Steve's 64 Short-bed Project

[FarmMotorSports]

Which end is the cut on, trans end or pinion?

Pinion bearings will take a good beating...
Trans bushings not so much....

At this point weld it up and see how it feels...

If you don't like the results you have a pattern to hand the nearest drive line shop...

[9Fingers]

Can you set up the dial indicator on the opposite end of the driveshaft at the rear axle and see if you get a comparable reading? Not sure, but might indicate if the drive shaft tube is just slightly out of true round along it's whole length? Is there a thick area on the shaft that accounts for the .03""? Seems like the shafts I've worked on had a welded seam the length of the shaft. Any chance cutting, bumping it around and getting the u-joint back inside the shaft caused the out of round. Three hundredths is a small number, but in the world of balanced shafts it may be way too much. I just googled and read an article about Spicer u-joints and it suggested 0.010" run-out at the ends of the shaft as a maximum.

We've shortened two shafts before. We used a scribe to strike a line down the shaft and onto the u-joint to use for realignment and used a flat surface to keep the u-joints aligned and in phase. One was welded with a stick welder and ground down to smooth up, the other with a mig welder with shielding gas. We had no issues with vibrations. We didn't check the run-out with a dial indicator.

[04sd]

I never even checked runout on all of the shafts I did and never had a problem. I'd weld it up and try it.

So if I just weld it up and drive it....I won't have any vibration?

I've never had a problem and never had one balanced. I've always taken as much care as I could to make sure they were straight, in phase, etc., and then welded them with a mig welder. This is on projects since 1980, including 455, 427, 460 powered vehicles. Not that you couldn't have problems but I think it's unlikely.

[SteveCanup]

Dropped the driveshaft off with the local professionals to balance it for me. It will be ready tomorrow...

[SteveCanup]

Stoopid grin on my face....

Picked up my driveshaft this afternoon, installed it and just went for my "maiden voyage."

FANTASTIC!!! So far....

Now I have to extend the shift length and install my shifter boot....and deal with the hole in the floor around the shifter area. (Easy Peazy).

Stay tuned....

[SteveCanup]

I have driven it 100 miles locally so far...all is good. I recommend swapping your old tired 3 speed out...you (and your truck) will love it.

[oldsmiley]

You always have the best, and most encouraging, ideas Steve......keep em coming

[SteveCanup]

You always have the best, and most encouraging, ideas Steve......keep em coming

Thanks!

[SteveCanup]

I did some digging from the tag number on my new T5. 1993 GM world class and the gear ratio is higher than I realized (I might have said that backwards, it might be "lower"...lol). But anyway, 1st gear is 4.03, 2nd is 2.37 and so forth, but 5th is .86. Based on an RPM calculator here's where I am at...with 28 inch tall rear tires and .86 final drive in the tranny and 3.70 rear axle gearing, then at 70 mph I am running 2673 rpm's. With the old 3 speed it was 3108 rpms at 70 mph. I like the T5 and it only cost me $100...so I'm going to find a rear axle with either 3.0 or 3.15 gears. That will drop the rpms down to 2167 to 2276 which is where I want to be at that speed. My gas mileage has improved...the best that I have ever gotten with the old 3 speed was about 15 mpg. The first tank of gas with the T5 was 18 mpg running around town and part of that mileage was hauling a bed full of lumber from the hardware store.

So, I'm just pontificating about this right now...happy with how much better the truck runs. But in the near future, if I can find the right axle with the right gearing...swapping the old axle out. It pays to do some homework....lol.....wanting to get the mileage over 20 mpg...hopefully.


Stay tuned....

[JeffinMooresville]

Looking good Steve. Pretty major upgrade with not exactly bolt on compatibility... has to feel good.

[SteveCanup]

Looking good Steve. Pretty major upgrade with not exactly bolt on compatibility... has to feel good.

