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Discussion Starter #1
I’ve read the threads on this and the best I can tell the primary objection is that this could damage the cover and cause a leak. It also appears that some owners report that their cover extends below the bottom of the housing which could make strain on the cover more likely when using this area as a jacking point. Attached are pics of my housing and cover. The cover doesn’t seem to extend below the housing at all. Am I missing something? My car is a 2012.
 

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I’ve read the threads on this and the best I can tell the primary objection is that this could damage the cover and cause a leak. It also appears that some owners report that their cover extends below the bottom of the housing which could make strain on the cover more likely when using this area as a jacking point. Attached are pics of my housing and cover. The cover doesn’t seem to extend below the housing at all. Am I missing something? My car is a 2012.
I think this was more of a CYA (cover your [email protected]#) situation due to the fact that if you jack the rear without blocking the front wheel (and you are on any sort of inclide), ugly things can happen very fast.

Just make sure the front wheels are blocked and you'll be fine (I've done on this car and many others before it)
 

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perfectly fine. I've done it numerous times on several mustangs and other RWD cars. you're not going to damage anything.

Just be smart and lift on a flat surface and use wheel chocks on BOTH sides of the front tires and you'll be fine.

also, in my experience, unless you're doing suspension work on the rear, simply backing the car up onto ramps is quicker, eaiser and safer since you can apply the parking brake.
 

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I actually think lifting on the diff housing is bad because the weight of the rear end of the car is carried way out at the ends of the axle tubes where the springs (and wheels) are. When you lift in the center, you're basically trying to bend the axle up in the middle, making it an inverted "V" shape. If the axle tubes bend even a tiny bit, your rear end will wear in some very mysterious ways before it finally fails.
 

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The concern is that the jack will cause a blemish on the rear axle paint, leading to surface rust of the cast iron.

The Owner's Manual states this: "Never use the rear differential as a jacking point."

This topic has good information.

My inclination (not a recommendation) would be to lift the rear from the center of the rear differential and to lift the front from the center of the front cross member.
 

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The reason Ford says to not jack from the diff housing is that all they give you for a jack(on cars that come with one) is the skimpy little scissor jack and you sure don't want to try and jack it up under the diff with one of those.

And as far as any fear of bending the housing by lifting from the diff is concerned, there is a hell of a lot more force exerted on the center of the axle by bouncing down the road than any that would occur by jacking up the car.
 

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And as far as any fear of bending the housing by lifting from the diff is concerned, there is a hell of a lot more force exerted on the center of the axle by bouncing down the road than any that would occur by jacking up the car.
This is incorrect, its not even close. The weight of the car near the end of the axle shafts has very little leverage on the axle as a whole due to the short distance from the spring mounts to the tires. The center of the axle is furthest from each spring mount and places far more stress on the axle than anything you could do to it on the road.

Do what you want with your car, its your money and Ford won't cover damage from misuse. . Things like this make me scared to buy a used car.
 

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The reason Ford says to not jack from the diff housing is that all they give you for a jack(on cars that come with one) is the skimpy little scissor jack and you sure don't want to try and jack it up under the diff with one of those.

And as far as any fear of bending the housing by lifting from the diff is concerned, there is a hell of a lot more force exerted on the center of the axle by bouncing down the road than any that would occur by jacking up the car.

agreed. it is for safety/stability concerns. if you are lifting it from the back, it is not like the entire weight of the car is on the housing; it is simple physics. the front end is still resting on the ground which has a normal force so you are sort of using a leverage principle; not the full weight. it is kind of like doing a pushup on the ground and saying you are pushing up your entire body weight.
 

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Wow, 8 months on the forum and there is still so much controversy on how to raise one corner of a vehicle up.

My car came with a spare and jack. If I get a flat on the highway, I will have no blocks for the front wheels. My options will be to call roadside assist or do it myself. As a layman, I hope to discover a way to change a flat properly, with limited tools, in less than ideal conditions, risking no damage to the car, and doing it in a safe way.
 

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ive done a bunch of times and never had any issues.
 

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As a layman, I hope to discover a way to change a flat properly, with limited tools, in less than ideal conditions, risking no damage to the car, and doing it in a safe way.

