Technical Let’s talk GM slip yoke

How much movement is realistically expected for the slip yoke? I’m running a 200r4 in the 39 Poncho. The yoke I have bottoms out with about an inch of shaft protruding. With weight on wheels , how far should the yoke be from bottoming out?
I’m wondering if I need a shorter yoke?
I’m getting ready to measure for a drive shaft so I need to do this math correctly. I also included pics of the numbers embossed on the yoke if that helps.

 

You need enough free play for the suspension to cycle.

It is not how much "sticks out" as much as how much you pulled it out before taking your measurement.

If it bottoms out, then you have full engagement. What is sticking out when it is bottomed out is irrelevant (within reason).

With ALL of the weight on the suspension at ride height, push the yoke in as far as it goes. Pull it back out at least 3/4". If you have a lot of suspension travel, or a short driveshaft, pull it out 1".

Measure from there.

 

With the weight on the rear axle if you have just enough room to put the rear U joint in place on the yoke on the trans and slip it back in the yoke and fasten it down (around 3/4 inch of movement life is good. If I was building the driveshaft from scratch I might opt for a slightly shorter yoke that left around 1/4 to 1/2 inch sticking out bottomed out though.

 

It is possible that the yoke is not going into the bushing in the tailshaft. Either the bushing ID is too small or the OD of the yoke is too big.

 

Read this local drive shaft company

 

I took my chevy front and Ford drive shaft to drive shaft guy. He told me how to measure. I phoned in the measurement. Two days later I picked up the drive shaft.
As I recall, the measurement he wanted was from the tip of the transmission output shaft to the face of the yoke on the differential.
Your experience may vary.

 

hey, I was gonna say 3/4 to 1"....

Generally if there's enough room so that it's easy to install the driveshaft, then it's sufficient clearance.

 

That's because you get it.

 

Driveline shop here told me to bottom the yoke in the trans, then back it out 3/4" and measure center to center on the U joints. Always works for me.

 

Mine is about 1 inch before it bottoms out.

 

Plus when it’s shoved in, take a sharpie and mark it so you can keep your eye on it. Friend of mine didn’t notice he pushed the yoke in with the tape measure. He went to install his new driveshaft and #)/+”$$@**’wtf.

 

I've shortened an overly long yoke. Just reshape the end to match the existing end and carefully debur the splines.

Chris