Thanks! I was a "job" to get done. I went to NC last night and obtained a '77 F-150 rear axle with 2.72 gearing. That will be my next upgrade. The transmission was not geared as I hoped, so the rear axle will make 1st gear and 5th gear do what I want. Hoping for mid-20's on gas mileage., the T5 is giving me 18 mpg so far. I'm expecting that if things politically go the way I fear they will....gas will go up, up, up. I want to be able to afford to drive my truck, lol.

[04sd]

Are your rear tires going to fit under the fender with the '77 axle?
Hard to tell until you try and easy to change but I think 2.72 might be going to far. It might put your rpms to low, not enough power, lugging the engine, more downshifts out of overdrive, etc. Will certainly be interesting to see how it works out. I've got 3.50 gears, an automatic overdrive, and likely 30" tires and I'm worried it should be geared a little lower. With 2.72 gears I'd guess that '77 truck had a 351 V8 and automatic.

[SteveCanup]

Are your rear tires going to fit under the fender with the '77 axle?
Hard to tell until you try and easy to change but I think 2.72 might be going to far. It might put your rpms to low, not enough power, lugging the engine, more downshifts out of overdrive, etc. Will certainly be interesting to see how it works out. I've got 3.50 gears, an automatic overdrive, and likely 30" tires and I'm worried it should be geared a little lower. With 2.72 gears I'd guess that '77 truck had a 351 V8 and automatic.

Well....I don't know yet about my tires fitting. The '77 axle is 2" wider, but I still have some room on each side for the tires. I did my homework and came up with 1967 rpms at 70 mph on the interstate. This should greatly increase my gas mileage...hopefully over 20 mpg. Right now I can't use first gear, it's 4.06 because it is "granny of the grannies" (lol) as far as I am concerned. Ideally, 3.0 or thereabouts would have been perfect, but I am going to give this a try.

[unibody madness]

Steve I put a Mustang T5 in the Turk with a final gear of .68, rear is a 3.50. I turn just over 2100 at seventy and average 22 mpg with my 292Y block.
never got much over 12 mpg with the original T98 and 3.89 gears so I am happy as a pig...
now it is still a little tourque-y in first-3rd but I also have to down shift on grades so I have the best of both worlds

[SteveCanup]

Steve I put a Mustang T5 in the Turk with a final gear of .68, rear is a 3.50. I turn just over 2100 at seventy and average 22 mpg with my 292Y block.
never got much over 12 mpg with the original T98 and 3.89 gears so I am happy as a pig...
now it is still a little tourque-y in first-3rd but I also have to down shift on grades so I have the best of both worlds

That's perfect. I am trying to do the same...glad to hear that someone else had success doing this.

[04sd]

With 2.72 rear you should be able to use 1st. The truck 4 spds with granny 1st gear are around 6:1.

[ratrapp]

are you going from 9" to 9"?if so wouldnt swapping center sections be easier?im not familiar if the 64 downs used a 9.i know my 66 does.

[04sd]

are you going from 9" to 9"?if so wouldnt swapping center sections be easier?im not familiar if the 64 downs used a 9.i know my 66 does.

Spline counts are different. Our trucks are 28 spline vs the newer 31 spline.

[SteveCanup]

are you going from 9" to 9"?if so wouldnt swapping center sections be easier?im not familiar if the 64 downs used a 9.i know my 66 does.

You are correct...swapping the center section (some call it the "chunk, lol) would be much easier. But the cost would be substantially higher. I'm thinking around $600-900. I bought this axle for $150 and other than welding the spring perches where I need them (relocating) I can just roll it under my truck and bolt it up.

At least I hope that is all I need to do. I have the cover off right now draining the gear oil. The gears look excellent and spin very smoothly. My original '64 axle has just a little bit of play in it, and that might have been how they were set up from the factory.

I need to get some pics and post.....

As usual....stay tuned........

[ratrapp]

you could pull both center sections and just swap the new ring gear on to your old 28 spline carrier.you 'll never have to touch the pinion or pinion depth and if you measure the backlash before you take it apart you should be able to get it back pretty close.ive done this several times in my swapping between car 28 spline and truck 31 spline stuff.