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Seam welding for road racing?

Old 10-08-18, 12:19 PM
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Seam welding for road racing?

I did a quick search and didn't find much on seam welding... got curious about it after watching Jay Leno's 100th Singer Porsche 911 video where they mention it:

I was thinking this might be a good idea if you're doing a full restoration, but it sounds like you need somebody with a lot of chassis experience.

Road & Track has a nice article about the process:

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Old 10-11-18, 08:25 AM
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The FD chassis is pretty stiff already and most people that do serious racing just put a cage in. So, I can only guess that it is either not worth it or not necessary. More realistically, the benefit is probably not worth the cost, particularly if you total it in the track it something you would not be able to recover.

However, if you wanted to do it, you have to pretty much strip it down to the shell so there is little chance of a fire and all areas are accessible. Then you would want to treat all the bare metal and paint it to protect it.

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Old 10-11-18, 01:05 PM
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Yes, it sounds a bit like an overkill solution. I think it's one that people don't discuss... you either know how to do it and you build race cars or you're an amateur like most of us and it's beyond the scope of a part-time lapping car.

I was thought it sounded like a good idea for someone who wanted a stiffer car and didn't want to add a lot of weight. I'm also curious whether there is a way to accurately CAD model the effects of seam welding on the chassis and its effect on suspension settings.
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Old 10-11-18, 01:46 PM
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I think mostly it's a labor intensive (costly) process for an application not many people are serious about. I might worry about rust, too.

Last edited by ptrhahn; 10-11-18 at 01:55 PM.
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Old 10-11-18, 03:41 PM
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There was a guy in a nordic country on here about 8~10 or more years ago, who seam welded his car. He continuously welded the seams - which is the wrong way to do it IMO - stitch welding is the way to go. The Japanese I see were using rivets up front on the shock towers, but I'd wonder if that was the usual fad over there, rather than something near useless structurally.

There's not a huge amount of extra labour for the usual stripped race car using a mig.....a rotisserie makes it less back breaking though. Old floppy 70s and 80s cars will benefit the most. Rally cars rather than circuit are usually more likely to have it done too, with the punishment they take.
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Old 10-12-18, 09:01 AM
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Mazda is very specific about where all the welds go
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Old 10-12-18, 08:48 PM
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Downloaded. Didn't know this manual existed!
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