Hot Rods Transmission and rear end choices

Hi, I am helping a friend out with a 1953 Ford F-100 pickup truck. He purchased this and previous owner made some changes to it. It has a 1965 Mustang 289 2 bbl engine in it. It has a 3 speed automatic behind the engine (possibly a mustang also of same vintage) And the rear end is a Ford 9 inch rear end. He had a mechanic install a lower numerical ratio pumpkin in it. At the moment at about 55 MPH it spins at 3000 RPM's. He is looking to get the RPM's down so at 60-65 MPH (highway speed ) she is not cranking so much for him. I asked what transmission he has (identification) and rear end ratio (now) and tire size now. He wants a better transmission and would like to know what transmission would be better suited for this application and would bolt up to the 289 engine. Also a quality after market floor shifter. The one in there now he can slide into reverse so assume no detent to prevent this!!Any thoughts as to what would bolt up for him in the truck? As soon as I hear back I can furnish more details to help him out on this. Thanks for any help.

 

All the common old automatics will have a 1:1 final drive ratio. He just needs to get a more realistic ratio in the rear end. Let us know his tire diameter and the needed ratio can be calculated. Easy peasy afternoon swap.

For a shifter I'd recommend a Genie Shifter. I think production of them is going to start again soon. Hopefully he has a C4 transmission.

 

something about this doesn't add up.....

3.00 gears would be a good place to start with the rear gear ratio. If someone already installed lower numerical gears, then I guess there was some miscommunication somewhere?

 

It sounds like he needs *taller* rearend gears, lower number like 3.0-3.5 range. His trans is likely a C4. But verify exactly. Regardless any 3 speed automatic is 1:1 high gear ratio.

 

With what’s likely a C4 and that speed and RPM I’m thinking there’s a 3:55 gear in that rear end….good for getting off the line…maybe a little to much for extended highway driving

 

A "lower numerical gears" wouldn't be turning 3,000 rpm at 55 mph unless it's got itty bitty tires on it. Sounds like it has a lower ratio (high numerical) rear end. My '53 F-100 with 327 Chevy and stock 3.92 rear end turned a lot of rpm at highway speed. As @squirrel said, 3.00 would be a good start.

A 3.55 rear end with 28" diameter tires would be turning 2,343 rpm at 55mph. A 4.56 rear ratio would be turning right at 3,000 rpm at 55 mph.

 

Hi, he is not a mechanic by any stretch of the imagination. With that said I try and ask questions he can answer. When he bought the truck what ever rear end pumpkin was in there he had someone install a lower numerical ratio in it. It made the truck more drive-able and lowered the RPM's but he wants them lower. He lives almost 1800 miles away from me so i have to depend on him for the info needed. Yes I agree with the final ratio of the transmission is a 1:1 and explained that to him and told him a rear end drop would be the best for him. His concern was there was never a kick down attached from the carb to the tranny so that was goofed up or previous owner never got to finish it plus the broken floor shifter issue. He had the transmission overhauled by a shop last year then installed it this year. Well the transmission is leaking from underneath and as he described it sounds like the front seal!! Shop that did the overhaul would not warranty their work because he waited too long to install it. I believe that is why he thought a different transmission installed with a proper kickdown set up and no leaks might be better. If I remember correctly he said a few years ago he thought the transmission shop said it was a FX transmission. How can I have him identify the current transmission? He only wants to cruise around town and use the interstate without cranking the motor. Could care less about torque too!! He lives in Utah. I think he wants to be around 2000 RPM's at 65 MPH. I will call him tomorrow to see if he got the rear end ratio, tire size and possibly records of the tranny rebuild to help him out.
if he has no info on the rear end I will have him jack it up and count revolutions of driveshaft with one full turn of the tire. That will give me a better idea of what he has back there. Thanks again.

 

A 3.00 ratio at 2500 with a 27” tire is 67 mph a 29” tire over 70 mph. Common 9” Ford ring and pinions are 2.70, 3.00, and 3.25.

The 289 is a short stroke engine and 3.00 is about as high as I would go as the 55 pickup is not very aerodynamic.

If it’s just a cruiser and he enjoys the highways a 2:70’s not that bad giving you 65+ at 2200 with the 27” tire. I’m close to that with a 56 car and early 3 speed automatic and love it.

