Welcome to the Access Norton Forum. Login as a VIP member to remove the advertising banners.


gearbox sprocket & belt drive

gearbox sprocket & belt drive

Postby chrisf1 » Fri Jan 01, 2016 7:07 am

Hi again everyone and a happy new year to you all. I will shortly be changing my norton gearbox for a triumph and will be fitting belt drive at the same time, I would like to know what size sprocket to use ? as for personal taste I like the idea of being able to lift the front wheel but I do not like the short gears that go with it I would much prefer to be able to hold it in the gears that bit longer without the engine screaming change me so suggestions and reasons please, also as I said I will be fitting a belt drive at the same time will I need any shock absorbent with a belt and if so what is reccomended I am or will be running an alternator many thanks everyone

chrisf1
Posts: 125
Joined: Sun Aug 23, 2015 4:22 am

Re: gearbox sprocket & belt drive

Postby Fast Eddie » Fri Jan 01, 2016 8:27 am

Stock pre unit Bonnies were 18/46 I think. If you like low gearing, this may be a good starting point.

I personally think stock Triumph twins always seem low geared.

My 750 TSS road bike was 22/46. I have run tuned Triumph twins as high as 23/42 with raised primary gearing too!

For belt drive, Newby is popular. But on Triumphs and even big Weslakes I always used Hayward kits. This keeps the Triumph clutch which can easily be upgraded with more / better plates and has the benefit of a half decent shock absorber built in to the design.
User avatar
Access Norton VIP Paying Member
Fast Eddie
VIP MEMBER
Posts: 3480
Joined: Fri Oct 04, 2013 12:48 am
Location: Oxford, England

Re: gearbox sprocket & belt drive

Postby J. M. Leadbeater » Tue Jan 26, 2016 7:49 am

Since when did Triumph twins have a reaL clutch fitted?? A great many years ago one Saturday afternoon I conducted a little clutch survey amoung some Triumph and Norton owners visiting Motor Cycle Shop in London.....remembering that a gearbox mounted motor cycle clutch is suppossed to ..
NOT slip when fully engaged even when hot....
Free off INSTANTLY without drag whenever required even when hot...
Be EASILY operated by the rider...
Possess the LIGHTEST rotating weight reasonably possible...
then the survey results might prove interesting.....

The following motorcycles were represented that afternoon:
Triumph: 5 x T140; 1 x TR7; 2 x 6T; 1 x T120; 2 x T100; 2 x T90.
Norton: 2 x 820 Commando; 2 x 750 Commando; 1 x 650SS; 2 x 99.
BSA owners were very few and far between so I have not bothered to include them.


Triumph Norton
YES NO YES NO
1. Are you happy with your primary drive system? 10 3 6 1

DOES IT SUFFER FROM…………

2. Clutch slip due to oil on the clutch plates which is cured by removing the oil
from the plates? 4 9 5 2

3. Clutch drag which requires the clutch to be ‘freed off’ prior to starting the bike? 8 5 5 2

4. Clutch drag immediately after starting the bike, making gear selection noisy? 7 6 4 3

5. Clutch drag when the clutch is hot, making gear changing and finding neutral
difficult? 9 4 4 3

6. An aching left wrist during or after a journey due to heavy clutch lever operation? 7 6 2 5

IF YOU HAVE ANSWERED YES TO ANY OF THE QUESTIONS ABOVE (2,3,4,5,6), DO YOU

7. Regard them as problems which are annoying? 11 2 6 1

8. Regard them as problems, but which are ‘normal’? 12 1 5 2

9. If you bought a motor car and had ANY of these clutch problems occur would you
consider them to be ‘normal’? 0 13 0 7

Two owners answered YES to only 2 of questions 2 – 6 all others answering YES to more than 2.

4 of the 5 T140 owners and all 4 Commando owners answered YES to question 2.

All 5 T140 owners and both 820 Commando owners answered YES to question 6.

