Tuesday, December 20, 2011

...the tools...

What tools will you need to tear down your TRW 500? So here ya go. You will need two extractors/pullers to disassemble your TRW 500. This is a little confusing so bear with me. If you are smart you have found the workshop manual for your TRW online. If you have not, then email me. The official manual lists 3 pullers; the cam shaft, the crank shaft, and the clutch hub puller. The part numbers listed in the manual are D178/183, ST/1940, and D.50, respectively. These numbers mean nothing to Triumph parts houses scattered around the glode. My guess is that these part numbers where based on military specs, as the bike was never sold by Triumph on the civilian market.

But never fear, I have found the civilian equivalents to two of these pullers, and a work around for the third! First, for the the camwheel you will want to use the equivalent puller for the crank pinion of the unit 'C' model twins ONLY, meaning 500cc, which have a threaded pinion. Sorry, I don't have an official part number. If I find one, I will be sure to post it.

For the hub you will want the standard clutch hub puller 46-1982 which is the puller for the 500 650 and 750.

I was unable to find the puller for the crank shaft wheel, but after a stroke of genius I discovered (I was not the first) you can thread the clutch hub onto the cam gear, then use a set of 3 jaw pullers to remove this gear. Here a few pics...

Clutch Hub

Clutch Hub on Gear

3 Jaw Puller

I finished up the tear down of the motor last week. The next post will include notes on that process.

Sunday, November 20, 2011

Whitworth history lesson...

...interesting tid bits via sohc.net and HondanutRider

An interesting trivia about Whitworth threads is that their pitch is Metric. While the profiles of the thread might be slightly different on standard Metric thread, they should match up and work if the same pitch is used. Whitworth nuts and bolts used unique head sizes that are different from either standard SAE of Metric sizes, and using a socket or wrench from these series will usually result in a "rounded" head.

Historically, Whitworth originated during/after WWI when the British brought some of the latest modern (at the time) thread cutting machines out of France for safe keeping during the war. These machines were capable of mass producing very accurate threads, but Metric of course, and the British war effort needed parts for the mechanized warfare that was evolving. After the war, they kept the machines and started producing their own "nuts and bolts" standardizing on the unique bolt heads. Because the original machines produced Metric threads, that's what Whitworth remained.

So, if a Whitworth bolt or nut gets "buggered" in removal. you likely can substitute a corresponding Metric-threaded one. However, it then won't be authentic and the "purist" concourse evaluator will mark you down.

...reprinted from sohc.net

Sunday, November 13, 2011


I've been doing custom motorcycle work for about six years, and wanted to do something different. Different you want? Different you get. This is a 195x Triumph TRW500 engine. Its a pretty interesting little mill. It is a twin (its a Triumph, could it be anything else), but what makes it more interesting is that its a side valve engine. Essentially, what this means is that rather than the valves being buried in the head (like most modern engines) the valves are in the the cylinders, beside the pistons, hence the moniker 'side valve', or 'flat head' (no valves in the head).

This motor was a war bike, and never sold on the civilian market. The side valve design has essentially been eliminated from modern automotive and motorcycle markets do do its lack of power. This motor puts out about 15 horse power. Contrast that to a modern 500cc motorcycle engine that would put out more than 50 hp.

I mentioned these were never sold on the civilian market, but they are all over the place. After the war years they were sold as surplus still in the crate. A few still exist today:


My first task is to acquire tools for this beast. Pre-unit triumph nuts and bolts used the whitworth standard, which is somewhere between standard and metric. Additionally there are a number of extractor tools I will need to get the thing a part. This should be fun, so stay tuned!!!