wingless

Both the vehicle model number and the jack pad dimensions have been provided. These were purchased from Performance Products, back in 1987. Don't they have enough information to match this component?

noka

Correct, not according to the guy I spoke with. I could try to ask to speak to someone else.

Rgds,
Norm

Narcissus

Best thing to use is a hockey puck instead of a piece of wood, perfect fit!

rguy

The wood isn't about the fit. The wood is about load distribution. By applying the force over a foot of framerail (including the hoisting pad) you distribute the load more evenly and put less pressure on any one point.

I hope this is clear now. Using a 12" 1x4 is better than a hockey puck.

noka

I do not understand how a 12" piece distributes the load more evenly than a piece equal to (or slightly greater than) the length of the jack pad itself (maybe 4" or so?). The jack pad protrudes down a bit further than the frame rail, so you are lifting only at the pad. The wood could not touch the frame rail although it would be close. Maybe you could clarify that.

Rgds,
Norm

rguy

When I did it, the entire length of the board touched the frame rail. Maybe this is the difference you are seeking. If the board only touched the hoist pad and the jack pad, then I would see your point.

Maybe this is academic for you and this is why you brought it up, but the hoist pad on your car is rubber and compressible. It is meant to cushion the transition between the car being on the ground and the car being in the air. A lot of people crush their pad using a normal floor jack because they support the entire load with the hoist pad. The hoist pads were not designed for this job. If you look at a car lift at your local service place, you should see that the lift pads are considerably wider than the hoist pads.

At any rate, unless your jack is smaller in diameter than the hoist pad (which is unlikely), you cannot jack the car using the hoist pad point without also touching the frame rail.

I hope this is clearer.

rguy

P.S.

If your hoist pads are different and aren't rubber (which is possible but not probable), then feel free not to use the board and take your chances. Meanwhile, on a ~60k dollar car, I will take the time to put a board between the jack and the car "just in case".

noka

Update: I just finished swapping wheels. The AMG double spoke 7.5x17 fit fine. The four lift pads that the stock jack would be inserted into look to me to be nearly identical to the lift pads I had on my M5. I also noted, without a doubt, that they are the lowest point of anything around them, except the side skirt which should be avoided, of course. I placed a wood board underneath the pad to check what it would touch and the lift pad is the only thing it touched. Knowing that, and also knowing how I used to do this on my M5, I removed the round lift device/interface from my floor jack, the top surface of which looks like a chess "Rook" or castle. It pulls right out. On my Sears 2-ton floor jack this leaves a perfectly flat metal lift surface which is exactly the length of the car's lift pad. I noted also that the lift pad is very hard rubber (plastic?) material that also has a flat surface around 3 sides of its perimeter. Long story short, I lifted from this point quite easily without deforming or damaging the lift pads in any way. Easy wheel swap. I will do it again this way. For my situation, using a block of wood buys me nothing and, I felt would introduce another variable for possible movement between the jack and lift pad. YMMV. I think the double spoke rims look great BTW. I used a torque of 87 ft-lb because that's what I have it set to for my GTI and it seems to be in the middle of what the Owner's Manual says and what others have posted that MB dealers use.

Thanks for all your info and replies! It helped me to sort out the details to be able to make decisions about the best (and safest) way for me to do it.


Rgds,
Norm

rguy

Congratulations on your new wheels. I don't really recall ever saying that the M5 had different hoisting pads (if that is what you were getting at). Also congratulations on not using a board. I am glad that you feel you were successful at this task, but I would like to remind you that I never said that the first time you do this you are going to see the jack come up through the frame rail and into the floor boards.

Over time, your hoisting pad will likely wear out (and will certainly wear out faster than using a board when used correctly), and you will just have to replace them then or use a board. Maybe the car will be sold by then, who knows. I try to speak in terms of ideals because ideally, I want my car to be treated the best it possibly can. I hope you can appreciate this thought.

I will keep using the board because my board is arranged to touch the frame rail (not the sideskirt, of course). It works for me, and I am glad two opinions exist on this board.

