JOB

I traditionally do almost all my own work on all cars I've ever owned, especially post-warranty. This means finding an efficient/handy way to get the cars suspended up in the air, at either one end or both ends. My Audi owner's manuals INSISTS that the car should never be jacked anywhere except at the 4 prescribed points at the outer edge of the body just ahead of the rear wheels and just behind the front wheels. (This advice, of course, offers the do-it-yourselfer no convenient/efficient way to get the car up and ready to work on, with either both wheels of front up together, or both back wheels up together, or all 4 wheels up together.)

Over this past weekend, I had my new A6 2.7t up on ramps in the front, with the plastic shroud removed from under the engine in the front. With this plastic off, one finds a rather massive steel crossmember (part of the subframe) running from side to side, just under the engine. Using my hydraulic floor jack, why could I not lift the front of the A6 with this crossmember without hurting the car? This crossmember seems VERY SUBSTANTIAL to this home mechanic.

Similarly, in the rear of the car, why could I not lift it under the VERY SUBSTANTIAL differential bottom?

In both cases, I'd be careful to put wood between my floor jack and the part in question.

Even though manuals on my 1977 BMW 530i also cautioned to jack only in "inconvenient" points
similar to Audi's advice, I've jacked the 530i as described above for 22 years and it's remained in perfect alignment. No harm of any detectable kind was done. I always used the front crossmember and the real differential only as initial lifting points and then set the car on "strategically placed" jack stands for the duration of the work.

BOTTOM LINE: I want to be able to lift my Audi efficiently/quickly for repairs/maintenance over the upcoming years of ownership but, of course, don't want to damage the car either. I find it HARD TO BELIEVE that jacking it where I've proposed above would hurt the car/frame/body in any way. OTHER OPINIONS? OTHER EXPERIENCES JACKING any Audi (A6 or otherwise) in the places I'm proposing? Thanks in advance for any constructive feedback.

Gerry

I also own a Jeep Grand Cherokee and I recall reading from a Jeep forum that one is not suppose to jack up the car/jeep on the rear differential. I am convinced base on the fact that while a car normally hit a bump the upward force is very close to the springs. whereas, when you jack in the middle, the force is furthest away from the springs! remember the magical power of leveraging! so the diff case is taking some pressure that it may not have designed for.


GT
A6 2.7T
ZJ 5.2

JOB

Never lift differential on any vehicle? I've done it for 35 yrs. Even NTB does it on my truck.

Gerry

I have to admit that I have done it too to my truck. Truck is a truck and is a little stronger. but is it built for that purpose? ask your dealer.. in this case the owner manual of our A6 is clear.

for example. I won't do it to my miata. although car is light, the read diff looks like some kind of aluminum alloy.


Also if something does happen to the diff (may not even be related)... and the dealer find scratch mark on the case.... need I say more.

GT

Todd W

You do not want to lift a car with independent rear suspension by the diff. The bushings are not designed to support the weight of the car, nor are the aluminum mounting arms of the diff. Jack from the suspension mounting points or the subframe. The engine mounts are stronger, but I still do not suggest lifting the car by the engine or transmission.

A live axle truck or car has a steel cased diff that is part of the suspension, and the loads are transferred through the normal suspension mounting points to the body. The pumpkin (diff) is the lowest point and therefore makes sense as a jacking point.

Todd W

JOB

The IRS vs non-IRS feedback is insightful. Thanks, and I do appreciate and uderstand your points. IRS setups certainly do tend to be somewhat lighter and more fragile and they do not have the solid steel differential housing and axle housing tubes of the non-IRS setups. However, I would still offer the following refinement of your suggested position: SOME IRS's (perhaps even the Audi A6's ?) MIGHT be harmed by even temporary jacking under the differential. It WOULD really DEPEND ON THE PARTICULAR CAR, the particular differential supporting structure/subframe, the particular rubber mounts, etc, etc. As I said in my orignal post, my '77 530i's differential carrier sub-frame and related rubber mounts were rather massive and decades of lifting there never hurt it in the least. I even had the main center rubber carrier/support bushing out for replacement once and was amazed that it still looked almost brand new, even after 20 years. (I replaced it anyway.)

I obviously have some doubts about whether to obey Audi on this jacking issue, else I would not poll other owners for their feedback. Bottom line is that I still believe that I need to investigate further before either starting to jack my car as proposed in my orignal post OR deciding to adhere strictly to Audi's warning forever. After all, we all know that manufacturers often develop their rules/guidelines for an assumed "idiot owner of IQ=25." These rules are often written very over conseratively for this assumed idiot and, therefore, turn out to be unnecessarily restrictive for the non-idiot owner who really wants to understand his car inside and out and wants to maintain it (perhaps even over maintain it) to a state of near perfection (mostly) by himself/herself.

Other feedback? I really am interested in hearing more, esp. from anyone who's found some easy/acceptable ways, at home, to simultaneously lift/jack either both rear wheels or both front wheels (w/o harming their Audi).