As title, seen people doing this in the past but wasn't really sure if a normal road car diff was up to the weight of lifting the car up. Where do you normally place the jack and aslo best place for axle stands too ? Mine is a my97 so sills aint an option.

Cheers.

 

Diffs ok, the impreza diff is cast steel. Just be carefull not to damage it. Structurally it's well mounted to the rear subframe, the rear of an impreza isn't that heavy. Axle stands under the plates at the front of the subframe (subframe mounts)

 

Thanks mate , where would I put the axle stands at the front of the car?

 

On the chassis legs or subframe

 

Thanks mate. Dont suppose you know if a ratchet fitting fits the rear diff drain/top up plugs do you ? Or do i need some kind of square socket tool for it ?

 

There is a diff plug tool you can get which fits exactly

 

A normal 1/2 inch drive ratchet fits the diff plugs just fine, just clean out any muck that might be stuck in them first.

 

A 1/2 inch ratchet / breaker bar fits the plugs directly

 

Ok great so at least i dont have to go looking for any special tools now then.
Cheers for that lads.

 

Lol, what have you tried in it?

 

I tried 1/2" racket which was loose in the hole so I got the correct diff plug tool

 

one of these should suit....

http://www.ebay.co.uk/itm/1512766972...RK%3AMEBIDX%3A

 

Cheers bud, ordered one. Not worth the risk of stripping the plug is it.

 

a 1/2 breaker bar was too loose in my diff plug to the extent of starting to damage it when twisted - i'd get the proper tool.

 

Hi Boostin,


Don't know if you've done the job yet.


A couple of tips when changing the back diff oil.


Remember to loosen the filler plug before the drain plug.


If you can't get the filler plug loose & you have already drained the oil from the drain plug how you going to replenish it? If you have time, also better to get a small screw driver & clean all the road dirt from both plugs where they screw into the diff housing & hit them with wd40 for a couple of days prior to slackening.


It is a bit awkward to get the (0.8 litres if memory serves me correctly) into the diff. I removed the offside rear wheel & routed a cut piece of garden hose long enough to go from the diff plug to the vertical position next to the rear shock (about 1 meter 200 mm, you will see yourself). I placed a small funnel in the end of the hose & was able to gravity feed the oil in - in just a couple of minutes - no oil spilt - no mess - job's a good one.


Hope that helps

 

Hiya Paulgeorge01,
I havent done it yet, it will probably be the weekend now. Im just hoping that they come undone alright. Thats a great help mate yeah thanks for your input mate

 

As said above you can use a 1/2 fitting but it's a 13mm hole if I remember correctly... so it WILL round it after a while. Use the right fitting. I got one for about £6 on ebay.

As for jacking yes it's fine to use the rear diff. Just make sure the jack is padded and well located.

As for axle stands you shouldn't use the flat plates in front of the rear wheel that most people use. These are thin steel and are very very easily bent with the whole weight of the car on them. These being bent can cause vibration through the mounts and car and if you bend the chassis where the smaller m8 bolts locate you have ruined your chassis as it's not an easy bit to repair. I used these points in the past and there are ok safety wise but they can damage your car. After seeing how easily the area is bent I stopped using them.

Hub carrier bottoms are safe with the right stand top as are the factory jacking points but again you need the right adaptors to prevent sill bending.

 

Cheers FMJ, I've bought one of the proper 13mm square tools for the diff, it was only about £3 so its not worth not getting one. Thanks alot for your help mate, I'll see if i can sit it on the hub carrier bottoms then with my axle stands. Just been cleaning up the brakes ready for a lick of paint and its new Godspeed disc's and pads

 

Not comparatively but its not exactly a light thing to lift and I have still seen those plates bent with axle stand and jack use (done it myself). Each to their own as it's their car I am just warning people. They are more then welcome to ignore me.

And yeah it's not much difference. You can equally use imperial spanners and sockets on the cars metric fittings in some places as there are only small differences but when you get to something that requires force you find that small movement has given the tool enough room to round things off just a little bit more each time. It's why quite a few Subaru rear diffs have partially rounded plug holes.... as I say, take it or leave it. It's your/their car. But you can't ignore the fact its all metric and SHOULD be treated as such.

 

But looking on what those bolts are attached to... it's just two welded nuts inside the chassis void. If the nuts snap their welds the car could shift. Bearing in mind people snap the welds just trying to torque the various nuts up under the car for the gearbox cradle and subframe etc I wouldn't want to put the weight of the car on those welds. Admittedly once the welds snap the bush itself would probably support the car but the shift could be enough to cause the car to slip... I have seen a few cars fall from stands after looking very stable before hand and it's scary. I personally would not recommend it no matter how many times it has been tried and seems safe. You only get one chance at not being in a wheel chair for life.

As you the plug... yep i'm sure it will be fine. And no they SHOULDN'T be tight. Depends who did the last service... some are very very tight and require a lot of force to undo. And no matter how close it is you should use the correct tool... surely that is a given? But yes I am sure a 1/2 will do the job. Same way you can just guess torques and it will be fine and many other things. But why not advise people to do it right?

 

Yep I get that. Was more thinking about any twist of the car causing the force to not push straight on that very small tube which would be a lot of stress in a small point (the welds being the other end) but maybe with the bolt torqued up it would have no chance of twisting? I really don't know with that as it would take lots of maths and science to calculate :-) but I personally don't like it.

Also that tube is pressing on what? The chassis. A hollow area. The metal it meets is 2mm steel at most? It's not solid the other side that bush is not designed to be loaded from directly underneath at all. Take a box section and jack a tube up against it with any force and it would distort the steel.

The bush is designed for what? To support the front weight of the rear diff and prop end. And to absorb the vibration. The weight of those parts is what? Maybe 20kg at most? Halved? Not the entire downwards weight of a quarter of the car.

We could go on for ages but I'm sure we will stick with what we do. I just want to ensure the safety of my mobility, life and chassis so if I see potential risk I air on the side of caution.

 

That bush is to resist the torque reaction from the diff when you launch your car, the nose of the diff wants to head up through the floor and essentially make the car "wheelie". I've looked at all this in great detail when I cut, welded and redesigned my own front subframe.
It does far more than just hold the weight of the diff!