Q. E. D.?????

J. M. Leadbeater
Inactive
Posts: 322
Joined: Tue Apr 21, 2015 4:22 pm

Re: gearbox sprocket & belt drive

Postby Fast Eddie » Tue Jan 26, 2016 7:41 pm

J. M. Leadbeater wrote:Since when did Triumph twins have a reaL clutch fitted?? A great many years ago one Saturday afternoon I conducted a little clutch survey amoung some Triumph and Norton owners visiting Motor Cycle Shop in London.....remembering that a gearbox mounted motor cycle clutch is suppossed to ..
NOT slip when fully engaged even when hot....
Free off INSTANTLY without drag whenever required even when hot...
Be EASILY operated by the rider...
Possess the LIGHTEST rotating weight reasonably possible...
then the survey results might prove interesting.....

The following motorcycles were represented that afternoon:
Triumph: 5 x T140; 1 x TR7; 2 x 6T; 1 x T120; 2 x T100; 2 x T90.
Norton: 2 x 820 Commando; 2 x 750 Commando; 1 x 650SS; 2 x 99.
BSA owners were very few and far between so I have not bothered to include them.


Triumph Norton
YES NO YES NO
1. Are you happy with your primary drive system? 10 3 6 1

DOES IT SUFFER FROM…………

2. Clutch slip due to oil on the clutch plates which is cured by removing the oil
from the plates? 4 9 5 2

3. Clutch drag which requires the clutch to be ‘freed off’ prior to starting the bike? 8 5 5 2

4. Clutch drag immediately after starting the bike, making gear selection noisy? 7 6 4 3

5. Clutch drag when the clutch is hot, making gear changing and finding neutral
difficult? 9 4 4 3

6. An aching left wrist during or after a journey due to heavy clutch lever operation? 7 6 2 5

IF YOU HAVE ANSWERED YES TO ANY OF THE QUESTIONS ABOVE (2,3,4,5,6), DO YOU

7. Regard them as problems which are annoying? 11 2 6 1

8. Regard them as problems, but which are ‘normal’? 12 1 5 2

9. If you bought a motor car and had ANY of these clutch problems occur would you
consider them to be ‘normal’? 0 13 0 7

Two owners answered YES to only 2 of questions 2 – 6 all others answering YES to more than 2.

4 of the 5 T140 owners and all 4 Commando owners answered YES to question 2.

All 5 T140 owners and both 820 Commando owners answered YES to question 6.

Q. E. D.?????


That's very interesting Mr Leadbeater...

Now, if I can refer you back to my post, I actually said that keeping the Triumph clutch is (IMHO) good because it has a half decent shock absorber in the centre. I then went on to say that the rest can be UPGRADED to make a good clutch.

When run with a belt drive (which is what this thread is about) it can be run dry. Then add an extra plate and some careful assembly, and you have a clutch that does not drag, or slip, even whilst doing race clutch starts with 84rwhp.

That was good enough for me.
User avatar
Access Norton VIP Paying Member
Fast Eddie
VIP MEMBER
Posts: 3480
Joined: Fri Oct 04, 2013 12:48 am
Location: Oxford, England

Re: gearbox sprocket & belt drive

Postby grandpaul » Wed Jan 27, 2016 7:25 am

My bone-stock '66/67/68/69 Triumph Bonneville 650 Historic Production Heavyweight roadracer clutch has never failed to operate exactly as it should from new, with no more than regular adjustment, proper lube, and cheap Emgo friction plates.

Once I got the hang of it (took 4 races), I was never bested off the line or into turn 1 in 29 race starts, typically lofting the front wheel and carrying it 30-50 feet till engaging 2nd gear. That is up against highly modded 750 Triumph twins, Tridents and OHC Honda Fours, and starting on the 2nd row in all but ONE race.

Image

Image

Image

STOCK clutch basket
STOCK plates
STOCK primary chain
STOCK gearing

Engine only .020 over, with electronic ignition. Stock everything, even heavy air cleaners, mufflers, etc.

With proper setup, the STOCK clutch is perfectly fine.

