[Editor's Note: We ran this story in the July 2017 issue of Classic Motorsports. Some information may be slightly different.]
Story by Listed Reference • Photos by The Staff of Classic Motorsports
The Triumph TR6 has been a cornerstone of the sports car world sin…
Very useful to me, as I recently got started on a TR6 project. I didn't have much of this information at the time I bought the car, but it looks like a got lucky!
One thing I'll add. The rear hubs are prone to fatigue and catastrophic failure. The stub axle breaks at the threaded end resulting in loss of the wheel. Given that these parts are now over 40 years old, I would replace them with a newer, stronger alternative as a matter of course. New hubs aren't much more expensive than rebuilt originals anyway.
They also have trouble with the sliding splines in the rear axle shafts - they can bind right in the middle of hard cornering. Guys racing TR-6s almost always swapped them out for different axles.
I saw where the TR6 metering needle (Stromberg 175 CD) can be fixed or adjustable. Which is generally preferred? I currently have what I believe is a fixed needle, but there are not any markings on it to tell for sure.
Thankss
I could probably get agreement from Tim. 
If only we could travel to Tallahassee and do a brain dump of J.K. Jackson's brain and somehow put all that knowledge in a easily assessable format. He is like a walking TR6 encyclopedia. 
The Stromburgs on my '73 TR6 had adjustible needles. I liked being able to tweak them, but it wasn't a lot of range. The only downside I can think of with the adjustable needle was that the o-ring sealing the threaded adjuster would leak some oil into the carb as it aged. AFAIK, the fixed needles could do the same thing. I would think fixed needles with the adjustable jets from a TR4 might be a better setup. There are kits to convert TR6 carbs over to adjustable jets, but I never found the need. That car didn't stray too far from stock, just a slightly hotter cam.
I never liked the Strombergs despite the fact that they probably have better mixture control than the SUs (perhaps why they used them to meet smog regs). They were smogged carbs and the later adjustable needle models didn't help all that much. The rubber diaphragm also introduced another wear/age service issue that the SU didn't have. But the older SUs are a bolt on so not a big deal to backdate.
When I bought my TR6 30+ years ago it was somewhat of a "basket case", and came with the transmission out and with several other parts in boxes. I think I got it cheap because the PO couldn't get the new clutch to fully disengage because the fork pin was sheared.
That was a fairly cheap and straightforward fix, but the more subtle problem was that he had misplaced the two tranny-to engine mounting bolts that act as alignment dowels, and replaced them with regular bolts. Neither of the two shop manuals I had at the time mentioned that you had to use those special bolts, so when I assembled the whole thing the clutch disengaged fine but continuously "chirped" with the pedal down, until I came across the info about the dowel bolts and properly aligned the throwout bearing to the pressure plate.
it also had too much crankshaft end play, along with steadily declining oil pressure as the engine got hot, but I was able to drop the pan, change the end play bearing, swap out the main and rod bearings, check the journals with plastigage (all good), all with the engine in the car. Oil pressure is great now. Also had a body shop replace rotted rear chassis trailing arm extensions, and install the differential mount reinforcing kit. My mounts were just starting to crack, so it was very fortunate timing.
A tip when replacing chassis rear trailing arm extensions: make sure chassis loading is on the four wheels while the work is done. If just the chassis is supported, when you put the car back on its wheels you'll find the rear door gaps will be all screwed up. That can be fixed (I know!) by loosening the rear body-to-frame mounts and inserting shims, if you can back the nuts off without breaking the bolts/studs, but what a pain-in-the-ass job!
PS - when you service the rear axles etc., may as well swap out for some new rear suspension springs to eliminate excessive squat on acceleration - the factory ones weren't well specced.
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