Lowering truck

[Terry Wilkerson]

When lowering the rear end of a square will the drive shaft need to be shortened?

 

[Turbo4whl]

Yes, or you can drill a new pin holes in the rear axle saddles, forward of the original pin hole. 1 inch to 1 1/4 inch center to center. This will move the axle back.

 

[Frankenchevy]

Measure the difference in the yoke stick out at ride height, then disconnect the axle end and bottom out the yoke into the transmission tail housing and remeasure.

What is that difference? 3/4” or greater and you are probably good. 1-1/2” or more (not likely if lowering) and you may look at lengthening.

If too long or short, do it right and have it rebuilt and balanced.

 

[Ricko1966]

I used to have driveshafts built,shortened,retubed often,for different projects. I used precision built in downtown KCMO., but after enough trips the guys there told me rebalancing a factory driveshaft shortened a couple of inches was unnecessary and a waste of money. Nice of them to tell me that,they could have just kept taking my money. After I learned how to shorten them,this statement makes perfect sense. To shorten one all you do is grind the factory weld off the end. Ever pull a pencil eraser out of the metal thing on a pencil? That's real similiar to how the yoke comes out,it's slid snuggley inside the driveshaft tube. Slide it out, make a square cut 1"2" whatever you need off the end of the tube. Slide the yoke back in and reseat it. The tube is a uniform thickness so you are taking off an even amount of weight 360* . The sleeve assembly keeps it square,if you can weld good you are putting a pretty even amount of weld weight on 360*. If you do it,make scribe lines down the tube so you can locate the yoke back in the tube in the same position it was in. If it was balanced before,it's still balanced. The diameter of the drive shaft also isn't huge like a tire or a flywheel the closer to center you are the harder to get something out of balance.

 

[TotalyHucked]

When lowering the rear end of a square will the drive shaft need to be shortened?

Not necessarily, depends on how low you're going. I know plenty of guys that have done a 4/6 and been fine with no driveshaft mods. Aren't you LS swapping as well? You'll need to get a driveshaft made anyway, so you can just measure when you're ready and get one made to your specs

 

[Keith Seymore]

I've done dozens at 3/4 and 4/6 (including the red truck in my avatar) and never shortened the shaft.

K

 

[Terry Wilkerson]

Yes it's an Ls swap and yes a new driveshaft will be made. I've been thinking about a mild drop. I've been told by my nephew we should do the drop before making the driveshaft. He probably right. This build has snowballed like crazy. They all do.

 

[Radiohead]

While you're asking about a one piece shaft I assume, half ton application, I found a static 3/4 kit listed for my c20 and I can't imagine it will matter to the short half shaft hanging out past the carrier bearing. But I don't know for certain, yet.

 

[Terry Wilkerson]

Anyone running 275 60 R15 on ralley's on the front with 2 1/2 drop spindles from lmc?

 

[86 C10 Shortbed]

I did the 4/6 drop and LS swap, I had a new aluminum driveshaft made to handle the 350hp at the rear wheels.

 

[Heysq86]

I did an LS swap and flipped the rear axle and did not have to shorten the driveshaft. Had .75 - 1 inch of movement.
How much HP is a stock 1/2 ton driveshaft good for? I am using the stock shaft with new U-joints.

 

[Ricko1966]

Anyone running 275 60 R15 on ralley's on the front with 2 1/2 drop spindles from lmc?

My thoughts on that big of tire is I'd go ahead and do the steering box weld in plates,more tire on the pavement is going to mean more stress on the frame.