Driveshaft failure

[endoscott]

So I have a 2003 3500 Quadcab, 70,000 miles, had free spin hubs installed (Yukon) and a custom one piece driveshaft. Went camping for a weekend and drove maybe 500 miles or so, backing up camper when we got home in low range without hubs turned and the new driveshaft (aluminum) sheared off at the front yoke. Took it back, the guy said the weld failed and I had him put my stock driveshaft back in because I though the aluminum welding was too unpredictable and I didn't ever want to have to worry about fatigue and losing another later, then drove down to pick up my boat 3 hours away, brought it back, backed it up into my driveway a couple of different times, again low range without the hubs turned (which all works great), but I looked under there when I heard it squeaking and the brand new stock driveshaft was twisted at the front yoke, same spot the aluminum failed. So now I am thinking there must be something really wrong at the rear end for that to happen and that tires should have been spinning long before the that yoke twisted. Could it POSSIBLY be related to the installation of the free spin hubs?? He did all new u-joints everywhere and new ball joints too, all he does is drivelines and rear ends for many years. I am taking it back to him tomorrow, but just wanted to get some other opinions.

 

[rscurtis]

Get your old 2-piece high-speed balanced and put it back in. Using low range is not increasing the torque load on the DS, it's just taking the torque multiplication away from the torque converter and moving it to the transfer case.



Be thankful that DS failed when you were practically stopped.

 

[BIGNASTY]

POLE VAULT TIME

 

[Bob4x4]

Get your old 2-piece high-speed balanced and put it back in. Using low range is not increasing the torque load on the DS, it's just taking the torque multiplication away from the torque converter and moving it to the transfer case.



Be thankful that DS failed when you were practically stopped.

Low range increases the torque available... ... so with a heavy foot or load. . yes there will be close to 3 time as much torque available

 

[endoscott]

Well the driveline shop recommended everything! A lot of people seem to have one piece aluminum driveshafts and free spin hubs without problems. It is being worked on right now

 

[Bob4x4]

Well the driveline shop recommended everything! A lot of people seem to have one piece aluminum driveshafts and free spin hubs without problems. It is being worked on right now

since it is all on your dime I am sure they are happy... .....



In my younger days I raced a 4x4 chevy on pavement in low range that gave me the equivalent of a 6. 14 rear end on 33's. It would embarass some pretty quick cars stop light to stop light. I up graded all the drive train to hold up better but it still killed the cast iron transfer case and of course that was with a lower torque gas engine

 

[Motorhead]

You are missing my point. The free spin kit is designed to allow the front axle and forward driveline to be somewhat at rest while driving down the road and to eliminate the unit bearings used for the front wheels.

I don't think it was ever intended to allow you to push a heavy load uphill with a 300hp Cummins engine in reverse in 4LO without having the front axle engaged.



You are riding the ragged edge of disaster and you will spend some serious money if you don't start locking the hubs in before shoving something around in 4LO. If you have to learn it the hard way, so be it.



I'd prefer that you didn't have to do that, that is why I posted.



Mike.

I am wondering if you speak from personal experience????? I don't see free spin hubs in your signature. Are you a driveline engineer???

I have had free spin hubs on my truck for 4 years and yes I use 2wd LOW to back my trailer and pull it forward if needed. Never had ANY issues and I am at 395hp at the crankshaft. I have the stock one piece driveshaft.

It seems to me he has some driveline build quality issues.

 

[jelag]

I have 2 comments on this... 1 - a mechanical engineer tells me that an aluminum weld needs to be at least 3 to 4 times the thickness of the base metal to have the strength its needs... a good example is the weld on an aluminum framed motorcycle... their huge all the way around the base metal. . 2 - a good friend of 30 years who owns a drive shaft shop shares that a one piece drive shaft in steel the length needed for a 3500 quad dually is asking for trouble and he'd never offer to do one in aluminum over that length with the torque that a Cummins has... . to much change for problems... He's much happier to repair the existing drive shaft than to replace it with a one piece. .

