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how to ID an AMG sports undercarriage 783 modification?
According to the workshop manual, in order to fit the wider AMG 18" wheels, there was a factory (or dealer?) modification referred to as a 783 modification, it involved crimping the inside of the wheel arches to give clearance (110 degrees) and changing a bolt in the wheel well etc. I have heard that later cars, maybe 1999 facelift on, might have had this stock no matter the wheels..
Does anyone know about this and how to identify a body that has it done? Or has anyone successfully done this? I love the part about using a plastic hammer and repairing any paint work.
Let me share my personal experience with you, if I may?
I have installed 18" AMG split rims on my 1999 SL500 with absolutely no problems. Straight up bolt-on!
Now, I can't speak for the pre-facelift models as i don't have one, but a friend of mine has the same wheels on his 1994, and required NO modifications whatsoever.
These wheels were specific to the R129, and I have to admit, that service manual shocked me.
I've notice you have an SL55 AMG, Mine is the standard 1999 SL500, if yours was and AMG car from factory it may have the body modification done as part of the AMG pack.
Here is a photo looking up into the fender lip. It does look to have a section more rolled. I'm not sure if this is what they are talking about, or if this is standard. Interesting if anyone has a chance to look at theirs.
Let me share my personal experience with you, if I may?
I have installed 18" AMG split rims on my 1999 SL500 with absolutely no problems. Straight up bolt-on!
Now, I can't speak for the pre-facelift models as i don't have one, but a friend of mine has the same wheels on his 1994, and required NO modifications whatsoever.
These wheels were specific to the R129, and I have to admit, that service manual shocked me.
i
Hi Ahmed
Thats odd since even with my SL55 AMG factory modifications these (standard) front wheels are rubbing slightly at the plastic cover of the wheel arch. (at full steering angle)
No problems at my folded fenders though.
While the undercarriage is straight, your observation is certainly right. I wonder if you have ever entangled it.
Frank, can you see what the lip inside your fender looks like? Is it crimped back further than mine in the picture above, or is that all that is required? Thanks!
Frank, can you see what the lip inside your fender looks like? Is it crimped back further than mine in the picture above, or is that all that is required? Thanks!
Its folded like in the WIS instructions.
The rear i dont remember…
Last edited by Frank_S500; Feb 7, 2024 at 04:22 AM.
Thank you for posting this, for I just went through it all. I've owned my 99 SL500 Sport (18" wheels) for 15 years now, and never knew that my front left fender was different from the rest.
While I was driving in an unfamiliar place at night, I made a left turn at high speed into a deep dip. The front end bottomed out, and since my left front tire was turning outward, it grabbed the inner lip of the fonder and bent it outward. Now that it's out, two left turns into driveways made it worse.
After my bodyman said $800 & 4 days, I decided to do it myself. I grabbed this roller off of my yacht, and she's good as new
If you picture the pulled out fender looking like a bell curve, I started at the outer edge which was pulled out the least and used the roller as a press to bend it upwards. I was able to bend the edge up high enough that its impossible for the tire to ever catch it again.
All to say that for those of you with non-sport models and larger wheels in front, what happened to me can happen to you if you don't have that horizontal inner lip of the fender bent upward.
It took out a chunk of my brand new Michelins as well:
Thanks Clipster, In my photo above, looking up to the underside of the lip, do you think that is folded back far enough in the middle or I should go ever further?
@sp3000 Hard to tell from the pic - I would say turn your steering wheel as far to one side as possible then check. If the outer edges of the tire could [in theory] catch the lip, then you haven't bent it far enough.
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