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Old 05-26-2015, 06:51 PM   #1
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8 inch rear end rebuild

What does it take to rebuild an 8 inch rear end? I just found one for sale for 125$ and so I asked the guy how many miles it had and he said he didn't know for sure but a lot. He says it ran when he pulled it but I don't know how long it'll last. If I was to rebuild it what would I do? Could I just get a new 3rd member off eBay or is there other stuff I need to do? I'm doing a v8 swap so I'm starting with the diff. Thanks


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Old 05-26-2015, 07:32 PM   #2
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Depends how much power you are wanting to put into your V8 swap. Also need to find out what the gearing off the rear end is too. I had a 8" with 3.00, four lug axles and drum brakes. Nothing about that screams strength, it's more like a nice "cruising" rear end.

Not sure what model year car you have, but in my case, I wanted to upgrade. 8" was too weak, the 9" is too expensive/hard to find. So, I went with an 8.8". Took me awhile to find one, but the '79-'93 mustang/thunderbird had the exact same width at my '70. Only thing that needs modification is to weld on spring perches. I bought a housing of eBay for $150 and will buy a 31 spline 5 lug 3.73 kit from American muscle here shortly.

Long story short, if you plan to crank out 350-400 HP with your car, the 8" just may not be durable enough to last much abuse.




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Old 05-26-2015, 07:36 PM   #3
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8 inch rear end rebuild

I only plan on about 300-325 hp out of a 302. It's a 66 coupe. I want the gear ratio around 3.20-3.80. So if I was to get a 8 inch housing would I only need a 3rd member, or is there anything else?
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Old 05-26-2015, 08:04 PM   #4
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Just depends on what you get when you buy. If you get a four lug and want to go to 5, then you need new axles. If you want to go from weaker 28 spline axles to stronger 31 spline, then you need a new diff.

But if you just plan on raising the gear ratio, you'd only need the gears and new bearings/seals


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Old 05-26-2015, 08:11 PM   #5
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Yeah I'm tossing out the 7.25 and getting a 8 inch with 5 lugs. I'll get new wheels and disc brakes for the front. Does a rear end only consist of the housing and the 3rd member? Like can I get a housing then buy the 3rd member I want and choose the gear ratio I want and whether or not it's posi


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Old 05-27-2015, 02:28 AM   #6
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You can just but a housings and 3rd member you'll also need Axels. But I got a 8in with 3.55 I think and it's decent on acceleration and top/rpm speed
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Old 05-27-2015, 09:15 AM   #7
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Quote:
Originally Posted by 66strate6 View Post
Yeah I'm tossing out the 7.25 and getting a 8 inch with 5 lugs. I'll get new wheels and disc brakes for the front. Does a rear end only consist of the housing and the 3rd member? Like can I get a housing then buy the 3rd member I want and choose the gear ratio I want and whether or not it's posi


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Yes. You can buy the housing and the third member with your choice of gear ratio. If you have to get axles, be sure to get the correct spline count. ie. 28 spline axles won't work with a 31 spline differential and vice versa.

I'd recommend getting new axle bearings/seals as well. Do it right the first time.


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