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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
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10,170 Posts
Discussion Starter #1
As many of you are aware Samson has been down since September 12th, when it was last limped into the Sikorsky Aircraft Auto Show to claim a second place trophy along with Delilah.

After installation of a limited slip diff and sticky summer tires followed by sever beatings in Cleavland Ohio, the rear differential mount had enough. Of course it couldn't break at a more inopportune time, one week before the show. well I guess it could have been wore, It could have been in South Carolina or Cleavland or anywhere in between.

In any case for the past 2 months I have been busy at work on weekends and with Delilah's quasi restoration and doing all the pre-winter services on all the other family cars so I didn't want to tie up the lift.

With all that behind me, I spent the day cleaning the garage and getting it ready for Samson. Tomorrow the rear sub frame will come out for surgery. I will hope to have Samson back up and running by end of year. It sure was nice to fire up the V-12. I forgot how nice it sounds.
 

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Premium Member
Audi A8, Land Rover
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276 Posts
I envy you, and would love to drive this monster :)
 

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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
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10,170 Posts
Discussion Starter #6 (Edited)
Gotta love that the ceiling rafters were cut out so the car can go all the way up on the lift.
Also note the micro lam beam tying in the clipped ceiling rafters. Another set of ceiling rafters is relocated about 1/3rd up. Also note the garage door tracks extend over the original ceiling rafters and a fake door panel was made out of angle iron to extend the garage door.
 

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Premium Member
1975 450SL
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2,440 Posts
It's a garage floor. Things get dropped, spilled, dripped, heated, dragged, greased, etc... The shame would be in having a pristine floor after 4 years. If you're actually working in there, things are going to happen. If nothing is being done in there, then nothing is going on.

It would be like buying an exotic sporstcar (say, a Mercedes 560SL), and putting it up on blocks in a garage. A waste.

You are USING it. Stuff happens. :thumbsup: Heck, you stuffed a V-12 into a 107.:bowdown: That ain't gonna happen without a few oopsies. Those are battle scars, take pride in them.

Scott
 

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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
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10,170 Posts
Discussion Starter #12 (Edited)
Finally got the rear subframe out today and was fully able to asses the damage. First thing I noticed was it still has a layer of pollen on it from South Carolina. My sleazy welding that I did essentially with my eyes closed (stick a MIG welder up in there and fire away), wasn't too bad. That weld got me to a car show and back.

While I hate doing this job it is a good opportunity to see how things were holding up. The differential pad that fractured was caused solely buy torque and apparently fatigued once I put in the limited slip diff and sticky tires coupled with a significant amount of driving. This is not an area where I had much concern for. I was more concerned about the aft diff mounts which are also the aft subframe mounts for this design. The two rear webs that attach to the differential also are subjected to road suspension loads. The extra arm welded on was a significant design challenge in that it is a highly stressed welded area with little room to add material. To address this I had to create a layered web that spread the load to a very wide area, thus alleviating a high concentration of load at a small welded joint on thin material. This is the first opportunity Ive had to fully inspect this area and so far all looks well.

Repairing the forward diff pad will take some time but wont cost too much. I will try to whittle away at it with a die grinder until I get it out. I believe the reason this part failed is because it was welded form the outside only due to access limitations. My next plan will be to build the pad and weld it into the tube out of the subframe from both sides, then weld it into the subframe as a cartridge.
 

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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
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10,170 Posts
Discussion Starter #14
This is actually going to be easier than I thought. I cut off the old one and mocked up a replacement, but unfortunately I mocked it up out of the same 0.120" wall tube I made the original one out of which did not hold up. But I believe my new concept will work just fine.

I ordered a heavier wall tube today 5/16" wall. That I will bore out to hold the plate as shown prior to welding. I also ordered a slightly heavier gauge steel to make the washer out if. I hope to have it ready for welding by next week end if my steel comes in.
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
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29,494 Posts
What is this gizmo?
 

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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
Joined
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10,170 Posts
Discussion Starter #18
What is this gizmo?
That's a height gauge. Its generally used to measure the height off a surface plate. In this case I'm measuring the height of the diff pad off a sub frame jig plate I made. I need that dimension to set the pad height in the right place when I re weld it.
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
Joined
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29,494 Posts
That's a height gauge. Its generally used to measure the height off a surface plate. In this case I'm measuring the height of the diff pad off a sub frame jig plate I made. I need that dimension to set the pad height in the right place when I re weld it.
Besides you, Johnny, who the fuck keeps one of those in their tool box???
 

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One of the BW Old Guard/R129, W204 Moderator
1997 SL500- 40th Anniversary
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7,166 Posts
John,

You keep it up and a group from here is going to have to come by and break your legs (making the rest of us look bad)!!!

Damn, you can and do good work.
Keep us updated...
 
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