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Driving with no rear driveshaft?

2K views 18 replies 8 participants last post by  StoneTower 
#1 ·
Quick question. I'm waiting for my rear driveshaft to arrive, could be several days to a week. If I want to go for a short drive in my CJ7, is it OK to lock the hubs and run it in 4WD high as a 'front wheel drive' Jeep? Are there any concerns?

Thanks,
John
 
#2 ·
I've did it during my build. Loads of torque steer. I did it around the neighborhood at less then 25mph. I wouldn't go beyond that, as it felt unsafe.
 
#4 ·
I am not saying someone should do it or that you are wrong but how would it be different than someone with a rear axel that has locking hubs on it? If you had a locker, I could see it being a problem. In my case, I have an ARB locker (or someone has a open diff) what would cause the problem?

Yes you can do it. But, as mentioned, the handling will be a bit wonky.

Also, I wouldn't advice doing it on pavement. The same component failures that arise from driving in 4WD on pavement also apply to using front wheel drive only on pavement.

Matt
 
#6 ·
I've done this lots of times. Like from a ujoint failure, etc. Sometimes I don't get around to fixing the ujoint for a week, and drive in front-wheel drive only.

Never had an issue. Seemed to drive the same to me. I think the issue is for some people is that front drive-shafts tend to be super wonky. Every used CJ I've ever bought has had loose front drive shafts, along with usually bad ujoints, etc.

The front is usually neglected since its usually only used off road. So driving FWD on the street will magnify all those issues.
 
#8 ·
I think Matt has something "wonky" going on with his front axle/driveline. As long as the driveline angle is properly set, everything is in good repair and there is no locker involved, you should be able to drive on hard pavement without the rear driveline installed. Now if you have a locker and it decides to engage while you are in a turn, things are going to get "wokny".

Rear wheel drive vehicles with a spool in the differential or a full locker do not do well on hard pavement either. They kind of slide around sharp corners slipping the inside tire. The typical damage that comes from driving locked on hard pavement is caused by gears trying to fight each other. With the rear driveline removed and the differential unlocked, there should be on fighting or binding of gears.
 
#15 ·
Its believe its called torque steer. I have the same issue, albeit significantly less in my wife's front wheel 2014 Tauras. Mash the gas and it pulls to one side. It just is much worse in my Jeep. pulls to one side on accel, and the other on decel. And I had just built the thing. no loose bolts or shi tty bushings etc etc.
 
#9 ·
Stone,

Are you saying you feel no difference in handling, especially during tight manuevering, while driving in FWD with the rear DS removed? I sure do, and I've done it several times.

My understanding is the u-joint front axle design of our Jeeps is what causes them to handle differently than a true FWD car.

Matt
 
#10 ·
I've done this on many different vehicles and if you have an open diff, you should have no problems.
My CJ actually drove better in FWD than RWD.

With an open diff, there should be no problem at all.

I never felt the any wobble in normal turns ( I never tried making a ""U"y in my drive but under normal driving conditions it was fine.

To Matt's point, u-joints are not the best way to transfer power to a wheel in a turn but the two front tires are not fighting each other.
 
#12 ·
John,

My front D30 is still open. I notice a big difference in handling between FWD only and RWD only, especially for things like parking. It's more pronounced on pavement than dirt. It's not the typical ratcheting feeling you get with a locker, but it's certainly different than RWD only.

That said, most of us have driven our Jeeps in FWD only on occasion without incident, so I'm sure the OP will be fine....as long as he doesn't drive it like a typical FWD vehicle.

Matt
 
#14 ·
Sorry, I was torn away by work (dammit). I think Matt and John are both right. During normal operation, mostly straight with minor turns, everything should be pretty smooth. The problem comes in tight turns, as Matt said. The reason is the speed variation from the U-joint at high angles. When the transfer case is in 2WD, it doesn't matter that the front driveshaft is speeding up and slowing down to some degree, because it's not tied to the transfer case output. With the transfer case in 4WD, the constant speed of the transfer case is fighting the irregular speed of the front driveshaft, especially in tighter turns. That is why true front wheel drive vehicles use CV (Constant Velocity) joints for the drive wheels. On dirt, it isn't a big deal because the tires can slip a little as the speed changes.

All of this assumes an OPEN differential.

So, my final take on this is I can drive the Jeep carefully, if needed, avoiding tight turns if I'm on paved roads. The good thing is, it's supposed to rain for the next four days, and by the time the weather improves, my rear driveshaft might just be here!

Thanks everyone for the the lively and informative discussion!

Regards,
John
 
#18 ·
This might help what Matt and Injected are talking about.

There is a reason it's not called Constant velocity joint.

Compare the difference in speed of the input shaft, (inner axle) with the output shaft.



Imagine the strain on the bearings as it tries to accelerate that output shaft. and then slow it down.

r.e.:https://en.wikipedia.org/wiki/Universal_joint

Torque steer is something else I think. that's when you have unequal axle length right to left (Like we have) and the one shaft twist more than the other side. causing one wheel to accelerate faster than the other side.

On a side note;
I could never figure out why my Liberty had a CV driveshaft going to the front axle that was mounted solidly to the frame. and u-Joints on the drive shaft going to the rear axle.
 
#19 ·
Correct me if I am wrong but I thought the 1994 and 1995 Grand Cherokee AWD front axels had u-joints on the axle shafts. I had several in that year range. The ones I had were all Quadratrac V8s but I can't remember about the axels for sure. Maybe only the ones with selectable 4wd had the u-joints and the Quadratrac had CV joints.
 
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