Time to change out rearends.

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Foomaster

Foomaster

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First off, I have a 72 318 original duster with a 7 1/4 rearend. I'm going to try and tackle taking it out this weekend. Just asking suggestion on how to take it out to make my life easier. I don't have a car lift so she is up on jacks. I'm going to hit all the bolts/nuts with liquid wrench tonight and let them soak.

Second I am putting back a 8 3/4, 3:55 trutrac gears rearend, disc brakes. The car is being setup with a 416 stroker. I'm was planning of hitting 425 horse but let's say we set the suspension of the car up for 500 horse. 727 tranny. Any Recommendation for beefing up suspension to handle the horse power. Will my current springs work or do I throw them out with the 7 1/4? By the way this is a mainly a street car.

Thanks
 
After removing the E Brake cables from the brakes and removing the driveshaft, cut the 7.25 U Bolts with a cut-off wheel as they are not wide enough to fit the axle housings of the 8.75. You'll want to buy new 3 in U Bolts. Get some help top lift the rear end out through one of the springs unless you're going to remove the springs as well.
 
Here's a couple of pics when I did mine. I went from a 7.25 to 8.75 but I swapped springs and all. It was super easy that way!

IMG_20150310_113155.jpg


IMG_20150310_130921.jpg
 
Actually with what your talking HP, I wouldn't even bother with the u-bolts on the 7 1/4 that is in there.
Take the 4 nuts off each front leaf spring hanger, then remove the two bolts on each rear leaf spring shackle bracket and roll the whole thing out from under the car. Your going to want to install new XHD leaf springs or SS springs. I'm sure your original front spring hangers have 7/16" bolts and nuts. The new springs will be 1/2", so your going to have to drill the old brackets out to 1/2" or buy new ones with 1/2" bolts and nuts. Your also going to replace the leaf spring bushings in the rear hangers also with new ones.
 
66fyssh, do you happen have a p# for the springs you use? Making sure I order the right kits.
 
I swapped the entire unit from another barracuda so I'm not sure what springs they are. There are lots of threads here about different brands and part number of springs. The important thing is to make sure your pinion angle is correct when you mount the housing on the spring perches. Lots of discussion on here about pinion angle also.

Great idea of soaking the nuts...it will help for sure. You'll love the 3:55. That's what I went to and except for the long highway drives, I love them.

Foomaster said:
66fyssh, do you happen have a p# for the springs you use? Making sure I order the right kits.
Click to expand...
 
66fyssh said:
I swapped the entire unit from another barracuda so I'm not sure what springs they are. There are lots of threads here about different brands and part number of springs. The important thing is to make sure your pinion angle is correct when you mount the housing on the spring perches. Lots of discussion on here about pinion angle also.

Great idea of soaking the nuts...it will help for sure. You'll love the 3:55. That's what I went to and except for the long highway drives, I love them.
Click to expand...
I just swapped the rearend in my 70 Dart with a big bolt pattern from my 73 parts car,,, soaking the nuts is good but I also heated the area up with a bottle of Maps gas,, that and my battery impact worked great. I wanted to use my springs so I just lowered the back and rolled it out and in with the jack. Then new U bolts.
 
If you are keeping your original springs and don't want to lift the rear end. Remove the two bolts on each of the rear shackle brackets that bolt to the body (9/16 socket). This will allow you to drop the rear of the springs to the ground easily once the old U bolts are cut. Then with tires installed on the new axle you can roll it under the car and then lift the springs up to it. Much easier than wrestling the axle across the springs if you don't have help. Also in regards to the emergency brake cables. You will probably want to use the old ones from the 7.25 and the easiest way to remove them from the backing plate is to slide the box end of a 9/16 wrench over the retainer and wobble it around while pulling on the cable sleeve on the other side of the backing plate. This is the easier way to press all three prongs on those clips.
 
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mguner said:
If you are keeping your original springs and don't want to lift the rear end. Remove the two bolts on each of the rear shackle brackets that bolt to the body (9/16 socket). This will allow you to drop the rear of the springs to the ground easily once the old U bolts are cut. Then with tires installed on the new axle you can roll it under the car and then lift the springs up to it. Much easier than wrestling the axle across the springs if you don't have help.
Click to expand...
if its not high enough
to roll it out the back with tires on
use a set of rims
 
FYI, I opted for no parking brake on my new disc brake setup from right stuff.
 
Got it out, easy peezy. Took about 2 hours with my 5 year old help. Thanks guys.
 
mguner said:
If you are keeping your original springs and don't want to lift the rear end. Remove the two bolts on each of the rear shackle brackets that bolt to the body (9/16 socket). This will allow you to drop the rear of the springs to the ground easily once the old U bolts are cut. Then with tires installed on the new axle you can roll it under the car and then lift the springs up to it. Much easier than wrestling the axle across the springs if you don't have help. Also in regards to the emergency brake cables. You will probably want to use the old ones from the 7.25 and the easiest way to remove them from the backing plate is to slide the box end of a 9/16 wrench over the retainer and wobble it around while pulling on the cable sleeve on the other side of the backing plate. This is the easier way to press all three prongs on those clips.
Click to expand...
Or you can use a hose clamp to compress the tangs on the e brake cable. It frees up your hands to pull the cable out of the backing plate
 
Another question. Before I go thru the trouble of torching the old U bolts off the 7 1/4. I was wondering if I could use the ubolt mounting plate on the springs.
I was thinking since I am a machinist, I could slot the old holes to fit the new ubolt for the 8 3/4, but I'm not sure slotting the holes is a great idea. Otherwise I could weld in the old holes and redrill. Anything else to worry about?
 
Yes. Done it on mine until I got the right plates. It was plenty strong and worked fine.
Foomaster said:
Another question. Before I go thru the trouble of torching the old U bolts off the 7 1/4. I was wondering if I could use the ubolt mounting plate on the springs.
I was thinking since I am a machinist, I could slot the old holes to fit the new ubolt for the 8 3/4, but I'm not sure slotting the holes is a great idea. Otherwise I could weld in the old holes and redrill. Anything else to worry about?
Click to expand...
 
Ok, today I received the SS springs from summit, reslotted the spring plate for the U bolts that Leo dart suggested, got new rear hangers with bushings and powder coated the old hanger brackets. Now time to assemble everything and put it under the car. Recommendation would be appreciated. Thanks guys.
 
its easy to pull as an assembly springs , shocks , e-brake cables , all at once it will roll out . then build your new set up outside the car , set up some better spring package , new center bolts , new u-bolts with shock plates and shocks on it , and roll that right in . you know the drive line well need to be shortened , just like this one . makes it easier to cut the exhaust off as well , :)
DSC07070.JPG
 
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