4mm Allen Nut Hot Rod Truss Rod

  • 93 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.

Read more

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
    • 2551
    • 0.232
    • 2552
    • 0.296
    • 2553
    • 0.385

Ratings & Reviews

4mm Allen Nut Hot Rod Truss Rod

  • Based on 93 Reviews
Displaying 9 of 10 1 2 3 4 5 6 7 8 9 10
Write a review


(Customer's Reviews) Saturday, January 29, 2011

I use the Hot Rod truss rod in all my guitars for me it is easy to install and works like a champ every time and has never let me down. I will continue to use it in all my custom builds Electric or Acoustic hands down its the best.

Thank you stewmac

By Michael Grannis from Phoenix, Az
(Customer's Reviews) Wednesday, January 19, 2011

A truly affordable product. Good size and adjust ability. Will certainly use again.

allen head truss rod

By D.M.Holzer Banjos from West Fargo, N.D.
(Customer's Reviews) Monday, January 17, 2011

i really like this truss rod and use it extensively in all my banjos. it's the ease of installing which i like. For the truss slot i know a router bit is suggested but what i do is use 3 circular saw blades on the table saw and make only one clean pass down the center of the neck. then i just drop the rod in and fill the rest of the truss rod channel. it is a nice fit and the allen head ensures no slippage when adjusting the rod. i want quality in my instruments and this rod is the one i prefer.

14-1/4" truss rod

By DhaenensGuitars from Aarschot, Belgium, Europe
(Customer's Reviews) Sunday, December 12, 2010

After trying out a few brands of other truss rods, I've used this type on all of my guitars. Excellent stuff!

not really happy ....

By Utopia Custom Shop from Alessandria -Italy
(Customer's Reviews) Tuesday, November 23, 2010

Sorry but I find the nut anchorage to the bar not enough resistant.

Others truss double action rod are more resistant in that zone

Hot Rod truss

By R Guess from North Florida
(Customer's Reviews) Tuesday, October 26, 2010

Well made, easy install and perfect fit using the Stew Mac truss rod router bit. I have used 6 now with very good results.


By James B. from Ontario Canada
(Customer's Reviews) Thursday, September 30, 2010

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

By Andrew t Bruton from st Catharines Ontario Canada
(Customer's Reviews) Thursday, September 16, 2010

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

By Strat41 from San Dimas, CA
(Customer's Reviews) Friday, September 03, 2010

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

By slingerland guitars from fairfax, va
(Customer's Reviews) Friday, August 13, 2010

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.

Displaying 9 of 10
1 2 3 4 5 6 7 8 9 10

Shown on page 72 of our latest catalog.
  • Hot Rod® is a registered trademark of Stewart-MacDonald Manufacturing Company, Inc.