nocooler's firechicken thread

[Steve Wood]

What we don't know from your pictures...or at least I don't know....is how much further the yoke on the front end of the shaft will slip into the transmission.  It does not look to me as if the splines have enuf "meshed" distance but without knowing how much further the yoke could have been pushed into the tranny before it bottomed out we are limited.

So, disconnect the driveshaft at the rear, push it all the way into the transmission and then see how much you have to pull it out to connect it to the rear yoke.  If that distance is say 3/4" to maybe 1.25", I would call it good.  If the shaft is too long, you cannot push it in far enuf to clear the rear yoke when installing the shaft.  If it is too short, you will not have enuf spline engagement.  With the power you are making, I would want it to be in that 3/4 to 1" range. 

I am not familiar with the modern transmissions to know just how far a yoke will slide in before hitting bottom.

[nocooler]

Yoke will go all the way in.
It's only in an inch - and from what I've read it needs to be in 2" to have good support from the tail shaft bushing. Right now it's not even hitting bushing - I can move it side to side, if I slip it in with an inch of yoke hanging out it feels solid.
 

[Steve Wood]

The yoke should be all the way in until it is stopped.  Then pull it out 3/4 to 1" and that is where it should be when installed. That will give you maximum spline engagement

[nocooler]

Yup and somehow all my shit worked perfectly in his car but I come up short. My lowers are adjusted to center the 28 slicks for clearance. At this point I might just put the stock length ones in to check.

[nocooler]

I’ve been talking with the previous owner and this is the pic he sent me that’s suspension unloaded, it still looks like it’s out a ways

[Grumpy]

No way would I trust that.  I'd be getting a new drive shaft.

[nocooler]

That’s my thoughts also Dan.
I’m going to verify that I don’t have anything bound up in the suspension and check everything over before I order a new shaft.

[wmsonta]

Yeah, I agree w/Grumpy, that looks scary. The fact, you can get play by hand was enough for me. Most who shake something, exert less than 50 ft pounds. The forces under power are many multiples.
engine torque x converter multiplication (1.5x-2.2x) x low gear ratio (1.72x-3.06x)= the force reacting against the given play. Think impact wrench.

If I was going to buy another driveshaft, I would first know the weight bias. I personally do not like to work with less than 40% rear. From memory, previous G-bodies were 42-43% oem. Those were not GN's.

[nocooler]

Just got off the phone with the chassis shop that built the rear end and suspension. The normal measurement for a 4th gen fbody and th400 with there suspension is 44.875”. So I’m 7/8 short at get go, and centering the rear for the 28” slicks is probably the other 1/2” or so I’m missing. Weather is pretty grey out I might just take another day away from it.

[Steve Wood]

you just talked me into it...

I meant out of it...gray cold days ain't my cup of tea!

[nocooler]

Trust me I’m looking for every answer I can before I ask the guy how he’s going to handle it.

[Steve Wood]

You have to get the yoke into it. 

I see two ways.  Longer drive shaft, or a longer yoke.

I suspect you moved the wheels back when you did the overhaul.  That just added to the problem.

[nocooler]

Just got home - found an issue in the suspension, but nothing that fixed my issue. Sway bar was rubbing shock bolts under extension not at ride height. My control arms are 1/8" longer so I'm not finding anything there. I cycled the suspension about 20 times to see if the car would settle any but no luck.

[nocooler]

I reached out the person I traded with. Just waiting to hear if he’s going to tell me to pound sand or work with me.

[nocooler]

So far he’s willing to help - but he doesn’t understand how it can come up short. I’m done thinking about it for today......