Need help adding threads to Mark IV chassis mount holes

[hartattak1]

Hi

I have a Mark IV combo with SUS-4, so it has the 400mm spacing for the mount holes.

I recently bought a Mark headshell, unfortunately it has the non SUS-4 416mm spacing.

My Mark IV chassis has holes for 400mm and 416mm spacing, however only the 400mm spacing will accept threads. It looks like there is a little metal piece, 10mm x 5mm x 1mm with threads that the mounting screws attach to the 400mm holes, but not the 416mm holes.

Does anyone know how these metal pieces are attached to the chassis? I tried to tap it out gently with a hammer, but it doesnt look like it moved at all. I dont see any weld marks, so I'm completely in the dark as to how these things hold. If I could get these things removed, or another set, then I can just use the existing holes in the headshell and the chassis.

Thanks for any info.

 

[gts]

Headshells don't have Sus-4 mounting.
Sus-4 is for combos.

As for the spacing.
The headshell you bought with the wider mounting hole spacing was made for an older chassis likely a Mk-IIA or early MkIIB.
The 400mm spacing (15-3/4") was used for later IIB's up through the MkIV.

The metal pieces you mention could be nuts welded to the chassis for the mounting screws to attach to.

Not sure what you mean by there also being 416mm spaced mounting holes.
Got any pics you can post?

 

[hartattak1]

Sorry don't know how to post inline images, so try this link.
http://bayimg.com/kaNhfaAeo

Let me know if this is clear enough.

BTW, I reached out to Mesa, and they told me the little metal thread plate is welded in.

any ideas on how to remove the thread plate without drilling out the spot welds (I'm only guessing its a spot weld)?

thx

 

[hartattak1]

Not sure if anyone cares, but I thought I would post the completion of this.

The metal plates are called weld nuts.

8-32 weld nuts, originally sourced from I think http://www.hpaulin.com
part no. 08-1414

Unfortunately the width of the weld nuts are 11.25 mm, and so they dont fit side by side in an 8 mm area ((416 mm - 400 mm) / 2)

So I will be grinding down the nuts from 11.25 mm down to 7 mm so that I can fit the new weld nut next to the existing weld nut side by side, and have a threaded hole.

then use some double sided tape to hold the new weld nuts in place long enough to get the screws started, and then I should be good to go.

thanks for listening.

 

[gts]

Sorry don't know how to post inline images, so try this link.
http://bayimg.com/kaNhfaAeo

Let me know if this is clear enough.

BTW, I reached out to Mesa, and they told me the little metal thread plate is welded in.

any ideas on how to remove the thread plate without drilling out the spot welds (I'm only guessing its a spot weld)?

thx