Using trolley jack

[db1]

Hi,

Is it standard practice to use a trolley jack located under the diff to lift both rear wheels simultaneously? If done correctly, I assume this does not damage the diff.

Thoughts?

DB1

 

[sportyreptile]

Sounds a bit iffy that. Good chance that the car could rock from side to side and fall off the jack.

A lot of weight on the diff casing can't be good.

I've had 2 bad experiences with jacking cars up, both due to my own stupid fault so I'm very careful, in fact I don't bother myself I go to a garage.

If you want to lift the whole rear of the car, use 2 jacks, one each side, under the jacking points on the sills to raise both wheels. The support with axle stands as well as the jacks.

AND BE VERY CAREFUL!

 

[big x]

No problem doing that as long as a block of wood is used.The load is spread across the rear subframe.
I've found buying 2 x Machinemart 2L trolly jacks on the jacking points more stable however.They are only £17 each.I always prefer to spend on tools rather than pay garage labour rates.With a Haynes manual for a c-class there really is very little the DIY person can't tackle because Mercs are so easy to work on compared to say French cars. :bannana:

adam

 

[imadoofus]

A diff casing is strong, but ultimately brittle. And balance is your biggest worry. Not a good idea, methinks.

The best method, as Sportyreptile says, is one jack to raise each side of the car in turn, before using axle stands for working support.

You should never use a jack for holding a car up when working on it, as a jack either has a very small footprint, or (in the case of a trolley jack) it has wheels. By their nature, wheels move(!)

I once removed the rear wheel of my Vauxhall Carlton using only a jack, and then left it like that for a couple of hours. when I came back, the car had dropped off the jack, onto the brake drum. It was a bugger to get back up again, as I couldn't get anything under the car. Of course, if I had been under there, there would have been enough clearance for a jack.

I would suggest you keep that image in your mind when going about whatever it is you're contemplating.

PJ

 

[db1]

Actually today I had two tyres replaced on the rear and the place where it was done has a v good reputation - in fact recommended by MB themselves as being cheaper and very good. One of the mechanics used to work for MB and he told me that was what they did at the MB dealer garage, ie no problems. I would expect however that if the diff was damaged it would crack and it would fail pretty soon - ie a few miles. There seems to be no odd sounds, no ill effects so far. It is due to go for a service soon so I will have them check it out.

I agree with all the points made earlier though - I should have asked them to use an alternative method, but by the time I got to see the car it was already on the jack.

DB1

 

[Hartzpartz]

I've been doing this for years but always put the weight of the car onto axle stands ASAP. The use of wood (or a jack with a rubber pad) isn't a bad idea.
Always remember the golden rule of, "never work under a car that is not supported by suitable axle stands" and you'll be ok.

 

[Richard W]

When working on Mk2 rally cars and LRs we would slide a jack under the diff, get it up to working height and get 2 stands under it sharpish - I've been at events where crews have missed the stands to save time and the car has fallen off onto a mechanic under the car. Not a good thing!

I wouldn't do it on a Merc because:
- the diff casing is alloy - already mentioned
- it's on a sub frame with bushes which aren't designed to take the weight in that plane, they may displace.
- MB put jacking points at particular places for a reason - the shell is designed to take the weight of the car in those locations.

 

[guydewdney]

- it's on a sub frame with bushes which aren't designed to take the weight in that plane, they may displace..

notwithstanding the other (valid) comments - what plane are you thinking??? its only being raised a few inches = a few degrees off vertical which is similar to being parked using parking brake on a hill... (facing down the hill)

 

[Brian WH]

I wouldn't do it on a Merc because:
- the diff casing is alloy - already mentioned
- it's on a sub frame with bushes which aren't designed to take the weight in that plane, they may displace.
- MB put jacking points at particular places for a reason - the shell is designed to take the weight of the car in those locations.

I totally agree. The diff is not designed to take the weight of the rear of the car. It is a shortcut that I will never allow to be done on any car I own. Use the proper side bearers, and prop the car after it is high enough..