Front Drive Shaft Update

[jvkintheusa]

What does not kill us makes us stronger! Another tool to add to the pack list.

Yeah mine is starting to look like a mobile garage

 

[jvkintheusa]

Do we need to put anti-seize on The mating surfaces when installing the front drive shaft?

 

[pmatusov]

Do we need to put anti-seize on The mating surfaces when installing the front drive shaft?

YES!!!

 

[255/85]

Or what about an “accordion” bellow - kind of like a toilet plunger. Multiple rings in the bellow.

I seem to remember someone trying an additional accordian boot (in Europe?) but the results were poor. A different boot design would be great if it worked.

RCV Performance (<-- this is a link) has a possible solution in their axle shaft boots that maybe hasn't been suggested here. The boots are external to the "bell'' of the CV. AFAIK they require constant additional lubrication but are considered suitable for exposed uses unlike, say, a traditional Birfield used in Land Cruisers, etc. They can handle a fair amount of angle.

It would require a complete redesign of the transfer box CV and wouldn't be cheap.

 

[Lexx]

What do you guys think about Owl Vans theory that these torn CV boots are due to the boot being pinched during installation, especially when lift kits are being installed? I wonder if this could even happen at the factory when they're building the Grenny?

 

[CrazyOldMan]

What do you guys think about Owl Vans theory that these torn CV boots are due to the boot being pinched during installation, especially when lift kits are being installed? I wonder if this could even happen at the factory when they're building the Grenny?

I’m kinda more inclined to think this has to do with the rubber composition and maybe @Zimm ’s point about no give/flex capacity on the material. So tearing from pulling - not pinching. But I don’t know.

 

[jvkintheusa]

I saw that video and I'm not completely convinced although when I compare the shaft angles between a non-lifted grenny and my 1.7 Eibach lift, the angle looks about the same. Not sure about a 4" lift.
Regardless, I'm removing my lift and keep the 275 tires.

 

[Zimm]

ultimately, I think we have learned these cv's are intended to accommodate movement from center line, but not necessarily live far off the center. Which, up 'till now, I didn't know.

 

[Zimm]

I saw that video and I'm not completely convinced although when I compare the shaft angles between a non-lifted grenny and my 1.7 Eibach lift, the angle looks about the same. Not sure about a 4" lift.
Regardless, I'm removing my lift and keep the 275 tires.

Yea I'm with ya, when you draw out the angles and distances, it does not appear like much, but I'm also betting the impact the angle has on failure is plotted on a curve that spikes, not a straight line.

 

[Dokatd]

What do you guys think about Owl Vans theory that these torn CV boots are due to the boot being pinched during installation, especially when lift kits are being installed? I wonder if this could even happen at the factory when they're building the Grenny?

The "boots being pinched at install" theory is fine and all, but it's only an accelerant. I have installed many Grenadier shafts at this point with 100% no pinching upon install and they all still failed.

And as for material and stretching etc. these boots are super supple and compliant. Once I started checking for it I have clearly seen evidence of the boot being pinched/squeezed in operation. I have the evidence from several joints on my desk as we speak. Being lifted just makes this condition easier to meet. So stock trucks get away with it for longer because they don't live as close to the extent of travel. But lifted trucks are always about 2" closer to max. Either lifted or non lifted trucks running on smooth roads without undulations will likely see 100k before a boot fails. But add in daily bumps, humps and jumps and you quickly loose mileage per boot. The bellows shape is inconsequential.

 

[CrazyOldMan]

The "boots being pinched at install" theory is fine and all, but it's only an accelerant. I have installed many Grenadier shafts at this point with 100% no pinching upon install and they all still failed.

And as for material and stretching etc. these boots are super supple and compliant. Once I started checking for it I have clearly seen evidence of the boot being pinched/squeezed in operation. I have the evidence from several joints on my desk as we speak. Being lifted just makes this condition easier to meet. So stock trucks get away with it for longer because they don't live as close to the extent of travel. But lifted trucks are always about 2" closer to max. Either lifted or non lifted trucks running on smooth roads without undulations will likely see 100k before a boot fails. But add in daily bumps, humps and jumps and you quickly loose mileage per boot. The bellows shape is inconsequential.

