I am shopping around for a rear ale for my brother's 74 Duster and came across a guy saying he has a A-body 8 1/4 rear axle for sale that has 2.45 gears and 11 inch brakes. Sounds to me like either he doesn't know what he is talking about or this is a rear end out of a v-8 car with a tow package and a four speed, maybe? I didn't think the 2.45 rear gear ratio came out until F-bodies in the late 70s. Then again, I don;t know much about rear gear ratios.

What do you guys think? Is this seller full of crap?

I had thot the same (no 2.45s in A-bodies) but it looks like we might be wrong. A search on car-part.com for '76 Dart rear axle 10-bolt pulls up several 2.45 listings. It would definitely not have come in a car with a manual transmission, tho — those got lower (numerically higher) ratios than automatics. Probably a V8/automatic/light-duty (non-tow) application; I don't have my '76 FPC handy to check.

As for the brake size, well, either the guy's incorrectly measuring his 10" brakes, or somebody swapped on some 11" brakes. The 10" and 11" backing plates share a common bolt pattern, and since this rear axle will have the 4½" bolt circle, it would be easy (if pointless) to swap on 11" brakes.

It's difficult to imagine a 2.45 rear axle working well with any transmission behind a slant-6, except perhaps in a locale below sea level where all the roads run downhill.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Yeah. This is a decent price for the axle, and my brother likes the idea of the 11 inch brakes since the car will be a manual disc/drum car when we are done. I would definitely want to swap to a 2.94 or 3.2 gearset.

however, i was researching on Valiant.org and it appears that at least 75 and 76 Darts and Valiants got 8 1/4 rear axles with 2.45 gears with both 318/904 and 318/manual transmission combinations. :shrug:

Yikes. I just priced out getting replacement gears and it looks like it will be much more cost effective to wait until I can find an axle with the right ratio to begin with! Replacement ring and pinion sets cost over $300, and that doesn't include installation and rebuilding the rest of the rear end!

I had a 2.45 geared 8 1/4 in my '71 Dart. The car was 318/904 and would run to 70 MPH in low. Cruising 65 MPH on level roads was pretty effortless. It even climbed hills fairly well, but I wouldn't try it with a slant unless you had a 4:1 or better 1st gear.

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Joshua

Hmmm. I read on Dippy.org that the 8 1/4 axles that got 2.45 gears are a different housing that will not accept any other gear ratios. Can anyone here confirm this?

Thanks.

Hi Reed. I have an 8¼ rear under my Dart with 2.45 gears. From the research I've done, the housing will work regardless of ratio, but the ring gear carrier has to be changed for the higher ratio gears. I'm just about to swap it out for a 3.21 rear with a sure-grip

As far as 11" brakes, I don't know if that was an option or if someone's upgraded.

Hope this helps,

Nat

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1970 four-door Dart, 225/A-904/2.45 gears. 0-60 in twenty three minutes!

I do believe Nat is correct about the differential case needing to be changed, but the axle housings are the same.

I've seen 11" brakes on A-bodies, but they are way overkill and way heavy. If you want increased fade resistance then get finned 10" drums and/or better brake shoes.

There were 440-6 E bodies with 11x3" front drums. My good friend Dave's '70 Satellite with a 383 had 10" drums all the way around. Neither had fins. My '62 Studebaker Lark Daytona had finned 11" drums out front and 10" drums in the back. It was a neat little 289, 4bbl, 4 speed, Twin-Traction hardtop.

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Joshua

Hmmmmm. Thanks for the input guys. I think I am going to pass on this rear axle. It would be much cheaper in the long run to just wait until I find one that has a better gear ratio.

These aren't getting any more common...the 2.45 would have been a standard ratio for a '73-76 318/904 Dart...the carriers are split down the middle with 2.45/2.56-ish (and later 2.26) being the odd ball, and the 2.76+ carrier being the more common...

How much is he asking for it Reed? ... these axles are either going in the garbage and not easy to find or are commanding a $3-400+ price tag...worst case scenario is I gut the 2.94 gears and open carrier out of the Dippy rear I have and you can put those in it... (at this rate you might be $$$ ahead just getting one of the 7 1/4" sure grips that pop up from time to time, and redo the stock rear with better gearing...

-D.Idiot

Well, the guy wants $100 for the axle. The brakes are complete but need rebuilding and the gears and carrier would need to be replaced. I wouldn't be ripping the gears out of the 5th ave though, so I would need to find a decently priced rear gearset and carrier, plus the shock plates.

I'll think about it. How common are these gearset and carriers used, and can i swap the gears and carrier out of a more common car, like a jeep or something?

If memory serves correctly, you can use the carrier and gears from a jeep with the 8¼ up until the late 90's (they changed the spline count on the axles around then).

Hope this helps,

Nat

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1970 four-door Dart, 225/A-904/2.45 gears. 0-60 in twenty three minutes!

'97 and newer 8 1/4s had 29 spline axles rather than 27 spline in the earlier models. Be careful, lots of Jeeps used the model 35 rear axle which is a 10-bolt cover with a 7.5" ring gear.

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Joshua

Hmmmm. This might be worth looking into after all. I'll have to talk to my brother about it. If I can score this axle for $100 then grab a carrier and gear from a Jeep in the local pull a part for under $100 then this might actually be an okay option. Hmmmmmm. Much to ponder....

My co-worker has a 1992 Cherokee with a 10 bolt rear...it looks exactly like the 8 1/4" under my Duster...it's not it's a Dana 35 and will not interchange... you have a better chance looking under a early-mid 90's Dakota or an 80's light duty ram pickup (worst case scenario, 1980's 5th ave,Dippy, Gran Fury, etc...
When pulling from a truck you'll need to confirm the ratio...it's not so fun when you get home an find you got a set of 3.55's or 3.91's for your A904 combo....

-D.Idiot

Thanks guys. I actually think I am going to go for this axle and then hunt around in a boneyard for an 8 1/4 gearset and carrier. I should be able to find a truck, van, or Jeep with a better gearset, and if it is a Jepp it might even be a limited slip differential.