So thinking I should double check before I starting spending $'s. Axle needed.... Light-ish chassis(2500-2700lbs), 5 speed, 315 lb-ft. Moderately wide at a bulge to bulge on the outsides of the (big) tires of ~71-72". Traditional looks are not really an issue, but overall weight is (trying to make this handle and ride a touch better than some others...) I have a small preference for the drop out center type. Wheel bolt pattern needs to be 5 on 4.5. Clutch type or torsen/Truetrac LSD avilability important. Would like disc brake package- one with internal drum type park brake (not cable-to-caliper) Gear ratio availability needed in the 3.20 to 3.80 range (to be decided) So what other options am I suggested by y'all? Or just go ahead with the 8" & send credit card numbers to Currie & Wilwood?
A 9 inch Ford is certainly BETTER Can be had with disc brakes, much stronger than a 8 inch, posi can be found easily, widths available from 58 inches to 66 or so. Aftermarket support unmatched by any other rear end. Aluminum center sections available ( along with aluminum Daytona pinion supports ) The aluminum pieces gets the 9 inch down to less weight ( overall ) than the same length 8 inch Ford. .
Dodge 8&3/4. Lighter, maybe not as stong but strong enough for anything you throw at it, cheaper in the salvage yards than the 9" and enough aftermarket support for any gear and discs brakes.
Ditto to all. Ford 9 or a Mopar 8 3/4 I'm a Mopar guy but there is certainly more aftermarket support to make a 9 inch anyway you want. edit: the 8.8 is an excellent suggestion as far as strength:cash ratio. If you swap gears, get a posi unit for better spline axles, then get the shafts and you should be fine. just doesn't happen to be a drop out unit
For that amount of power, an 8.8 rear out of a Ford Explorer can be found in large supply (#1 cash for clunkers vehicle), with modern factory disc brakes, 5-on 4-1/2" bolt circle. They are not as "glamorous" as an 8" or 9", but the are strong enough for your application, and way cheaper. The last one I purchased for a Jeep project was $150.00 complete, and could have been run as-is (with just a yoke change). It had 3.55 (common) gears and a clutch-style limited slip. Even the brakes were good (get the e-brake cables). It has a inner drum-style parking brake. The Detroit Truetrac (Torsen-type) is available, as are all of the other "flavors" of limited-slip. Ratios: 3.08, 3.27, 3.31, 3.55, 3.73, and 3.90 are right in your range. Aftermarket support is adequate. It is not as strong as a 9", but few really need that strength (>$).
315 lb-ft, 2600 lbs, here guys... The typical 9" is 205-210 lbs with nodular iron 3rd member... maybe can get it down to around 180 lbs with careful selection of lighter brakes and aluminum 3rd member. 8" is around 165-175 OE, with same alum 3rd member and LW brakes, should be just under 150 lbs. That's one of my big criteria. Before I'd look at at 9", I think I'd look at 8.8", but I don't think there are any lightweight versions... not counting the IRS. As far as I know, the only aluminum, non-drop out style axle is the Jeep D44A, and it had issues.
I vote for an 8.8 Mine has 3.73 gears limited slip and seems to hold up fine. Got mine for $200 have seen them as low as $50 called and it was gone.
I may be mistaken ... but I do not believe the 8 inch Ford has a aluminum center section available. and a posi is difficult to find. Another thing to consider is that when Ford Motor Company built the early Mustangs ... they installed the 8 inch rear ends under the lower horsepower models. The ones with over 230/240 Horsepower got the 9 inch Ford. I believe the early Mustangs did not weigh much ( if any ) more than your projected weight of 2600 pounds. Also ... all 8 inch Fords came with small axle bearings ... and the 9 inch Fords came with small or larger bearings. COST wise $$$ The 8.8 is the better choice ... but only because the rear ends came from the factory equipped with disc brakes. The down side is ... NO removal center section
Ok, so how much does an 8.8 disc brake axle weigh? I've heard ~280...? Seems alot to me. Currie are the ones who make a 8" aluminum 3rd member, btw.
I think your looking for everything and expecting no compromises. Good luck to that!!!! If unsprung weight is so important to you I'd suggest a V8 IRS. You'll get your weight down and most likely get the disc setup as well with the IRS. If thats a bit too complex then maybe go for a De Dion tube setup...with the brakes at the diff for even lower unsprung weight, but with a solid axle style of suspension attachment to the vehicle. Me...not knowing exactly what your building...I'd still look hard at the 8.8.
My vote is for the 8.8 out of the explorer. They are holding up to off roaders 400 hp v-8's running 35's with 4:10 gears........stock. It isn't super light but for what they are going for you could buy 3 and not touch what a similar 9 inch set up would cost. A vast majority of them came with trac-loc from the factory. The most popular gears were 355, 373, 410 with an occasional 456 though i have never seen one. There is a ton of crap to cut off, but after 95 all came with rear discs. They are still c-clip type axles but the disc brakes act as an "axle retainer" long enough to get yourself together.
i have an 8 inch with 4.11's, and an auburn pro series locker in my 65 comet...I have a 14 to 1 289 in front of a dynamic racing C4....and its still there..now i dont run slicks often (and i havent had it at the track), it doesnt hook very well on the street, so im sure thats why it has survived under my 2900 lb car.....
they do offer c-clip eliminator clips for 8.8's. My friend put one in his mustang. You see a lot of 8.8's under sub 10second cars at NMRA events, even though they are spiral bevel they are plenty strong for a street car, and spiral bevel rear end types have the benefit of being more effecient, meaning less lost power. When doing calculations we would factor 9'' cars at 15% drivetrain loss, 8.8 cars (sprial bevel) at 12% loss. I don't know about the weight though? and integral, not removable. But cheap compared to 9in and 8in build ups.
Myself, I wouldn't put a car together around an 8" Ford or 8 3/4" Chrysler rearend. And if you're very serious about how you're gonna hammer the vehicle, a factory 9" Ford donor can be the wrong part for the job. With what I'm reading, a budget minded person could use a Ranger 7.5 or Exploder 8.8 rearend and not have to spend too much money. or even a Camaro or S-10 rear. C-clip axle worries? GM used the 8 7/8" rg 12 bolt rearend behind factory SS454's in Chevelles and Monte Carlos. Also used in many GM, Ford, and Dodge 3/4 ton pickup rearends after 1978. Grab a wheel seal/bearing catalog and some experience. Real deal, gonna hammer it hard because that's it's job, no c-clip axles.
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