7 1/2 axle swap help.

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Shane6073

Shane6073

1974 Plymouth scamp
Joined
Jan 9, 2016
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Location
Redding CA
Hey guys I have a 74 scamp with a 7.25. I do not think the axle will hold up for more that an hour once I get the engine in. My question is what is the most common axle that people use thy swaps fairly easily? All while keepin a reasonable budget. And what cars are they found in.
 
I have had good luck with a 8 1/4 found in a lot of a bodies usually for a few hundred with a open carrier.
 
8 1/4 - 8 3/4 or a Dana 60.

8 1/4 = cheap / plentiful
8 3/4 = most expensive / hard to find
Dana 60 = strongest, typically less expensive than the 8 3/4 even after you have some housing rework done. They came in an assortment of vehicles, lot of them out there
 
Shane6073 said:
My question is what is the most common axle that people use thy swaps fairly easily? All while keeping a reasonable budget.
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Budget is relative. If you have the need to keep it on the down low, 8 1/4, if your budget has a 1000.00 bucks then I would look for an 8 3/4.
 
I am running 500 hp 440 with a 8 1/4 and a track lock on the street, works really well.
 
Furd Exploder 8.8 will get you a super strong axle with 31 spline axles and 4 1/2" disk brakes for well under $400. They come with tough limited slip, ratios from 3.31 to 4.1. There are a few stickys about doing it. For 1/3 the price of a drum brake 8 3/4 sure grip, you get the same strength and disks.
 
picked up 8 1/4 for 150 rebuild kit complete 75.00 dodge dakota 355 sure grip 50 from salvage yard, shock mounts used 50, new drums and breaks and rear lines wheel cylinders,125, 450.00 but you will need some tools for rebuild ,125.00 at hf total 575.00 complete rebuild and new brakes sure grip rear works great and you have small press and bearing installer for next project
 
mikec said:
picked up 8 1/4 for 150 rebuild kit complete 75.00 dodge dakota 355 sure grip 50 from salvage yard, shock mounts used 50, new drums and breaks and rear lines wheel cylinders,125, 450.00 but you will need some tools for rebuild ,125.00 at hf total 575.00 complete rebuild and new brakes sure grip rear works great and you have small press and bearing installer for next project
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You can also get the sure grip's from Cherokees along with the disk breaks, either work well.
 
Thank you i was already leaning towards the 8.25 but wasn't to sure on if i had to do any driveline work or perch relocation. I never thought about doing an axle out of a jeep. when i'm done with this project iill have a procharged gen 3 hemi hopefully pushing close to 500 hp. (if i can ever get out of japan)
 
Deployed or stationed? Not sure about the drive shaft length though. There is a interchange chart here somewhere.
 
There are no plug and play substitutes for the Mopar A-body 7¼ axle. The 7¼ axle has smaller tubes than the 8¼ and 8.75 units do. This means larger shock plates and clips (u-bolts) for 3" axle tubes will be needed. The other issue has to do with driveshaft length. Because of different pinion lengths and center housings, a different driveshaft will be needed as well. I mention this, not to be a prophet of doom, but as a reminder that these items need to be considered when harvesting parts or planning a budget for the upgrade.

Besides the A-body 8¼ and 8.75 units, Ford offers some rears with the same spring mount spacing as the Mopar A-body. Look for 5-bolt hubs on the following cars:

64-66 Mustang, Falcon, and Mercury Comet
69-77 Maverick
71-77 Mercury Comet
75-80 Monarch and Mercury Monarch
77-80 Lincoln Versailles - these have rear disk brakes

IMO, the safest bet for a driveshaft is to have either a known good one cut down to length or have a completely new one made up. Shops that work on large pieces of agricultural equipment can do either job, or steer you towards their out source partners.
 
Thanks Gents, appreciate the help. Kind of shot down my hopes for a easy one hour axle change but no worries. Better to take the time and do it right. So to escape spending time worrying about keeping the axle perches in the same spot have you guys ever seen or installed the leaf spring relocation kits? and if so are they worth it? eventually i hope to Mini tub it but at the same time i only have a few weeks in the states every year. so i don't really want to waste precious time on that now.
 
i have an "A" body freshly regeared with 3:91' ( no selling in this thread)
 
I installed a mopar perf spring relocation kit in my 71 scamp, and mini tubbed it at the same time. It took lots of cutting and welding and time, but it worked out great. If do a decent job most folks cant tell the car has been modified, the stock trunk hinges and springs even work with a little trimming- its almost like the factory should've done this in the first place. I did this for a bracket race car and now have big slicks that would never fit in the factory wheel house. There is quite a bit of info on it on this site, and it is a fairly common mod, whether or not it would be worth it is up to you. I don't plan on ever doing it to my daily driver. Good luck
 
I found an 8.25" A-body rear at my local salvage yard and got two lucky breaks: first, the donor car had the same wheelbase as mine so I can use the donor car's driveshaft without cutting; and second, it turned out to be a sure-grip. I got the shock plates and the U-bolts too. The U-bolt threads were stripped, but those are cheap to replace. The whole lot came to $350.

One thing that hasn't been mentioned yet is the 7.25" axles are the only ones with small bolt pattern. If you change axles, you'll change your bolt pattern.
 
magnummopar said:
super charged hemi might be a bit much for a 8 1/4. Just my $.02. If you get it too hook up, it might be short lived.
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Small world, I used to live in Grants Pass!then i moved to Klamath falls! when i come home on leave i still come to Grants pass just to fish on the Rouge! wouldnt happen to have any spare parts laying around? lol
 
One thing that hasn't been mentioned yet is the 7.25" axles are the only ones with small bolt pattern. If you change axles, you'll change your bolt pattern.
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Not true. 8.75 a body rear ends have SBP.
 
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