4mm Allen Nut Hot Rod Truss Rod

  • 96 Reviews
  • Write a review

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

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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
In stock, ready to ship!


6 or more $13.91
12 or more $13.11

18" overall length

Item # 2552
In stock, ready to ship!


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
Quantity Discount Prices apply when you buy multiples of the same item number.
Total: $0.00
Quantity: 20


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)

Ratings & Reviews

4mm Allen Nut Hot Rod Truss Rod

  • Based on 96 Reviews
Displaying 2 of 10 1 2 3 4 5 6 7 8 9 10
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One of the best rods on the market

By Garon from Los Angeles
(Customer's Reviews) Sunday, April 06, 2014

The functionality of the rod is unparalleled. However, when I received mine, there was some rust and corrosion on the two brass blocks and the adjusting nut. A few minutes with some 320-grit sandpaper took care of it and brought it back to a nice sheen. It's not enough to detract a star from the rating, but as the adjusting nut would be visible in my finished product, it's worth noting. I bought it with the router bit and routed my truss rod slot without any hassle.

A tough one to review

By Pacific North Coast Guitars from Washington USA
(Customer's Reviews) Tuesday, April 01, 2014

Ive used lots of these rods of different lengths. They all work great and still do. But then on final setup of a maple/cocobolo neck with custom inlay work I used a 4mm Allen key and gave it a turn to bring it up to tension (since these are floating rods i.e. they don't glue to anything) and the head twisted right off. Of course StewMac's customer service was fantastic and they immediately shipped me a replacement with their apologies. I was able to get the broken rod out and put a new one in but I had to drill a hole in the heel of the custom neck. I guess the lesson I learned is to make sure they are functioning fully before you install them cause once they're in, they're a bear to get out. I pretty sure I just got a bad rod, which is bound to happen with any product. But I can't bring myself to give it a 5th star.


By Lotus from Arlington WA
(Customer's Reviews) Saturday, March 15, 2014

They really are a little short to get the full neck set needed. I haven't had one break as warned but just started using them. We'll see if I continue with them.


By preetcher from Beaufort, NC
(Customer's Reviews) Saturday, February 08, 2014

works OK but it is a little high and you can't make your neck as thin as you would like. Other than that it is an excellent device.

Good deal

By Chris R from Qu+¬bec, Canada
(Customer's Reviews) Thursday, February 06, 2014

Nice trust rod, almost too easy to drop in a corresponding pre-made neck. Only needed to oversize the slot a bit (little over a 64th) for the allenkey insert on the rod.

works perfect

By ScottyDP from Georgia
(Customer's Reviews) Thursday, January 30, 2014

good product, well designed, easy to install pending your channel routing.

Hot Rod Truss Rod

By Rog+¬rio Rocha Matos from Brazil,S+úo Paulo
(Customer's Reviews) Monday, January 20, 2014

Wonderful, always work well!

Great rods

By Tai Fu from Taiwan
(Customer's Reviews) Monday, November 11, 2013

These rods work very well, don't be fooled by its size, they are quite strong and will bend the neck whichever way you want it to. I used these because I wanted a lighter replacement for the Gotoh Martin style steel U channel truss rod. While they are well made they are quite heavy, contributing to the weight of the guitar. This rod is light enough not to make your guitar too heavy yet it does the job. One thing though, for acoustic guitars make sure you make it a headstock adjust, because the rod is only long enough to make it to the end of the neck, requiring special allen wrench to actually adjust it... Adjusting the neck from the headstock makes the guitar tech's job much easier.


By Retro Guitars from Hilliard, Ohio
(Customer's Reviews) Thursday, October 17, 2013

No complaints other than they are a little pricey.

Truss rods confidence 

By Mack's Project from Springfield Louisiana
(Customer's Reviews) Tuesday, July 16, 2013

StewMacs truss rods are the only ones I will ever trust again. The cheap price of another brand or style is long forgotten after the hassle and hard work it takes to remedy a mistake.

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Shown on page 72 of our latest catalog.
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