The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: davedental on 16.04. 2022 15:47
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I know this is an old subject now but I could do with some advice. I have a 4 spring ‘triumph’ clutch with new friction plates and a new centre. I have a dti set up to try to get even pressure but when I press the cover plate with the clutch lever held open it never returns to the same place so setting it up evenly seems impossible. I have a new spring set and new spring screws and the steel plates seem fine. Bike still pulls away in fits and starts! Help! Bike is 1958 A7 SS
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I know this is an old subject now but I could do with some advice. I have a 4 spring ‘triumph’ clutch with new friction plates and a new centre. I have a dti set up to try to get even pressure but when I press the cover plate with the clutch lever held open it never returns to the same place so setting it up evenly seems impossible. I have a new spring set and new spring screws and the steel plates seem fine. Bike still pulls away in fits and starts! Help! Bike is 1958 A7 SS
On my 6 spring I used a dti to measure the movement of the clutch plate in 4 positions eg 90 degrees apart. The “wobble” of the plate made it not really possible take a dti measurement relative to a fixed point eg the drive inner cover.
On mine the dti went round something like 1 3/4 turns when the clutch lever was pulled in, as the plate moved, and getting the plate movement equal at the 4 points to within a quarter of a turn was good enough to ensure neutral was easily found. As you say the measurement is not 100% accurately repeatable but on mine it did repeat well within a quarter of a turn.
Using a dti this way is FAR more accurate than adjusting the springs “by eye”.
I’ve got a BNR belt drive now, for my A10 and B31, the 6 spring clutches sit in boxes on the shelf, they worked very well but now I don’t have oil leaks and the hassle if making gaskets *smile*
You won’t get smooth clutch action on the road, if there are notches in the baskets where the plate tangs wear , I guess you have looked into that?
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Which is why when I renewed my clutch plates, springs, nuts and cups, after previously changing everything else I bit the bullet and bought the SRM billet pressure plate with integral roller bearing lifter. It has made a huge difference. Easy to set up and now there’s no slip, no crunching into gear from neutral and neutral is easy to find.
This was on an A10 fitted with Triumph 4 spring type clutch.
Try a search for “SRM clutch” and you’ll find loads of info.
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Thanks for your thoughts. I think the SRM cover system may be the answer but really annoyed with myself that I can’t see why the current set up doesn’t work. I get smooth operation, no drag, no slip and I can find neutral. The only problem is I can’t pull away without kangarooing all over the place! All the friction plates are new and the steel plates look flat with no damaged tabs.
SRM here I come!
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Has the Triumph clutch got the cush built into the driven centre? If so with a conventional cush arrangement on the front sprocket there are two areas of flex within the primary drive. Unlikely, but you never know. Make sure that front sprocket nut is good and tight, always assuming the correct parts are fitted.
Otherwise a change of clutch cable may help. If all else fails it must be down to the new friction material needing to be shown who's boss. I'd recommend Bergs as a man who could warm a clutch up in a matter of moments.........maybe that style of take up will achieve the result.
Swarfy
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Hi Swarfy, no it’s not a Cush drive version and the clutch centre is torqued to 65 lbft. The crankshaft nut is also f tight. You may be right about the new friction material causing issues, I may try again with the old plates as a comparison. The bike was a bit of a basket case when I bought her so I never had the chance to ride and try out the engine/ clutch etc. Everything else is sorted so this last thing is exasperating
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I was going to add that my new SRM clutch plates while working very well with no sign of slip, as before, are now almost too grippy. The clutch action is almost like a switch, either in or out. With care I can drive it smoothly but it is no longer forgiving of any shoddy lever work!
Another thing may be primary and final drive chain tension but you’ve probably already checked these. I also run mine on the slack side and don’t get the kangaroo effect despite living down under *smile*
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Sudden clutch action can be caused by the wrong handlebar lever.
These were made with 1 1/16 inch centres and 7/8 inch centres. The former give a more sudden action with heavier lever action and more lift at clutch end, the later give a lighter more progressive action but with less lift at clutch end.
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Thanks for that, I had not realised there were differences in the rotational centres before. I do get a lot of lift so that’s a possibility. I’ll be sure to check that
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Dave
Further to the good advice you’ve already received also pay attention to the clutch cable (quality & routing) and the position of the clutch operating arm on the gearbox lever arm.
Useful links below
https://www.a7a10.net/forum/index.php?topic=16044.0
https://www.a7a10.net/forum/index.php?topic=15344.0