Similar failure pattern for OEM and aftermarket?

 

[Happyoldgit]

I seem to remember someone trying an additional accordian boot (in Europe?) but the results were poor. A different boot design would be great if it worked.

RCV Performance (<-- this is a link) has a possible solution in their axle shaft boots that maybe hasn't been suggested here. The boots are external to the "bell'' of the CV. AFAIK they require constant additional lubrication but are considered suitable for exposed uses unlike, say, a traditional Birfield used in Land Cruisers, etc. They can handle a fair amount of angle.

It would require a complete redesign of the transfer box CV and wouldn't be cheap.

Interesting. Additional lubrication would suggest they have zerk fittings installed?

 

[Dokatd]

Similar failure pattern for OEM and aftermarket?

I have OEM boots and Terra boots. I have cut cross sections of both. They all fail the same way. They thin out at the pinch, show evidence of light surface on surface friction and of course a tear/crack. The thinned out area directly correlates to how far in or out the boots collar is placed on the shaft.

The evidence I have collected is not up for debate as far as I am concerned. We can all have opinions, but I have hard evidence over many joints to prove my theory out. If you want to fix the problem today without voiding warranty then you need to install limit straps that reduce overall travel of the front end by maybe 1-2". I bet you can get over 100k mi with that setup. But you're neutering the truck at that point.

 

[TCMColorado]

Dokatd......you recently mentioned a potential solution in the works, a custom drive shaft of some kind. Any update on the timing of that?

 

[Tenac]

Dokatd......you recently mentioned a potential solution in the works, a custom drive shaft of some kind. Any update on the timing of that?

Good luck he been saying that for EVER!!!!

 

[Dokatd]

Dokatd......you recently mentioned a potential solution in the works, a custom drive shaft of some kind. Any update on the timing of that?

Got update today; 2wks maybe to first test unit.

To be clear, I am solely driving development but will not be a vendor. Assuming success, I will make sure the parts are readily available in some form or another. Long term testing will come from Beta users at own risk.

 

[Tenac]

Got update today; 2wks maybe to first test unit.

To be clear, I am solely driving development but will not be a vendor. Assuming success, I will make sure the parts are readily available in some form or another. Long term testing will come from Beta users at own risk.

sign me up I beta test everything

 

[Lexx]

The "boots being pinched at install" theory is fine and all, but it's only an accelerant. I have installed many Grenadier shafts at this point with 100% no pinching upon install and they all still failed.

And as for material and stretching etc. these boots are super supple and compliant. Once I started checking for it I have clearly seen evidence of the boot being pinched/squeezed in operation. I have the evidence from several joints on my desk as we speak. Being lifted just makes this condition easier to meet. So stock trucks get away with it for longer because they don't live as close to the extent of travel. But lifted trucks are always about 2" closer to max. Either lifted or non lifted trucks running on smooth roads without undulations will likely see 100k before a boot fails. But add in daily bumps, humps and jumps and you quickly loose mileage per boot. The bellows shape is inconsequential.

So what's the thing that is causing the failures - pinion angle and just plain ol wear due to the rubber being stretched? Does lifted mean more pinion angle and thus accelerates the wear?

 

[TCMColorado]

So what's the thing that is causing the failures - pinion angle and just plain ol wear due to the rubber being stretched? Does lifted mean more pinion angle and thus accelerates the wear?

The rubber is being pinched when the axle droops and the angle at the CV increases. A lifted vehicle puts the CV at a higher angle all the time and closer to the pinch point. Higher caster angle also increase the CV angle and again closer to the pinch point for the boot. Adding longer shocks will increase the CV angle even more by allowing for more droop. This is highly inadvisable.