Well, if you can read then the owers manual tells you how to change a flat.:bigthumbsup
 

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If this is for a flat, there is a place near the wheel. If this is to crawl under the car for some other purpose, like installing aftermarket goodies, you probably should use jack-stands. Never be under a car with only the jack, shop-jack or otherwise. I personally knew a guy for whom that was his bitter end.

With jack-stands, you can boost one side, then the other. Then you aren't risking any issues against the differential or your own health.
 

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Discussion Starter #15
Isn't the S197 diff basically the same 8.8 that's been in Mustangs since 1986? Is there something different about the housing, tubes or something else that makes the S197 more vulnerable when liffting by the pumpkin? Does a 3 link vs 4 link have an effect on stress via floor jack?
 

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I actually think lifting on the diff housing is bad because the weight of the rear end of the car is carried way out at the ends of the axle tubes where the springs (and wheels) are. When you lift in the center, you're basically trying to bend the axle up in the middle, making it an inverted "V" shape. If the axle tubes bend even a tiny bit, your rear end will wear in some very mysterious ways before it finally fails.
This is ridiculous. As a real engineer, not an armchair one, I can say that this is totally false. If you could really bend an axle tube that easy, what do you think would happen if you went over a bump at 100mph with just the left tire and not the right? If we follow your theory of forces put on the axle tubes bending them, then your rear end is now a pretzel...
 

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Isn't the S197 diff basically the same 8.8 that's been in Mustangs since 1986? Is there something different about the housing, tubes or something else that makes the S197 more vulnerable when liffting by the pumpkin? Does a 3 link vs 4 link have an effect on stress via floor jack?
I don't know and getting some definitive answer from Ford would take a while, if ever.

The easiest solution is to assume there is a problem at the pumpkin and use a floor jack on the sides to boost to jackstands. No risk and plenty of support.
 

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This is too funny..... Unless the center section and diff housing is aluminum, like you would commonly see on an IRS axle, I wouldn't hesistate to lift it by the pumpkin. In fact, I have seen this and personally done this probably a hundred times on everything from dump trucks to duallies to passenger cars. Depending on what you are doing, it is sometimes the only way to support it adequately.I wouldn't do it in a fully loaded down truck, but anything else should hold.

Being the only solid chunk of cast iron on the car, it's probably the stiffest damn thing on the car. Certainly more stout that a pinch weld or axle tube. Be careful to not grab the lip of the cover, and I don't know what you could hurt.

BTW, the axle is bare metal. I don't think Ford was worried about scratching it and rusting.
 

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This is ridiculous. As a real engineer, not an armchair one, I can say that this is totally false. If you could really bend an axle tube that easy, what do you think would happen if you went over a bump at 100mph with just the left tire and not the right? If we follow your theory of forces put on the axle tubes bending them, then your rear end is now a pretzel...
Ever heard the joke about "civil engineer" being an oxymoron?

The rear suspension design localizes the forces on the axle assembly to the ends of the axle - little is transmitted from one end to the other or to the middle. The only load on the center is the weight of the pumpkin itself. The pumpkin weighs about 100 pounds; the rest of the rear axle load (body, wheels, brakes, etc) is about 1500 pounds. When you lift the rear of the car under the pumpkin the load on the joints between the axle tubes and the pumpkin casting increases from 50 pounds to 750 pounds per side. That's a fifteen-fold increase in load.

So the issue is whether the axle tubes will stay attached (I believe it's a press-fit joint) to the pumpkin when 750 pounds is applied at right angles 18" or so from the joint. Most likely they will, but if one doesn't stay stuck, Ford won't warranty it.
 

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I have never ever seen or heard of a rear axle having the tubes pop out due to lifting it up by the center. This is common practice in service from passenger cars to medium duty trucks. The owners manual will advise you to not do a lot of things, mainly because owners would kill or hurt themselves or the car if they don't know what they are doing. The tubes are pressed in, but large plug welds are also used to retain them. This is not a special 8.8, I'd be willing to bet tens of thousands of these have been lifted this way, and I'd also bet not one failed as a result of being jacked up.
 
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