Technical 8 inch rear end ratio for use with 302/AOD in '54 Ranch Wagon

Here is a chart. If you think you want to drive on an expressway and enjoy your engine turning 3000 rpms, pick the ratio that does that. Just remember that x way speeds ain't 55 anymore.
If you want to enjoy driving with your engine turning 1800/2000 rpms at 70/80 mph..........then pick the gear that does that. Its that simple. One point......I have never heard anyone complain about their engine quietly turning 1800 rpms for an hours long drive.
Note: This chart is for only 60 mph so err on the side of a lower numerical ratio if you plan to drive faster on the xway.

 

I think you'd end up being happy with either one, really. If it were my choice, I'd go with the 3.80 gears.

 

@ekimneirbo, I did say I seem to be in the minority. I’m no authority on where a particular engine is happiest. I think the cam has a lot to do with where the rpms should be. IMHO dogging a motor is worse than revving it a bit. I know that an OD trans. seems to be manna from heaven. I just don’t think your doing any damage keeping an engine in its power band. I’m not one to be a stickler to the rules by a long shot but isn’t an OD kind of off topic anyway? They are OK with me, I just thought we couldn’t talk about it. (Actually I’m just a poor retired guy that uses what he has on hand)......(and this is a hot rod site, right?)

 

My final ratio is 2.74 with a 27” tire and at 70 it’s at 2000 +-. I’d want a gear that wouldn’t hunt as I drive over an overpass and an OD trans will do that more than a solid 3speed automatic. All these thing need to be considered. Good luck..

 

Not trying to insult you, just saying that only you know/ or think you know what you will be happy with. Personally I'm all for overdrive transmissions and won't build anything that doesn't have one, so please don't misunderstand where I'm coming from.
Here is the point. One of the biggest mistakes (in my opinion) a builder makes is to build his car so that it is annoying to drive long distances (50/100 miles). The drone of an engine becomes tiring, parts wear much faster, gas mileage sucks and is costly......but the builder is stuck with it because he already spent a lot of money. You virtually never hear anyone say they are sorry they have overdrive. You do see a lot of people who drive way below the speed limit because they have gotten tired of listening to the noise......or their wife doesn't like it. Go get in your newest daily driver and get on an xway. Manually Put the vehicle in a gear that is not overdrive and drive it 20 miles and see how you like it and note the rpms (get 3000). Drive it at 70 (80) mph to keep up with traffic. Then put it in overdrive for the return trip. Remember that your hot rod will be even louder than your daily driver. To me having an engine operate at 1800/2000 rpms @ 75/80 mph is a requirement, not an option.
When you use overdrive it gives you that option and you can still get decent low end performance too. Its not about keeping the engine in its power band when you are on the highway, its about enjoying the drive.

How many of you readers out there would love to have an overdrive in place of their 350 turbo? Be honest.......

 

I'm all for traditional. My '39 p/u has 3 pedals, 3 speeds, and no valve covers. But I do want something in the Hamb era that and the missus and I can get in and drive on the Freeway up the coast for a weekend get away or whatever. That means a/c and an automatic so the little woman can drive it (can't drive a stick anymore due to leg braces). Yes, and an AOD may be OT but then so are T-5's and there are a boat load of them discussed here. I appreciate all the postings. Leaning towards the 3.55's but not set in concrete yet. It'll be a while before its on the road but when it is I'll report back with how things sorted. Again, thanks to all who provided info in answer to my question.

 

@ekimneirbo Insulted? I can’t remember the last time I was insulted. The OP and I’m sure many others would be happy with an OD trans. I’m not knocking them and I’m sure they would have been popular back in the 60s. I am just saddened by the direction our hobby seems to be headed. The engine revs too high, the exhaust is too loud, where is the A/C?, the car is too noisy and uncomfortable on the highway, etc. I personally like em loud and a little squirrelly but as I said I seem to be in the minority.

 

Go with the 3:55's if you go numerically higher the AOD will upshift too quick and you will need this https://transmissioncenter.net/shop/gov-kit-aod-hirev-79-93/ When you click on this they have a "Chat" feature to give you more advice on the AOD,ust it !

 

I strongly suggest you read this: http://www.silverfoxtrans.com/resources/GOVERNOR SWAP.pdf or stick with 3:55's instead of the 3:73's or you too will be needing this: https://transmissioncenter.net/shop/gov-kit-aod-hirev-79-93/ Silverfox is THE AOD Guru period. http://www.silverfoxtrans.com/files.html

 

Your chart does not take into acccount that the AOD trans has a .67 overdrive ratio. The chart assumes transmission is 1:1 final drive.

