Marshall Caster replacement tutorial

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Marshall Caster replacement tutorial

Postby Scumback Speakers » Tue Jul 07, 2009 1:35 pm

During the last five years I've wound up retrofitting/restoring many old cabs. One of the many problems I've had to address are the casters being bad, and replacing them. So here's what I do.

Caster hardware needed:
http://www.tubesandmore.com
These are what I use to retrofit old cabs. 4.95 per, so $20 for a whole set.
P-HW01S 2007 Catalog page 80

GUITAR CASTER, WITH SOCKET, PUSH-IN, 2", FENDER TYPE

Heavy duty swivel castor for use on Fender and other amps. 2" diameter wheel supports 44 lbs. Can be purchased as individual component
Pic here: Image
http://www.southbayampworks.com/69spec/dm1&2.jpg

Caster base mounting hardware needed: Sixteen #8 x 1" (up to 1.5") long wood screws, zinc plated so they don't rust.

Tools needed: Electric drill, measuring tape, 2" masking tape, 9/16" drill bit, Sharpie, philips screwdriver bit, cardboard if you want to make a template for exact placement.

Tools & parts pic here: http://www.southbayampworks.com/casteri ... -parts.jpg

Drilling the new caster base hole:

For Vintage cabs, pre 1975:
1) You need to drill out the hole they have in the bottom of the cab (under each caster base) with a 1/2" or 9/16" drill the same depth as the new caster base, which is 1 1/2" deep. You should measure that on your drill bit and tape it off with masking tape at 1.5" from the tip.

For 75 and later cabs you probably have the plastic base casters, or something equivalent.

1) You need to measure out the hole to be drilled in the bottom of the cab (also under each caster base) with a 1/2" or 9/16" drill the same depth as the caster base, which is 1 1/2" deep. You should measure that on your drill bit and tape it off with masking tape at 1.5" from the tip.

2) The exact location to drill the 9/16" hole is 1.75" in from the front (or back) of the cab edge, and 3.75" in from the side. This will align the caster base to fit on top of a regular (1968-2000 era) Marshall straight cab, and allow the cabs to align on the sides when stacked. The casters will need to face IN towards the center, not out towards the sides, in the straight cab caster bases if you want them to align correctly.

3) You'll also need #8 x 1 - 1.5 inch long wood screws. You'll need 16 total to mount all four caster bases. Select the appropriate drill bit (1/8" or less) for the #8 screw, and use the caster base to align where to drill. Then screw in the new wood screws into the caster base.

4) Slide in your new casters and they should "pop-in" or lock within the last 1/4/-3/8" so they don't fall out.

Now start rolling your cab around without spending $80 on the Marshall replacement casters.

Installation pics:

Caster socket base installed. Orient the base like this in case you use longer screws, you don't want the screws coming out in front of your grill cloth piping! If you do use longer screws, these will drill into your baffle board, making it more solid, and connected to the bottom of the cab, too.

Image

Caster base pics inside cab:

Rear caster base sticks up in wood support for back panel.
Image

Front caster base is almost hidden in this pic. That's because the 69 spec cab I do has support triangles for the caster base to make the cab more solid. When you have a later baffle board without these triangles, you'll see the metal part of the caster base on the back side, but partly drilled into the baffle board. You can just see the tip of the caster base in the edge of the triangular brace if you look in the lower left portion of the triangle.

Image
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Re: Marshall Caster replacement tutorial

Postby neikeel » Sun Jul 12, 2009 7:08 am

Hi JIm

I have a 69 B cab which has had a couple of wooded strips screwed to the botttom of the cab but the original tubes for the pop in Revvos are still there in good condition.

Do these Fender (or for that matter the Ernie Balls) drop directly into these tubes? I have a lead on one chrome pop-in but doubt I will ever find a fixable set (although I do have Black revvos, bronze homas and the triangular plate ones with brakes :roll:) so I might as well bite the bullet and get a set of these anyway.
Neil
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Re: Marshall Caster replacement tutorial

Postby thousandshirts » Sun Jul 12, 2009 9:25 am

If you have a micrometer, and can measure the Revvos, I can compare to the socket holes for you.

That being said I should probably order a few more sets of these anyways, for the price.

Nice photojournal, Jim!
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Re: Marshall Caster replacement tutorial

Postby Scumback Speakers » Sun Jul 12, 2009 11:11 am

Neil, they're not going to fit the holes already there for the Revvos THAT I KNOW OF. You'll have to drill them out a really small amount. Probably 1/16 to 1/8" or the thickness of two thumbnails (how's that for international measurement conversion?).

The 72 checkerboard cab I just got has what I think are the old Revvo metal caster bases in it, but I can see it has the hole drilled above it for the old pin type caster bases.

Here are some pics of the cab caster bases.

72 caster holes pic. Typical Marshall consistency. Front-left side, rear right side. Rear hole is completely drilled through on one side. Image

On the other side it's not. :lol:
Image

The caster bases are the EXACT same screw pattern/size. I put the new Fender pop-in caster in the hole that was completely drilled, and used the same screws to mount it, too.

The other holes will need a 9/16" drill, and drilled to around 1.5 inches or slightly deeper to mount them. I would take a razor knife and cut the checkerboard cloth in the hole first (or an exacto knife) so that the drill doesn't grab threads and potentially pull them.

Then just drill your hole out, install the new casters, mount with the old screws and you're good to go. Make sure you drill the new hole straight so you don't wind up drilling into the front of the baffle board and ripping your cloth. You'd have to go real far off to do it, but as we've seen there are others who could screw up a wet dream on this board, and I don't want anyone to follow in that member's footsteps with their checkerboard turned JCM 800 cab and blame me for it, OK? :wink:

Front caster hole, showing checkerboard cloth on baffle board.
Image

Caster base comparison:
Image
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Re: Marshall Caster replacement tutorial

Postby Scumback Speakers » Tue Jul 14, 2009 1:51 pm

Ok, I finished retrofitting the checkerboard cab. Had to drill out three of the caster holes to accept the new caster bases. I reused the original screws from the original caster bases as well since the hole pattern was the same. If you do this right, you'll see a portion of the new caster base sticking up into the baffle board, more towards the inside than the front.

Inside of the baffle board caster base pics.
Image

Image
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Re: Marshall Caster replacement tutorial

Postby neikeel » Wed Jul 15, 2009 5:08 am

Thanks Jim

My 72 chequerboard cab is the same as yours but has black painted revvos which screw into the inserts you show. My earlier cab is just a cheap metal tube pressed into the cab, these protrude into the bottom of the cab and the lower triangular supports in the same way that those Fender tubes do. The Fender ones look much more secure as it has the plates with the four screws as well.

I discovered an oddity - the bronze painted Homas on one of my cabs do do not allow stacking of an A on B as the wheels are too small and fat to fit into the metal castor cups :roll:

Not that I am going to be touring with a full stack, most of our gigs are to around 250-300 people so a 100watter is always on a leash :wink:
Neil
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