4mm Allen Nut Hot Rod Truss Rod

  • 97 Reviews
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12-1/4" overall length

Item # 2550
In stock, ready to ship!


6 or more $13.74
12 or more $12.95

14-1/4" overall length

Item # 2551
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6 or more $13.91
12 or more $13.11

18" overall length

Item # 2552
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6 or more $14.78
12 or more $13.93

24" overall length

Item # 2553
In stock, ready to ship!


6 or more $18.26
12 or more $17.21
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4mm Allen Nut Hot Rod Truss Rod

A smaller 4mm (5/32") Allen nut for most instruments. Smooth two-way action corrects upbow and backbow, giving complete control over the neck.

Easy to install. The Hot Rod® fits in a straight channel. For proper operation, this truss rod must be installed so that the active rod (the rod with the adjustment nut) is below the passive rod. A wooden filler stick is not required.

Smooth 2-way action with superior strength for stubborn necks.
Our Hot Rod neck adjustment system features twin rods in threaded brass collars. The stainless steel active rod turns for smooth neck alignment, with 2-way action to correct upbow and backbow.

The Hot Rod requires an access cavity for the adjustment nut, and a straight 7/32"-wide x 7/16"-deep slot (measured from the bottom of the fretboard) for installation.

Pick the Hot Rod Truss Rod size you'll need:
(overall length includes the nut)

Resonator guitar
Acoustic guitar with 12th fret at the body
Acoustic guitar with 14th fret at the body
Electric guitar

We've designed the Router Bit for Hot Rod Truss Rods especially for routing your neck to fit our truss rods.

Product Instructions

Hot Rod Adjustable Truss Rods

Installation and adjustment instructions for Hot Rod Adjustable Truss Rod.

    • Item #
    • Weight
    • 2550
    • 0.197 lbs. (0.09 kg)
    • 2551
    • 0.232 lbs. (0.11 kg)
    • 2552
    • 0.296 lbs. (0.13 kg)
    • 2553
    • 0.385 lbs. (0.17 kg)

Customer Reviews

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  • 4.42 average rating from 97 reviews
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(Customer's Reviews)

I have built 8 electrics with these and I find them convenient to install since they use just a flat bottom channel.

I had one shear at the adjuster once, which made me livid, but I was able to save the neck and replace the truss rod without removing the fretboard. Always lubricate the threads and test it before installing. Proceed with caution while adjusting any truss rod.

On Fender style necks, with the adjuster oriented just under the fret board, the tightening/loosening direction is opposite to conventional so watch out for that!!

Finally, I'm glad there is now metric adjuster sizes!!


4mm Allen Nut Hot Rod

(Customer's Reviews)

It works realy well no rattle in the neck.Also theres no need for a large truss rod cover


HotRod installation for Fender headstock adjustment

(Customer's Reviews)

Just received the 4mm allen nut Hot Rod, and butchered a nice piece of wood trying to install it with adjustment at head stock end. CAN'T BE DONE ON A FENDER GUITAR but StewMac doesn't mention that anywhere. It can only be installed as a heel end adjuster) The 7/16 slot depth puts the adjuster too low into the head stock to allow access. If you want a heel end adjuster, buy the Fender style model, and don't mess around with an oddball 4mm adjustment.


4mm Allen Nut Hot Rod

(Customer's Reviews)

I love these hot rod truss rods. They are incredibly easy to install and use. The dual action has come in handy on a kit guitar I built. I use them on my electrics and acoustics.


Simply perfect

(Customer's Reviews)

Installs easily and precisely and the fact that works in both directions allows you to straighten the fretboard wile leveling the frets. Perfect


Great Product!

(Customer's Reviews)

I have always used these truss rods for my guitars. They work perfectly every time!


Great product

(Customer's Reviews)

I have purchased many of these truss rods and they work great. I use some woods harder then rock maple and have never had a problem with installation or use. Their service is top notch and I always get my order in two days. The trade secrets articles have given me the confidence and knowledge to do many guitar projects right the first time.

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StewMac PDF Catalog, page 74 See 4mm Allen Nut Hot Rod Truss Rod
on page 74 of our StewMac Catalog PDF

16MB File

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  • Hot Rod® is a registered trademark of Stewart-MacDonald Manufacturing Company, Inc.