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8 inch rear end input

6

68angrypony

Member
I'm going to rebuild my 1968 mustang's 8 inch rear end. I believe it has 2.88's and is open. I know I could go 8.8 or 9inch but I don't want to have to deal with modifying it and tracking them down etc. I have a buddy who can help me rebuild it for 200. So I have the rear end already and the outer bearings. I should have the 28 spline axles right? I really only need the new gears and the trac loc/lsd to rebuild it correct? Can anyone give me a break down of the parts I will need and what are good brands to look for? I have a 351c that is going in with either a 5 or 6 speed. Its looking more like a t5. I saw on ebay you can get 3.55 or 3.80 gears or higher/lower. Any suggestions/recommendations?
 
Engine brake HP? Vehicle weight?

Flywheel weight and clutch type?

Tire size?

Intended use?

I ask because the differential should be built for its specific purpose, especially when running a 335 series and manual transmission in a '68 in front of it. Generally, for the same BHP, less weight, more gear and a slipperier clutch/tire make things easier on the differential.

We used to race 8" rears in stock and super stock class and they'd take a lot of abuse but they were built for the application.

If this is going to be a stock weight vehicle, HP over 350, heavy flywheel, a tight clutch and sticky tires, I'd cherry pick high quality parts and spend the extra money.
 
"camachinist" said:
Engine brake HP? Vehicle weight?

Flywheel weight and clutch type?

Tire size?

Intended use?

I ask because the differential should be built for its specific purpose, especially when running a 335 series and manual transmission in a '68 in front of it. Generally, for the same BHP, less weight, more gear and a slipperier clutch/tire make things easier on the differential.

We used to race 8" rears in stock and super stock class and they'd take a lot of abuse but they were built for the application.

If this is going to be a stock weight vehicle, HP over 350, heavy flywheel, a tight clutch and sticky tires, I'd cherry pick high quality parts and spend the extra money.
Click to expand...

Not sure what the hp/tq is from the motor I got it used. Think it is mild with just and intake and carb. Not sure what clutch/fly wheel yet as that depends on trans but it will be more of a performance type set up. Tires are the bf goodrich supercomp 2 I believe. What are the higher quality parts you would recommend?
 
Some examples would be a Yukon Trac-Loc:

http://www.yukongear.com/ProductDetails ... rodID=1265

Richmond Gears:

http://www.summitracing.com/parts/rmg-4901111/overview/

If running a manual with OD, I'd recommend the 3:80 ratio for a performance application.

Timken bearing kit:

http://www.ebay.com/itm/8-Inch-Ford-Tim ... 5893c065d1

I made a unit similar to this for severe duty applications, like a manual transmission race car:

http://www.yukongear.com/ProductDetails ... rodID=1286

Lastly, don't just throw a case at the deal. Check it out thoroughly. I've got a number of different style cases out in the shop from different year vehicles and the primary area I'd always check is the web thickness in the rear pinion support bearing area. That's the area which would fail when we'd spit pinions out of the units. With all that money going into the differential, you don't want an in-service failure taking it all out and, trust me, it will!

Do a lot of guys run plain-jane 8" without any problems? Yes! What I'm thinking of is when a group of us get together like at the Mini-Feed and do burnouts on Nick's driveway and it's a long one where you can grab a couple gears. Easy to break stuff. Trust me, with the power, you'll be doing it!

Edited to add, last but not least, control that differential and housing with a quality rear suspension setup. Nothing worse than things banging around from bad shock setup, spring windup, lack of smooth power application, etc, etc, to put excess stress on the differential. Everything works together!

Have fun!
 
Other than using a non-OEM case, which last time I looked wasn't available, the only thing to do is set everything up to spec, use the best OEM case one can find ('67-up cases appear to be a bit stronger) and, though I don't really think it's necessary for your application, use an aftermarket pinion support like I linked to in my prior post.

All of this will likely never come into play unless you bolt on some sticky tires and do some hard launches and/or power shifts. Under most driving conditions, non-issue.

One other issue, if this is to be DIY. Clean, clean, clean. I use something which looks like a huge dishwasher and sprays 180 degree water with a special aqueous cleaning solution and then flash-dries. Whatever you use, make sure everything is clean and stays clean until it gets sealed into the housing. Never rush. Take your time and if something doesn't seem right, stop.
 
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