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Dominator gearbox/clutch problem

Submitted by ken_rawlinson on Mon, 10/06/2024
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Heavy Twins
The 1959 ex Paul Smart 600cc Dominator which is immaculate and was totally rebuilt by a mechanic friend of Paul's "lurches" forward when pulling away in both first and second gear, The clutch was totally stuck when I got the bike so I had to free the plates by stripping it down, the plates look like new and the clutch looked in very good condition, a lot of money having been spent on the bike. Thanks, Ken 

Submitted by bob_matthews on Mon, 10/06/2024

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Hi Ken Sounds like the clutch is grabbing to me.  You could put it in third or fourth with the throttle open and slip the clutch for a few seconds at a time to see if that helps to bed it in, but failing that, I suspect it's a clutch strip down again and check all the plates for flatness on an engineer's surface plate - or the kitchen worktop as an alternative - wife permitting that is :)

Submitted by paul_standeven on Mon, 10/06/2024

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can be obtained from a local glazier, and will allow you to flat the clutch plates and also any casting that need to be sorted.  No need to annoy 'she who must be obeyed' Paul

Submitted by howard_robinson on Tue, 11/06/2024

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Hiyah Ken - Were the shock absorber rubbers new or new old stock ?  I have had similar issues when the rubbers are too hard or too soft.   You probably know this anyway but other readers may not.   Is it an SS eleven-plate clutch or the nine-plate standard fare ?  Cheers, howard  

Hi Bob, The clutch had been totally rebuilt by Paul Smart's mechanic and I have receipts amounting to £1,000's spent on the bike including a clutch rebuild with new rubbers, the speedo only has 250 miles on the clock and I think that this was reset when the bike was rebuilt. The clutch plates were extremely stuck together when I got the bike and I had to use brute force to separate the plates which I tested and they were flat. The plates do stick together even if the bike is left for a few days so I have to pull the clutch in when standing by putting a strong elastic band round the clutch lever. I think that I will try putting some old plates that I have in the clutch. Thanks, Ken

Hi Howard, See reply to Bob, new rubbers fitted during rebuild but I do not know whether they were new or old stock, I think that there are the standard 9 plates but I will need to check. I will try fitting some old plates that I have. Thanks, Ken

Submitted by ian_soady on Tue, 11/06/2024

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... passed to me by Tony Cooper of dynamo and magneto fame was to drop a 3/8" bolt (Cycle thread for the purists) between clutch lever and its abutment when the bike is left standing. This raises the clutch slightly and helps to prevent the plates sticking. Bet to free up before by operating the kickstart with the clutch fully lifted. Although your problem sounds as if maybe the friction material is incorrect.

Submitted by ken_rawlinson on Wed, 12/06/2024

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Hi Ian, thanks for the tip. Yes I agree as I do now think that it is the friction material grabbing the metal plates rather than slipping and gradually taking up the grip on them. I will change the friction plates, a bit of a pain as I have got the chaincase nice and oil tight although my method for this has worked in the past. Best regards, Ken

Submitted by ken_rawlinson on Fri, 28/06/2024

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Hi all, the problem with the clutch grabbing on the Paul Smart Dommie has been resolved, it was the new clutch plates that had been fitted during the rebuild. I have fitted a good set of old plates that I had and the bike is now OK. Thanks for all of the advice. Ken

 


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