Why did my drive shaft just fall out of the transmission?

[geezer#99]

Originally Posted by centuryhouse

If a slip yoke is bolted in, it would no longer be a 'slip' yoke because it can't 'slip', right? Which would create stress where there shouldn't be any, right?

And wouldn't the yoke need a hole in it for a bolt to go through?

And no bolt in the end if the splined shaft - a hole with grease in it. Is that where you are saying a bolt should go? Through the yoke from the u-joint area, and into the splined shaft?

It's bolted in because you need the splines to drive the yoke which drives the rear shaft.
And your no hole yoke may not be the right one.
The end of your shaft looks knarly. Shouldn't be like that. Should be smooth with a dimple in the centre. Just like the output shaft on your tranny is.

Check those rear ujoints too. The caps are crooked in the straps.

[MikeyMan]

Originally Posted by centuryhouse

Could the rear end effect this? It looks like mine is a 12-bolt Chrysler 8.75 - not sure if that was original or not. It seems like the rear end is the only other component that should effect where the parts line up for that rear shaft.

That might be the cause of your issue.
If the rear end has been changed, the depth could be less than the original.
That would require a longer shaft, which could be why you only had an inch slip on the splines.
You definitely need that back shaft checked. It's most likely too short and possibly bent and out of balance. Don't take chances with driveline issues. Vibration will cause premature failure of the carrier bearing and U-Joints.

[chiefcfd]

Now we are getting somewhere, if the rear end is not original none of these measurements matter. You will need a one of a kind drive shaft. You can mate different rear ends to the drive line but you can't use standard parts. The slip yoke definitely needs to engage more of the spline. The only measurement that matters is from u-joint to u=joint. As others have said a driveline shop is your best bet to fix the problem. Hope you get this figured out.

[Matt Cramer]

Originally Posted by centuryhouse

Could the rear end effect this? It looks like mine is a 12-bolt Chrysler 8.75 - not sure if that was original or not. It seems like the rear end is the only other component that should effect where the parts line up for that rear shaft.

Chrysler 8.75" axles would have no bolts on the back and a diff "chunk" that unbolts from the front. If you have that sort of axle, it's definitely not original - and likely to need an odd length custom driveshaft.

[chevy_mike]

There are two different styles of driveshafts that were installed. The Light Duty style, which has no slip joint at the carrier bearing but does at the transmission. The carrier bearing mounts with a "T" style mount. The Heavy Duty driveshaft is typically fixed at the transmission and has the slip yoke at the carrier bearing. The carrier bearing is mounted with a large "U" shape bracket. Each of these styles of carrier bearing had different mounting brackets on the frame side as well.

If the OP has a slip joint at the trans (Turbo 350 would) and a slip joint at the carrier bearing, something has likely been changed at some point. Most HD styles were behind manual trans.

[centuryhouse]

Originally Posted by Baddflash

Here's how that section looks on my truck.

How do the front and rear shafts connect at the carrier bearing?

Is there a spline from the front shaft that goes through the CB? And a yoke from the rear that goes over it, inside of the CB?

I'm really confused about how it works.

[Redline novdog]

Centuryhouse you are doing an excellent job with the pics,measurements,and explanations!!
Hopefully I won't start a war, but. FYI a photo of a track bar rear suspension does not compare to a leaf spring suspension. A slip yoke does not bolt on! It would be nice if someone would come up with a good shot of a leaf spring suspension driveshaft setup.I personnally have the coil/trackbar on the '67. I garantee with the 4x4's Ive owned the shaft to pinion is to short. Be it a different differeintial/yoke/pinion angle or not!! If you did not need to drive the vehicle the you could spent the time to find the cause. If you need to drive it. put the shaft back on( it should have a cap on it) LOAD the truck down and drive it until you can figure/afford to fix it.With a load on it will put the yoke on mor splines,don't go Dukes of Hazzard over bumps

[MikeyMan]

Ignore that pic from Baddflash.

That is NOT the setup you have.

Bite the bullet and get your truck to a driveline shop.

You need the rear shaft lengthened.

[centuryhouse]

Originally Posted by Redline novdog

a photo of a track bar rear suspension does not compare to a leaf spring suspension. A slip yoke does not bolt on! It would be nice if someone would come up with a good shot of a leaf spring suspension driveshaft setup.

......put the shaft back on( it should have a cap on it) LOAD the truck down and drive it until you can figure/afford to fix it.With a load on it will put the yoke on more splines

Thanks for that! I wondered how the springs/load effected the spline engagement on a slip yoke, and your answer tells me some about that.

My shocks are ancient and practically non-functioning. I have new shocks ready to install. I wonder if that would effect this?

When the shaft dropped off, it was right after I'd come to a hard stop for a red light, and then hit the gas somewhat hard to take back off.

Originally Posted by MikeyMan

Ignore that pic from Baddflash.
That is NOT the setup you have.
Bite the bullet and get your truck to a driveline shop.
You need the rear shaft lengthened.

I reinstalled the shaft this weekend and had planned to chance the 13 miles drive to the nearest drive shaft shop on Monday, but extra child support and an electric bill twice the normal amount forced me to have to put this off til next payday.

I'm concerned a new shaft alone wont fix it. There are around 6" of exposed spline; the slip yoke only has 3" of usable engagement length, and it is currently already engaged for around 2".

At best, this yoke can only make 1" more engagement - so even a longer shaft wont significantly help - or so it seems to me. I guess we'll see.

