Jacking under diff question.

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AuroraGirl

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You guys are thinking too new here. I still have the original bumper jack for my 76 Trans Am. I don't trust it at all. Reason being, and I'm not afraid to admit this, is that I really don't know how to use the thing. Maybe it's incomplete, maybe it doesn't function correctly, but as to the point of the OP... definitely not using a bumper jack on a rear diff.

Ahhhh @RichLo you beat me to it....
I still have my 1977 electras, brand new looking. I also have a 75 grand ams and some g bodys... comes down to it I have like 10 of these *******, but only 2 of them are nicer, larger ones which are confidence inspiring. My dad tho has a really cool one that "folds" down and has rubber protection on the contact area, im guessing the bumpers were not notched.

Also to answer your question, you use the jack on flat ground and all the owners manual goodies in the slot on the back bumper. when you do this you only lift the corner you need to change tire, so you dont have a huge unsafe scenario since most things the axle isnt gonna just droop that far or control arm drop that far, you just make sure you use a wheel incase it falls and dont go under the car
 

Schurkey

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Been dicking with cars (and trucks) for decades.

It never occurred to me until a couple years ago that jacking the middle of the rear axle could cause problems.

Truth is, it can...depending on the vehicle weight. If there's enough weight, the axle housing can be permanently distorted by lifting the whole rear of the vehicle by jacking under the differential area. The axle axle could be bowed down at the ends.

I don't think there's any risk when jacking up a solid-axle RWD car, or a typical pickup. A motor-home, or school-bus may be different. A 2-ton grain truck even without a load could be an issue.

Since I don't work on bigass vehicles, I don't worry about it.
 

someotherguy

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Been dicking with cars (and trucks) for decades.

It never occurred to me until a couple years ago that jacking the middle of the rear axle could cause problems.

Truth is, it can...depending on the vehicle weight. If there's enough weight, the axle housing can be permanently distorted by lifting the whole rear of the vehicle by jacking under the differential area. The axle axle could be bowed down at the ends.

I don't think there's any risk when jacking up a solid-axle RWD car, or a typical pickup. A motor-home, or school-bus may be different. A 2-ton grain truck even without a load could be an issue.

Since I don't work on bigass vehicles, I don't worry about it.
The F450SD wrecker I drive actually has a factory bottle jack wing-nutted behind the seat. First one I've ever seen without a "jack delete" - literally every brand-new wrecker I've been in did not come with the factory jack.

I cannot possibly imagine trying to lift this heavy SOB with that jack. The wrecker unit and associated bed bodywork is ridiculously heavy. As a bonus, there's nowhere to carry a spare tire anyway.

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Richard
 

454cid

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The F450SD wrecker I drive actually has a factory bottle jack wing-nutted behind the seat. First one I've ever seen without a "jack delete" - literally every brand-new wrecker I've been in did not come with the factory jack.

I wonder if it's the company that does the conversion that "deletes" the jack. I've seen the yellow Ford jacks in a local auction quite a bit.
 
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