Girder fork rebound springs.

Your 125mm (5") is about the same as my 16H. It's sitting in the shed and the coils are a little bit open. It's certainly not slack...the clevices are in tension. Over the pins it's just over 6".

Inter springs are normally parallel whilst all the others are barrel shaped. Does anyone know why?  The length over the clevis pins is the same.

David, I understand Inter’s were also barrel form; only the works competition machines had the parallel springs from 1937/8 which rolled on with various tuners getting/ making them later.    

Cheers

Jon

Thanks Jonathan...another tiny piece in the jigsaw of knowledge!

....show the 3187 'Rebound Spring' for 'All Models' in the pre-war lists, up to and including 1939. The books don't show anything relating to the bikes built to 'Full Manx Racing Specification.

hi Iam new to the club,I’ve got a 1929 model18 with best Lloyd 9200 pump total loose system .can anyone tell me how much oil I need to put into crankcase after rebuild and what to use .also I’ve got a hole in the barrel which comes out on the base of the cylinder there two base gaskets one metal one paper not sure why both  holes which match the cylinder one however there’s no hole in the crankcases.any thoughts

John:

Your question about your 1929 Model 18 Total Loss Oiling System (lucky sod) had been appended to Peter's question about rebound springs.

The answers you are looking for might not be forthcoming as the members that have the knowledge you need might well have skipped over Peter's question about rebound springs.

It would have been better if you had generated a new question in the same forum but with the title something like "Best and Lloyd Model 9200 total Loss System"

Hopefully, then the members with the knowledge you need will see the question and reply.

All the best

Mike 

The reason rebound springs are barrel shaped (apart from appearance and ease of end connection) is simply that they provide a measure of variable rate, ie each unit of load applied results in a decrease of extension or compression. Have a look at your seat springs for example.

The same effect in parallel springs is achieved by changing the pitch of the coils - if you can be bothered have a look at the suspension on a car.

I would not trust a spring for critical use unless I knew what material it was made from; it needs to be high carbon steel in order to take a temper which in turns partly determines the spring rate.

The hole centre on the springs on my 1938 Model 50 are 6 1/8" installed. 

I hope this helps.

John Stapleton