Just my thoughts...

 

[Prairie Dog]

The one piece units that Dodge started installing in our trucks in 06 have been working great. I retrofitted mine and perform the same maneuvers the OP described without failure sans the front DS lockout (which I doubt has anything to do withthe problem).
I believe the engineers at Dodge did a good job on this one - the DS and joints are much. much bigger than the steel units. The local DS builder that shortened and balanced my shaft said they have been doing lots of them and guys are thrilled with them.

 

[mwilson]

I am wondering if you speak from personal experience????? I don't see free spin hubs in your signature. Are you a driveline engineer???

I have had free spin hubs on my truck for 4 years and yes I use 2wd LOW to back my trailer and pull it forward if needed. Never had ANY issues and I am at 395hp at the crankshaft. I have the stock one piece driveshaft.

It seems to me he has some driveline build quality issues.

Ok, now that I am off of the night shift and not as touchy as I was Friday evening I'll try this again.



No, I am not a "driveline engineer" nor do I have "Freespin hubs" in my signature.

However I do possess a good healthy batch of "Common Sense" and that very sense tells me that he is overloading his driveline somehow, the first driveline could have been defective but the second "stock" driveline was most likely fine. It did not break the weld, it "twisted".



My solution offered was to start locking the hubs in before attempting whatever maneuver is turning his driveline into a pretzel. That seems pretty simple to me and feel that it is a very easy fix before he drains his savings account wondering why he can't keep a driveline in the truck.



If you do need my qualifications before I can make a statement then here is a rough overview.

Born and raised around diesel powered equipment. Also operated and repaired such equipment from Scouts right up to a Link Belt Cable Shovel. I know a thing or two about strain and what happens when components are pushed beyond the limit. So I guess I learned by doing rather than going to engineering school.



I doubt that you have ever had to take a loaded 10-wheeler dump through mud and rocks up to the fuel tanks and not break anything, or had said truck lose the throttle action as a result of the engine and frame twisting so far that the linkage could not keep up... ... or in reverse have the main transmission lever hit your leg so hard that you see stars. And still not break anything.



When you graduate from dump truck school you get the crappiest, most underpowered 18-wheeler that the company owns and haul the same load though the mud and up the hills as the shiny new trucks. You learn right off quick how not to break anything as changing a rear end or driveline in the woods loaded is not a good time.



So with that being said a twisted driveline indicates to me that it was over stressed either by operator error or the hill is simply too steep for one driving axle to cope with in 4LO without the hubs locked in.



So yes, I feel that I am qualified to make that statement and to recommend that he lock his hubs in.



I don't care if some of you have been to the moon and back in 2WD 4LO, in the OP's case it is not working out for him.



If he does as I have suggested he will not have any more trouble.



Mike.

 

[SierraRam]

Since it seems to happen in reverse only I would suspect something binding in the rear differential.



I too have backed in low range multiple times in low range with the hubs unlocked, makes it a heck of a lot easier to back while idling. I can think of no reason for this being an issue or cause any damage. Backing on asphault in low range with the hubs locked can create all kinds of bad things.

 

[AH64ID]

There is something else going on. The stress created by 2LO is far less than 4LO since only 2 tires have to spin, your not dealing with 2 different axles working.

2LO is a great tool, and one of the main benefit's of the free spin kit.

I can't imagine the force required to twist an OEM driveshaft, look at the guys doing boosted launches on them. That's a LOT more torque applied than 2LO while backing. You don't have enough traction in 2LO reverse to spin the shaft and not the tires, even backing into a wall would break the tires loose in an otherwise operational pickup.

I wonder if something isn't binding in the front end, which is keeping the pickup from moving and the force required to spin the driveshaft is less than the force required to push (slide) the rear axle with a tongue weight on it.

