A first for me

[Bears63]

Me and my '71 Cheyenne were heading home from work last night and I was at a stoplight. Light goes green and I go to take off, nothing crazy just a normal attempt at going when BAM! CLANG, CLANG, CLANG.... and no power to the wheels. Okay, I think, that weak u-joint finally had enough and so I get the truck off the road and parked at a curb on a side street.

Oh no, I didn't have a u-joint cut loose... Nope, couldn't be that simple In this case the front driveshaft broke about 8" behind the transmission. First time I've ever accomplished that with a bone stock engine and transmission combo

[BigMike]

Wow, didn't see that coming. I thought maybe spider gears in the rear end.

Mike

[leftybass209]

Never would have thought the center section of the drive shaft could be a weak point! Could it be a bad angle causing undo stress, or just a freak happenstance?

[68bowtie]

got a pic of the shear point?

[Bears63]

I'll take some pictures of the break tonight and post them tomorrow, but from the way it looks to me is that it had a crack in the tube for quite a while. Some of the break is clean metal while part of the area is corroded and not shiny at all. My family says I have a knack for doing things in a big way out of the ordinary.... I think this qualifies

[Daubs]

Wow. The last time i heard "BAM! CLANG, CLANG, CLANG" was on interstate driving home from college in my 71 C-20, 6cyl three-on-tree. Valve in #2 cylinder broke off, caused piston to disintegrate, and rod punched hole in block. Done.

Dad drove out and towed me home. I got a new truck (82 K-10) and dropped a $50 250 6cyl in the old 71. My brother ended up driving that truck for three more years before we finally sold it.

D.

[Bears63]

The mystery on the breakage is solved. It was a terrible weld job that caused the break. This is apparently a replacement front and it had been lengthened. It broke right on one of the welds and looking at the ends of the break it is easy to see that there was inadequate weld penetration.

[WIDESIDE72]

Good reason to never lengthen a driveshaft. Shortening is OK but lengthening is bound to fail sooner or later.

[Bears63]

I agree! Lengthening makes for two potential weak points where shortening leaves one weld that had more time spend on it. On this shaft the othe end of the splice was easy to spot. The inside of the tube wasn't even discolored so the weld had poor penetration on both ends. It was a rushed job by the looks of it.

[Old Truck Man]

A drive shaft should never be lengthened by welding sections of tube together like yours was. impossible to get it straight and balanced. . To lengthen or shorten you grind off the welds at the yoke and press them into a tube of the proper length. after the ends are welded it should be balanced and trued on a lathe.

[Bears63]

Finally, after 6 weeks my '71 is back on the road. It was quite the adventure getting the driveshaft sorted out. I picked up a couple of replacement driveshafts off the boards here but the problem is that both of them were 1 1/4" too long. So the next adventure was to find a place to get it shortened and balanced. Well, here in Watertown, SD, there is not a single shop that touches driveshafts anymore. I asked around for weeks until I finally got steered in the right direction.

It turns out that the local Sturdevant's parts store is a drop-off location for a shop in Sioux Falls that does driveline work. On this past Wednesday morning I dropped off the driveshaft and I got a call at noon on Thursday saying it was back and I could pick it up. In just over 24 hours this driveshaft was driven to Sioux Falls, shortened, balanced, cleaned, painted, had new Spicer u-joints installed and driven back to Watertown. All that was a grand total of $136. I was a very happy camper on that!

[terry b]

Now thats service.