30 PU max safe driving speed

[30 Closed Cab PU]

I am confused, as usual. What changes, the speedometer end or the driveshaft end?


Seems you could do either, have some one change/recalibrate the speedometer, or change the gearing/turtle on the drive shaft end. Please correct me if wrong.


Thanks.

[Tom Wesenberg]

With the 3.27 and a 5.5 high compression head, your pickup should do fine. If you use the 3.27, then Bert's also sells the speedometer cable adaptor to correct for the ratio difference.

[30 Closed Cab PU]

Originally Posted by Tom Wesenberg

With the 3.27 and a 5.5 high compression head, your pickup should do fine. If you use the 3.27, then Bert's also sells the speedometer cable adaptor to correct for the ratio difference.

Tom do not have a high compression head, thinking of the 3.54.


Still need to change the turtle/cable, different part than for the 3.27?


Thanks, this question should clear up things for this thick skull of mine.

[Tom Wesenberg]

Yes, you need the right speedometer gear and housing for the ratio you use in the rear end.

[30 Closed Cab PU]

Update,


Thanks all for the advice/tech info. I like being a little more knowledgeable.


Have changed my mind, going to have work done over the winter Thanks for making me think about it again Tom). Did a little research , talked to people, talked to the Model A repair facility, and visited them today. Getting picked up tomorrow. Motor and Differential work, a general going over to see if anything else needs attention. Figured get things over with instead of taking issues piecemeal, and always worrying about what's next.


Looks like major bucks flying out of the Bank Account!


Not happy about that, lukily I am divorced, no wife to contend with.

[DHZIEMAN]

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For me, the safest driving speed of my Model A ford is how fast I can stop it!

[daveymc29]

I bought a Borg Warner O/D with a complete differential and torque tube, even had near new brake shoes. I put it in my coupe with 3:78 gears but it would be a much better performer with 4:11's. Plans are to change that as I already have all the gears and bearings. IF, just if, you have thoughts of putting in an OD, talk to Mitchell's about getting them to make a 33% box for you and keep the 4:11, the son told me that is the best combo going for all around use. Wish I had known that before I bought the 26%, but it works real well also though I would like a lower ratio when pulling the Sierra Nevada's. Great in the low hills around the SF Bay Area.

[Charlie Stephens]

Originally Posted by Big hammer

No you will need to change the little gear in the turtle, it's attached to the drive shaft tube on the end of the speedometer cable.
My Tudor came to me with 16in wheels and 3.78 gears,it didn't like anything above 40mph. Went with 19in wheels with 31in tires and and 50-55mph doable.

I type really slow :-(

My advice would be to get a new turtle to match the new gear, they are slightly different.

Charlie Stephens

[DHZIEMAN]

Originally Posted by 30 Closed Cab PU

Have been looking at what max speeds are safe for the motor.


Found info on the Barn and other places on the Internet.


Everyone seems to agree 2200rpm is max, due to lubrication issues above that rpm.


I have the 4.1 rear end in my truck, 16 inch wheels but the tire circumference seems to be the same as the 19s The speedometer is spot on/correct at 40mph. Measured at one of the speed indicators sometimes put at the side of the road.


Some say 50 is max, some say 45 is max, some say 40 is max. Which is correct?


If I want to convert to 3.78, is it a simple diff gear swap, or do axels have to also be changed? Would I experience a noticeable loss of power and acceleration?


Am considering this, most in clubs prefer to cruise at 45-50. May change if changing is not a major expense like when putting in an overdrive.

My concern is how fast I can stop the car if I am doing 50mph and need to get it stopped. I have done my best to assure the brakes work as Henry intended,but not much tire surface on the road. 50MPH is all I want to do in this car.