 

That should keep the fenders shiny!

 

Yes, you are correct but it should be pretty simple for someone to calculate the difference when they know their overdrive ratio. I haven't seen any charts that actually have overdrive calculations because all the manufacturers use different od ratios. Heck, some of em even have 2 overdrive ratios in the manual trannies. I've even got an OT 6 speed automatic sitting in my garage. So about all anyone can do is start with a chart like this and them calculate from there.

 

I just meant that I hoped my way of saying things didn't insult because it wasn't meant to. If you wish to build your car that way and are sure you like it that way,......thats the way you should build it. I like a throaty sound for short periods of driving. I see no advantage to running an engine at higher rpms when its not needed. I would much rather drive with my windows down than use A/C........but I don't like getting to my destination with my clothes wringing wet. Another thing I don't enjoy in my old age is being hard of hearing and having to say "What" all the time.

Air conditioning in cars has been around since 1935 and there were overdrives available for 3 speed trannys in the fifties if not before. I think I even had one way back in the sixties.

 

Not hamb friendly accept for its wheels but my truck has a 10 speed and 7th is 1-1 and a 3.55 rear and that’s where I tow..3 OD’s seem like over kill.

 

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator
I have been using this one today and plugging in .67 into the transmission gear ratio box.
Now I come up with 3:40 Gears as my best guess on e-bay for about $200 from National drivetrain

 

I came home from overseas and was supposed to be stationed at Ft. Carson where my O/T 69 big block Camaro was being stored and updated while I was gone. At the last minute my orders got changed to Ft.Campbell, Ky.
My car had a brand new ZLX 427 with a tunnel ram and 2x4's and a 4.88 gear and I was going to be the car to beat on the streets of Colorado Springs. Well I did not have time to get a gear change done before I headed east and it didn't take long for me to wish I had 14 overdrive gears. I made it to my brothers house in Michigan and for those who have never driven a 600 hp car with a 4.88 gear and N50 -15 Pro Tracs in 6 inches of new snow you will be in for a real treat if you ever have to.
The car wouldn't turn over 5500 rpm's by the time I got there because the valve springs were shot. I had turned off the radio in Kansas because you couldn't hear it over the Hooker side mount headers that I had on the car.
Yes there is something about a rowdy hot rod for a short burst down the road ,but after about a 100 miles it gets old and I wasn't old back then. I am now and I would never run anything lower than a 3.55 without overdrive in any of my cars and then it would have to have a tall tire.

 

I tend to stick with a max of 2000 rpms at whatever your cruise (frwy) speed is going to be (in final gear, 1 to 1 or o/d). It's not a performance view but it gets the best mpg for me. Even my old panel gets the best mileage at 2000 rpm in o/d.

My .02

 

Got the 8 inch Maverick rear end home and pulled the pumpkin. Decided on 3.55's. Dropping it off at the shop to have the gears installed tomorrow. It will be months until I get the 302/AOD installed and ready to drive. First I have to get it set in for an initial test fit to set the rear trans mount and drive shaft angle. Then back out to go through the engine and trans before the final install, wiring, plumbing, exhaust, etc. Simple bolt in job, right? Thanks again for all the replies.

 

On the '06 Power Tour I saw a guy driving a Pro-Street car on the Interstate. He was doing 45-50. Only time I've ever seen one being driven.

 

This is the perfect example. Thanks for posting it. Personally I have always felt that the choice of a transmission was THE most important decision a builder makes, because it is what makes the rear end usable. Still, a builder has to start with a rear ratio thats reasonable.

 

I’ve just read through this thread again.. and looking at even 3.55’s times .67 is way too high for me. The original statement says a 2.80 gear was too high but to me is perfect when you’re in OD and to get that a 4.11 is the perfect axle ratio. I don’t have an OD and have a 2.74 rear gear and it perfect running 70 at 2000rpm on the freeway. And it fine in town.
A 4.11 in town would be really snappy and be pretty ez on any engine depending on how you use your car.. I would never want a final gear ratio in the 2.20-2.30 range as the engine would be so far below its torque range it would probably down shift going over an underpass... Just my thoughts.

 

I’ve got a 410 8.8 And an AOD I’ll put in my ‘54 Country Squire when I get the cash saved up for the y block to AOD adapter. This car has 205 65 15 tires.

In the foxbody world it’s 410 for AOD and 373 for T5 with about 25-1//2” Tire.

I got a deal on 10-1/2x27” tires for one of my cars that is 302-t5 powered with 355 and it definitely needs more gear.


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