Gonna need a bit more info. What exactly is happening when you are driving it?

 

it shifts fine when you go from 2nd to 3rd it just winds uptight at 45 mph and that's all she wants to do its like your red lining it at 45

 

Slipping Clutch..???



When you're all reved up tight at 45 mph in 3rd gear, do you smell the clutch burning...? If you have 3:55 gears, you should be going a heck of a lot faster than 45 mph if your engine is red-lining..:tu

So it's got to be one of two things...

1. either your clutch is slipping or...

2. you'be got a 4:11 or 4:56 gear ratio in that rear-end.

Have you checked the tag on the rear gear case?

Let us know what you discover, best of luck with it!

BDR...:shakehands:

 

Rear gear ratio

Are you sure the rear gear ratio is 3.55? Standard transmission ratios are 3.73 for 3-speed and 4.11 for overdrive. (If I am not mistaken). If it was an OD car and someone repaced the transmission that could account for the low top end. Just a thought! There is also a stock 3.36 gear in there somewhere too.

 

Speedometer error ?? ...or part of the problem ??

 

You're shifting it back into first gear. Drop it into 3rd. You'll be fine.

 

Could be . Let us know if Powerglide is right . Mike

 

If you can plug in the figures into this calculator, you can determine your gear ratio:

http://www.summitracing.com/expertadviceandnews/calcsandtools/gear-ratio-calculator

 

I agree with BDR. These old Chevys are not that complicated. High rpm and no power gain at 45 mph. Yep, number 1.

 

You are correct, 3:55 in 57 with 3 speed. Even if you had 4:11, which I ran for many years on the street with my 6 motors, you would be able to get way more than 45 mph. Just to be complete, it almost sounds like you are shifting from third into second. So. sitting in the drivers seat, pulling the stick toward you and down is first, up to the middle, push away at the middle and up is second, straight down from second is third. You and I are on the same page correct? From here, I would borrow a tachometer if you don't own one, and hook it us so you can read it while driving. Watch your rpms when you shift, the shift point in particular for first to second, and second to third. Then figure out whether you get into third, hit 45mph and then see if the rpms keep rising but the motor does not keep pulling. As the others have said, may be a bad clutch, slipping or oil coated or something. You should actually smell the clutch burning/over heating if that is the case. You could also crawl under the car. There is an inspection pan under the bell housing. Its four small bolts, or sometimes screws. Pull the cover and see if there is a lot of black smelly crud in there. Usually a good sign that you have a clutch headed south. The other thing that comes to mind is that some trucks had a governor installed on them, and the parts houses of the day also sold aftermarket governors as a mileage booster. Not having seen a picture of your motor and carb no way to tell but certainly a possibility (very remote)

 

If its an open differential jack up one wheel . Mark the wheel to the ground and marke the pinion to the case. put her in neutral and have someone rotate that tire two complete revolutions and count how many times you pass those pinion marks. A little shy of 3 probably a 3:73, 3-1/2 turns probably a 3;55, a little over 4 probably a 4:11 . eliminate this as a possibility.

 

He's double clutching it, matching RPMs and sticking it back into first.

 

Is the car hard starting? Have you checked the initial timing? ^ cylinders were timed at Zero, no initial advance. They respond very well to advancing the timing. With overdrive my 6 cylinder 57 got 20mpg around town, but only 24 mpg on the highway. I wish I had tried 3.70 rearend gears to turn the 6 slower. It's really a tractor engine, doesn't like to rev but tons of torque for the displacement. At 8:1 compression you have plenty of room for advancing the initial timing.