107 Subframe update

[Roncallo]

I need to purchase a new subframe for my 1986 560SL. I know at one time the 107 subframes were updated for strength. Does anyone know when this occured. I prefer to get one that came updated from the factory rather than strengthend acording to the service campagian. So far I have located two subframes one from an 85 380SL and one from an 84 280SL Euro.

John Roncallo

[ljmauricio]

Originally Posted by Roncallo

I need to purchase a new subframe for my 1986 560SL. I know at one time the 107 subframes were updated for strength. Does anyone know when this occured. I prefer to get one that came updated from the factory rather than strengthend acording to the service campagian. So far I have located two subframes one from an 85 380SL and one from an 84 280SL Euro.

John Roncallo

John, since I also own an '86 107 I am wondering why you are needing a sub frame. I thought the sub frame problems were solved by that time. I had a '82 500 SL that had a small crack which my shop welded and then added gussets at other points to strengten according to the recall. He thought it was now stronger than new. It is my understanding that adding the gussets were part of the factory repair, since my mechanic mentioned getting them from dealer, or making them if unavailable. Never questioned him further on the gussets, so I don't know which way he went.

[Richard Wooldridge]

The subframe problem never went away, Mercedes just decided to ignore it when they put the lighter aluminum V8 in the car! I had to replace the subframe in my '82 380SL because one of the lower control arm mounting tabs broke off! I have the new subframe in my '79 450SL, and it is MUCH stronger than the one in the '82, which is now the original subframe style with the reinforcing tabs. All the reinforcing tabs do is add some metal to each side of the lower control arm tabs. A new subframe from Performance products comes with the tabs boxed in, easily twice as strong as the original setup in the tab area. I imagine that all 380SLs and 560SLs will eventually need new subframes, or at least the reinforcing tabs installed. I don't know how they got away with limiting the recall to only the cars with cast iron engines installed.

[Roncallo]

Originally Posted by Richard Wooldridge

The subframe problem never went away, Mercedes just decided to ignore it when they put the lighter aluminum V8 in the car! I had to replace the subframe in my '82 380SL because one of the lower control arm mounting tabs broke off! I have the new subframe in my '79 450SL, and it is MUCH stronger than the one in the '82, which is now the original subframe style with the reinforcing tabs. All the reinforcing tabs do is add some metal to each side of the lower control arm tabs. A new subframe from Performance products comes with the tabs boxed in, easily twice as strong as the original setup in the tab area. I imagine that all 380SLs and 560SLs will eventually need new subframes, or at least the reinforcing tabs installed. I don't know how they got away with limiting the recall to only the cars with cast iron engines installed.

Rich

Please look at the attached photos. Is this subframe

1) An old unmodified
2) An old modified
3) or a new replacement boxed type

Thank You
John Roncallo

[Richard Wooldridge]

Hi John,
That is the newer boxed unit. The original lower control attachment points on the rear of the subframe didn't have the boxed area at all. They only had the tabs projecting down, and no side reinforcements at all, so if the car was curbed the tabs would break off. It would be pretty easy to box the front tabs also, and would probably be a good idea for your project. The whole front subframe began with the 114 cars, in fact my '82 has a 114 subframe under it right now. I had thought I remembered the boxing of the rear lower control arm tabs on the '79 going right under the arms, but after looking under my two cars just now, I can see that it is like your photos. Not as strong as I remembered, but a huge step up from the old setup, which as someone said, they continued with through the '85 model year.

[Roncallo]

Originally Posted by Richard Wooldridge

Hi John,
That is the newer boxed unit. The original lower control attachment points on the rear of the subframe didn't have the boxed area at all. They only had the tabs projecting down, and no side reinforcements at all, so if the car was curbed the tabs would break off. It would be pretty easy to box the front tabs also, and would probably be a good idea for your project. The whole front subframe began with the 114 cars, in fact my '82 has a 114 subframe under it right now. I had thought I remembered the boxing of the rear lower control arm tabs on the '79 going right under the arms, but after looking under my two cars just now, I can see that it is like your photos. Not as strong as I remembered, but a huge step up from the old setup, which as someone said, they continued with through the '85 model year.

Thanks Rich

That confirms what I susspected. Both of my 560SL have the subframe shown in the pictures. The pictures of the subframe in my manual do not have boxed aft control arm supports. Since I now know the week points I know where to focus my modifications.

John Roncallo

[Roncallo]

Originally Posted by ljmauricio

John, since I also own an '86 107 I am wondering why you are needing a sub frame. I thought the sub frame problems were solved by that time. I had a '82 500 SL that had a small crack which my shop welded and then added gussets at other points to strengten according to the recall. He thought it was now stronger than new. It is my understanding that adding the gussets were part of the factory repair, since my mechanic mentioned getting them from dealer, or making them if unavailable. Never questioned him further on the gussets, so I don't know which way he went.

This subframe is to be modified for the installation of an M120 V12. I need the strongest solution I can get.

[jstreeter]

HI,Ron
I need to buy those gussets, or the gusset kit. Could you post the part number of the $98 kit? my '78 350slc thanks you.

Also, dare I ask for a posted scan of the TSB? Ive called MBUSA and they claim that 33/001 11/85 TSB doesnt exist and the recall was only for '73 and '74 cars. anyway, thanks for the help,
John S.
1978 350 SLC 4 speed manual

[ljmauricio]

There is a subframe on eBay. Seller claims in good condition. No cracks.