Front drive shaft break at 75 mph

thechrisjones · Aug 4, 2015

Well I finished my build took it out Sunday on some trails and left feeling good nothing broke.... Then about 40 miles in on the drive back home at around 75 MPH u-joint breaks at the front drive shaft and the transfer case! $250 dollars later I got it towed to the house. Take off the front drive shaft and the only damage I see is the 4 wheel drive cable and bracket is broken, exhaust manifold has a nice dent, heat protecter is twisted up pretty good, the insulation is tore up and my floor board is raised about 4 inches higher. I got a rubber mallet and beat the floor back down. I'm going to order a new bracket and 4 wheel drive cable and install it myself then thinking about taking it to the dealer and let them do an inspection. Does anyone have any advice? I drove it to the car wash today and it seems to drive fine.

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dannymalkin · Aug 4, 2015

What kind of shaft was it, and who installed it? It looks like an odd way to fall off, I'm sure someone else will chime in.

OverlanderJK · Aug 4, 2015

You probably didn't tighten it all the way or have it aligned properly when you bolted it on.

thechrisjones · Aug 4, 2015

Coast drive shaft.... I've put more the 4k miles on it with no problems. No vibrations or anything. One of the head mechanics at the jeep dealership is a friend of the family and we put the lift on together. He used to own a snap on truck run and has a garage shop behind his house with lift and all... He builds trucks and motorcycles from the ground up as a hobby, I feel like he has the experience

OverlanderJK · Aug 4, 2015

thechrisjones said:
Coast drive shaft.... I've put more the 4k miles on it with no problems. No vibrations or anything. One of the head mechanics at the jeep dealership is a friend of the family and we put the lift on together. He used to own a snap on truck run and has a garage shop behind his house with lift and all... He builds trucks and motorcycles from the ground up as a hobby, I feel like he has the experience

Cool story. Why post and ask for advice then? Why not ask the all mighty snap on truck owning mechanic?

thechrisjones · Aug 4, 2015

I would like to add after deflating the tires I reinflated them to 32 PSI instead of what I usually run which is around 29 psi. I noticed a small vibration looking in my rear view mirror driving home but thought it was just the tire tread wear due to the different PSI. I never felt any vibrations in the steering or jeep.

JAGS · Aug 4, 2015

thechrisjones said:
Coast drive shaft.... I've put more the 4k miles on it with no problems. No vibrations or anything. One of the head mechanics at the jeep dealership is a friend of the family and we put the lift on together. He used to own a snap on truck run and has a garage shop behind his house with lift and all... He builds trucks and motorcycles from the ground up as a hobby, I feel like he has the experience

So you had the same driveshaft from before the lift to after the lift? Maybe the new lift and the flex run you did added stress differently than it had on it before. Am also wondering if your angles were set with the new lift and shaft. That's the extent of my knowledge, but hopefully others can chime in.

Main thing is glad you are safe.

thechrisjones · Aug 4, 2015

OverlanderJK said:
Cool story. Why post and ask for advice then? Why not ask the all mighty snap on truck owning mechanic?

Because he's in Memphis and I live in Nashville. I'm concerned that the jeep dealer might flag my jeep. He told me that the location he works are not assholes and are cool about lifts and the nature of things of this matter, but he can't speak for the Nashville dealers. So the reason I ask for advice is to see if anyone else has experience this or can give me advice.

OverlanderJK · Aug 4, 2015

thechrisjones said:
Because he's in Memphis and I live in Nashville. I'm concerned that the jeep dealer might flag my jeep. He told me that the location he works are not assholes and are cool about lifts and the nature of things of this matter, but he can't speak for the Nashville dealers. So the reason I ask for advice is to see if anyone else has experience this or can give me advice.

I've broken a few driveshafts but carry on.

thechrisjones · Aug 4, 2015

Thanks JAGS! I had the lift, driveshaft, and tires all put on at the same time I had the alignment done and the caster was set at around 4. I think during trail riding and flexing one of the U bolts must have come lose and once I started diving on the interstate the vibration worked it completely off.