 

[mwilson]

And before I forget, you will never see a "Freespin" kit in my signature as I prefer 4WD being at my immediate disposal without having to wish that I had locked the hubs in while sinking in a mudhole or sliding sideways up the road approaching a snowbank. I did my time with that style back in the '80s and don't miss it.

Besides when you leave the hubs locked out for long periods of time the knuckle u-joints will seize from lack of excercise and create another issue.



That is my opinion only, I'm sure that it solves problems for those that install it.



Mike.

 

[AH64ID]

The lack of hubs is one of the major engineering downfalls of this truck. You can still have 4wd at your disposal, just lock your hubs when you leave the pavement.

In any way, unless improperly installed, the free-spin kit it not the issue here.

 

[mwilson]

There is something else going on. The stress created by 2LO is far less than 4LO since only 2 tires have to spin, your not dealing with 2 different axles working.



2LO is a great tool, and one of the main benefit's of the free spin kit.



I can't imagine the force required to twist an OEM driveshaft, look at the guys doing boosted launches on them. That's a LOT more torque applied than 2LO while backing. You don't have enough traction in 2LO reverse to spin the shaft and not the tires, even backing into a wall would break the tires loose in an otherwise operational pickup.



I wonder if something isn't binding in the front end, which is keeping the pickup from moving and the force required to spin the driveshaft is less than the force required to push (slide) the rear axle with a tongue weight on it.

What we don't know is how steep the hill is or how big his trailers are.



With the weight of the trailer on the rear of the truck it might not be able to spin. It sure as Hell can't stall. It is a clear indication of too much torque in my non-engineer opinion.



You can break anything with the correct combinations of events.



Mike.

 

[mwilson]

There is something else going on. The stress created by 2LO is far less than 4LO since only 2 tires have to spin, your not dealing with 2 different axles working.

Until it comes upon an unmovable obstacle. Think about it this way. You have an 8,000lb. truck pushing a trailer uphill. You are in low range which at least triples the torque coming out of the transfer case. You have one driving unit involved rather than the two driving units that it was designed

for.



It fetches up on whatever and can not spin, nor stall. The weak link is now the single driveshaft as it is carrying the load all by itself.



In a tandem tractor for example the intermediate driveline is always one to two sizes smaller than the main driveline of the truck. The reason being is that makes it a "fuse" and will twist or shear when forces become too great.



Any time I have ever seen a driveline twist it has been a result of too much foot on the go pedal for the circumstances at the time.



This may not be the case but it sure sounds like it to me.



Mike.

 

[AH64ID]

There just simply isn't enough traction, unless the rear axle is at 9,350 (assuming a DRW), and it would take a serious amount of pedal applied and torque management would kick in anyhow.

If it is as simple as nowhere to go so the weakest link spun, then being in 4wd would have grenaded the transfer case. The transfer-case neither knows nor cares if you are have the hubs locked or not. They are 2 separate systems.

 

[jhenderson]

The case is made to take the torque. The drive shaft isn't. When you are in 4 lo, the torque is supposed to be split between the front and rear diffs. When you put it all through the rear, it's more than the shaft was designed for. I pull an 18,500 lb GN dump on a regular basis. If you don't think you can put enough pin wt. on the rear to keep the tires from spinning on asphalt, you are sadly mistaken. None of the trucks mentioned making full boost launches has any wt added to it.

 

[AH64ID]

It is possible, but not really probable.

There is nothing that makes the torque split 50:50 in 4LO just because the hubs are locked. 4LO is for slippery conditions where 1 axle may be getting all the power because the other is slipping.

Transfer cases grenading are far more common that twisted driveshafts.

 

[Bob4x4]

It is possible, but not really probable.



There is nothing that makes the torque split 50:50 in 4LO just because the hubs are locked. 4LO is for slippery conditions where 1 axle may be getting all the power because the other is slipping.



Transfer cases grenading are far more common that twisted driveshafts.

The design splits the torque 50/50.

Now the actual load each axle sees will vary by

Surface friction,weight on axle,and angle of truck