CV Axle Seperation

[Paveltolz]

Fingers uncrossed. Differential failed...axle was pulled out of the passenger side like what initially started the differential dance last October.
Replaced it with a strip yard unit.
Then there was a funny noise like the actuator had fired but the transfer case was still in 2 High. I had run through a big puddle, up to the doors and since it was on the salt flats.... it stopped as quickly as it started, the ratcheting noise, but a vibration was present at 65.
I worked over the electrical and it stopped *actuator circuit).
I decided to take it for a test run in 4x4 to see about the new diff and while coming out of an 8" deep dip and over a 6" rock on the other side of it...BUSTED another differential in the same place as the last one.

Figure it has more to do with turning down the 3" torsion bar key lift kit to save tie rods and idler arm etc. The extended upper control arms are still in place as are the longer shocks but the front is turned all the way down and the cv's are level. Even a stock height K1500 has 30 degrees of angle on the half shafts... guess I screwed myself...what else is new.

Considering an SAS but that's proving to be a larger project than I care to $ource out cause I ain't doing it by me onesies.

 

[bison]

That sucks!.
Cut the cv joints and make it a 2 wheel drive

 

[Will L.]

Dang! When I was reading the other post with the broken shackle pic, I was hoping things were going to start on the upswing for you now.
I wish I knew someone that REALLY knew these trucks for off-roading to help you with this. You could always move your set up into a hmmwv and go for worlds fastest in that class...0-60 in a minute instead of an hour like mine.:hihi:

 

[btfarm]

3rd time will be the charm Paul. Live and learn eh?

 

[Burning oil]

Damn!
I was thinking SAS also.

 

[Paveltolz]

I’ve been hesitant to resurrect this thread with a new issue but, don’t want to bog down the ‘What did you do to your 6.5 today’ thread with the resurgence of an old issue.

CLIFF NOTES to save re-reading the thread.
I’ve had a chronic issue with driver’s side half-shaft coming apart at the differential while the font end is articulating up/down.
Early spring 2014 is when the separation issue started but I’ve had issues with the front differential itself in the fall of 2013. Initially the truck had a 3” suspension lift which was lowered a bit (torsion keys turned down) after correcting the 2013 differential problem.
Separation meaning the tripot bearing set is being pulled out of the Tripot Housing which is what attaches to the differential.

Only on the driver’s side

The first separation happened going over a speed hump. I carried too much speed and the tripot bearings came out of the housing. Not realizing the full affects of the impact the Half-Shaft’s axel made against the differential, I simply replaced the half-shaft and considered the incident a learning experience. After a second Half-Shaft failure within days, and subsequent inspections for the cause I learned the Differential’s mounts on the driver’s side had sheered from the impact, shifting the differential an inch or so to the passenger side. Skipping quickly over the differential repair, re-breakage, replacement, etc. suffice it to say that I thought I had the issue corrected.
1. Lower the front end further and…
2. Remove the after market upper control arms that were part of the 3” suspension lift.
3. And, add a couple of spacers for a total of 1/2 on each side between the tripots and the differential at both passenger and driver’s sides as the half-shaft assemblies put up no fight going in and there’s a lot of space between the tripot housing and the differential where it should fit snuggly.
4. Stock length shocks (Bilstein 4600) replace the off road 5100’s.

After several years of no issues and the half shafts angled slightly upwards from the differential to the hubs, I lost another driver’s side half-shaft while braking on a dirt road prior to making a right turn.

Tripot Bearings and Tripot Housing...exploded views.





Damage to the Tripot Housing. Supposed to be round....

Fortunately, it doesn’t appear the differential mountings sheered as they’ve done in the past. However, now that the new half-shaft is installed, there is a leak at driver's side output shaft. Most likely from the seal so that musta took a hit. I've added some AT-205 Seal Restore and need to drive it a few hours before it is supposed to have any real affect. I did go about 65 miles and it took a full day for anything to weep out whereas before it was dripping as soon as I stopped.

It was observed I didn’t have the bump stops so those were replaced when I replaced the busted unit with the newest sacrificial [half-shaft]. We’ll see.


With the truck’s front end fully off the ground, the half shafts are approximately level to the ground.
Back on the ground, as stated, the half shafts are angled slightly upwards to the wheels.
I thought that turning the wheel would cause the tripot assembly to move but they don’t. They only move in and out under up/down suspension travel. Only the CV joints move while turning.

