How I Replaced Mark llC Combo Shock Mounts

[Buster Leggs]

Can a shock mount replacement kit be had for Mark llc's? If so where can I buy them? Was there a major issue with the prior mark combo amps that were hard fastened? Those tubes get closer to the EVM speaker as the years go by. I'm careful with my gear would I be better off figuring out a way hard fasten my C combos? If anyone has done that please let me know what you did. THANKS

 

[MrMarkIII]

Call Mesa. Don't email, call. They will get back to you.
I kinda doubt SUS-4 mounts are still available.

 

[Monsta-Tone]

Somebody told me that they were aircraft instrument mounting bushings. Don't know if that's true.

I might have a set just laying around, I'll check when I'm in the shop today.

 

[Buster Leggs]

Andy sent you P.M.

 

[gts]

Can a shock mount replacement kit be had for Mark llc's? If so where can I buy them? Was there a major issue with the prior mark combo amps that were hard fastened? Those tubes get closer to the EVM speaker as the years go by. I'm careful with my gear would I be better off figuring out a way hard fasten my C combos? If anyone has done that please let me know what you did. THANKS

Pretty sure the idea behind shock mount system was to help alleviate vibration to the chassis and tubes.
There are plenty of amps out there that never had a shock mount system (or anything similar) and have worked with no vibration related issue(s) for years.
I bet if you found a way to hard fasten the chassis to the combo everything would work just fine.

 

[Monsta-Tone]

I only had 2, and they are in sad shape, sorry.

I removed them in the last amp that I had with them.
It desperately needed a re-tolex, so I filled the holes with dowel rods and re-drilled the holes for standard chassis bolts.

 

[Buster Leggs]

Guys thanks for the info and thanks for huntin around the shop those A.T.

 

[rjg]

Buster,

I ran into the same situation. I wanted to put a Subway Rocket chassis into a 1 x 12 combo shell. I found an old combo shell that was in rough shape on the local CL (modestly priced). I filled the holes of the former shock mounts with epoxy. I also mixed a little Black liquid RIT dye into the epoxy so the epoxy cured the same color as the cab. After the epoxy cured, I drilled through the epoxy and installed the chassis mount screws. It works perfectly. It might not be quite as nice as a cab that was original without shock mounts but it serves its purpose and the chassis is secure.

Ron

 

[Buster Leggs]

RJG,

That's a good idea and would work for the black tolex combo but not so much for the hardwood combo. Also, I would like it to look original when I'm done, I'm going to spend some time in the up coming week and see what I can figure out. If any one else would share what they've done I would appreciate it. This has to be a some what common issue. If I come up with a great fix idea I'll put it out there but would like to here what others have done.............THANKS

 

[rjg]

Thanks Buster, I did not realize that you had a hardwood cab. The only other thing that I can think of, is using some hardwood dowels like Andy did. You could get some dowels that are the same OD (or close to it) as the ID of the holes (which are ~1" or 25mm) and install them with epoxy. Then you would have to sand and stain them to match the cab before drilling the holes for the mounting screws. Use some nice stainless finish washers and stainless screws and it will look nice. Granted, it would be quite a bit of work but certainly doable.

rjg

 

[Buster Leggs]

As most of you know, sus 4's are no longer available. This seems like an obvious fix but here goes. I removed the original mount, cut a piece of 1/8" thick steel, 1 1/4" square ( original mount is 1/16" thick, I doubled that for strength ).I drilled 4 holes to match the original mounting holes. I drilled a 3/16 hole in center of steel plate for chassis mounting screw to pass through. I painted it to prevent rust. I mounted the steel plate to the underside, same place the original plate was mounted. I used mounting screws that were 1/32 larger in diameter for better bite. I put 3 rubber washers 1/8" thick in the top hole resting on the mounting plate. Then I put the original steel washer on the rubber washers and used the original mounting screw to attach the chassis to the cabinet. Although this method doesn't have the same shock resistance as the sus 4's, I was surprised at the shock resistance it did provide. Also, it pretty much retains the original look although the cabinet holes are 3/8 shallower due to the rubber washers. I suppose you can omit the rubber washers if that's an issue for you but that didn't matter to me. I hope this helps somebody else that is unsure of how to fix this problem, as I was, without replacement parts available.

 

[cho]

Sounds like a good solution! Do you have any pics youi can share?

 

[Buster Leggs]

Sounds like a good solution! Do you have any pics youi can share?

No sorry, I didn't think to take any. It pretty much just looks the way you'd envision it looking. If I thought anyone would benefit from me taking it back apart and snappin a couple of pic's, I would. But I don't think photos add more clarity, or not enough to justify me taking them back apart. I's a pretty simple procedure.

 

[Buster Leggs]

As most of you know, sus 4's are no longer available. This seems like an obvious fix but here goes. I removed the original mount, cut a piece of 1/8" thick steel, 1 1/4" square ( original mount is 1/16" thick, I doubled that for strength ).I drilled 4 holes to match the original mounting holes. I drilled a 3/16 hole in center of steel plate for chassis mounting screw to pass through. I painted it to prevent rust. I mounted the steel plate to the underside, same place the original plate was mounted. I used mounting screws that were 1/32 larger in diameter for better bite. I put 3 rubber washers 1/8" thick in the top hole resting on the mounting plate. Then I put the original steel washer on the rubber washers and used the original mounting screw to attach the chassis to the cabinet. Although this method doesn't have the same shock resistance as the sus 4's, I was surprised at the shock resistance it did provide. Also, it pretty much retains the original look although the cabinet holes are 3/8 shallower due to the rubber washers. I suppose you can omit the rubber washers if that's an issue for you but that didn't matter to me. I hope this helps somebody else that is unsure of how to fix this problem, as I was, without replacement parts available.

OR......(can't believe I didn't think of this in the first place). Simply remove the chassis screw and black washer- Drop three 5/16 ID flat washers into the hole on top of the shock mount- replace black washer and reinstall screw. As you tighten the screw, the sleeve in shock mount will pull up tight through the hole in the flat washers up to the original black washer hence pulling the chassis up tight to the top of the combo cabinet. And will still have some shock mount properties ...........Talk about overthinking :?:

 

[jonathanccwong]

sorry for resurrecting this, but do you have a picture?

 

[Buster Leggs]

sorry for resurrecting this, but do you have a picture?

I didn't take any pictures but I'll go ahead and take some for ya. I'll have them up by this time tomorrow at the latest.

 

[Buster Leggs]

sorry for resurrecting this, but do you have a picture?

I didn't take any pictures but I'll go ahead and take some for ya. I'll have them up by this time tomorrow at the latest.

I unscrewed the original screw , removed it along with the original black washer.

I put 3, 5/16 I.D. flat washers into the countersunk hole.

I replaced the original black washer on top of the 5/16 flat washers, reinstalled the screw until its slightly snug. I repeated this until all 4 holes were completed in this manner. Then I gave each screw a few turns 1 at a time until they were tight. it sucks the sleeve on the original mount up through the center hole in the 3 flat 5/16 washers until it meets the original black washer.

As you can see the chassis is hard fastened to the top of the combo cabinet. I hope I explained it effectively, I'm really tired and realized I didn't have time to do this tomorrow. It should be self explanatory but if you have any questions please ask me but its pretty simple.