SA primary chaincase wanted

[Dean]

I have finally discovered why I could never get the belt drive clutch working properly. I need to aircool it!
So does anyone have a spare outer primary case that is in a bit of a state and therefor OK to hack about to make ventilation holes?

[Rocket Racer]

If for a road bike, you could always consider ventilating the inner cover not the outer. They are more commonly available (I think I have half a dozen inner cases spare but only one good spare outer)

By opening up the inner cover you can make access to the gearbox sprocket a doddle, the inner cover can be fitted without removing the clutch, just slipping the belt off.

The other advantage of opening up the inner case is externally the bike looks stock.

If you wanted to go that way and cannot source one, please PM me and make me an offer... 

[Klaus]

Hi Dean,

I use a belt drive in two Beezas and have no problems about this, fit no ventilated chaincase.
Whats you problem, clutch drag?
This will case in other things but not the belt.
May be the belt is too tight? Check this, by twisting the belt in nearly 90 degrees.

cheers Klaus

[Dean]

Hi Rocket racer.
Thanks for your tip on opening up the rear cover. I'm glad you said this because I had been wondering whether it was the way to go. I think I have seen some inners on ebay. I'll see what thay are going for and then get back to you.

[Dean]

Hi Dean,

I use a belt drive in two Beezas and have no problems about this, fit no ventilated chaincase.
Whats you problem, clutch drag?
This will case in other things but not the belt.
May be the belt is too tight? Check this, by twisting the belt in nearly 90 degrees.

cheers Klaus

Hi Klaus
Yes clucth drag and difficulty engaging gear from neutral when the engine has warmed up. On bad days I end up holding it in first on the cltch at traffic lights to make sure I can get away. Of course this is likely to heat up the plates even more!
I have been living with this for 10 years (OK its not  a daily drive) and in that time have tried every adjustment.
Then the other day I came across the cooling advice (ATF or ventilation) on the internet.
I am on the verge of giving up with the belt and going back to standard, especially as the belt is running inboard and rubbing on the inner primary as well.
I have collected the parts to go back to standard and have fitted them this morning only to discover the shock absorber nut is stiil not fully home before it locks up on the sliding sleeve!
Getting close to bucket of petrol and a box of matches with this

[chaterlea25]

HI Dean,

I have collected the parts to go back to standard and have fitted them this morning only to discover the shock absorber nut is stiil not fully home before it locks up on the sliding sleeve!

That is correct, the nut should pull the crank /push the drive sleeve solidly together
See the guide I put together here
http://www.a7a10.net/forum/index.php?topic=9646.msg70166;topicseen#msg70166

A common problem with belt drives that use the original clutch roller bearing if they are run dry is that soon the bearings loose their lube, then this can cause drag
Secondly, on the clutches that retain the standard triumph type cush drive, wear on the cush drive side plates and spider causes excess side play in the chain wheel leading to wobble and drag

A big disadvantage of cutting the cases is that all sorts of road dirt get in there and causes more problems

Have you considered an oil proof belt and oil in the primary ? this is what I did with a Tri**ph that came with a Hayward drive, its working well now

HTH
John

[Dean]

Hi John and thanks for your helpful advice.

Yes I have the oilproof belt and since my last post I've decided to give the belt drive another chance. I was thinking of avoising the oil option only because the cases are pretty old and may prove hard to get oil tight. However as this is an area where there are unlikely to be problems with being generous with the bath sealer ( ) I'll give oil a go.

I need to do more reseacrh to find out what is going on with the original crank cush drive in the event I want to change back to chain drive.

Yes the nut does do up tight against the sleeve and the sleeve against the spacer, bearing, crank as you describe. The problem though is that when is had done this there is no crank thread protuding thrugh the nut so the split pin cannot be fitted and the outer case cannot be fitted as it is held off by about an eigth of an inch!

[bsa-bill]

The problem though is that when is had done this there is no crank thread protuding thrugh the nut so the split pin cannot be fitted and the outer case cannot be fitted as it is held off by about an eigth of an inch!