(although a carefully improved one is also fine, just a bit more expensive)
GrandPaul
author "Old Bikes"
too many bikes to list, including:
952 Prototype, MkIII Interstate, Combat Dunstall, Triton
User avatar
Access Norton VIP Paying Member
grandpaul
VIP MEMBER
Posts: 9524
View Photo Album - Images: 30
Joined: Tue Jan 15, 2008 1:11 pm
Location: Laredo (south) Texas

Re: gearbox sprocket & belt drive

Postby J. M. Leadbeater » Thu Feb 11, 2016 1:48 pm

I find it interesting to note typical Triumph twin owners thoughts on the lumps Triumph refered to as clutches. All I can say is that if ANY of them bought a motor car with clutches that worked as badly they would very quickly be returning their new car back to the dealer demanding their money back as the car was unfit for purpose. No car owner would put up with such problems.Not an owner with a brain that is.
Certainly Triumph twin clutches work OK for the average owner unaware of how a clutch should work. The same applies to Norton clutches and owners.... However even road tests reported serious problems and the writers were being paid by magazines who depended upon the advertising paid for by the motor cycle manufacturers to pay the writers!! For example in Motor Cycle Sport one Triumph tester reported...As with the last Triumph tested it was possible to start the engine with the clutch lever back to the bar. Another reported for a 650 model.....It was as easy to change gear without the clutch as with which was just as well as clutch lever action was heavy. So what did the Triumph do to increase clutch torque capacity for the 750 motor??? They fitted 30% stronger springs making clutch lever operation even heavier. When I once asked Mr Hele if he had been aware of the Triumph clutch drag problems whilst at Triumph he replied something to the effect that it was a problem they did notmanage to get round to curing.
As for the Triumph clutch so called shock absorber One Triumph Gentleman said that it was a copy of one that had been around in 1the 1920s and 'we' in the design office felt ot did not work as well as the old crankshaft mounted one used previously. Mr Jack Williams in his 1950s design note book for the AJS 7R and E95 motors stated that a shock absorber mounted on the slower rotating shaft could not work correctly as it did not possess the required mechanical movement and that he had requested a car type shock absorber mounted on the crank. Personally I have NEVER found any test results showing a BSA/Norton/Triumph clutch shock absorber to work correctly and in fact the only Triumph testing I know of was conducted with a long lever attached to a basket with the centre locked off and weights hung on the basket lever to check how far the rubbers compressed. I was told that even then Triumph got it wrong and they had to change the composition of the material after bikes had been in production for a while. (I talked with a Gentleman who worked under Mr Turner). Ever read the tale about the Harley so called shock absorber when Gates and Harley were developing the all belt driven motor cycle?? It makes interesting reading. Bet Harley owners had thought for decades that their shock absorbers were working OK....... See the S.A E. Technical Paper Series paper mimber 800972. The Development of a Belt Drive Motorcycle.
As for the use of trapizoidal toothform belts for power transmission on our motor cycles please go learn something about belts. Rotary Norton learnt the hard way..they had a UK system maker who pestered them till eventually they tried his trapizoidal toothform belts on the rotary race bike. The race shop Gent I talked with told me they did not complete a lap of the local race circuit before failing. The Rotary Norton that won that TT back in the 1990s employed a, so I was told, standard stock off the shelf 8mm pitch 25mm wide HTD toothform Gates Polychain belt on the primary and that the belt was not changed during the whole years racing.......When many years ago I checked the Poly Chain belt width on the supposed TT winning bike in the National Museum it was 30mm wide. Testing done many years ago to compare the trapizoidal and HTD toothforms showed the trapizoidal toothform belts to carry approx only 1/3 the torque that could be carried by an HTD tothform belt before ratchetting occured. .It was because of the low torque carrying capacity of the trapizoidal toothform that Uniroyal came up with the HTD (High Torque Drive) toothform in the 1970s. Ok so AT10 belts work.....so did chain......and so did flat and V belts used before chain.....

J. M. Leadbeater
Inactive
Posts: 322
Joined: Tue Apr 21, 2015 4:22 pm

Re: gearbox sprocket & belt drive

Postby grandpaul » Fri Feb 12, 2016 7:00 am

I'm definitely not the typical Triumph owner/rider..
GrandPaul
author "Old Bikes"
too many bikes to list, including:
952 Prototype, MkIII Interstate, Combat Dunstall, Triton
User avatar
Access Norton VIP Paying Member
grandpaul
VIP MEMBER
Posts: 9524
View Photo Album - Images: 30
Joined: Tue Jan 15, 2008 1:11 pm
Location: Laredo (south) Texas


Return to Triton

Who is online

Users browsing this forum: No registered users and 0 guests