BigT surmised the lack of bump stops allowed too much suspension compression and, I guess, there was enough upward articulation that the tripot assembly was apart.

Now that the new half-shaft is installed, I'll just have to see what happens and cross fingers the leak resolves or, its out with the old and in with a 'new' unit.

 

[Big T]

Never seen anything like this and it’s a total head scratcher. I’m thinking it’s something done by prior owner in lifting it.

Why were the bump stops missing? Was that from prior owner?

The CV axles angled up when suspension is loaded seems wrong. I’ll check on mine today, but memory says they should be angled slight down while loaded.

 

[Big T]

Went out and took a pic of the driver’s side CV axle on the ‘99 K2500 Suburban. My memory is accurate, as it is angled down while loaded.

 

[Twisted Steel Performance]

From my understanding the shaft is best when straight or level, maybe along the way the keys were turned to raise the front a bit?

 

[Big T]

Thinking this through…
1. Think of the arc scribed by the swing of the control arms.
2. Loaded, his CV axle angle upward, meaning the axle is already closer to it limit within the tripod.
2. No bump stops allows CV axle to swing further up, extending axle further out and likely breaching its tripot range limit.

 

[Twisted Steel Performance]

Thinking this through…
1. Think of the arc scribed by the swing of the control arms.
2. Loaded, his CV axle angle upward, meaning the axle is already closer to it limit within the tripod.
2. No bump stops allows CV axle to swing further up, extending axle further out and likely breaching its tripot range limit.

Could be.... you would think it would be engineered so that wouldn't happen ... but this is GM after all....

 

[dbrannon79]

I'm trying to picture the angle on the cv axles in my head here. angled upwards with the truck sitting and suspension relaxed. if I am thinking correctly the center of the spindles are higher off the ground than the front diff. wouldn't the raised suspension help this situation or GM / auto parts chineese copies made the cv axle slightly too short to begin with.

something I would look at is where the outer shaft sits in the spindle and how much sticks out where the nut holds it to the spindle. I have seen some (chevy, and others) where the shaft sticks out to the point you'd think the nut was going to bottom out before it tightened up. would it change anything or hurt anything by making a spacer to be placed on the shaft before it went into the spindle. maybe about an 1/8 or 3/16" spacer so the other end where it is separating stays put?

I just installed the front diff in a 2003 burb for a friend. I need to go look at it and see what kind of angle the cv shafts are.

 

[Will L.]

Could be.... you would think it would be engineered so that wouldn't happen ... but this is GM after all....

It was
But someone’s lift kit and removing the stops allows excessive travel.
See this often in offroading when guys try to make regular pickups keep up with Jeeps or hummers.

Long arms are fun. Ever measure your arms on this rig?

 

[Paveltolz]

Appreciate the insights, observations and suggestions.
Will L., the vanishing bump stops are a mystery. I give credit, if any, to the shop that installed the lift back in N.C. I shoulda known I'd made a big mistake when I notice the truck driving sideways/crabwalking down the road when I was driving behind it. The ID 10-T apprentice had installed one of the 4" BDS leaf springs on backwards. Those leaf springs are gone now which means the geometry for my ladder bars was off and they are gone too. I digress as per the norm.

Control Arms: They are all now stock length units. At one time I had thought about an off road front end mod but... No Dinero ($$$) Amigo for that kinda fun.

Spacer inside the spindle: Pretty sure it would certainly create new issues with the ABS sensor rings.

The bumps tops: Given they seem to be over sized as it is, they are in full contact with the lower control arms when the truck is on the ground. Combined with the upward angle of the shafts makes for a great argument for raising the front end (torsion keys) a good one. The bolts that adjust the keys are as let out as I dare without removing them so the truck is as low as it can go without drop spindles and shackles.

The upward slant of the shafts: As stated, this is very concerning. Especially noting that the Tripot boot is more extended with the truck weighted than when it is raised up. Hmmmm


What's strange to me is the stock shock length Bilstien 4600's are beyond fully extended when the wheels are off the ground. Extended to the point that I needed to put a jack under the lower control arm in order to close the gap to get them on.

Since raising the front up a bit to get the shafts at least level is seemingly a must, it is a good thing I still have the 5100s.

