Drivability with rear driveshaft removed?

[SnowDrifter]

Long story short, I'm swapping my front diff next weekend and need to expedite break in since we don't have snow or anything else low traction to really get it working.

Can I just pop the rear driveshaft out at the u joints, put the tcase in 4wd, then drive around with a front wheel drive tahoe? Or is there a concern with the slip yoke walking out of the tcase?

 

[Erickk120]

Slip yoke would fall and the Tcase would leak. I know everyone wants to be proper and what not, but I dont see why you couldnt just find a way to stop the tcase from leaking, Personally I would just duck tape the tailshaft pretty good. Then go for a test drive if it didn't leak it wont leak. There have been plenty of people driving their trucks without a driveshaft when they break their rear end/ ujoint failure. The only difference has been that they have a slip yoke eliminator installed or their tcase doesnt use a slip yoke, essentially aside from the leaking I dont see a difference. Just be easy on it, but then again you are doing a diff break in, so am sure that wont be a problem. dont drive at highway speeds while breaking it in 55 or less if possible and keep trips short 15 miles til you complete atleast the first 100 miles to prevent the gears from overheating. Oil change after 500 miles and repeat 15 mile cycles and cooldowns when you tow for the first time with it, for a total of 45 miles and then you'll be set. Doing this will ensure a long life of the new ring and pinion.

 

[SnowDrifter]

Slip yoke would fall and the Tcase would leak. I know everyone wants to be proper and what not, but I dont see why you couldnt just find a way to stop the tcase from leaking, Personally I would just duck tape the tailshaft pretty good. Then go for a test drive if it didn't leak it wont leak. There have been plenty of people driving their trucks without a driveshaft when they break their rear end/ ujoint failure. The only difference has been that they have a slip yoke eliminator installed or their tcase doesnt use a slip yoke, essentially aside from the leaking I dont see a difference. Just be easy on it, but then again you are doing a diff break in, so am sure that wont be a problem. dont drive at highway speeds while breaking it in 55 or less if possible and keep trips short 15 miles til you complete atleast the first 100 miles to prevent the gears from overheating. Oil change after 500 miles and repeat 15 mile cycles and cooldowns when you tow for the first time with it, for a total of 45 miles and then you'll be set. Doing this will ensure a long life of the new ring and pinion.

Much appreciated.

Unfortunately I'm familiar with the break in process. Put a reman diff in 3.5k ago and the things been growling since day 1 started leaking out the right output shaft seal at 2k. Just been too ****** out until now to actually get the thing warranted out.

Went back and forth with the company a bunch of times. They said it's my front wheel bearings making the noise. I say they're good. They say it's common. I say it's good. They say they can't help me until I replace the wheel bearings to rule them out. So there goes $400 on front bearings just have the privelage of warranting a bad front diff.

Oh yeah and the bearings are half the price on Amazon but I had to pay out the ass at the local parts store due to time constraints.

**** me right?

 

[Erickk120]

Forgot to add, you got me curious. I thought the front ds spins therefore the front diff ring and pinion should be also spinning, the only thing not spinning would be the axles since those are engaged by the encoder motor. Therefore in theory they should be breaking in while not engaged. I would assume the coast and drive side would be both getting input if thats the case. Then again am not entirely sure if thats the case. Do you know if it spins while in RWD mode?

 

[Erickk120]

Much appreciated.

Unfortunately I'm familiar with the break in process. Put a reman diff in 3.5k ago and the things been growling since day 1 started leaking out the right output shaft seal at 2k. Just been too ****** out until now to actually get the thing warranted out.

Went back and forth with the company a bunch of times. They said it's my front wheel bearings making the noise. I say they're good. They say it's common. I say it's good. They say they can't help me until I replace the wheel bearings to rule them out. So there goes $400 on front bearings just have the privelage of warranting a bad front diff.

Oh yeah and the bearings are half the price on Amazon but I had to pay out the ass at the local parts store due to time constraints.

