TR6 Tube Shock Conversion: Modern Shocks and Competition Coils Give Real Handling Rewards

The rear end of a TR6 responds well to simple upgrades that enhance ride quality and drivability. With a few items from the Moss Motors catalog and a Saturday afternoon, your TR can become a much more civilized and competent driver—with real rewards coming during spirited driving.

Positive word-of-mouth from fellow Southern California Triumph Owners Association ( members and attendance at the club’s annual “open garage” event at Britalia in Fullerton, California, encouraged me to order the Moss Tube Shock Conversion Kit with Koni shocks (#670-128) and fortify the suspension with Moss Motors Competition Springs (#670-168).

The Tube Shock Kit consists of three brackets per side that combine to anchor the upper end of the Koni tube shock. The setup’s main benefit is that it locates the upper tube-shock mount close to the body and transmits any stress through the body to the frame. Adding the Competition Springs restores ride height and overcomes the stock springs’ tendency to squat over bumps and under hard acceleration.


After seeing the TR6 suspension upgrades at Britalia, I enlisted Walter Kelley there to do the installation, which is easier on a lift than on a driveway. However, Moss’s instructions are comprehensive, and anyone who does normal maintenance on their Triumph should be able to do this simple drill-and-bolt-together project in four hours or so. Having an assistant makes the job go even faster.

Prepwork involves draining and removing the gas tank. This improves access for drilling the necessary holes and for bolting on the Moss kit’s brackets. (Plus, those chunks in the tank could probably stand to be cleaned out anyway.) Whenever dealing with gas, make sure to work in a well-ventilated area away from ignition sources such as welders and chain-smokers. Have a fire extinguisher handy just in case.

Once the tank is yanked, the stock lever shocks and trailing arm links can be removed from the chassis. Make sure that the arm is supported from below, then use caution when releasing the coil springs. (The Moss Competition Coils are direct replacements for the stock springs.) Next, the Tub Shock kit’s largest brackets are direct replacements for the original lever shocks (or for brackets from other tube-shock conversion kits).

Highlights of the major installation steps are shown in these photos. One re-tanking tip is to use a dab of assembly lubricant to ease the filler neck re-install. Then pour some fuel into the tank and check for leaks before lowering the car onto the ground. If the fuel system is leak-free, slap on the skins, un-jack the TR, prime the pump, and you should be ready to run. Promptly go to your favorite twisty bits and enjoy your properly damped TR6.

How-To: TR6 Tube Shock Conversion 


The Tube Shock kit

1. The Tube Shock kit includes everything necessary to complete the job at home: Koni shocks, brackets, isolation pads, and a comprehensive 3-page instruction manual.

2. Compare the stock spring on the left with the Moss Competition Spring on the right. These Moss springs combat the dreaded TR6 rear squat and gives slightly stiffer, more predictable handling.

3. Draining the gas and removing the tank isn’t necessary but improves access for drilling the necessary holes, making the job go faster.

4. The stock lever shocks and trailing arm links must then be removed.

5. Installing the Moss Competition Coil is a straight remove-and-replace job that should be done by someone who’s familiar with coil-spring safety procedures. Next, Walter test-fits one of the primary (large) brackets.

6. Once the primary brackets are test-fit with the supplied bolts and rubber isolation pads, the holes can be marked.

7. Drill four holes per side up through the trunk floor; Moss’s instructions recommend using a right-angle drill motor due to tight clearances.

The Moss Tube Shock Conversion Kit uses a triangulated-bracket system to help Isolate the body from the chassis.

The Moss Tube Shock Conversion Kit uses a triangulated-bracket system to help Isolate the body from the chassis.

8. Once the primary brackets are fitted, pass four bolts per side through the trunk floor and secure the smaller triangular brackets against the fender well. Test-fit the brackets and mark the holes for drilling.

9. Drill through the inner fender and secure the outer bracket with the included hardware—tricky if ht gas tank is still in place.

10. The adjustable Koni shocks bolt between the upper mounts and the trailing arms with the supplied rubber bushings and bolts. Tighten the bolts so that the rubber bushings bulge slightly, but don’t over-tighten—you don’t want them flattened.

11. Re-install the gas tank, refit the filler neck, reconnect the vent and fuel lines, and tighten the requisite clamps.

12. Moss Motors suggests running a 195/60-15 tire with this kit.

By Rob Mullner

'TR6 Tube Shock Conversion: Modern Shocks and Competition Coils Give Real Handling Rewards' has 1 comment

  1. November 10, 2016 @ 9:51 am Daniel

    Does making this conversion hamper Heritage Foundations requirements?


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