DIY Workshop: Greco to Les Paul Goldtop conversion (Part One)

Do you wish your guitar had that classic Goldtop look? Huw Price shows you how to turn your tired old single-cut into a ’54-style golden wonder with soapbar P-90s and a wrapover bridge…

By now you’ve probably recognised a theme that’s common to many of G&B’s Workshop projects – if you can’t afford to buy a guitar that you want, then build something similar yourself! So, in recent years we’ve done the 1959 LP wannabe, a 1954-spec S-type, a beat to bits interpretation of an Esquire and even a Gretsch 6120 conversion.

We’re using a 1989 Greco LP-style with humbuckers as the donor guitar for this project

It was bad enough when the workshop projects were just an excuse to cure my own GAS, but now that G&B’s editor and some of the boys in the office have caught the conversion bug, it seems as though this might never end! And to be honest, these projects are so much fun, that’s just how I like it! So without further ado, it’s Goldtop time.

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Greco guitars from this era sport a logo with opening at the top of the letter ‘O’

The plan this time is to take a neglected and unloved LP-style guitar and turn it into a mid-50s-style Goldtop with P-90 pickups and a wrapover tailpiece. I’ll also be removing the fingerboard to add a backing veneer that will increase the neck depth for a more authentic fat neck feel. There will be fresh frets, hopefully with fret nibs, so that means re-binding the neck and a 50s-spec nylon nut will have to be made.

The complicating factor is that the donor guitar was built for PAF-style humbucker pickups, so the existing pickup cavities will have to be plugged and re-routed for P-90s. I’ll also be plugging the stop tailpiece bushings and drilling new holes for the wrapover bridge. Of course it would be a lot easier do a later spec P-90 Goldtop with a tune-o-matic, but where’s the fun in that?

The serial number confirms this is a 1989 model so we’re certainly dealing with some old wood here

The modified top will almost certainly have to be re-veneered and that means re-binding the body, too. Some of the existing plastic parts and hardware will be reused, but the search is on for period-correct control knobs, cavity covers and a pickguard. A set of authentic-looking ‘grey tiger’ tone capacitors would also add to the sonic vibe and I’m looking forward to testing some P-90 pickups…

Body snatching
I bought this guitar several years ago as a stripped down husk. It’s actually a 1989 Greco, although I can’t be certain of the exact model. This guitar was made towards the end of the first ‘golden era’ of Japanese guitar making and it must be said that it’s not as well made as the Greco I used for the ’59 Burst-inspired project we did a few years back.

The bridge posts and stud bushings all have to be removed, but it’s quite straightforward

The fret installation is nothing like as good and you can tell it’s from the lower end of Greco’s product range because it doesn’t have fret nibs. The frets are also somewhat larger than vintage-spec Gibson wire. There is also a structural issue that makes the bridge replacement unavoidable. The original tailpiece and bridge were installed off-centre, so the strings were always skewed towards to the bass side of the guitar – it certainly wasn’t like that on an original Goldtop!

However, despite the various issues, there are still numerous plus points that make this guitar a good candidate for conversion. Despite the lower quality workmanship, Grecos of this era still had long tenon neck joints, which is more than you can say for 1980s Gibsons!

The kit for post removal includes two thumbwheels with a washer placed in-between

Other 1950s-correct features that the Grecos retained include volute-free necks and a correct back angle for the headstock. The mahogany body appears to be a two-piece, with a join just under the control cavity. The cap is centre-jointed solid maple but it’s very much a plain top and it’s not bookmatched. The stacked heel is another inauthentic feature, so because of that and the body join this guitar will either end up as an all-gold or a dark back Goldtop.

Although it’s almost certainly East Indian rosewood, the fingerboard has an attractive reddish brown hue and the pearloid inlays have sharp points with a deep colour. So I’ll be keeping those. Fortunately the headstock has never been drilled to accept more modern machine heads, so there’ll be no need to convert them back to take Kluson-style tuners.

Our bushing removal kit includes a bolt with the same diameter and thread as the tailpiece stud, two metal spacers from some Ikea shelves and a spanner

But the best thing of all is the body weight. Fully loaded with parts and pickups, this guitar weighs just 3.8kg/8.37lbs. Although the late-1954 All Gold that we featured in 2015 weighed in at 10lbs, the Greco’s sub 9lbs weight is closer to the Minnesota Burst we looked at last year, and what we would expect from a mid-to-late 50s Les Paul. It also sounds particularly good acoustically.

Switch craft
Stripping the Greco back down to the body is a fairly straightforward process. I begin by cutting off the five remaining strings then removing the bridge and tailpiece. Strings go in the recycling but when working on these types of project, I always use an old takeaway container to collect the parts and keep everything in one place.

The switch wires are then de-soldered from the volume potentiometers and the output jack and pulled out along with the switch. By removing the pot nuts and pointers, you should be able to lift out the complete control assembly – once you’ve disconnected the ground wire.

The bushing is half way out but if the bolt is too short you’ll need to remove it and add a second spacer

After unscrewing the strap buttons and removing the tuners, next I have to get the tuners’ bushings out. Quite often they’re wedged in tight but you should avoid any temptation to prise them out from the front because you will almost certainly damage the headstock face.
Instead, place a flat head screwdriver through the post holes at the back of the headstock, put the screwdriver against the back of the bushing and tap the screwdriver gently with a small hammer.

