drive shaft issues

[Max Headroom]

I'm with Hoopty Mike on this. I think what happened is that you put a too long drive shaft in place. It probably fit at the limit of clearance when you did the motor swap. As you apply power to the drive train, the yoke on the front of the rear end rotates through an arc of up to several degrees. With the swap you were probably putting the u-joints in a bind every time you drove the car. Not quite enough to grenade the driveshaft but very close. When you swapped gears the new gears took up more space than the worn gears making the front end of the crush sleeve a few thousandths closer to the trans. that moves the u-joint closer to the trans also. That may have been enough to jam both ends of the drive shaft into too short a space, so it bailed from the car.

You should be able to push the front drive shaft yoke at least an inch and a half further into the tail housing of the trans than you need to to bolt the u-joints in. This allows the rear end to go through its arc without creating a bind on the drive shaft. This is not something I read in Hot Rod. I still have the tee-shirt.

 

[Kalis-Ls_Gbody]

Strap failed. The one still installed looks 'not new'. Those strap kits are darn cheap, buy new. The ones that pontiacgp posted a pic of are really nice, but you truly don't need them. ou have to work to get the UJ centered in that yoke, but it can be done. I use the ones in the 1st pic that pgp posted and we put the wood to it - they work.

Regarding your shaft, you mot likely need a new one. The chances of that shaft being salvageable are slim to none. Find a local truck shop that builds shafts -is there a FleetPride in your area? They are economical. The front two yokes on yours should be good, then you'll need tube and rear yoke. The yoke on the rear end should be fine from the looks of it. Make sure the UJ fits in it properly and it should be good to go.

p.s. - you're livin' life on the edge with a 4L60 if your LS is much beyond stock.

Thanks for the info, all info helps, and yes to the fleet pride, but been actually thinking about ordering one from Denny’s drive shaft, and the yes the LS is stock. For now at least

 

[Hoopty_Mike]

Your slip yoke should be out about an inch from the tail shaft of the transmission. If it was bottoming out that could of added to your issues. Whatever driveshaft company you go with should tell you exactly how they want it measured.

 

[64nailhead]

Thanks for the info, all info helps, and yes to the fleet pride, but been actually thinking about ordering one from Denny’s drive shaft, and the yes the LS is stock. For now at least

Be economical. You don't need to spend big money on a shaft. If FleetPride is cheaper, then I'd talk to them about insuring it gets balanced properly and have them do it. Also, if there is a local speed shop or two, or dyno shop then ask someone there. I'm extremely fortunate that my son works for the largest truck parts company in upstate and they have 4 locations that make driveshfts. They employ 4 guys that make driveshafts all day. All of the local old guys that drag race get them there. A truck shaft designed to handle a 1000+ ft/lbs will withstand anything. But for what you're doing you'd be in the $150-200 range with new UJ's, yokes and balanced.

Good luck.

 

[lilbowtie]

The reason I asked earlier if the drive shaft was still in one piece was driveshaft critical rpm. Please look into this before ordering your new shaft. Here is a chart from PST. I've been bit twice.

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Critical Speed Chart

Critical Speed is the RPM at which the driveshaft is computer projected to bend or whip. Exceeding Critical Speed can produce vibrations that can result in driveshaft failure.
The vibrations can also cause damage to the differential gears and bearings. The transmission extension housing, along with the torque converter and planetary gears can also be destroyed.
When you take a small piece of steel and bend it repeatedly, the stress will eventually break the steel. The same effect occurs on your complete driveline when no attention is paid to Critical Speed.