Which rear end to use in an AV8?

Here's another dopey question from the new guy sitting in the back of the class. Basically, I don't plan to tear up every intersection at the green light, and I don't intend to pull tree stumps. What ratio banjo rear end would you guys recommend.

Details: I am going to drop a '51 8BA/'39 top loader in a full fendered Coupe. Other than a rebuild, the only mods to the engine are a 3/4 street Potvin profile on the cam. Still plan on keeping the 2 bbl 97 at this point. I haven't checked 1st or 2nd gear rations on the top loader yet.

"The book" recommends a 4.11 rear end. I'm not sure, but this seems a little tall. I would like to be able to take it out on the highway. I currently have a 1941 3.54 in my possession. One of my contacts says I'm sitting on gold, and just use that. I also have a 1942 3.78, but being I'm going full fendered, it's too wide. I suppose I could swap gears with the '41 if it was worth the effort.

Thanks for your input.

Mike

 

If you're running 16x7.00 tires, 30" tall with 4.11 gears you'd be pushing 3000rpms @65
2750 w/3.78
2500 w/3.54
You pick.

I'm currently going through a similar situation but with a banger motor.
I'm really leaning towards putting in an OD. It just cost more and is more work.
If you're going to do a cam and add carbs eventually, you might be perfectly happy with the 3.54.

 

i'm running the stock model a rear, with a '38 flathead 85 H.P. and an s 10 t5 there 411 50-55 mph 2 grand

 

I have a good bit of experience with htis and my general feeling is if your going to be running a lot of long hauls the 3.54 is decent. They are a little anemic out of the hole but livable. The 4.11 is a real stump puller and pretty testy on the open road. My personal favorite in the car you describe is the 3.78 if most of your driving is around town with the occasional road trip and a healthy flatty.

In my opinion, except for racing, Lincoln gears are a waste of cash. Put it in the motor for a great ignition and 2x2, see Bubba on here, and you'll be a lot happier.

My 2 cents!

 

I have 3:54s in my sedan. Stock '41 Merc/'39box. I cruise all day at 65 and can easily run at 70/75.

4:11 will grow tiresome quickly, unless you like running through the gears from light to light.

I have 3:78 in my roadster. 276" 59a, Isky Max 1 cam/ '39 box. I can run along just fine at 70 or above with that cam and the engine sounds like pure music.

 

If you've got a nice fresh engine, a 3.54 set will be great. I had a mildly hopped up 8ba in my A roadster with 3.48's in the quickchange and I loved it. It would still spin the tires if I wound it up and I wasn't beating it to death going 65-70 mph. I had 4.11 in there at first, and honestly I thought it sucked.

 

Im using 3:54s in an A rear, basically stock 59AB, 39 Trans. It does great. Ive put many miles on it and no issues.

 

honestly, i don't care for the 411 i am shifting all the time and the gas milage sucks. JAN T&A where did u get the 3:54's out of?

 

Thanks for all the input. Yeah, I forgot to mention the rear wheels, but Walls is spot on. I'm planning on using '35 spokers 16x7.00 in the rear.

 

Many years ago I had a very healthy B motor in a 29 rst pickup. Cook 4 port head with 2 windfield carbs. Had a 39 box with ford gears and a model A rear end with 3.27's and 750x16's

Not to good out of the hole but gangbusters after that.

Tim

 

Yeah, tell us where you got the 3:54's

 

Ring and pinions are readily available though not cheaply....
Sacramento Vintage lists them for model A rear ends for $495.00 for 3:54 and 3:78.

About 10 years ago I bought 3:54s for the V8 axle in my '30 sedan from All Ford for about $400.00

I think they can be had cheaper than those prices, though.

I'd say try Speedway but so much of their stuf now comes from China..????

Try Hot Rod Works in Idaho.... Ken and Nick specialize in early Ford axles...modern brake conversions, quick change centers, open drive conversions, etc... 208-455-7971

 

Speedway is selling Italian made Motive Gear now. They are decent gears that seem to be holding up well. The last five sets I've gotten from them spec'ed very nice and went in without any machine foolishness at all. Simple install and setup. Macs is selling the same brand for $100 more, JobLot has the same ones. I still have two sets of old Getz that I've been hoarding. The two factory 3.54 rears I've acquired in my entire lifetime were both from midwestern cars if that helps. I think they used that ratio in areas where there wern't a lot of hills?

Does anybody know if Speedway has purchased the Getz name? I've heard rumours, (rhymes with China).

 

Just a little correction on your terminology of tall and short gears. I know this can be a bit confusing to newer rodders, (and probably some older) but when you refer to a tall or high gear ratio you are actually refering to smaller numericals such as 3:23, 2:73 etc. These tall/high gears are usually used for lower engine rpms on the highway and around town. Short gears (lower gear ratios) are the larger numericals such as your 4:11 and are typically better for strip/race use. So your 4:11s are the short (low) gears and your 3:55s are taller/higher. The larger the number the shorter (lower) the gear ratio, the lower the number the taller(higher) the ratio.

 

Dont ponder. If you have a 3.54 ratio diff please use it. We have. A 32 3w with 255 merc , 39 3 spd and 3.54 rear , 7.50 x 16 rears. Couldn't be happier with the way it drives and the revs it pulls on the highway.

 

X2.... The best all around ratio if your driving on the road. The stock 239 in my Sedan is great with this ratio.... It's pulled itself up some fairly long, steep grades with no problems.... Mpg is good too

 

Thanks to all of you guys. Once again, I owe a lot to HAMBers helping me out. I'm going to try to meet with Don Marks (Phx) next week and maybe see what we got to work with.

1930 - I agree 100%, and kind of winced after I put that up, because I knew I had tall & short bass ackwards.

 

Awesome thread!


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I know im digging this one up from the grave, but just wondering if you went with the 3.54's and how its working out?
Im about to tear into my 35 rear with 4.11's . I have a 276 cu in flatty, 39 trans and 7.50 tires in the rear. Cant decide on which gear ratio. I have a 3.54 and a 3.78 sitting on my bench. I want good pull out the hole and highway speeds. I plan on driving pretty good distances

 

I see your from AZ and I assume lots of open roads. I'd use the 3.54's in a heartbeat. Let the engine cruise.

 

276 flatty and 750x16 tires , no question in a light coupe 3.54 gears and it will eat up the highway , and the torque will pull it up any hill.