so i went out and bought a floor jack today and im going to change my rear shocks this weekend, but where is it ok to place the jack. the manual is useless all it says is dont place jack under the differential. can i place it anywhere except for there??

 

Yes you can except for body panels and such where the metal will bend. You'll just want to jack up on the frame so the suspension will drop and extend the shock so it is easier to get off and put the new one ones in.

 

I have always lifted off of my diff even though they say dont and havent had any problems. it is best to lift it one side at a time and set it on jack stands of course but you are very limited when you are trying to lift both wheels at the same time.

 

I have always placed the floor jack under the diff on all the trucks that I have ever had the need to use a floor jack on. There is not reason why you can't, you aren't going to hurt anything. But if you still don't want to, then place it on the axle tube just inboard of the wheel.

 

If it won't hurt anything, why do they tell you not to? Not trying to be a jag off, but some guys say no problem, others say don't do it. I've done it and had nothing go wrong, but I'd like to know the risk involved. I also use the axle close to the tire which is royal pain if you want a jack stand under there as well. The frame rails on mine are so far forward I can barely get it off the ground.

 

Why do you need a floor jack to change rear shocks out??

 

I've always used the diff as well without a problem.

-TXF150- raises a good question...

 

Bingo. You shouldn't need to jack the truck up to change shocks, unless yours is too low to lay under (and from the pic on your post, I would say it isn't). You may need a jack to raise the bottom of the new shock up in order to get the lower bolt in, because new ones are pretty stiff.

 

just lay a 4x4" peice of wood under the spare left to right, and lift up on the wood

the wood will give you some extra height clearance, and stability.

 

I was thinking about getting a floor a jack when I get home. I just put a 6" lift on my truck, is there a certain one I should look for? Will they go up high enough?

Thanks

 

I'd say that the manual says not to because Ford was afraid of people jacking on the diff and breaking the cover. I know that on my F-body that I have to jack in front of the cover due to the cover being slightly lower than the diff. I have not looked on the F150 yet to see of this is the case or not.
Besides that I don't see anything wrong with using the diff.

While on the subject where are you guys jacking the front of these? On my old ranger I jacked on the I-beam suspension. I figure that the middle of the front cross member would be fine correct?

just thought of this can we jack one whole side at a time? Place the jack somewhere around the door and jack on the frame.....Nascar style?

 

Hi.

Just thinking out loud, but I think another reason Ford states not to use the diff alone is liability and axle damage.

If you think about it, the combination of width, truck weight and the leverge produced from the leaf mounts (where all the rear weight rests) to the diff itself, when lifting from the diff may overly stress the rear diff:

Like this:



[]=v========O=======v=[]

--------------^^-------------

Where;

[] is the wheel
^^ is the jack
O is the diff
== is the axle
v is the leaf spring mounts
- is the ground


Now, that's for a vehicle of this kind of weight & track... I did a quick Google & yes lots of pros recommmed it for Miatas, Bimmers, Puegots, ec - but those are light and narrow - Miata's even have a boss on the diff for this purpose, and some have IRS rears anyway.

I would think it's prudent to avoid doing it this way if at all possible.

You should be able to change them with the truck on the ground, no problem.

Cheers
Bubba

 

you'd have to have a jack that extends pretty tall to do a whole side at a time. it would be faster/easier to jack each wheel up and jackstand em. just my .02

it could definately be done on the ground, but i'd rather just jack the whole *** end up, just so i didnt have to worry about compressing the shock.

btw, what shocks are you putting in and why?

 

Isnt that what happens when you tow a trailer, or payload, stress on the axle?

And frame and bed over the rear of the truck make up around (rough guess) 25% of the vehicles weight, so there definetly isnt that much stress on the axle that way

 

Hi Pat.

Weight distribution on my Screw is approx 60/40 with a full tank. Still a fair amount of weight being supported on a component that was not intended to support it in that manner.

As for towing or payload - same thing - it's the axle itself via the two leaf mounts out near each wheel doing the supporting in both horizontal & vertical planes. Not the diff - it's just hangin' here.

It's the bending moment I'm concerned about - imagine a 6 foot length of abs pipe or whatever placed across your shoulders behind you neck. Now grab each end and pull down. Chances are you'll distort the pipe ( if your neck don't give out first ). See what I'm saying?

No other stress under normal operation puts quite the same kind of load on the pumpkin... but like I said I could very well be worried about nothing.

We need a mechanical engineer-in-training to chime in here LOL!

Cheers
Bubba