Le Putain De Merde Sprag Clutch

It's important to ensure that the battery is always good with plenty of charge so that when you hit the starter it starts quickly and cleanly with little hesitation. Laboured repeated slow starting is what can destroy sprag clutches. Replacing the engine mounting bolts seems like overkill to me unless they are single use stretch bolts which seems unlikely?

 

The answer to the second part of your question is "YES"!

AFAIK the sprag clutch design remained the same throughout the lifecycle of the first generation of Hinckley bikes - quite possibly beyond the first generation for all I know. The point is, as I understand it, the design and application aren't the best in the world. They do work - there are many, many examples of very high mileage T300 range bikes that haven't suffered ANY sprag clutch failures - it isn't a given; it isn't pre-ordained but it is quite common.

The anxiety that you will feel can be overcome but it needs - nay, demands - the observation of some 'rules'.

NEVER attempt to start the cold engine with a weak battery; fit the biggest CCA battery that will fit in the space; keep the battery well maintained and fully charged; keep the fuel fresh; press the starter button firmly and use the choke if it's cold. All fairly obvious but easy to overlook. What's difficult, perhaps impossible, to do is to entirely remove the anxiety.

I've never heard of not re-using engine mounting bolts for fear of loosening but, then, I've not read the workshop manual so couldn't gainsay it. If that is the case, then surely an aircraft grade threadlock should address such a concern?

 

The way I see it is that the original sprag lasted for more than 25 years so can see no reason to think a new one, with a good battery should break very soon. You will get used to the turning power, should fire easily, if it labours do not keep pressing the starter button, check battery.
I thought that the gear ratio was altered to improve the problem at least on replacement sprags.
I had mine done on my Sprint and it started very strongly after it was done, you soon get over worrying about it. Good luck.

 

I have a Haynes Manual which gives the following information: The engine number should be stamped into the top of the crankcase on the right hand side next to the clutch cover. The starter clutch components were modified in late 1995 from engine number 23707. The new components have a 15 tooth starter idler gear and a 51 tooth starter clutch gear. Earlier engines modified parts use a 13 tooth idler gear and a 53 tooth starter clutch gear set which appears to be sold as an assembly rather than individual parts. All seems a bit confusing but hope this helps.

 

I replaced the sprag twice on my 1993 trophy the first with an ebay one!!! and a few weeks later with a new one from Triumph ( lesson there).
The new one was slightly bigger and required a little metal removed from the crankcase. I am lucky that my early model has the removeable lid so that the change could be done with engine in place, biggest problem was reassembly of the clutch drum centre splined sleeve ( some swearing needed ).
I made up a special tool to hold the alternator drive to allow the bolt to be undone and replaced, and to lock the clutch drum I bolted an inner and outer plate together with four short self tappers ( file of any burrs before refitting )
no problems with this system ( I am a qualified Bodger )
Yes all remarks on here about battery condition and cold starting are endorsed.
Take it steady and good luck.

 

Your pictres made me thankful that I have an ealy model with the lid over the sprag! Enables change without stripping the engine.

I have today put new chain and sprockets on my Trophy and came across the "special "tools that I used for the tool to lock the alternator drive to allow undoing the bolt on the other end, and the clutch locking plates to allow clutch center nut to be undone and tightened up again.
The nut on a stick is the one that hides behind the gearbox on the end of the bolt that holds the left footrest, it is the standard nut with a 2BA bolt about 3inches long screwed into one point of the nut, once the footrest bolt is tightened the 2 BA bolt stays in place until the next footrest removal. I gripped the extension with a small vice grip to give enough length for the job.

 

Lets try to upload the pictures again!!

 

Nice one. Trust me, you soon stop stressing out about the starter if you have a good high power battery fitted. Don't scrimp and get the biggest cca you can that fits, think mine was a 220 cca, some sellers will sell you a 150 cca.