[TR] TR6 rear shock mount break

[Brian Kemp]

I too had frame cracks from the tube shock brackets I installed.  I had a local welder come out and weld up the cracks and add differential reinforcement brackets.  I had done minor welding, but didn't have a welder or adequate power in my apartment garage.  It was well worth paying someone to weld in an overhead location.  I was nearby with a good fire extinguisher and a garden hose as I to was concerned about the welding near the gas can.

To prevent the problem in the future I added diagonal braces down to the frame behind the shock brackets and a cross brace between the two shock brackets.

For anyone installing the tube shock conversion brackets that just bolt to with the original lever shock bolts, test the range of motion without the spring installed.  The trailing arm goes through an angular motion that puts a sideways force on the frame cross member that it wasn't designed for.  

I remade the brackets to move the top of the shock about 1.5 inches for a better range of motion.  If I were to go back in time, I would just have the heavy duty rebuild of the original lever shocks.

Brian 

-----Original Message-----
From: Stan Foster <stan at redtr6.com>
Sent: Oct 8, 2025 2:40 PM
To: Tim Gaines <mtgaines at presby.edu>, Triumphs <triumphs at autox.team.net>
Subject: Re: [TR] TR6 rear shock mount break

I had those brackets and the stress caused the cross ember to be torn off the frame. I fitted the cross member from RATCO and switched back to lever arm schocks.
 
Stan
 
From: Triumphs <triumphs-bounces at autox.team.net> On Behalf Of Tim Gaines
Sent: Wednesday, October 8, 2025 4:37 PM
To: Triumphs <triumphs at autox.team.net>
Subject: [TR] TR6 rear shock mount break



I have been hearing a slapping sound either under or behind me in the 1974 TR6 when I encounter even slightly rough pavement, so today I decided to sort it out. I thought I had found the problem quickly when I saw that the spare tire securing hook bolt had come loose, but no such luck. When I finally gave up on simple fixes and jacked up the left rear end and removed the tire, I saw that the cross member had cracked near where the after market shock mount adaptor bolts on. I did a quick check with the Moss parts catalog and that cross member is not available with them. So, I'm wondering if this shock mount replacement for the old lever shock (I installed a couple of decades ago) was a bad idea and put too much pressure on that frame member. It occurs to me that there may be some folks out there who have gone through this and can tell me just how a fix should be attempted.
 

That crack shown in the photo seems to be only on the back side of the cross member. I have learned some welding skills in the last few years, and I have a mig welder, but I have never done anything under a car. I really don't like the proximity of the gas tank either. I am thinking that my local pro welder would be the guy to call on, but is this really something that can be fixed that way?
 

 
 

 
 

 




 
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