Rear Suspension Broken Weld Question

[fireant911]

Please see picture below (crack in weld near bolt with 'speck of red'): Can this simply be welded by a reputable welding shop? Any precautions to be aware of? What caused the weld to break (in your opinion)?

[Chuck Moreland]

Not that uncommon.

Any reasonable welder can fix that right up. The metal has just fatigued, it's just sheet metal.

While you have the welder out, create some reinforcements for those sway bar mounts. They will fail eventually, easier to solve the problem now before it happens.

[widebody911]

BTDT, it's an easy fix

Here's what mine looked like:


After:

[Jim Sims]

You need to clean the paint off and look for cracks in the sheet metal. The cracks often originate at the bottom of the toe of the fillet weld around the threaded bosses. If cracks are found then their tips should be drilled to blunt them. Then a skilled welder should be engaged to weld up the cracks. If you jack up the car and then separately jack up the rear suspension by the trailing arms you can likely effect the weld repairs without taking the suspension apart. We made this repair to my son's '73T while also repairing and reinforcing the rear sway bar mounts. Metal fatigue is part of the reason for the cracks but also the factory welds around the bosses are really quite poor. Almost all of them are "cold welds" with inadequate fusion; rather lousy workmanship for a Porsche. Jim

[addictionMS]

pretty sure that is not a crack, that is a removable spacer, it allows you to put on the spring plate and cover plate without that bolt and letting the torsion bar be unstressed. once the plate is on place, load it up and it moves out of the way of that hole and the spacer can be put in along with the bolt.

every 911 I have seen has had a spacer there which is removeable

Jim

[Jim Sims]

The crack will typically be at the toe of the weld where it should be fused to the sheet metal. The bosses are different than the spacer bushing (a removeable part) and do crack away from the sheet metal due to a combination of lousy welding, over loading (impact loading) and metal fatigue. Jim

[mb911]

Jim I am very impressed with your terms of welding. Are you a welder?? Any how Jim is correct in his explanation I have seen many similar cases in my welding lab at school (I teach wedling but not that type Hopefully)

Good luck should be no problem for someone thats good. Try an aircraft welder. (not an a&p) but a welder that speacializes in air craft parts. They are normally more precise in what they do

Ben

[Jim Sims]

A mechanical engineer not a welder, but I specify and design welds. I know some welders and we hired the best one in Los Alamos to make our repairs one evening using a friend's welding machine. My son had done all the prep work and fit up of pieces. When the welder was done it looked like a robot had made the welds; nearly perfect and consistent beads. Jim

[mb911]

I am impressed. As you can tell its not often that people understand welding. Most think you just point and shoot!

[mb911]

Hey I know this is an old thread but I just found 2 cracks in my car just like that.

Ben