 

take some pictures of it.

 

This might help.

 

might help to have the older ones too

 

You can run a C4 without a kickdown ..
I’m currently not running one, I manually down shift mine
https://www.jalopyjournal.com/forum/threads/c4-kickdown-the-real-truth.625358/

 

I'd seriously consider an AOD from an '86-'93 Mustang 5.0 for his truck. Since he's already got transmission issues to deal with, why not just use the later Mustang OD automatic, and have a truck that still has good acceleration, but can also cruise at 2000 rpm's down the freeway? For me that's the route I'd go, as there are plenty of donor trans, and plenty of support for performance rebuilds of the Ford AOD.

 

Check to see if you have a 6 bolt block if so look for an AOD trans best of both worlds.

 

Sounds like the owner is not a mechanic, and can’t find a trustworthy one near him. Switching to a different kind of transmission would likely require a new crossmember and driveshaft, which he can’t fabricate. I still think he should look into a pumpkin swap to a good ratio.

 

Are you sure about the 9" rear end? If the engine is a 289, the transmission a C4, it's likely the rear end is an 8", which looks very similar to a 9." If all 3 components came from the same donor vehicle, and 8" rear is more likely.

The numerically lowest ring and pinion set listed on Summit is 3.00. If you want something lower, it will probably have to be a used set. Make sure the ring and pinion are a matched set from the same vehicle, or it could be noisy. If you can find 2.73 gears, they will put you at about 2200 at 65 mph/w 27-inch tires. However, if your friend plans on doing any towing/hauling, he might prefer a numerically higher gear ratio. An AOD transmission will allow a numerically higher gear ratio, while providing a highway rpm he can live with.

 

8” had a stock 2.80 available; automatic 66 Mustangs 2 barrels used them if you can find one. Gevos Rears and Gears in upstate NY has a lot and will ship.

 

I had a 9 inch that came out of a early 80 f150 with 2:56 gears. Not sure how common that was. The AOD rout is also the way I would go.

 

Could the shifter that needs to be replaced, not be installed properly and he’s only in 2nd gear? I don’t recall how C4’s work.
The other thing, didn’t we have a thread recently along the same lines and the tach wasn’t set correctly for the V8?

 

9 inch out of a 57/early 60's F 100 usually bolts right in those early f100 trucks.

Using this calculator Tire Size, RPM, Speed, and Differential Ratio Calculator (advanced-ev.com)
Yup that's an electric vehicle site but you can plug in three and get the forth component all too easy.

3000 rpm at 55 mph with a 28.1 inch tall tire says that the truck has 4.56 gears in it.

The same rig with a 28.1 tall tire, 3.0 gear rear end and at 55 mph would be running 1973 rpm

You can measure his tire diameter and pretty well figure out exactly what rear gear ratio is in it.

I'd say that there was a big communication gap between your buddy and the guy who did the gear change or the guy thought he wanted to go drag racing or four wheeling. Most likely the gears that were in the rear end would have come a lot closer to being cruise down the highway gears.

 

Well I agree with all of you. He is not a Hot Rodder for sure and just wanted an old truck he could drive around. If I was there I could answer almost all these questions. Yes swapping out cross members and modifying would be probably more than he could do. I will verify what rear end he has also. I will have him send me a photo of transmission pan to zero in on just what he has. Believe he said the shifter was a Hurst unit in there now. And yes will verify the tach is showing correct RPM's. From the sounds of it previous owner just slapped parts on and got it running. He bought the truck because it was almost rust free from out West. He found a better box not beat up for a great price too. Thanks for updates and will talk to him to zero these things down. Thanks again.

 

If it is a 9" rear you can't get to the bottom bolt of the center section with a socket, you have to use a box wrench or open end wrench. Easy enough to check out.