With the posts and bushings extracted you can remove the ground wire from the treble side bushing hole and we’re ready for stripping

Move the screwdriver tip around the bushing and use very little force. You should see the bushing begin to move out of its hole and eventually pop out. The idea is to avoid damage to the postholes and the veneer overlay. It’s a simple procedure and once you’ve done the first one, simply rinse and repeat until they’re all out.

Bridge post and bushings
All that’s left by this stage are the bridge posts and tailpiece bushings. Sometimes the bridge posts are quite loose and you can simply unscrew them, but they may be stuck tight. If that’s the case, you can use the thumbwheels to get them out. To do this, screw one thumbwheel half way down the post, the place a washer over the top and screw the other thumbwheel down on top of the washer.

Once that’s done, slowly turn the lower washer anti-clockwise and it will tighten up against the washer and the top thumbwheel. Since the thumbwheel will then be unable to move higher up the bridge post, if you continue turning the thumbwheel anti-clockwise the post itself should start unscrewing from the body. Just keep going until it’s fully extracted.

The original back finish was a glossy crimson that made the guitar look like a toffee apple

If the thumbwheel method doesn’t work because you cannot get the post to turn using your fingers, replace the thumbwheels with nuts separated by a washer. You will then be able to use a spanner on the lower nut and the extra leverage should do the trick.
Getting the tailpiece stud bushings out is a bit trickier because they are pressed into the body and since no glue is used, the holes are drilled for a tight fit. Find a bolt with the same diameter and thread as your tailpiece stud. You will need to drop a short metal rod into the bushing hole before screwing in your hex bolt.

As the bolt touches the metal rod, it’s prevented from getting any deeper into the hole. Keep turning and you should see the bushing begin to move and emerge from the hole. If you bolt is on the short side, you may need to remove it and add a second spacer rod before you can fully extract the bushing.

Heat will cause the finish to blister but you don’t need to get it that hot before it will come off

Once you’re done, look inside the treble side-bushing hole and you should see the original wire that connected the tailpiece to ground. This can now be removed, but make a mental note that a new one will be needed for the relocated bridge.

At this point I take the opportunity to weigh the body once again and it’s almost exactly 3kg – or 6.6lbs if you prefer. So if you are ever buying a husk or making a Les Paul style guitar, this is a good target weight to shoot for if you want to end up with a relatively lightweight mid-50s-style sub-9lbs guitar.

Strip teaser
Unfortunately, the next part of the process is by far the most tedious and dull to do, but it’s also completely unavoidable! Before we can go any further the thick, brittle and impervious gloss finish has to be completely stripped off. The first task is to determine what sort of finish it is.

When scraped, the heated finish comes off in strips or shards depending on whether it’s polyester or polyurethane

Nitrocellulose will come off when you wipe it with acetone and you can test an out of sight area with some acetone on a cotton bud. If it is nitro, you’ll see the finish transfer onto the cotton bud with a couple of passes. If this is the case then stripping the finish with Nitromors is an option. Of course, the finish on this guitar isn’t nitro so it’s almost certainly ‘poly’. Two types of poly finish can be found on guitars like this – polyurethane and polyester – but both are tough to remove.

Until quite recently you could acquire industrial strength methyl chloride-based varnish strippers to remove poly finishes. However, those pesky bureaucrats have colluded with scientists and health professionals to deny us our freedom to use this carcinogenic and environmentally damaging chemical. So, with that off the table, a heat gun is needed to strip our guitar.

When stripping the neck and body the finish is left intact on the flammable binding because it will eventually be replaced

There are numerous potential pitfalls in using heat guns on guitars. For one, it’s easy to scorch the wood beneath the finish and melt the binding. Glue joints can also open up and too much heat may cause the neck to bend or twist. With that in mind, I set about stripping the finish.

When heated, poly tends to blister, go brittle and crack. Once that occurs it’s simple enough to scrape the finish off the guitar. However after getting a little way through, I discover the poly doesn’t need that much heat and merely softening it is sufficient.

Stripping the maple is far easier because the gloss coats were applied over a softer tinted base coat

Use a fairly blunt metal scraper and slide it under the finish. If it’s polyester, it might come off in long strips, but polyurethane tends to chip and splinter. Take care because hot shards of finish can fly off and burn you so cover your arms, and wear gloves and goggles. Also work outdoors, because the fumes are horrible and almost certainly bad for you.

Never try to force the finish off when you feel resistance because you may end up gouging into the wood. Also if the finish is well and truly stuck on, it can lift wood fibres if you try and prise it loose. Soft open pore woods like mahogany are particularly vulnerable, but it is slightly easier to strip maple.

Inevitably, you’ll probably just be getting the hang of it as you’re almost done. Keep the heat gun moving and work on small areas. Don’t wait for the finish to blister, but instead press your scraper against the finish and when it’s ready to go, the scraper will slide under the finish. Also remember that metal scrapers will become very hot. This probably assists the removal process but be careful not to burn your fingers.

Goldtop Conversion

After stripping, the back looks a bit of a mess, but with a bit of scraping and sanding it should end up okay

I was somewhat concerned about applying heat to the neck so I left it until last and my technique was pretty well honed by that point. I worked only on small areas and stopped after each one to allow things to cool down. All in all the whole finish removal process took me about three hours and with all the finish removed the husk ended up 150g lighter, and the tap tone was clearer and louder.

I suspect the binding may have been cellulose because it caught fire on a couple of occasions due to the heat. So be mindful of that if you try this at home. The maple came out really well but I think there’s some kind of filler or base coat in the pores of the mahogany and quite a bit more scraping and sanding will be required before finish can be applied. But at least that’s the boring and messy bit out of the way and now the fun can really begin!

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