107 Front subframe overhaul

[Rasputin]

107 Front subframe overhaul

Further to some considerations for subframe refurbishment procedures, I had decided to overhaul completely the front subframe on my 107 450SLC 5.0.

One of the key subjects referred to by members on other forums, is how to support the engine during subframe removal and reinstallation. Some of the ideas given by members were quite ingenious in constructing a rig or cradle support bar, coming up with some clever designs. I have however, not having welding experience, resorted to using a pair of 2 x5 meter x 25mm two-part Heavy Duty Ratchet Tie Down Straps made of 100% Polyester webbing. Minimum breaking strength: 800kg max. with claw hooks as per picks and they are more than capable to lift an engine.


This is the state the subframe came out…….

This is the new state it went back in….

The subframe was wholly overhauled, sandblasted, resprayed, with new springs& pads, upper arms, wheel bearings, rotors, pads, balljoints, subframe mounts, motor mounts, suspension bushes, sway bar bushes & links, etc, etc. And all with the assistance of a very nice Welsh lady who helped no end with lowering and reinstalling the subframe, and actively participating at every stage of the job.

I just unbolted the engine support bracket bolt from the motor mounts once the engine was jacked up and pushed aside the motor shock absorber with its bracket, removed the heat shields from the mounts and reinserted the bolt back on its bracket to serve as a stop for the straps around the engine bracket. The straps were hooked on the edge of the chassis at each side of the engine shock as per pics and wrapped around the exhaust manifold for further support. Supported the engine beautifully while the subframe was removed. Used the floor jack to further support the engine until the subframe was ready for reinstallation.

Below, a few pics of the different stages of the operation.

Having the “C” press for the ball joints and the right spring compressor made to job rather easy.

 

[Cole@MBS]

Thats a good days work there!

Nice job!!

 

[Xtractorfan]

Nice looking job on the subframe, the screw jack balancing on the pieces of wood scares me, but then thinking back I've probably done worse..

 

[spotweld]

Hi looks like a good job how long did it take you
I have another question you might be able to answer
I have a 77 350SL ( 107) and have read that there was a recall by Merc due to potential cracking of subframe mounts/brakets do you know if it applies to this model or was it just for the american version am also told that Merc will still honour this and fit reinforcing bits hoping you can shed some light on this as you can guess not had the car long but love it
Regards
Bill Mac

 

[SilverSaloon]

Hi looks like a good job how long did it take you
I have another question you might be able to answer
I have a 77 350SL ( 107) and have read that there was a recall by Merc due to potential cracking of subframe mounts/brakets do you know if it applies to this model or was it just for the american version am also told that Merc will still honour this and fit reinforcing bits hoping you can shed some light on this as you can guess not had the car long but love it
Regards
Bill Mac

pretty sure it was only an official recall in the states... if i'm wrong though and it was a proper recall then yes they have to honour it still i believe.

 

[Rasputin]

Thats a good days work there!
Nice job!!

Thanks SAM, actually the real work was less than a day's work, just left the paint to dry for 3 days before assembly.

Nice looking job on the subframe, the screw jack balancing on the pieces of wood scares me, but then thinking back I've probably done worse..

Cheers for your comments Xtractorfan, but the floor jack was secure on the block of wood and was only as additional support to the engine which was already secured by the straps while the frame was removed. No risk taking here. Just to take the stress off the straps while overhauling the frame.

* * * *


That’s a very pertinent question Spotweld, and thanks for your comments.
The actual dismantling and reassembly were just a few hours, but I left 3 days to allow for the primer to dry and 3 coats of paint.

As SilverSaloon mentions, this repair was only undertaking in USA. The earliest recall still in force by Mercedes dates back to 1980 and only for specific issues. The subframe brackets for the 107 series was never officially recognised, however since 1986 Mercedes modified those brackets as per pic below, but Mercedes did repair a number of customer claims to avoid corporate image damage.
Every Mercedes agent have a different version about this supposed recall.
There is a labyrinth of legal issues that change from country to country and all recall issues have a legal time limitation aspect and vehicles over 20 years old would hardly qualify for a recall indemnity. They would argue that if it has lasted 20 years it cannot be considered a recall defect.

Check this Mercedes Recall list
http://www.autobuyguide.com/1980/12-aut/mercedes-benz/450-series/recalls/index.html


Here is a pic of a bracket failure from a member of another forum.

