Chevy Astro and GMC Safari Forum banner

Blew My Driveshaft!

7K views 23 replies 17 participants last post by  Mmusicman 
#1 ·
No, it's probably not what you're thinking!

So, a few weeks ago I'm cruising home from work in my 2000 AWD... and while in fairly heavy traffic I make a quick jam on the brakes and suddenly I hear all this crunching grinding banging noises while I slow to a stop! My first thought was something blew in the rear drum brakes. So I slow and come to a stop into a left turn lane to assess the situation, only to realize my speedometer is still showing speed even though I'm now stopped.. and I'm not going anywhere!

Well my next initial impression is that I must have blown something in my new 233 transfer case... the engine is turning but output is not. So I get out to look, uncertain what I will find, only to discover my driveshaft has come out of the transfer case, but is STILL attached to the rear-end... with a small trail to where I'm now stopped!

I'm naturally surprised, and ponder my situation for a moment. The driveshaft had been flying and banging around underneath, denting my muffler and gas tank. It was unknown what damage it may have taken on too.. the yoke was pretty scraped up. Being in heavy traffic on a 6 lane road, I decided I didn't want to stick around and be a sitting duck, and wanted to get off the road as quickly as possible.

Then it occurred to me, that with my 4x4 transfer case, that I could actually put it in 4-wheel drive and have the front end drive me away! Fortunately I had some tools, and pulling the rear drive-shaft requires nothing more than a single 5/16 wrench. So I pulled the shaft quickly, being nervous about being under the vehicle while cars were driving by. Since it was rush hour, traffic was mostly backing up from the traffic light.. and was going past me slow enough.

I managed to quickly pull the shaft, but in the process knocked off one of the caps off the rear u-joint which sent a bunch of the needle bearings onto the road. I gathered them up quickly hoping I had seen them all, and threw all the parts and the drive-shaft in the van. I put the van in 4x4, and got back in traffic and drove to a nearby parking lot.

At this point I figured I couldn't really drive very far without the rear driveshaft yoke in place (in the transfer case) without loosing a bunch of fluid, so figured I would clean things up and put it all back together for the rest of my ride home. I wound up short a couple needle bearings, but it all still re-assembled good enough... and my drive home went smoothly.

The needle bearings I picked up off the road:

20180927_175724.jpg

Here's my "side of the road" parking lot shot where I re-installed my driveshaft:

20180927_180624.jpg

When I got home I noticed the yoke was out a little bit further than normal...

20180927_194103.jpg

It's always been out quite a bit (even with the AWD case) which I thought was normal?
After the 233 case swap, it was out roughly about a 1/4" further than where it had sat before...
but now was even further out than normal.

Here's a photo showing where the banged up yoke had been riding for many years.
For reference: the yoke is 5" long (to dampener)..
..and I had roughly a little more than 2" of engagement with output shaft.

20180927_195446.jpg

Some measurements for reference:
The output shaft is 1" past seal lip

20180929_171419.jpg

The seal extends 1/4" past the output shaft:

20180929_171635.jpg

I took some more measurements and learned that something had moved since the last time I measured it... and that my measurements were not remaining consistent! I discovered my engine had shifted forward (I have bad front motor mounts).. and when I added spacers to the rear mount, I may have inadvertently allowed the position to move forward a little. I also discovered some flex and movement with the rear as well, possibly exasperated by worn spring bushing and excessive lift.

Here's a shot of my transmission mount spacers (added to correct drive-shaft angle alignment with 233 case)
Here's more on that: https://www.astrosafari.com/viewtopic.p ... &start=109

20181027_175111.jpg

So I pulled engine back as far as it would go, put a block in place between rear mount and frame, and tightly locked it in place.

Naturally as expected, there will be some additional push-pull on the driveshaft depending on rear height and braking flex in the rear springs... so I jacked up the rear to take some additional measurements.

20181027_180255.jpg

My yoke has typically been sitting about 2 1/2"s out..
Here it is with the van rear jacked way up showing quite a bit more movement:

20181027_183458.jpg

So I've concluded.. with the shift of the engine forward, plus the rear motion and flex while hard braking, plus the yoke already not being far enough in.. was enough to eject the driveshaft in a split second! I've never had a driveshaft yoke come out of a trans before in my life... so this was a first for me. Apparently though, it may not be completely uncommon.