 

What about the possibility the tach is switchable (4/6/8) and is on ‘6’…..of course if the engine is actually screaming at 55/60…well then, ‘never mind’…

 

What a freakin mess.
A gentleman in New York is asking about his Buddy's truck in Utah.
It ain't jiving. Something is lost in the translation. Either somebody is exaggerating or somebody has no idea what they have and what's been done. We sure don't have any idea.
3K at 55 on average truck tires equates to 4.56 gears.
4.56s make 4.11 seem normal and 3.73 a "Lakes Gear"

1953 F100???...Could be a '52 F1 or even a '63 F100???....We don't know. I don't know if the owner knows.

Poor, Donald Wemple Jr.... He's just going by what he has been told.

Engine.....1965 289 out of a Mustang...OK.
Transmission, thought to be or assumed to be a C4, now it's reported to be a FX???
FX!!!! That's a 1950s Cruisomatic.
289s were never offered with a iron cased FX or MX transmission.
If it's a FX Cruiso, it's not a 289.
What's going on.....who knows?
What came with the iron Fordo/Cruiso....FEs and Y blocks.....Geesh Louise!
If it is a 50s Cruisomatic, with screwed up linkage, he may running around in 2nd gear! And it won't be behind a 289. A352 or 292, Maybe. Who knows?

Another thing....what about stall speeds and converters. 2K is at the lower end of a SBF power band and if it's cammed, it's below the power band. If it's high stall the converter could be slipping. This is another "could be."

The more info that comes second hand from the owner....
The more the goalposts move.

 

Where some '65s were built in '64 with 5 bolt bells.

 

If your friend can send pics of the truck , engine and trans. We can figure it out for him.

good on ya for helping him .

over the phone or over the internet diagnostic Is hard without correct info.

keep the info coming and we’ll do our best to give you 20 different answers

 

A lot depends on the bellhousing bolt pattern if 5 or 6 bolt style. 6 bolt has better options for trans swap like an AOD. If a 5 bolt bellhousing 289, it limits choices. I still think the easiest solution is a taller rear end gear; and the unknown variable of what exact rearend it has. Tell your friend to get pictures of engine (at the rear showing bellhousing bolts is best), the trans, and rearend. With all that info we can figure better suggestions.
Even if your friend is not mechanical, there are shops that work on old vehicles that can help him out, just takes money.

 

Junkyard math. Most manufacturer's rear end gears come in spaced out ratios -- like 3.08, 3.54, 3.78, 4.11 or so. Not (at least for the same housing) in close changes like 3.54, 3.60, 3.65. So, you put one rear tire on the ground, chalk a vertical mark on the other near the ground and turn it one complete revolution while counting the driveshaft rotations -- like 8 and 1/4 revolutions of the driveshaft divided by 2 gives you a clear guess that it's a 4.11 (as they probably don't make a 4.125).

(Did I do this right, it's been years. It lead me to put a little too low a gear in my Hemi-powered 54 Plymouth that turned out having a lot more midrange power that didn't need what I put in.)

 

Hi All O.K. New info. My friend said he has 235/65 R16 tires on the truck. He said the transmission in the truck is a 1970 FMX 3 speed from a Mercury. It shifts properly but after about a week sitting there is a baseball size spot on the ground from under the inspection cover. This has been this way since he installed the transmission. Possibly he ripped the front pump seal when he put the torque converter in or nicked it. At the moment that is a minor issue. As far as the rear end he said the pumpkin that was removed made the truck engine scream and the new one put in is much better but still would like something lower. he is going to spin the wheel and count revolutions on the driveshaft tomorrow for me and get back to me. The Tachometer, gauges and the new gauge panel he bought from LMC Truck. He now has 12volt system in it. The truck when he got it had a cobbled up 1 1/2 inch square tube for a transmission cross member. He purchased a nice aftermarket one that fits the truck and the transmission fits correctly now. He also told me tonight that the engine was bored and stroked by the previous owner. Hopefully someone who knew what they were doing did it for the previous owner!! What that means??? He says it runs well and it is snappy and does not overheat or has leaks! So hopefully that was not a cob job. He is driving it as we speak. Told him about the Genie shifter recommendation too. Thanks for the help. You guys are the best!!

 

You said he still wants a lower rear gear ratio. You said it backwards, and you should make sure your buddy understands too. A smaller number, like a 3.00 is a higher gear. A larger number like a 4.11 is a lower gear. Very important to understand when he goes to buy different gears. Whatever his current gears turn out to be, he wants a number smaller than those.