brakes over to the other rear...either way, the gasket needs to be replaced as it is leaking some.
 
swisherred said:
Im going to be swapping the springs too...any reason i cannot use the original U bolts?
Click to expand...

If you are not going to remove the u-bolts, no need to replace them.. FYI it is a major PIA to replace the springs and axle assembly as a unit as something always fails to line up when moving the axle from one car to another. Been there, done that, do not want to do it again. Spring bushings should be replaced with the springs out of the car unless they are in pristine condition. Do the brake lines at the same time and carefully inspect the E-Brake cables as well.

Dave
 
Davea Lux said:
If you are not going to remove the u-bolts, no need to replace them.. FYI it is a major PIA to replace the springs and axle assembly as a unit as something always fails to line up when moving the axle from one car to another. Been there, done that, do not want to do it again. Spring bushings should be replaced with the springs out of the car unless they are in pristine condition. Do the brake lines at the same time and carefully inspect the E-Brake cables as well.

Dave
Click to expand...
I have all new bushings and the cables are new. I have already cut the old U bolts off...I didnt intend to swap the whole rear so they had to go. I havent looked at mine yet, but i guess I should figure on replacing them. Amazon has some 3"x7" for 7000lbs axles for about $20...I think that is the size I need..
 
well....those U bolts wont work for me. only grade 5...I want grade 8. anyone have a source or number for new U bolts?
 
I think I should not get in a hurry. I found a set of used 3.23 gears for sale. I think i want to get those and rebuild the new rear end entirely with new gaskets, seals, gears, bolts...everything and then swap that and the springs/torsion bars all at the same time with new brake lines. If I'm going to do it...I should do it right.
 
actually....lets talk about the gears before I make any decisions.
I currently have in my car:
*stock 383/727 with 4bbl 650 avs non HP and 915 heads.
*Single exhaust now, but getting everything I need to convert to dual. 2.76 one legger with 215/70r14 tires. (25.4")

*I also have a set of 225/70r15 (27") wheels and a 2.76 clutch sure grip, police springs/torsion bars.

I want a good highway car, but love the "put you in your seat" torque at lights/passing gear.
with the tire change and the gear change, would I be where I want to be? or should I just stay with the 2.76" or the 14s" (I have no future goals of disc brakes)
 
3.23 gears with 225/70R-15 is a pretty good combo. For reference, the SFGT ran 3.23 gears with a 235/70R15 equivalent. (H-70/15). You are going to still have a big heavy Chrysler in any case but the lower gears will give you good highway and stop light to stop light performance. 3.23 versus 2.76 is going to drop the mileage some, probably something in the 2-3 mpg range, a lot will depend on how you drive. This car is heavy enough that you probably do not really need a sure grip unless you live in an area with lots of snow. If you live in a rural area with crowned roads, the sure grip will tend to cause problems in icy conditions because if both wheels are spinning at the same speed from a dead stop, the rear of the car tends to follow the crown down towards the ditch. 70 series tires tend to have very poor traction on ice to start with and the sure grip makes the problem worse.

Dave
 
I rarely see snow and have no intention of driving this in it...but we do get alot of rain and we have crowned roads..
 
I have used 3.23's for as long as I can remember and love them. I had them in my wagon then removed them to try a set of 2.76 for holiday travel...,great high speed cruising but would bog down on through the mountains a bit, 440 with it's torque made the difference. Swapped the 3.23's back in and it was almost night and day the difference in performance and drivability, would never use another ratio.
 
Ok...so if I don't need the posi for this then it makes sense for me to sell it to buy some other parts I need...any thoughts on a fair price for it? It would be nice to get the 3.23 and a few other things.
 
swisherred said:
Ok...so if I don't need the posi for this then it makes sense for me to sell it to buy some other parts I need...any thoughts on a fair price for it? It would be nice to get the 3.23 and a few other things.
Click to expand...

Try putting it in the "For Sale" on this site. 2.76 sure grips rear ends have a limited appeal because the big foot crowd usually goes for 3.23 or 3.55. I would try the make offer option and see what happens. You can always list it on E-Bay later if it does not work out.

Dave
 
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