I don't know if you were indescriptive or whether you are leaving your torque wrench at 87 ft-lbs, but if you are and the wrench is manually set (read not something automatic that sets torque when you turn it on and drops it when you turn it off) you should stop. Leaving a torque wrench set (at least with every type and brand that I have used) will change the calibration of the torque wrench, thus making the 87ft-lbs setting, much less likely to be applying 87 ft-lbs of torque. However, if you get your wrench calibrated every year, then you should be fine. I hope this helps if you were leaving at 87ft-lbs.

Please don't take any offense to this post, as I don't intend any. Sometimes it is hard to convey emotion in writing. Even the pros have difficulty with this little tidbit. I just want to make sure everyone's opinion is out there. And when I say that I appreciate people disagreeing with me or presenting another option, I truly am happy about it. The only thing I worry about is the point of my original post, to teach someone who has never done this before how to save a bundle of money for relatively little investment and at the same time increase their automotive knowledge and enjoyment, has been lost for the sake of a 1x4 board.

Maybe we should open separate threads when stuff like this comes up so as not to bury the real message on page two of a ten page thread? Thanks for reading.

KWiK

WOW! Talk about making a thread unnecessarily long...


Yes, it does. Just have a look under the car. The C55 is just like all the other W203.

noka

I was only saying that the M5 had quite similar lift pads and since I lifted there successfully with my floor jack, I thought it would also work for the C55 ... and it did.

I suppose that is possible. Obviousy, the lift pads are designed to be strong enough when used with the OEM jack, however, maybe they were designed for only rare use, since we don't typically get so many flats per year. I still don't understand how your C55 can spread the load using the board because, as I mentioned, the lift pad is the lowest point and a board placed underneath it touches nothing but the lift pad itself (at least on my car). Perhaps someone else could confirm that at some point.

I do leave it set at 87. I better check the instructions for my Craftsman torque wrench and see about getting calibration checked.

None taken. Thanks for the reply.

Rgds,
Norm

noka

You are, of course entitled to your opinion. Sorry if you feel it is a waste of time.

Well, it being so low to the ground, I couldn't see that well underneath. I do believe I see a rectangular 'pad' in the front as your picture shows. Can you show me where the one in the rear is for the C55?

Rgds,
Norm

KWiK

I'll see if I have a pic, but it's just like the first pic shows. Place the jack directly under the rear diff and lift.

noka

Unless I'm mistaken, isn't the C55 differential different than other W203's? The fins on the bottom don't look like they would take the weight too well. My service manager advised against it also (but that's not the first time MB service would be wrong). There is no "pad" to lift from in the rear that I can see.

Rgds,
Norm

rguy

C55 differential is vastly larger than other w203 because of the high torque and the (almost redundantly) the large size of the engine. The fins obviously help evacuate heat that is a constant problem for AMG in general.

If your wrench is a craftsman, then that is most likely bad news. I don't know about their digitork wrench, which you may have, but the others recommend leaving it below 20% torque setting. They also recommend never applying pressure anywhere besides the handle, as that can change calibration. Lastly, they suggest tightening to 60% torque and then 100% torque. I hope everything is okay with your wrench. It would probably be worth it to talk to sears about a calibration. I don't know how much it would cost, but if your wrench is torqueing to a torque you don't want, bad things can happen. I am sure you know this fact. Obviously you don't want to strip your lug bolts or have your wheels fall off while driving. This really is the last thing, but they recommend retorqueing at 20 and 100 miles. Hope this helps.

rguy

By the way, I sincerely tried to get my "racing" jack under the car far enough to hit any presumed jacking points, but no dice. I think lifting it one corner at a time is the only sane possibility.

Maybe you could drive it up on some ramps and then jack it, but I don't think that is the safest way to go, especially when you don't need to jack the car that high. Not directly speaking to you here, Noka, just putting it out there for Kwik and others.

I also know that my AMG differential is not going to be put through the paces of supporting the entire back half of the car (or some component of it). I just don't think it was designed for that task. On a honda civic, I might say it wasn't the end of the world if something bad happened, but I can't say the same about the c55.

Lastly, I couldn't even get my head under the front end of the car, let alone the jack so seeing something that far back is beyond expectation.

noka

As a followup, this is not necessary since unlocking (disarming) also disables the tow alarm feature.

Rgds,
Norm

bnz616

Where do you guys usually stick the jack stands since the jack points have the rectangular surrounds? Where is the best place to put them?