[MikeyMan]

Install those new shocks first and then check the engagement of the yoke.
Check and inspect the rear end and make sure everything is secure.
My very first C/10 had a bad trailing arm which caused the rear end to shift around ever so slightly. I was breaking the carrier bearing bracket (like the one in Baddflash's pic) all the time. The rear end sloppiness was putting undue stress on the driveline, as was my heavy right foot.

[Redline novdog]

the springs support the truck.The shocks keep the truck from bouncing. The new shocks will keep the rear end from separating from the truck(same as jacking up the truck by the frame) When you crest a hill and get the roller coaster effect that is when your driveshaft is trying to pull itself off of the splines.New shocks will help that.The fact the driveshaft/rear end/springs...etc is too short is another problem that needs to be addressed at some time. The closer the frame is to the rear end the farther the slip yoke will engage until passing center line.

[brad_man_72]

Wow there's so much misinformation in one post.

A. Get your shaft and or truck to a driveline shop. It at least needs to be rebalanced because it has come apart while moving and probably bent and damaged several parts. It also looks like some hack has been messing with it.

B. Your rear shaft needs to be retubed and balanced with the front shaft at a minimum. Maybe $200 at a driveline shop.

C. You really do have a slip joint in your driveshaft it is not like the other one that people keep posting that has a much different carrier bearing that allows the driveshaft to slip at the transmission that is used on coil spring trucks. Ignore all post about the other design. There's a ton of misinformation about that design around here too that should be saved for other post.

D. At full droop the driveshaft will be shorter than at ride height. Think of the front half of the leaf spring as a short control arm.

E. Shocks aren't going to make your driveshaft too short. I can go take the shocks off of my truck and my driveshaft is still the correct length.

F. Pic of my last job, I probably don't know anything about driveshafts........

[hamjet]

F. Pic of my last job, I probably don't know anything about driveshafts........
I think that one may a little on the long side for him..

[Xeen]

Originally Posted by alsriv2

Due to the huge amount of changes and variations that could have been done throughout the years to your truck, it might be best to just run it down to a drive shaft shop to get yours fixed correctly.

This is a smart guy and I agree, take it to a professional and let them do it.
Also if you tell them you don't have tons of money and you aren't in a hurry and ask them to take it easy on you they might cut you a small break on the cost of the job.

[MikeyMan]

brad_man, about time a pro chimed in. I'm all about taking it to a driveline shop myself.
I believe the OP would've done so by now, but stated his financial difficulties at this time.

Though I have coil spring set ups on all my trucks, I'm curious what the proper amount of "slip" or "engagement" there is on centuryhouse's slip joint set up.

[brad_man_72]

Originally Posted by MikeyMan

brad_man, about time a pro chimed in. I'm all about taking it to a driveline shop myself.
I believe the OP would've done so by now, but stated his financial difficulties at this time.

Though I have coil spring set ups on all my trucks, I'm curious what the proper amount of "slip" or "engagement" there is on centuryhouse's slip joint set up.

I like to see an inch from bottomed out at ride height for stock suspension. Keith is also a pro he knows his stuff and has taught me a thing or two.

Financial difficulties is the best reason to take it to a pro and have it done right the first time. Driveshafts are deceptivly easy to swap parts on, these shafts need to be balanced after they are messed with. Many of my days at the driveline shop were spent repairing driveshafts tht had been worked on by machine shops and other mechanics.

[centuryhouse]

Originally Posted by brad_man_72

I like to see an inch from bottomed out at ride height for stock suspension.

Financial difficulties is the best reason to take it to a pro and have it done right the first time.

For sure. My type of financial situation is more like "I only have $45 to get by on for the next week". There is no pointing going to the shop if I can't pay for the work, so I'll have to wait until I have some money. Hopefully I can set aside a few hundred on next payday and hopefully they can do it for that.

I tried to get a ballpark idea of the best/worst it might likely cost so I'd know how much to save before going, but the guy at the drive shaft shop was a complete jerk about it so I'm still in the dark.

[lil hoodlum]

Years ago I also was faced with issues with my driveshaft ( i.e. u-joints, center support bearing, balancing etc). I tried to do my best and fix what I could do thinking it would save me time and money. My "fixes" helped but never solved anything.


So I finally got fed up one day and took my truck in to Inland Drive Empire. They fixed me up and made all necessary repairs and fixes. Paid around $125 if I recall correctly. Have not had one single issue with the driveshaft since and that was around 15 years ago. Money well spent in my book.

[brad_man_72]

Originally Posted by centuryhouse

For sure. My type of financial situation is more like "I only have $45 to get by on for the next week". There is no pointing going to the shop if I can't pay for the work, so I'll have to wait until I have some money. Hopefully I can set aside a few hundred on next payday and hopefully they can do it for that.

I tried to get a ballpark idea of the best/worst it might likely cost so I'd know how much to save before going, but the guy at the drive shaft shop was a complete jerk about it so I'm still in the dark.

Yeah there's no way to know the condition of your shaft. Do the ujoints have play, are the yokes bent from being tossed from the truck, is the stub bent, is the tubing bent, are the slip and stub worn out, is the transmission yoke worn out. Way too many variables to throw out a price. Dial indicators, a lathe, and some experience is required to determine condition.
You can't drive the truck like it is, take the shaft to the shop, let them know you don't have much money and you may not be able to pick the shaft up for a couple of weeks depending on the repairs needed. You might be pleasantly suprized, probably not.

[ERASER5]

Originally Posted by brad_man_72

F. Pic of my last job, I probably don't know anything about driveshafts........

Just another guy bragging about his driveshaft.....

[brad_man_72]

Originally Posted by ERASER5

Just another guy bragging about his driveshaft.....

That wasn't my driveshaft, my driveshaft is much shorter.