And this is the post 1986 frames

 

[White230CE]

Paint type

Hi Rasputin,

Great result on a job which I hope one day to attempt. What paint did you use please and what's the aerosol equivalent?

Thanks

 

[Rasputin]

Hi White230CE,
I used one coat of Arcol Rust Converter, left it about 6 hours, then one coat of Hammerite metal primer. Next day 3 coats of Hammerite metal pain satin black at about 1-2 hours intervals. Then left it for 2 days for paint to harden before assembly.
Hammerite comes in aerosols.

 

[White230CE]

Thanks Rasputin. That's what I used for my bumper brackets and battery tray, but I wasn't sure how hard wearing it would be. I guess if it's good enough for a sub-frame, it's good enough for those bits.

 

[damocles03]

Hi,

I know this is a rather timelate enquiry but I am planning to do the same to my 1975 350SL's front suspension. One aspect concerns me - removing and replacing the springs as serious injury/damage could occur should they be released inadvertently. Could you tell me the make and model of the compressor that you used please? You mentioned that it was the 'right spring compressor' so would be grateful for information about it. Many thanks in advance. All the best, Charlie

 

[Rasputin]

Hi,

I know this is a rather timelate enquiry but I am planning to do the same to my 1975 350SL's front suspension. One aspect concerns me - removing and replacing the springs as serious injury/damage could occur should they be released inadvertently. Could you tell me the make and model of the compressor that you used please? You mentioned that it was the 'right spring compressor' so would be grateful for information about it. Many thanks in advance. All the best, Charlie

Hi Charlie,

The 107 front springs cannot be compressed sufficiently to withdraw from the suspension control arms. Once compressed by the spring compressor then the upper or lower balljoint needs to be split to withdraw the spring.

The Klann original spring compressor is prohibitively expensive but the clone Bergen (German made) does the job just as well and the price is very reasonable

BERGEN SPRING COMPRESSOR

Make sure you obtain all the parts and tools you need for a complete overhaul.

If you wish I can provide a series of pics for the parts you need and the tools required.

 

[damocles03]

rebuild

Hi

Many thanks for that and a set of pics showing the entire rebuild and the tools needed would be fantastic. My email is my username @yahoo.co.uk

Thanks so very much for your help.

All the best,

Charlie

 

[damocles03]

I've just bought the spring compressor from eBay through the link that you kindly sent me! I think that I have just about everything that I need in terms of components. I rebuilt my BMW 2000s suspension front and rear about 28 years ago....so I think I may be a little rusty by now! Grateful for any hints and tips - particularly those that prevent dangerous and/or expensive incidents! Did you tackle your rear subframe bushes too? I recently bought a bargain set made by Meyle.

 

[Rasputin]

I've just bought the spring compressor from eBay through the link that you kindly sent me! I think that I have just about everything that I need in terms of components. I rebuilt my BMW 2000s suspension front and rear about 28 years ago....so I think I may be a little rusty by now! Grateful for any hints and tips - particularly those that prevent dangerous and/or expensive incidents! Did you tackle your rear subframe bushes too? I recently bought a bargain set made by Meyle.

Hi Charlie,

I am impressed by your quick actions!! You are serious about this! and I know you can do it.
That spring compressor is one of the best and some resellers are asking up to £300 for it!!.

Yes, I did a complete overhaul of the front & rear subframes, rear hubs and bearings, brakes, differential, propshaft, driveshafts, steering pump & steering box and components and engine overhaul.


Once you have removed the front subframe drill a couple of holes on the underside of the frame (see pic) as your 1975 model would not have them and the subframe tend to rust inside out as water penetration has nowhere to go with subsequent breaking of the brackets.

Will prepare a series of pics with tools required and if you need process of removal/assembly I have them too.

Here is a few pics of the rear subframe overhaul sandblasted, primed and painted.

 

[damocles03]

Gosh - looks like you did exactly what I am planning to do! If you could kindly send me pics of the tools and parts you used and also the stage by stage pics that you have so expertly taken, I would be extremely grateful. How long did the rebuild take? I'm not in a mad rush but hope to have the job done before the end of January. Did you sandblast the components yourself? Ive seen sanblasting cabinets for sale but I don't have a compressor and am not sure how much I'd use it (unless I start a classic Mercedes collection - a possibility!). Cheers, Charlie

 

[jrhendo]

I know this is an old thread, but if you've still got all the details of what you did, I'd really appreciate if you could send them to me.
Regards
John