Still accumulating parts for my powertrain swap and got to wondering if the original rear end will hold up under the increased power of the 302 and AOD combo. The car presently has the flathead inline 6 and 3 on the tree. The new 302 will be close to stock- a mild cam, 4 barrel, and headers will be the only upgrades. If I need to change it can someone suggest a replacement rear end that will be fairly painless to install? As always, thanks in advance for sharing the knowledge
Had the same set up in a 50. I think I used a 53-54 ford rear end out of a v8 car. Seemed to work ok. You should be able to use any rear end you want as long as it isn't too wide or narrow.
Maverick 5 slug rear ends are popular on shoeboxes.If i remember right,it was 1" narrower than the original and its Ford 8",so there should be differentials that will work with the AOD.
The original would be OK , but most are plain old and worn out and you can't mix n match ratios. We have an 8" with 3.7 gears and 4 speed auto in or shoe box. 205 X 15 rear tyres and it ticks along at about 2000 rpm at 60.
To just answer your basic question, Yes the stock rear Axle will handle the new drive train. I used to know all the ratio numbers but that part of my Memory File system seems to have faded. If your lucky you can find a small tin tag on one of the housing studs with the gear ratio stamped on it. The next question is what condition is it in over all. My avitar runs a Granada 9" because my rear housing was in pieces and left out in the weather. Rebuilding it was just not a good option. You won't brake any axles or damage the gear set with the 302. Another good thing is no brake problems unless your changing the front, maybe not even then. The gear ratio may be less than you want but were it me and I knew things appeared to be in good shape I'd hook it up and run it. If you just can't live with it then look into changing it out. The Wizzard
Remember all those 49-51 Fords in the early small Mag's? Lot's ran Olds, Caddys, Buick motors and near None got a rear housing changed along with the Motor swap. We just didn't even think of doing it. The Wizard
I broke several shubox rear ends when I was in high school but I drove like an idiot. A stock rear would hold up as long as you don't do any neutral-drops. The overdrive cars got the 4.11 gears and I believe the non O.D. cars got a 3.70 gear. That said, I went with a maverick 8 inch in my last shubox. Had a 350 turbo [1 to 1 in 3rd gear] and a 3.00 gear. Loved it!
Used Chevy S10 / 3:73 in a '51 - only buy if you get it out of a pick up that still has the vehicle code sticker inside glove box door Sent from my SM-G930V using The H.A.M.B. mobile app
A later Explorer 8.8 would do, 3.73:1, traction lock, discs, 31 spline. Ideal ratio for an OD. You need engine RPM at cruising speed to be between 1800 to 2100rpm to be beneficial.
Unless I missed it above a 57 ford 9" is a bolt in- the 59 rancheros and wagons had big bearing 9" housings. I have a 57 9" for my 49. Like Rocky said those rears will break- I've twisted several axles in mine. 49 year was more prone to snapping as the casting was flawed they fixed it in 50/51... but I would abuse mine with second gear drops with tires barking etc... Sent from my iPhone using The H.A.M.B. mobile app
Thanks for all the info, don't know what I'd do without all the experience and knowledge ya'll are always willing to share! As far as I have been able to find, the stock rear end was either a 3.70 or 3.73 (depends on where I found the spec.'s). That seems to be too low for an overdrive transmission but I'm no expert. I guess I'll plan on using the original and see how it goes; I can always upgrade it later. When/if I change it, I'll be looking for the easiest to install, I'd like to avoid welding and cutting if possible- my back is getting to the point that I need to drive more and wrench less. BTW, Rocky, I love the look on the white Shoebox in the photo- stance, color, wheels... it all works just right! Congrats on a fine looking ride.
you should reconsider using the original rearend beyond just testing things - they are a weak spot in the link - 3:73 is a good ratio for modern overdrive trans
I found that the weakest point on the stock rear end is the pinion yoke. I have broken two of them in the last 25 or so years. The ratios in the shoebox rear ends are overdrive 4:11, 3 speed no overdrive 3:73, Fordomatic ('51 only) 3:31 (3:54 optional). I have a '57 9" in my '49 coupe. The spring perch spacing is about 1/2" different than the shoebox rear spacing. The leaf spring play will allow it to be a bolt-in.
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