---------------------------------------------

I drive my van daily needing it for work, and do a lot of highway driving too.. and can't take chances...
So without knowing how badly I may have damaged my driveshaft and/or yoke... I quickly that evening found another one on Ebay and ordered it immediately. Note: we don't have AWD vans in junk yards in South Florida... anywhere! Finding one so cheap online should have been a clue for me... but $50 (incl free shipping) was hard to pass up, considering most were selling much higher. Ordering it from a junk yard in Michigan should have been another clue!

So here is the rusty mess I bought:

20181006_093640.jpg

20181006_093645.jpg

This may look normal to you people up north? .. but I was appalled!
I was planning to send it back.. plus considering the one I banged up was actually doing fine.

None the less, by now I knew this was going to only be temporary, and that I would need to have a LONGER driveshaft made.

I took very careful measurements and determined I needed the drive-shaft to be 2" longer. This would put the yoke 3/4-1" from bottoming out. I found a local company that builds driveshafts and ships online nationally.. and best of all it was right around the corner from my shop in South Florida!

The owner was super nice... agreed with my measurements, worked with me, and informed me I could use the yokes from rusty driveshaft and he would weld them to a new tube. So I had him build my a DS exactly 2" longer than stock.

My shiny new shaft:

20181106_172418.jpg

The old and new...

20181107_173020.jpg

For reference:
They also installed high quality solid Spicer joints...
3R U-joint front: 5-795X
1350 U-joint rear: 5-1350X

20181107_170724.jpg

So here's a picture where it sat before:
(probably going to be the last photo of my little helper.. he's old and not doing well anymore)

20181107_172350.jpg

And here's where it sits now (below)
The new shaft yoke depth came out perfectly!

20181108_134710.jpg

I don't think this drive-shaft will be falling out anytime soon!
That's the latest! Hope you enjoyed the story and pictures!
 
See less See more
16
#2 ·
Wow, Thanks for the story and pictures Mike.

Thankfully you didn't pole vault over the drive shaft!

The last Drive shaft I blew up was on an Oldsmobile. I somehow sucked up a rag while driving, it wrapped itself around my driveshaft in a CV joint and blew apart the CV. I was able to limp home (about 5 miles on side roads) but the sound is real "scary" when it happens. Sounds and feels like an explosion under the vehicle.

I've seen a car pole vault and blow the rear end out of a vehicle. That's pretty spectacular except for the aftermath.
 
#4 ·
Whoa... I wasn't sure how this story was going to read with the idea of blowing a shaft, but wow. Good information to know. And always thanks for posting the problem, detailed pictures and a solution all in one thread.

Guess who is going to go out back and put a tape measure to his shaft shaft....
 
#5 ·
Blew My Driveshaft!
:eek:

Guess who is going to go out back and put a tape measure to his shaft
:eek: :eek:

:rofl:
Theres just too much here...Ive gone into overload!!! lol.

Great writeup MM, thats a beautiful new driveshaft for sure.
That one you got off ebay looks pristine...what are you talking about??? :p
 
#8 ·
MechBob said:
Great write up,great pictures.I used to see this a lot in the late 70's,early 80's,with homemade lift kits on pickup trucks.
^^^^Yeah, THAT^^^^. Bob beat me by 20 minutes or so.
Funny thing is/was......I remember chatting with Mark a few years back about this type of thing.
Glad you kept your cool and found your way out of this mess, Scott!
-M!ke-
 
#10 ·
albrow100 said:
do you think you'll have any issues with it bottoming out in the transfer case when the rear axle compresses fully? It's hard to tell in the pictures

seems like it could cause some damage if the shaft gets jammed into the transfer case
Great point.It all boils down to measuring everything,which is why companies that sell lift kits have insurance.It was all figured out in the 70's,I am amazed this even happened,except not a purchased product.Sorry.Research measures these issues,which is why aftermarket retailers set standards.If you do it own your own,you own it.Probably 90% of the people that do it on their own,never have a problem,so,there is no issue.When you do something "outside of the box",you own it,and all repercussions are yours.
 
#13 ·
Technically, my drive-train is still in proportionate alignment... both front and rear.
The lift raises the body.. does not affect the relationship of the drive-train.
Most say 3/4"-1"... my yoke is currently now at 1" (the vehicle it came out of was about 3/4")
I had about 2" engagement (on a 5" slip-yoke).. now I have 4" engagement with 1" to spare.
I have no doubt it is correct.
 
#14 ·
Yikes hat could have turned out really, really bad. If hat shaft bi into the pavement it could have been disastrous. Great analytics and repair!!
 
