What to do...Highway Speeds

I'm looking to be able to run about 65-70 mph comfortably on the highway. I have a '59 Thunderbird with a 66 390 and a cruise-o-matic transmission. Not sure what the rear-end has in it. Any suggestions? Would a different tranny be better? If so, what would fit?

Thank you for your time...

 

I guess you have a nine inch Ford rear end. It should have a tag on it with the ratio stamped in to it. For a freeway cruiser they came with 3.00s or 2.75s or something like that. Surely the stock gearing will be fine for 65 mph.

 

I would think that a 59 Tbird would already cruise at at least 70 comfortably unless there is something wrong with it.Is it revving too high?I think they usually came with a 2:90or a 3:00 rear end in them, that should give you a good cruise rpm .My 2¢

 

Take it up to 70 and see how it feels?

 

Heck 59s were crusing at 65 and 70 regularly,just make sure your front suspension is in good shape.

 

Any 50s 8-cylinder car should be able to cruise at 65-70 MPH all day long UNLESS they were sold in high mountain country and have very low rearend ratios for that reason.

 

Anyone who bought/drove new cars for the last 25 years got used to the super low rpm at that speed.


My 1970 daily car sounds like it's screaming at 60

 

I don't see where you will have any problems . The car was built to run at those speeds when it was built . 60 mph was about the speed at all the highways back then and you know as well as I do most people drove them at faster speed than 60 mph !
You can hook a small tack up and they are fairly cheap , to see what your RPM's are at different speed if that is a big concern for you .
I myself would drive the car at those speeds and not worry a bit about it either , AS long as the engine is in good mechanical condition . That is the key to driving at higher speeds . As long as the engine is solid , go out and enjoy the car for what it was made to do . They drive and run so well at those speed also . They were made to be cruising down the highway at 65 & 70 mph . Enjoy that car at any speed !
Retro Jim

 

I don't know about your '59, but my '61 'Bird/ 390 was just loafing along at 70.

 

352 auto = 3.10 to 1 rear
430 auto = 2.91 to 1 rear
352 atandard = 3.70 to 1 (Od trans the same)

Cruising at 70 with stock sized tires (27 inch inflated diameter for 8.50X14)
should be about 2800 rpm withthe 3.10 and lower with the 2.91, Probably about 3000 with the standard trans. Whats to worry????

 

I had a stock 67 TBird in 69 or 70 and my wife at the time drove from New Mexico back to Iowa in it, she told me that while on the turnpike in Kansas she was just cruising along and looked at the speedo and was doing 90 MPH. My dad's 58 Dodge would cruise at 75 on gravel roads, so you shouldn't have any trouble keeping up with that 'Bird.

 

I agree with 56don, there would have to be something drastically wrong with a 59 Bird with a 390 if it couldn't cruise at real highway speeds and run most of the stuff on the road into the ground in the process.

 

Thank you for all your input. Maybe it's just that i'm new to this and it seems to be operating at a higher rpm than it should be? The other thing that I was thinking about was the Overdrive in the transmission. When I have the car in D2, it will shift at about 20 into 2nd gear then it won't shift again. I thought these cruise-o-matics were 3 speeds? Am I wrong? Will be getting under the car tonight to see if i can find some numbers on the tranny so I can identify it. Could it be caused by the overdrive kickdown switch or overdrive solenoid? Again, I'm new to this so please let me know if I'm way off here. Thanks again for all your help...

 

Exactly what he said, I would expect you have the 3.10 rear end that I have in my 58 TBird. I am running a 390 also, she runs down the road at 70 a little to easily actually.

Not sure how my tire size compares though, I am running a set of 17 inch Mustang Bullits on mine with 275x45x17.

 

I have 14's...

 

First that trans does not have overdrive. Second when you run in D2 you are starting in 2nd and shifting to 3rd. No more gears to go into.

L is 1st gear only, and D1 is 1st, 2nd, and 3rd.

 

With that trans you need to start with the car in D1, if I remember right D2 starts in second and goes straight to third, skips first gear all together. At least that is the way my 58 seems to work.

I am also pretty sure that there is no kickdown switch or solenoid you should have a bar off the linkage that goes down and acts as the kickdown. Here are photos of what mine looks like.

Also for a great source of info and support on your tbird go checkout the web site squarebirds.org the guys over there eat, sleep and dream only about them....

I learned alot over there.

Cheers
RustyNCA

 

.......Do you have a tach in the car?.....if its running at high rpm's.......it could be stuck in drive two....or maybe the passing rod to the carb is holding it in 2nd gear.....

 

In the cruise O matic that was in my galaxie, until the 4 spd, from memory...

-L or 1 (can't remember)- first gear
-Then what a white dot?- only second and third, it will skip first, this was intended as "traction control" on slippery surfaces.
-The green dot, as i remember (whatever was closest to N) is D: 1,2,3.

It is my guess that you are in the white dot, not the green. You are shifting from 2nd, to 3rd at 20. This seems about right and thats about what mine would do.

Also, and If you're a hot rodder you need to know... When taking off (think race):
1). put car in Low. Accelerate
2). shift up to white dot (car will shift)
3). now pull it back into low.---car is now locked in second and will not shift up.
4). Finally, shift into either dot and it will shift to 3rd.

You don't have an overdrive. Third gear ratio is 1.00:1.00 and you only have 3 gears. There aren't solenoids or kickdown switches on a 66 c-4 or c-6. Kickdown is mechanical, linkage is attached to accelerator by the carb. If you or someone else took the rod off (goes down to trans), then that might be the problem.

Which dot are you in? It can be confusing until you figure out what each one does.

Pop the hood, the rod for the kickdown is by and attached to the accelerator rod. If its not there then that could be a problem.

Adam

 

It seems like everything is intact, doesn't mean that it's working though I guess. I'll take it out tonight when the wife gets home try starting it out in D1 and try that shifting pattern...then I'll go from there.

Thanks again to all...

 

Just put it in D1 and drive it, you should get all three gears - no "shifting" necessary.

 

one way to find out .
some people like to kruz faster then others.

 

my 53 ford has a 302 c6 with 3:50 gears 26'' tall tires .3000rpm at 75...it aint happy....next road trip gets a 3:00

 

Before OD became the norm 3000rpm at 70mph was normal.