Need Help - Re: welding on frame rails

[dave harris]

I thought I'd move this question over from the transaxle thread I started with the pilot bearing question.

I was trying to mount my Kennedy Engineering starter in the DRB (289 + G50) - and it did not fit - interference with the frame rail. So, having looked at a more recient frame pic (Thanks to Dave S.) it seems that DRB has modified the frame in this area to let the starters clear.

So, my question is this - the car's almost complete - can I weld on the rear chassis (right by the rear A-arm mount point) with all of the electronics installed? (MSD 6-AL, radio, all gauges etc.?)

if I keep the ground point within 6 inches of where I'm welding would that be sufficient - also, the battery is NOT connected, so only ground connections would be present to the rest of the electronics - should not be any conduction paths that I can think of.

What about the HF caused by the arc itself?

Same basic question for my Plasma cutter - as that's what going to be used to do the "trimming"?

it would be a real pain to try to disconnect everything at this point!

Thanks in advance for the help / advice!

Dave H.

 

[Randy V]

Hi Dave,

I've never had any problem with MSD ignitions when welding on the chassis'.. However - This is a snip from MSD's support site:

Welding: ​

​

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If you are welding on your vehicle, to avoid the chance of damage, always disconnect both Heavy Power cables of the MSD. (You should also disconnect the tach ground wire too).​

 

[dave harris]

Thanks Randy,

I'd read the info on the MSD site, but just wanted to check to be sure no one else had had other problems.

Regards,

Dave

 

[Phil]

Dave
Essentially everything near the arc becomes an antenna...I am assuming you are going to disconnect your battery. I would suggest that you also ground the chassis to a separate source such as a water pipe or electrical ground in your shop, you don't need a particularly large guage wire, just something to sink any stray radiation to ground. This is a problem I encountered when welding aluminum with high frequency arc, and grounding my work table solved it, and mig welding also emits RF but to a lesser degree. Plasma cutting can also emit some really spurious radiation as the arc voltage is much higher than most welders, but you should be OK with a good ground.
Hope this helps
Phil

 

[dave harris]

thanks Phil!

I've been installing a seperate ground rod today just for this adventure! I'll let everyone know what happens.

Dave