**** me right?

Yeah if they didn't cheap out and used a quality ring and pinion the thing should be dead silent, Some gear sets are noisey but that is mostly for performance oriented ones, I would assume they used yukon/aam/motive blue as those seem to the the ones that perform the quietest out of most out there, aam are the oem ones. Growling would have me concerned though, can you describe it does it happen deceling/acceling certain speed range?

 

[asand]

Forgot to add, you got me curious. I thought the front ds spins therefore the front diff ring and pinion should be also spinning, the only thing not spinning would be the axles since those are engaged by the encoder motor. Therefore in theory they should be breaking in while not engaged. I would assume the coast and drive side would be both getting input if thats the case. Then again am not entirely sure if thats the case. Do you know if it spins while in RWD mode?

With 4WD (not AWD) the front DS does not spin in 2WD. The Center axle disconnect severs the connection at the passenger side axle shaft. Both CV axle half shafts spin, the spider gears spin, and the two halves of the passenger side axle shaft spin opposite directions. The ring gear, pinion, diff carrier, and driveline all sit stationary.

Running low on oil, or a cheap diff would absolutely have cause to go bad in quick order. Daily driving is akin to doing a one wheel peel ALL the time. Spider gears spinning on the trunnion will cause much heat and wear.

 

[SnowDrifter]

Growling would have me concerned though, can you describe it does it happen deceling/acceling certain speed range?

Load and speed dependent noise when front diff is engaged. More load, more loud. Higher pitched the faster I go. Growling akin to a loose bearing over a bad gearset. Silent in 2wd. Loudest at 30 to 35. Faster than that and road noise takes over. Above 65 it's indescernable from background noise

It's quite noticeable in low traction when front diff is putting in some work

 

[SnowDrifter]

With 4WD (not AWD) the front DS does not spin in 2WD. The Center axle disconnect severs the connection at the passenger side axle shaft. Both CV axle half shafts spin, the spider gears spin, and the two halves of the passenger side axle shaft spin opposite directions. The ring gear, pinion, diff carrier, and driveline all sit stationary.

Running low on oil, or a cheap diff would absolutely have cause to go bad in quick order. Daily driving is akin to doing a one wheel peel ALL the time. Spider gears spinning on the trunnion will cause much heat and wear.

Honestly I'm always amazed those spider gears don't grenade doing what they're doing. Seems like they should blow right the **** up, especially without the slash lubrication of the ring gear turning. Wonder if the diff is designed so that they're always submerged on oil?

 

[asand]

Couldn't say. Furthest I've had one apart was to replace a bearing and seal in the passenger side.

 

[Erickk120]

That makes sense, good to know, sadly to properly break them in that means you have to drive in 4

Honestly I'm always amazed those spider gears don't grenade doing what they're doing. Seems like they should blow right the **** up, especially without the slash lubrication of the ring gear turning. Wonder if the diff is designed so that they're always submerged on oil?

I've never dug into an IFS unit, waiting for mine to blow to get a shot. Although from replacing the seal in both sides, it seems to me that the passenger side is never engaging the spider gears. I think its the driver side stubby axle that does engage them, as it seems to be directly connected to the unit, unlike the other side which is engaged by a coupler when commanded by the actuator, so for the most part they just spin with no real torque while not in use. The spider gears in solid/ifs axles are submerged in oil by default, so unless as mentioned above running low on oil, they hardly see wear while not in use.

As far as the noise its probably the installers fault, either backlash or depth is off hard to tell, as they tend to whine when they are set too deep, or if the backlash is too tight/too lose, if its heard while on both decel and accel its then a depth issue or a combo of the two, might not be off by much but a few thousands of an inch is enough to get any sort of noise. I doubt its bearing related since its pretty hard to mess the preload up, and you would see that in the oil. Being off a bit isn't the end of the world but tooth engagement should be spot on, specially when you are paying a premium for it, I my self would return it and get a quiet unit. One thing I've learn over the years is that if it makes noise from the start it will never be quiet and or might get louder with mileage, doesn't mean its about to blow on you, it just means it isn't meshing as good as it could.