Possible to drive without rear driveshaft?

[Copperfield]

As I was changing my muffler yesterday night , I decided to check the rear driveshaft because of some vibration whilte going over 65 and leaving the gaz ,so I decided to check and driveshaft and it turns out there is a play in the u-joint.
Now I took it out and I am going to send it for rebuild but it might take a couple days to get it back , is it safe to drive with the car on the highway??I already moved it a bit and it moves no problem so I am guessing my TC is working perfectly.

[TobyB]

Don't you have a viscous center diff?
Running one of those with one side disconnected
would be really hard on it, at best...

t

[nando]

This has been debated endlessly. Some will say it works fine (and have done so), others think it will self destruct in a giant nuclear explosion.

In the end, it's up to your own tolerance for risk. For a short period of time, I think it will be OK. I'm not sure if I would personally do it.

[flyboyx]

for a few days of driving, i guess you could get by. it would be my preference to drive another vehicle or use uber if you can.

[nomansland92]

I wanna see a fwd burn out....

[Copperfield]

Yeah I guess I won't risk it but I kinda wanted to see 8f the vibration was gone like this :-x

[95BMWIC]

This has been debated endlessly. Some will say it works fine (and have done so), others think it will self destruct in a giant nuclear explosion.

In the end, it's up to your own tolerance for risk. For a short period of time, I think it will be OK. I'm not sure if I would personally do it.

I dont recall the rear driveshaft debate - only the front.. The front driveshaft can be removed and as long as the VC is good the rear driveshaft will power the car..

My guess is that the rear driveshaft removed would greatly under-power your car as the front diff only received about 30% of the power from the t-case..

The damage may come from you driving it harder to overcompensate for the power loss..

I may be missing something - so I defer to Chris on this.

[flyboyx]

whether the front or rear, if you drive the car around with only one shaft, the only thing that is going to be pulling along the car is the silicone in the viscous coupling. when the engine/car is producing torque, i promise you that the vc will be slipping and producing heat. this is not simply a theory. this is a fact. if you wish to test what i am saying, find a car with a known bad viscous coupling, remove a drive shaft. put the car in gear, and try to drive it around. the coupling will slip and the car won't go anywhere. iirc, the vc seals are good for about 300 degrees f. when you hit this temp, your seals will indeed melt, you will mix silicone with the xfer case lube and that will be the end of it.

now, with this said, there are lots of people driving ix's around on one shaft. i actually bought a running driving car that was missing the front one. the case housing had a hole broken in it, and it had been run dry for so long, all the bearings were shot. oddly, the vc was still in good shape. i assume because it never reached a temp high enough to melt the o rings. i took the case apart and used the viscous coupling in another xfer case that i rebuilt. i don't own the car anymore, but to my knowlede, it is still working.

i am not saying that this is instant Armageddon. i am saying it is my opinion that this is a terrible idea.

[nando]

I dont recall the rear driveshaft debate - only the front.. The front driveshaft can be removed and as long as the VC is good the rear driveshaft will power the car..

My guess is that the rear driveshaft removed would greatly under-power your car as the front diff only received about 30% of the power from the t-case..

The damage may come from you driving it harder to overcompensate for the power loss..

I may be missing something - so I defer to Chris on this.

it doesn't work like that. the transfercase splits the torque, but the VC only controls the output shaft speed between the front and the rear.

my theory is most of the slipping occurs under acceleration. at cruise, with both wheel speeds equal, the output shaft speed would also be equal - even with the rear shaft (or front) unhooked slippage would be minimal.

I mean if the VC were *that* sensitive, any significant driving on snow/ice (which can easily cause the VC to slip/lock) would break it. We know that's not the case..

[z122643]

Let me put it this way...

Why would you drive without a drive shaft? In the end you are MISSING a critical component!

So, no don't drive it without the drive shaft (rear/front) doesn't matter.
*********
"Just because you can do a thing, doesn't mean you should"

-"but it would be a shame not to try"

[The Dark Side of Will]

whether the front or rear, if you drive the car around with only one shaft, the only thing that is going to be pulling along the car is the silicone in the viscous coupling. when the engine/car is producing torque, i promise you that the vc will be slipping and producing heat. this is not simply a theory. this is a fact. if you wish to test what i am saying, find a car with a known bad viscous coupling, remove a drive shaft. put the car in gear, and try to drive it around. the coupling will slip and the car won't go anywhere. iirc, the vc seals are good for about 300 degrees f. when you hit this temp, your seals will indeed melt, you will mix silicone with the xfer case lube and that will be the end of it.

Do the seals actually melt or does the silicone fluid expand with the heat and develop enough internal pressure to pop the seals out?

it doesn't work like that. the transfercase splits the torque, but the VC only controls the output shaft speed between the front and the rear.

my theory is most of the slipping occurs under acceleration. at cruise, with both wheel speeds equal, the output shaft speed would also be equal - even with the rear shaft (or front) unhooked slippage would be minimal.

The fact that people can drive their cars thousands of miles without the front driveshaft means that the VC doesn't slip enough in that configuration to generate the heat required to hurt it.

With no front shaft, 33% of driveline torque goes to the front output. The VC has a ftlbs / RPM relationship. Put a certain number of ftlbs across it, and it will slip at a certain RPM. Put 33% of driveline torque across it and it'll slip accordingly. At this level, it doesn't slip enough to hurt it, even in the long term.

However, with the rear shaft removed, the coupling has to deal with 66% of driveline torque. It will slip at a higher RPM. Is this enough to hurt it? I don't know. Exposure is key. Driving it around the block will develop a lot less heat than taking a trip across the country.

As Nando said, the coupling in a shaftless iX slips the most under acceleration. This is when driveline torque is highest. A car driving on a straight an level road at 55ish typically uses less than 20 HP to maintain speed. At 2500 RPM, that's ~42 ftlbs at the engine. In 5th gear, that's 34 ftlbs hitting the transfer case. 33% of that is ~11 ftlbs that the coupling has to deal with. This is a very light load.

However, in first gear, 150 ftlbs at the engine pushes ~570 ftlbs into the T-case, leaving 189 for the VC to deal with if the front shaft is out. If the rear shaft is out, that's 378 ftlbs at the VC.

[nando]

I don't think we really know, but it seems likely that the seals melt. somebody figured out what their maximum temp would be - it's not very high.

the fluid shouldn't expand enough to push the seals out, since the volume is about 40% air.

[Nisse Järnet]

When I tested driving my E34 setup without front ds I could move the car but only bearly with the TC unlocked.
It would slip alot and move forward pretty slow. I were unable to maintain like 40mph without it slipping badly.
The clutch pack probably creates a little drag even unlocked to help it move a little.
Off course when I locked it it was all good :)

[Copperfield]

Well thanks for all the input , I actually just received the rebuild DS , 200$ , not too bad!!! I was just being a little bit curious is all.