Technical Anybody run 3.25 gears in their banjo rearends?.

I'm going to have to rebuild my banjo rearend in my 41 Ford eventually and i'm thinking about putting 3.25 gears in it to get a little more out of it on the highway. I don't think it'll be too bad taking off as the first gear is pretty low. It would go from 2722 rpm down to 2340 rpm At 60 miles an hour. Definitely would help me cruise a little easier. Has anybody done this and is there any special parts involved other than bearings and such?

 

I'm running 3:54 gears and didn't notice any change in performance, don't think dropping from 3:54 to 3:25 especially with a warmed up flathead would be noticeable.

 

My Flathead is isn't warmed up Lol, but I've got 378 gears in it now.

 

I have them in my 33, but have only driven around the block with them.
I got mine from Eckers (macs) and there was no issue with install.

 

Cool, thanks for the reply. I'm sure one outfit makes them for everybody and you can buy them from C& g or macs or whoever.

 

No gears to talk about as I don't even know what year the banjo rear that I have had for 40 years is let alone what gears.
here are links to two speed, rpm, tire size and gear ratio calculators I use.
The first one lets you put in the trans output ratio. The second one jacked from an EV conversion site lets you plug in three factors and get the fourth but if you have an overdrive transmisson you have to calculate the overdrive ratio into either the engine rpm or gear ratio to get the other three right.

Calculate RPM for Given Speed(MPH), Rear Gear Ratio, and Trans Gear Ratio (purperformance.com)
Don't get the undies in a knot because this one is from Advanced EV. If you are running a 39 box it is perfect for your needs and fun to play with. Put in three know factors and get the 4th.
https://www.advanced-ev.com/Calculators/TireSize/
This shows that at 70 mph with a 28 inch tall tire and 3.25 gears you are running 2730 rpm.

 

Were 3.25 gears ever a factory option on something?

 

Don't think so but I don't know everything

 

Yes, they were, I have a 1970 Ford truck rear end in my 48 and it has 3:25 ratio.

 

it may depend on your rear tire size.

 

I did a Wintrs QC in a ch***is for a customer years ago who wanted a final drive gear of 3.25. His motor was a FH with a 5 speed and tall tires. After while I think he ordered spur gears to get the ratio to around 3.50 or 3.78. He found he couldn't enjoy the T5 OD with the 3.25 gears.

 

I have a 2.5L Chevy 4 cylinder Iron Duke in my Model A coupe. I put a 8" Ford rearend in it that had a 3.00 rear gear, along with a 1:1 top gear ratio transmission. I would say at about 100-ish HP the 2.5L is roughly the same HP as an unmodified flathead. I think the Model A coupe is quite a bit lighter than your 41 Ford. It didn't take long before I took out the 3.00 gear and went to a 3.55. It made a huge difference when pulling hills.

FWIW...the S-10 engine came from a donor truck that had a 3.73 with a 5-speed. I think had a .72:1 or .78-1 overdrive 5th gear, so in the S-10 the actual gear in 5th was about a 3.00.

Best wishes with whatever you decide to do.

Lynn

 

I’d be concerned about not having enough HP to turn those gears. There’s a reason 3.78 was the most common ratio. My uncle had a Columbia behind a flathead and he could only use it on flat ground with no head wind. I believe the final drive or the Columbia was 3.25.

I had 3.54 gears and 750 16s behind a SBC and it was pretty good. Ran 70-75 no problem.

 

Put 3:25 gears in my Zipper and even with a light car and a performance A engine, the results were unsatisfactory. Went back to 3:54. The A truck with a T-5 has 3:54

 

Your 1970 truck rearend is not an early Ford banjo. The ratios that were available stock in it are irrelevant to the question.

 

What diameter tire? That makes all the difference.

 

@wheeltramp brian,
Before you go changing anything, try this:
Using your before and after numbers, while cruising @ 2340 RPM in high gear, floor it and see how long it takes you to get to 2722 RPM. Now cruise @ 1958 RPM and see how long it takes to get back to 2340. (Same 382 RPM difference)
This will give you an approximation of the feeling that the change of gears will make. (It will actually be LESS responsive)
My very first experience with trying to overgear was in a jacked up TriFive Chevrolet. I went from a 3.70 R&P to a 3.55 with an overdrive transmission (Resulting in a final drive ratio of 3.01) . The mileage got worse, and the top speed remined the same. (That thing was pushing a LOT of air) There went my dreams of finding and installing a 3.08 with the .85 O.D. for land speed racing. 20 year-olds can do anything.

The best combination was the 3.70 with the O.D.

Later the car got 5.13s and the top speed went up too (but so did the horsepower)!

The problem with trying to gear an old car like a new one is that the engine is not able to dial itself in to the perfect A/F ratio, timing etc. and no computer to select the right 1 of 6 or more transmission speeds.

My guess is that you would be happiest with a 3.54 R&P. (or a Quickchange )

 

I run them in my car and I love them. I easily cruise from 45-80 mph in high gear. They work well with a 2 carb flathead. I run a 29" tall tire and ford gears in a 3 spd.

 

Hey, Ford Mike, what type of car are they in a little hot rod or a full-sized car?

 

In a Model A roadster, or?

 

When I did my calculations, I checked the OPs figures. I believe he is running 30 1/2" tires.

 

Actually, my tires are 6 70 15 and are 28 and a 1/2 inches tall. And I may have typed in 29 inches into the calculator.

 

Mike: Any hills in PA?

 

I put them in my 32 5W. I loved them. It had a 276 flat motor and 19 tooth close ratio gears. It climbed my steep hills better than the 241 hemi powered roadster with 3.00 gears

 

Had them in my banger coupe that sold earlier this year, 100 HP B motor, pulled like a freight train, For town performance Id say 3.54, freeway flying 3.2 is where its at, I was regularly cruising 70 on the freeway. She pulled real good hills in the hill country in Texas and never faltered, I never had to downshift pulling grades.

Liked em enough I am installing a new set into my 34 Tudor, figured 100 hp Flatty, and the weights of the cars only differ by 500 lbs roughly. Why not, should be golden again. Anything is better than my 4.11 in there now.

 

I have them in a 36 ford cabriolet. I have another set that will be in a model a roadster.

And yes there are hills here, you will get used to driving it. It's not a trans am racecar...

 

Sounds like I've got some thinking to do. On the way home there is one Hill. That's pretty steep and the car slows down to about 45 at the top in top gear. So I imagine if I have the 323 gears. I would definitely be down shifting in a second, but that's no big deal.

 

Why not try some oversized tires to see what effect the change would have. If you went from your 28.5"tires to (say) 31.5"you would be close to the money. Tires are much cheaper than gears and a whole lot less labour. If they prove you can, or can't, do the swap problem solved.

 

Good idea, zuffen. I can take the rears off of my hot rod which are 750 16 and try that.

 

I'm still cornfused (about a lot of things), but were there factory 3.25 gears available for banjo rear ends?