Mounting a Mark II head chassis in a combo cab?

[scelerat]

Hi, I bought a used Mesa 1x12 combo cab thinking I could mount my Mark IIB chassis in it. It turns out the mounting screws required for the cab are much narrower than those for mounting the amp chassis. Is there some special hardware required for mounting this that I don't have?

The cab is a Mesa Boogie "Sus 4" hardwood cab.
The amp is a 1980 Mark IIB.

Images of the cab: https://imgur.com/gallery/9sM002f

 

[jrb32]

Is the hole spacing off or OK?

If the holes line up, the chassis fits and you have the correct size and length mounting bolts, then you could carefully drill through the existing holes to widen them to fit the bolts for the amp chassis (if I've understood correctly). If it's the other way around then there are some washers that are used to mount these that you might be missing.

If the holes don't line up then you'd probably have to do some modification to the chassis (probably by tapping some new holes with the correct thread for the bolts). It's worth a call to Boogie though to ask their advice.

 

[s-fresh]

Not sure the exact point in time, but sometime in the late/middle IIB era (82/83?) the spacing on the chassis bolts got a little tighter. So most of Mark I, IIA, and early IIB have the wider spacing, then later IIB through IV all have the narrower spacing. Given the SUS-4 hardware is pretty much stuck in place, and there is no metal on the chassis where you would need to tap new holes, you're going to need some more involved metalwork to get an early chassis working with a later cab like that.

 

[gts]

Measure the distance (Left to Right) between the mounting holes on your chassis and let us know what you find.

s-fresh is correct, sometime during the IIB period Mesa changed the mounting hole L->R spacing.

Regardless of what the width is on your chassis.... I'm not sure there is enough metal on the chassis to tap new holes to match up with the hole spacing on the combo cab.
It'll be close but.....