#15 ·
If you think that drive shaft was rusty, you definitely wouldn't have wanted to see what the van it came from looked like. :shock: That's the kind of rust we deal with daily. I know people who would have just cleaned up the slip yoke and used it without a 2nd thought. And I've also seen people use worse. :doh:
I'm glad you were able to find someone who could custom fab up a drive shaft for you, as those places are disappearing slowly and quietly. We used to have several in my area, but now we only have one.

Might be worth looking into having a custom built one for your 92 as well, unless it was/is really expensive to have them build one. Just a thought.
Glad to hear it's fixed, and should now give you plenty of trouble free miles, even if the engine moves forward again. :clap: :poke:
 
#16 ·
90safari said:
Might be worth looking into having a custom built one for your 92 as well, unless it was/is really expensive to have them build one. Just a thought..
Yes, they're not too cheap. I've had "custom" high-strength shafts built before.. but I'm not too concerned about the 92 since it's a small block and traction (even on fat radials) is moderate at best. I've broken my share of U-joints and rear-ends.. but never a drive-shaft.

It was cool to find this dude right around the corner from my shop! He had stacks of shafts and shipping tubes.. sending them all over the U.S. Nice balancing and press machines.. nice weld work.. took time to talk.. and anything I wanted was "no problem". He even knew me by first name when I walked back in a week later... regular down to earth guy!
 
#17 ·
Mmusicman said:
90safari said:
Might be worth looking into having a custom built one for your 92 as well, unless it was/is really expensive to have them build one. Just a thought..
Yes, they're not too cheap. I've had "custom" high-strength shafts built before.. but I'm not too concerned about the 92 since it's a small block and traction (even on fat radials) is moderate at best. I've broken my share of U-joints and rear-ends.. but never a drive-shaft.

It was cool to find this dude right around the corner from my shop! He had stacks of shafts and shipping tubes.. sending them all over the U.S. Nice balancing and press machines.. nice weld work.. took time to talk.. and anything I wanted was "no problem". He even knew me by first name when I walked back in a week later... regular down to earth guy!
That kind of place, as mentioned above, is disappearing quickly and worth its weight in gold.

And you got lucky not to have done the pole-vault. Yikes....
 
#18 ·
Leeann_93 said:
That kind of place, as mentioned above, is disappearing quickly and worth its weight in gold.
And you got lucky not to have done the pole-vault. Yikes....
Yep.. as soon as I found this guy, I told him he would be getting my business.
And yes.. I was lucky that I was on a smooth flat stretch of road... no lips or bumps.
But it was flopping around madly, while it was spinning.
Surprisingly, damages were minimal, mostly a couple dents and a few scrapes.
I was even able to re-attach, and drive on the old driveshaft for several weeks, and consider it a viable temporary backup if ever needed.
 
#19 ·
Mmusicman said:
I was even able to re-attach, and drive on the old driveshaft for several weeks, and consider it a viable temporary backup if ever needed.
Just no hard braking eh :)
 
#21 ·
So I had a minor temporary setback. I discovered my new driveshaft has a small amount of "runout" where the driveshaft is slightly off center.. having a high and low spot. I ran it in low gear (with wheels off the ground) and a very small amount of runout was actually visual to the naked eye if you looked carefully.

I have since done a lot of research on the topic... which includes runout, balancing, phasing, etc.

I pulled the drive-shaft last week and took it back to the builder who said he would check it out. It is going to need to be determined if it's a shaft issue, a yoke issue, or even an output shaft issue. It's ready, so I'll be picking it up, hopefully finding out what was wrong, and putting it back in later today.

After putting my original spare (short) shaft temporarily back in... I wanted to accurately check the output shaft of the transfer case, to be sure I didn't damage it when I originally threw the old shaft. Happy to say there appears to be no runout at the output-shaft of the TC itself (with the old yoke).

20181120_174149a.jpg

I did discover about .020 runout in the factory shaft as well (at the front u-joint). I haven't found an exact spec.. but from what I can gather (from doing a lot of reading) there is some expected acceptable manufacture tolerance, and this may be within normal limits. I also found the front (original) u-joint (the one with the plastic retaining caps) is not pressed perfectly centered in the shaft. It is unclear if the factory balances the shaft under this condition.. but it appears so. Again, all within factory spec?

I'll report back after my new shaft is back in.
 
#23 ·
Do you think the new motor mounts would have brought the engine back a half inch or so and not made the custom driveshaft necessary?

I will have close to the same setup as you soon - 2” +1 Journeys Lift, 233c t-case, new motor mounts, control arms and a trans mount that might get shimmed.

My driving will be intensely off-road at time, so I expect a lot of movement of the drivetrain.

I did not budget for a new driveshaft lol.
 
Top