The Jalopy Journal
Discussion in 'The Hokey Ass Message Board' started by chris dozier, Aug 5, 2016.
should have 4.11 gears. You should be able to drive 55-60 with it, if everything is in good condition. If the engine etc. is worn out and makes a lot of racket at these speeds, maybe the rear end gears are not the problem?
My son's 59 chevy truck with the six and 4 speed granny box, with it's original 3.90 gears, and not that tall 15" tires, cruises at 65 ok.
My truck has the factory 6.00/16's and its screaming at 45. Mine has a 4 speed which I thought was weird for a 1/2 ton truck. Maybe I have the heavy duty 5.42 or 6.16 ratio but I'd assume it would be a 2 speed rear if so which it's isn't. I guess I need to take it apart to see what I have. The engine plasti gauged perfect. It's quite and has plenty of power. Good compression too.
Thanks so much for the response
the chevy specs show either 3.82 or 4.11 ratio offered in the half ton, although only the 4.11 was available with the 4 speed trans. Maybe you could put a tach on the engine, and see how fast it's turning. It's not easy to count the gear ratio turns with a torque tube, although you can pull off the rear cover and count teeth or turns. and you'd want a replacement cover gasket before you do that.
Maybe not what ya had in mind but a T5 swap might be the ticket. I know a T5 in our crate really helps the flathead 8 come to life. Just a thought........................
But honestly my first thought after reading all the posts is to at least temporarily install a tach.
Between the road noise and the engine noise it's gonna be loud at speed, I think a lot of us are used to late models cruising 70 at 1200 rpm
If the engine checked out good as you state I would be curious to see what the tach says. Could just be loud at that rpm even though it's got room to spare.
should only be getting up to 3000 at 60, which is just fine....
Ok, just drove it on the highway. The truck literally runs out of rpm at 55 mph. It's screaming at 4900rpm
what gear is the transmission in?
Lol, 2nd duh!
4900 rpms should be 100 mph. do you have the correct tach in it? is the clutch slipping? or as Jim said are you in high gear??
If you can get to the crank pulley and turn it?
Jack up only one rear tire. Put a chalk mark on the driveway at the tire chalk mark.
put a chalk mark on the crank pulley at dead top, or some spot you can see. Truck in high gear.
One person watches the rear tire and you start to turn the engine by hand. Have your helper tell you when it is exactly two turns on the tire. If you turned the pulley just a tick past 4 turns, you have 411.
I just swapped an entire rear end in my stock 32 Nash because it had 4.73, which would give 40 mph sweet spot on the motor. I now have a mid 60s rear that I can get any aftermarket ratio I want for $150
I'm on your side with RPM. I'd sell the vehicle if I could not do 60 without having the motor sound like the pistons are "swappin' holes"
4th gear, I'm almost positive the tach is correct? Negative side of coil. Idles at 900 rpm. Clutch works fine. I can floor it in high gear from 20mph and it doesn't slip at all.
Is the tach set for a 6 or whatever? It's been years, but I seem to remember some tachs having a 4-6-8 switch/jumper/connection.
if the tach is set to 4 cyl and you install it on a 6 cyl it will read 33% fast.
I like the suggestion above to count turns of the crank pulley and tires, and figure out exactly what your gear ratio is.
Let us know! this one is interesting
I did the crank and rotation of the tire trick... 4.11's for sure.
You will see a big change if that later housing with aftermarket 3.55 will fit.
But, don't expect miracle changes in how it sounds at 65 in the slow lane on expressway.
The guys with stock 40s Dodge pickups use a later Mopar 3.55 rear, and I was just in one a while ago, on a short connector highway. His speedo gear was not corrected, so no speed reading. But I felt we were doing 60-ish, maybe touching 65, and the road noise/cab tinny-ness, made it tough to hear the RPM, but I was not too thrilled if it had to go 50-100 mile trip on the highway.
Main problem with going to a lower number under 3.50, is that on certain long grades, you can run out of power and speed slowly drops. You can't downshift at 50, so on a real bad looong hill, you are hugging the gutter where all the glass and nails are, trying not to get rear-ended
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