W210 Spring Perch Failure...Looks Like My Number is UP! - Page 2 - PeachParts Mercedes-Benz Forum

nhdoc · #16 04-07-2008, 08:49 PM

Quote:

Originally Posted by aklim

For your sake, I hope they rivet it. From what I understand, welding IS a problem since the heat from the weld will change the temperament of the metal. Do you want it to become softer after the weld? I would think not.

AFAIK, the rivets are VERY difficult to work with. The local shop broke 3 riveters before buying a pneumatic or hydraulic one that would hold up.

Once again, RIVET the spring perch not weld.

I'm not too concerned. The shop has certified welders and a welded joint can be just as strong if not stronger than a riveted one.

The body shop is under contract to the dealership and they are paying them. I really have no say in the method of repair, though I told them that the current factory procedure is riveting not welding. If they weld it and it fails again guess what? They will have to fix it again.

The failure at speed is apparently not all that much of a problem...described by some as less dramatic than getting a blowout tire. I don't want it to happen but I don't fear a failure the way I did when I first heard about it.

BigBen · #17 04-07-2008, 11:35 PM

Would installing rivets before the problem occurs be a good preventive maintenance?

aklim · #18 04-08-2008, 12:43 AM

Quote:

Originally Posted by nhdoc

I'm not too concerned. The shop has certified welders and a welded joint can be just as strong if not stronger than a riveted one.

The weld, yes. But don't you think that the heat will change the temper of the metal? I would check with a metallurgist.

turbobenz · #19 04-08-2008, 01:07 AM

If it were my car, and I was capable of repairing it myself, i would rivet it and weld it. I do not trust rivets at all. They would just be a back up IMO

aklim · #20 04-08-2008, 01:09 AM

Quote:

Originally Posted by turbobenz

If it were my car, and I was capable of repairing it myself, i would rivet it and weld it. I do not trust rivets at all. They would just be a back up IMO

Why? Aircraft use rivets all the time. Have you seen the rivets they use? It isn't something you buy from Home Depot

turbobenz · #21 04-08-2008, 01:15 AM

Quote:

Originally Posted by aklim

Why? Aircraft use rivets all the time. Have you seen the rivets they use? It isn't something you buy from Home Depot

because welding is a superior way to join metals.
Id rather have my spring perch be one piece with the car, than be attached to it with rivets

aklim · #22 04-08-2008, 01:16 AM

Quote:

Originally Posted by turbobenz

because welding is a superior way to join metals.
Id rather have my spring perch be one piece with the car, than be attached to it with rivets

But how can you be certain they won't change the temper of the metal during welding?

turbobenz · #23 04-08-2008, 01:32 AM

Quote:

Originally Posted by aklim

But how can you be certain they won't change the temper of the metal during welding?

. Im not sure, but maybe thats why they make thousands of different types of welding rods and a good welder can keep the heat localized

aklim · #24 04-08-2008, 01:42 AM

Quote:

Originally Posted by turbobenz

. Im not sure, but maybe thats why they make thousands of different types of welding rods and a good welder can keep the heat localized

I'll have to check into that. I asked a few body shops if they would do it and they didn't want to because of liability. They would rivet them though but not weld them because they were afraid of changing the temper.

nhdoc · #25 04-08-2008, 08:08 AM

Quote:

Originally Posted by turbobenz

If it were my car, and I was capable of repairing it myself, i would rivet it and weld it. I do not trust rivets at all. They would just be a back up IMO

Yeah, that's my opinion too, if you get both methods you have the best attachment you can make. The problem with rivets is you are primarily opposing a shearing motion in this attachment. If the rivets don't stay 100% tight I can see the perch getting loose over time, then elongating the holes and bending back and forth and possibly tearing through the sheet metal they are attached to. Mechanical fasteners like rivets and bolts are great for tension but in shear connections they rely upon friction from the tightness of the connection to keep them intact. At least with a weld it will be solid and act as one piece (until it fails that is). I think if they used both it would last as long as the rest of the car would last.

Big Jim · #26 04-08-2008, 07:29 PM

Quote:

Originally Posted by BigBen

Would installing rivets before the problem occurs be a good preventive maintenance?

In my particular failure, the perch itself rusted out. I dont think its a matter of the perch welds breaking and the perch falling off. The design leaves a nice water trap at the bend of the perch where it leaves the frame and starts to curve. All the sealant in the world would eventually let water through. It is a totally bad design. Salt doesnt help the matter either. Jim

Big Jim · #27 04-08-2008, 07:43 PM

Quote:

Originally Posted by nhdoc

Yeah, that's my opinion too, if you get both methods you have the best attachment you can make. The problem with rivets is you are primarily opposing a shearing motion in this attachment. If the rivets don't stay 100% tight I can see the perch getting loose over time, then elongating the holes and bending back and forth and possibly tearing through the sheet metal they are attached to. Mechanical fasteners like rivets and bolts are great for tension but in shear connections they rely upon friction from the tightness of the connection to keep them intact. At least with a weld it will be solid and act as one piece (until it fails that is). I think if they used both it would last as long as the rest of the car would last.

I had a pipefitter buddy of mine weld the perches on for me and he wasnt too comfortable with the finished product. It looked to me like they were welded from the backside before the car was assembled. there is no way to weld the replacement perches on the way the factory did it IMHO. Anyway, I used some !/4 grip steel Q rivets for peace of mind. 4 or 5 in each. There is about an inch and a half of good meaty steel at the bottom of the rib part of where the perches mount to and i am quite confident in my install. Jim

bob_98sr5 · #28 04-08-2008, 07:58 PM

Jim,

So it sounds like he removed the old perch, cleaned the metal, and riveted and welded in the new perch? Or did he reinforce the old one? and if its not too much trouble, could you take a pic? I"d like to see where he used the rivets

Thanks,
Bob

Big Jim · #29 04-08-2008, 09:12 PM

Quote:

Originally Posted by bob_98sr5

Jim,

So it sounds like he removed the old perch, cleaned the metal, and riveted and welded in the new perch? Or did he reinforce the old one? and if its not too much trouble, could you take a pic? I"d like to see where he used the rivets

Thanks,
Bob

Yes, I removed the old perches and did as you describe. I will try to post pics now. the pics of the new perches are kind of dark because of the waxoyl I applied. Jim

aklim · #30 04-08-2008, 09:53 PM

Quote:

Originally Posted by bob_98sr5

Jim,

So it sounds like he removed the old perch, cleaned the metal, and riveted and welded in the new perch? Or did he reinforce the old one? and if its not too much trouble, could you take a pic? I"d like to see where he used the rivets

Thanks,
Bob

That is pretty much what they did to mine. Of course the put some new sealant on it.