Brethren, thank you for the collective inputs. I'll get on this tomorrow and report back. Naturally, I'll have to get another alignment done after raising it up...crap never ends does it!

 

[dbrannon79]

looking at your photo reminded me when I reinstalled the front diff on that burb. when I did the removal and install I did not touch the suspension, just unbolted the shafts from the diff and out it came. when I put it back in I recall that I had to really fight using a prybar compressing the shafts to get them onto the diff hubs. this was with the suspension fully in the down position (wheels off the ground) as if the shafts were almost fully compressed. this makes me wonder about your shafts and how they are in length. I know it's a lot of work to pull them out, unboot the inners clean all the grease out and reinstall just to see just how close to the edge they are when the suspension is in different positions. I assume you could do this with the truck in the air and without having to pull the suspension apart. just pull from the diff first then unbolt the shaft nut on the spindle. loosen the torsion bars as much as possible and use a floor jack on the tire to raise/lower watching the inner part of the drive shaft travel.

your photo showing the shaft and joints position like they would be putting the bearings under pressure causing premature failure over time. I would think with the truck on the ground the joints should be relatively straight with the shaft running down the freeway. suing the same concept as is used for the rear driveshaft with u-joints.

as for alignment changing the height, you should only have to worry about the toe adjustment if I'm thinking correctly.

when the shop that did the lift did their work, they didn't by chance do any modifications to the front diff mounting?

 

[Paveltolz]

Not to worried about the alignment from a cost or execution standpoint as I’m still inside the Les Schwab ‘warranty’ period. They honored it when other work has been done to suspension in the past.

You might be on to something with the differential mount. I didn’t think the 3” Rough Country lift kit involved the differential but, the kit listed now has a (as in one) drop bracket. I don’t know if it did in 2009. Current offering says it’s an updated design. I don’t see anything that would accommodate the other mounting points though. Certainly wasn’t anything on there when I swapped differentials initially in 2012 and it doesn’t look dropped now.

Here’s the current offering.
Differential drop bracket highlighted in Yellow. I don’t know what the bracket is that I’ve highlighted in Red. Didn’t use the rear hardware as I went with upgraded 4” leaf springs from BDS.

 

[Paveltolz]

An additional thought on the differential drop bracket. On the gasser truck, to drop the differential a little or, with a 6" lift a lot, wouldn't be an issue but, you just can't do that with the 6.5 because of the front drive shaft to exhaust cross over clearance. It's tight as it is and wouldn't clear the pipe if the differential is dropped. I'll check under there and see later when, and if, I go after all this today. Might have some grandkid time coming my way and this crew isn't 'under the truck' age yet.

 

[Paveltolz]

Edit time limit expired. BLUF, the lift kit I bought in 2007 didn't have a drop kit for the differential.
With reference to the picture in post #76 above...

Now, for the Upgraded Set Up, one has to cut the lower driver's side differential mount from the frame, grind it down to ensure clearance for their drop bracket (outlined in Yellow). My OEM brackets are all still in place.


The passenger side mount is unbolted and their bracket (outlined in Red) is bolted in.
There is an upper bracket that the kit doesn't picture.



The upper mounting bracket consists of the two pieces not highlighted to the left of the passenger mount.

Oh yeah, then there's step 28....


Ok, grand kiddie time approacheth.

 

[Big T]

Edit time limit expired. BLUF, the lift kit I bought in 2007 didn't have a drop kit for the differential.
With reference to the picture in post #76 above...

Now, for the Upgraded Set Up, one has to cut the lower driver's side differential mount from the frame, grind it down to ensure clearance for their drop bracket (outlined in Yellow). My OEM brackets are all still in place.
View attachment 88857

The passenger side mount is unbolted and their bracket (outlined in Red) is bolted in.
There is an upper bracket that the kit doesn't picture.

View attachment 88859

The upper mounting bracket consists of the two pieces not highlighted to the left of the passenger mount.

Oh yeah, then there's step 28....
View attachment 88858

Ok, grand kiddie time approacheth.

That there is some mods I would never do. How often do you really need the lift mod? 98% of use will be on highway.

 

[Paveltolz]

Well, I’m the one who’s got his finger on the the ID-10-T Mode Engaged” button.
More ignorant really but, feeling stooopid.

I’m checking out the differential and now know what a “Differential Lowering Bracket” looks like vs. OEM lower diff. Mount.

It looks like this: