107 Subframe update
 

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.

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.

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

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

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

Is MB still honoring the recall? I've heard varying report that they are/aren't.

MB will honor the recall, but it only applies to the 450SLs with the cast iron engine. Not the 380SL or 560SL. In my opinion, they should have recalled all the 380SLs also.

The 1983 Euro 280sl I just bought has the lower ctl. arm broken off. that's why I only paid $700. It dosn't matter how much weight there is on the system it still cracks up.

I just got the service bulletin from my local dealer. The bulliten covers 350 and 450 SL's and SLC's only. Those are 107.023/.043/.024/.044. The bulliten was issued in 11/85 so all 560SL should have had this implemented at the factory. It does apear thet if you have a 280/300/380/420 you are screwed. My dealer here in North Haven CT is still honnoring this update for the 350 and 450 SL's and SLC's.

The kit is still available at $98.00 US

John Roncallo

Their are some procedures ( removing the springs, the control arms) that require unbolting the lower arm at the sub-frame and lowering it. Seems like extending the boxing under the arm itself might make that a little dicey.

This is a very informative and interesting post. Can anyone tell me if post 1985 “face lifted” models (and specifically the 107.041 Euro 300 SL) are affected?

The list of post 1985 enhancements I copied from Mr. Wooldridge is listed below. Does one of these items specially address the sub-frame problem?

1. The springs have a different spring rate, front and rear.
2. The front stabilizer bar has a 26mm diameter instead of 25mm diameter.
3. The shock absorbers are shorter and have a harder rate.
4. An additional polyurethane bottoming spring has been added.
5. Some model 124 front end parts are used on the front end - the following parts are redesigned:
Front axle carrier, lower and upper control arms, Steering knuckle, Steering knuckle arm, front wheel hub with bearing. The front axle carrier has a newly modified contour, can be used on older model 107s.
6. Limited slip differential
7. The rear axle carrier mount has been offset by 124mm to the left.
8. The rear carrier front rubber mounts are not interchangeable, marked with L and R, have different stiffnesses.
9. The rear axle center is now elastically mounted to the rear carrier both at the front and rear mounts.
10. The rear axle shafts are provided with CV joints similar to model 126 coupe.
11. New light alloy wheels similar to model 201, new mounting screws.
12. New propeller shaft center mount, similar to model 124, not interchangeable with older 107s.
13. Four piston brake calipers on front.
14. Light alloy Master cylinder.
15. Double diaphragm brake booster.
16 Redesigned steering gear, designation 765.707 (LS80), NOT interchangeable with old unit, reduced travel for redesigned front end. Code letter R stamped into the housing. (The 560's turning circle is not as short as previous cars, less "sensitive" steering.)
17. Power steering pump relief pressure changed to 82 +-5 bar.
18. Sheet metal floor under fuel tank changed, mounting positions of tank and filler neck changed.
19. Outside Temperature indicator changed from Celsius to Fahrenheit.
20. Exterior lamp failure indicator added.
21. Fuses and electrical feeds changed.
22. BODY SHEET METAL CHANGES:
Radiator mount changed, hood changed, firewall changed, side-member connecting point front right changed, A-pillars changed, doors changed, B-pillars changed, main floor changed, rear floor changed, cross-member under the driver seat changed, sheet metal shrouds changed, various stiffeners and small parts changed.
23. Door handles changed, similar to model 126.
24. Door lock and striker changed.
25. Central locking system changed, electric vacuum pump similar to models 126 and 201.
26. Fuel tank flap actuating element and guide bushing changed.
27. Outside heated rear view mirrors.
28. Rear high mounted stop lamp added.
29. New Grand Prix radio - larger display indicator with tone setting and more sensitivity - three levels, but returns to least sensitive when turned off.
30. Front bumper and spoiler.
31. Front bumper inner fender liners added.
32. Front seats changed to include lateral support similar to model 124.
33. Hood- a depression was added to the hood reinforcement to clear new brake booster, previous hood will not fit on car.

Hi there,
I just looked at the factory manual "supplement for 107.048 (560SL)" again, looking for specific subframe info, and it doesn't say anything about the control arm attachment points. It does say that the subframes (They call them "Front Axle Carriers") have a new contour in the rear passenger side area on the top to accomodate all the various engine types world-wide. They also state that the lower control arms are lengthened and have replaceable ball joints. They show a picture, and the difference is quite apparent. They say that the upper control arms are now made of cast steel, not stamped. The changes were apparently made to use more 124 parts - the lower ball joints are from the 124, the steering stop screws are from the 124, and the control measurements are the same as on the model 124.
Hope this helps!

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