safely running a vehicle on jack

RatLabGuy

RatLabGuy

You look like a monkey and smell like one too
Joined
May 18, 2005
Location
Churchville, MD
i have a noise which I cannot quite locate, it is either in the T-case or rearend. The problem is it only appears at >45 mph, and only as transitioning from gas applied to coasting.
I'm nearly positive the weight has to be on the axles.

So I figure the best way to diagnose is to jack the rear axle so teh tires can spin... have 1 guy "drive" another listen.
What's the safest way to do/secure this using typical at-home stuff?
That's a hella lot of potential energy if it comes off the stands!

i'm debating maybe driving the nose up against a tree and lifting it there, so if it does fall there's nowhere to go.... but then the stands will be on dirt, scratch that.
 
Against the tree sounds good. I would use stands and some type of base below them that cannot break from the weight of them.

Here's another thought.......Simply try jacking it up and see if the noise is still there with the weight off the wheels. If it is, then proceed with the tree method. If it's not, then your going to need to somehow do it on a roller for resistance.

You could also pull the rear shaft and check out the t-case and tranny that way. This may eliminate the rear axle but you may not get the noise to appear without some resistance from the rear axle not being inline anymore. ???
 
i just jack it up, put jackstands under it, but also leave the jack under the center of the rear. then chuck the front tires.
but like stated before, most of the time you don't hear the noise without resistance.
 
Dave, Ive broke in gears several times on 4 stands...

The only other precaution I take is keeping someone in the vehicle, not just letting it idle or blocking the pedal....so if something gives you have a driver to steer that PE....
 
I always anchor the vehicle that is on stands to a tree or another heavier vehicle. You can use the brakes or ebrake as your resistance.
 
SkyHiK5 said:
Dave, Ive broke in gears several times on 4 stands...

The only other precaution I take is keeping someone in the vehicle, not just letting it idle or blocking the pedal....so if something gives you have a driver to steer that PE....
Click to expand...

Oh, definitely will have somebody in it - need to have constant changes between gas, coast, gas, coast...
The only difference I see is the "speed" needs to be pretty high
 
I would make sure you have some high capacity jack stands, and not those autozone cheapys. I have run vehicles on stands before to try and find vibrations, and had the speedo registering in the 50-60 range for short periods of time. I would suggest only jacking it up as far as to have the rear tires clear the ground, and then set your stands to the lowest point to allow clearance. This way if something does give, or if the rig rocks off the stands, you minimalize the chances of major breakage, and your "driver" being thrown out or not being able to keep control.
 
if u do follow throu with this keep yourself clear of the tires and driveshaft. dont use a prybar to listen to the front pinon bearing if it slips and hits the flange it may be sticking out the other side of your head. if at all possible try to stay behind the axle housing. dont rule out the center support bearing if u have a 2 peice driveshaft or possible springwrap causing a change in pinion angle. thats nearly inpossible do duplicate on stands. so good luck
 
Well it's done - and look I'm still here and conscious to tell!

Here's what I did. And damnit didn't take any pics.
Avoided garage - too many precious objects around!
Foudn a tree near one ond of teh driveway, back up near it, 4" strap tied bumper/frame off to tree, stretched to "close" to but not tight.
Jacked via rear diff, put stands under axle, left jack under pumpkin, tires 2" off ground.
Chocked front tires via bottoms of ramps.
(that way if it takes off, it will both launch airborn AND pull a tree down on top of it.)

Did teh trick, only took about 60 sec of buddy in car, me listening closely to identify sound. unfortunately tehrewas no way to avoid getting up under it to pinpoint locale.
Turns out the noise was actually louder this way, coudl find it at lower "mph"... applying the e-brake quieted it more like "normal on road".
Oh and no I didn't take the tires off, I figured I needed typical rolling resistance, plus I didn't want the drums getting flung off lol
 
So, what was the noise coming from?
 
96tacolx said:
So, what was the noise coming from?
Click to expand...

Rear of transfer case. It really sounded like the driveshaft, but i knew that wasn't it b/c i'd swapped it w/ another. Turns out the driveshaft was resonating the noise from the TC.
Guessing a bad output bearing.
 
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