Something wrong there Dean,
an eight of an inch is about the thickness of the spacer between crankcase and inner primary cover ???
That would not explain the pin not having a hole to live in, perhaps some wrong bits there

[Rocket Racer]

A big disadvantage of cutting the cases is that all sorts of road dirt get in there and causes more problems

John

John,
 I'd have to disagree with you on that point; an awful lot of (or possibly a lot of awful) road bikes run belt final drives out in the open without any issues.
Due to my track use, mine is excessively ventilated front and rear and even with excursions to the kitty litter have never had any  issues.

However, I wouldn't expect ventilation to be necessary to prevent slip.
so yes other things at play here
Tim

[Dean]

Tim
my problem is drag, not slip, which I understand may be due to overheating clutch.

John
I've had a look at your very helpful detailed post on the cush drive set up. The photo you have posted showing the relative rotation of the sprocket cams was really helpful. It shows the full extent of rotation and if I rotate mon ey the same amount I still have about a quarter of an inch free(ie redundant) spline between the cam and the nut. If I shorten the sleeve by this amount the nut will then thread on enough to expose the split pin hole. I must have a sleeve off another model?

[Rocket Racer]

I can't comment on your clutch but certainly my BNR clutch takes a beating with race use and has been impeccable, no drag, no slip.
When I'm sitting on the grid holding it in gear waiting for the flag then nailing it off at launch while also cooking in my leathers, am glad of any ventilation I can provide.
But for a road bike it just shouldn't (famous last words) be necessary (but can't hurt).

[chaterlea25]

Hi Dean,

Yes the nut does do up tight against the sleeve and the sleeve against the spacer, bearing, crank as you describe. The problem though is that when is had done this there is no crank thread protuding thrugh the nut so the split pin cannot be fitted and the outer case cannot be fitted as it is held off by about an eigth of an inch!

Go to the bottom of my post and compare the shoulder depth and length of the crank sleeve
Then you need to check sprocket alignment
Ignore the splitpin, my opinion is that its a waste of time !!! use loctite thread locker
What make of clutch is fitted? the wear I described leads to drag


RR

I'd have to disagree with you on that point; an awful lot of (or possibly a lot of awful) road bikes run belt final drives out in the open without any issues.
Due to my track use, mine is excessively ventilated front and rear and even with excursions to the kitty litter have never had any  issues.

Final drive is a very different kettle of fish, 
much lower belt speed and room for bigger belts, yes they fail too

Road dirt gets everywhere especially with a climate like here,
The Triumph I rebuilt had picked up lots of metal particles that were attracted to the alternator rotor
imagine the mess!!!
The roller clutch bearing was a total mess from grit

Regards
John

[Rocket Racer]

Road dirt gets everywhere especially with a climate like here,
The Triumph I rebuilt had picked up lots of metal particles that were attracted to the alternator rotor
imagine the mess!!!
The roller clutch bearing was a total mess from grit

fair comment, I don't have an alternator rotor to collect swarf and my clutch runs a sealed bearing, so a different animal...

[Klaus]

Driving belts fully enclosed in Roadbike and open on the racers. I never had a fail with the belt on Roadbikes, but with the racers. I never expeceted such a drit on the race tracks with little stones picked up and punched the belt and pully.

I had BNR cluches and NEB ones. The advantage with NEB is the closed bearing the clutchbasked run on. You can dismantel without loosing any rollers and no lubrication need. By good tuning the pressure plate stops by pulling the clutch lever, with no engaged gear.

So I guess the problem is not the belt himself. Have a look at the rod and  his operatinglever. Also the springtension is with no wobbling the pressureplate.

Klaus

[Dean]

Thanks for all your helpful input guys.
I've spoken to Tony Hayward and he has advised checking my gearbox alignment. Fair enough given I'm usig alloy engine and gearbox plates. I've got an extra gearbox adjuster on order I'll have one on each side and can tweet the gearbox alignment with the cases off and the engine running to get the belt run right.
If that faisl or I loose too many fingers I will revert to chain. In which case L'll chop a quarter inch off the end of the sleeve to get the nut sufficiently inboard.

I'll keep you posted although with fewer fingers my tryping might be even worse that usual.