My Atlas clutch slips a bit when its cold but after 5 minutes or so of riding it stops slipping. I recall it didn't do that until I managed to get the jetting and carb tuning spot on, at which point there was quite a bit more oomph from those high compression pistons. It's actually not a problem, its even quite a quirky characteristic of the bike. I just don't give it a wristful when I'm setting off and after a bit there's no problem.
The plates were all in relatively good order when I took the clutch apart several months ago. They were really gummed up from standing for decades but there was no warping and they cleaned up nicely. I made sure that all the indents in the splines were smoothed out. In fact, I spent quite a bit of time and effort on the clutch to ensure it operated smoothly.
Selecting first gear is and always has been a crunchy affair but thereafter it's smooth as silk.
Worn springs maybe?
The primary oil level is correct, i.e. just lapping onto the bottom of the primary chain
More than likely due to…
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The oil thins out as it…
The oil thins out as it warms up.
I had similar problems with Surflex plates until I relined them with cork.
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I thought about that (the…
I thought about that (the oil contaminating the plates & then spinning off) but the oil shouldn't actually get onto the plates much if the primary case level is just lapping onto the bottom of the chain, which it is. I'm using W20 oil in there. The plates are old, at least 50 years old anyway. They're bonded plates, which all looked pretty good once they were cleaned up; the plain plates looked ok too.
Like I said, it's not an issue. Goes away after a few miles and then the clutch is strong and doesn't fade.
I'll fit some stronger springs next time I check the primary case internals and see how that works. I'm probably going to change the 19 tooth engine sprocket to a 20 tooth at the same time, just to reduce the revs a bit
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If you shuffled the plates…
If you shuffled the plates when cleaning ( normal !) then they will take a while before they blend together . The slight slip/lag in grip can be utilized to drop the clutch for a fast getaway to rid youself of a pesky tailgator at the lights .
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Slip sliding away
Two points to write about. Robert has named one of them. ie. if the plates are replaced in a different order then, like brake linings, they have to bed in again before working 100%.
The second biggest problem with the Atlas clutch is its design. It just isn't up to the job that it is expected to do. The original Model 7 clutch was designed to cope with no more than 29bhp and not the 49+ of the bigger engines. Add on around 3 times the original torque; all being handled by a pressure plate with just 3 springs. These springs were thickened and shortened in the Atlas (& 650) clutch but just added to the slippage problem.
If the spring adjusters were screwed in to stop the plates slipping you then need the hand of a Gorilla to operate the clutch lever and put up with the regular cable end breaks.
There are a few modification suggestions on this WebSite giving good advice on how to get the best of both worlds. ie. light action and no slippage. Of possible comfort to Atlas owners being that Commando clutches were equally prone to slipping.
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Based on these responses it…
Based on these responses it sounds like this ol' clutch aint doing that bad then. Maybe I'll just leave it be. I've only done about 300 miles since getting it back on the road so maybe it'll sort itself out.
This engine does produce a fair few horses that's for sure. The clutch action is pretty good at the mo; i.e. not that hard to pull in. I replaced the original chrome levers with dog legged alloy ones which actually made it even better. The spring adjusters were tightened down to the top of the studs when I rebuilt it and I was careful to keep the original order when putting the plates back.
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Slipping clutch
Graham,
In your photo some suggestions.
The cable outer looks very second hand where it goes into the adjuster.
The lever looks hard up against the lever bracket, as though there is some residual tension in the cable. You need free play.
The slot on your cable adjuster is vertical. Try arranging so that the slot is back facing. This gives a much better path for the cable inner as the clutch is operated.
The locking ring goes against the bracket as I'm sure you know.
Anything that results in residual tension in the cable inner, like a few broken cable strands, will tip the clutch towards slipping.
The cable is a much simpler fix and I hope it works for you.
Peter
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There is actually free play,…
There is actually free play, about 5mm, it just doesn't show in the pic. The cable's ok, albeit a bit tatty on the outside and it's lubed. I don't think it's the cable.
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More than likely due to slight oil contamination on the clutch plates. As you use the bike, the clutch spins any oil out with centrifugal force and so doesn't slip after a few miles.