JAGS · Aug 4, 2015

You said earlier the DS had 4k on it. So I'm confused. Anyways.

I recently had my front rebuilt and balanced after 27k. The CVs were jacked, but the thing didn't fly off and break.

To overlanders point, if things were torqued properly, nothing should have come loose in a simple flex run. Something wasn't right.

A.J. · Aug 4, 2015

Looks like the bolts were not tight. Possibly one of the cups was not all the way in its place or they did not get torqued. Mistakes happen it will just make you more careful in the future. A paint marker is a great tool when doing final check on bolts. I bet it scared the crap out of you when it went. The vibration was your warning. Great carnage pics. Make sure you check every nut and bolt while you are underneath fixing it. Mark them with a paint pen as you go.

big dr · Aug 4, 2015

My advise is,,, DONT RUN THAT SHAFT,,,,,, until you have it checked and re-balanced. This is from personal experience. Your shaft banging around could have slightly bent it, taking it out of balance. As a kid I had a driveshaft shake my transmission so bad that it cracked my engine block!!! Not a cheap fix! The weird part is I didnt feel any vibration as it did this.:doh: Check your shaft!!!!

thechrisjones · Aug 4, 2015

A.J. said:
Looks like the bolts were not tight. Possibly one of the cups was not all the way in its place or they did not get torqued. Mistakes happen it will just make you more careful in the future. A paint marker is a great tool when doing final check on bolts. I bet it scared the crap out of you when it went. The vibration was your warning. Great carnage pics. Make sure you check every nut and bolt while you are underneath fixing it. Mark them with a paint pen as you go.

I think your right, good call out with the paint pen! It's easy to miss a bolt. And yes I about shit my pants, wish my friend behind me had his gopro on when it happened; it would have been some good footage.

thechrisjones · Aug 4, 2015

big dr said:
My advise is,,, DONT RUN THAT SHAFT,,,,,, until you have it checked and re-balanced. This is from personal experience. Your shaft banging around could have slightly bent it, taking it out of balance. As a kid I had a driveshaft shake my transmission so bad that it cracked my engine block!!! Not a cheap fix! The weird part is I didnt feel any vibration as it did this.:doh: Check your shaft!!!!

Thanks Big Dr, I was thinking about buying a new shaft just to play it safe.

Spudcannons · Aug 4, 2015

From what the pictures showed I would think the U-bolts came apart after not being torqued properly or from the drive shafts hitting something and knocking them loose.

wayoflife · Aug 4, 2015

thechrisjones said:
One of the head mechanics at the jeep dealership is a friend of the family and we put the lift on together. He used to own a snap on truck run and has a garage shop behind his house with lift and all... He builds trucks and motorcycles from the ground up as a hobby, I feel like he has the experience

Did you guys make sure to put a drop of red locktite on the threads of the u-bolts like YOU'RE SUPPOSED TO DO? Don't get me wrong but I've seen a lot of "head mechanics" make rookie mistakes like this. Sometimes, it's just a simple oversight but more times than not, they just don't have a clue how to work on anything other than factory parts.

piginajeep · Aug 4, 2015

Lol!! The "head" mechanic at my dealership didn't even tighten the motor mounts when they replaced the motor.

OverlanderJK · Aug 4, 2015

wayoflife said:
Did you guys make sure to put a drop of red locktite on the threads of the u-bolts like YOU'RE SUPPOSED TO DO? Don't get me wrong but I've seen a lot of "head mechanics" make rookie mistakes like this. Sometimes, it's just a simple oversight but more times than not, they just don't have a clue how to work on anything other than factory parts.

piginajeep said:
Lol!! The "head" mechanic at my dealership didn't even tighten the motor mounts when they replaced the motor.

I believe you two are missing the main point here. This guy owned a snap on truck!

mudmobeeler · Aug 4, 2015

The head mechanic at my dealership drove away with a sensor head off of the alignment machine still attached to the wheel. He's been turning wrenches for over 40 years. Everybody can screw up at anytime.

Front drive shaft break at 75 mph

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