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#196024 - 08/01/06 9:36 pm Re: belt drives  
Joined: Apr 2006
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johnm Online content
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Thank you for this data. I spent some time last night plotting up the belt / chain data and calculating primary and rear chain speeds for a range of sprocket combinations, engine rpm and maximum speeds.

From your data I guestimated about a max chain speed of 4800 ft / min for reasonable efficiency but noted that the test did not specify chain size. I imagine larger chains would be worse.( I assumed the 6000 ft/min value was for the 90 mph values)

Anyway for a range of typical Dommie primary engine sprockets from 18 to 23 teeth and engine rpm from 6400 to 7400 the speed of 4800 ft/min is meet only for an 18 tooth sprocket and 6400 rpm. Every other combination is faster eg a 23 sprocket at 7400 rpm is 7092 ft/min. A recommended minimum sprocket size of 19 teeth has a chain veocity of 5067 ft/min at 6400 rpm going up to 5542 at 7000rpm.

Hence the enthusiasim especially on race bikes for belt drives.

For the rear chain I didnt find such a problem becaue the rpm is lower. I calculated for an Avon 110/80 18" race tyre and found for the same 4800 ft/min threashold a max sprocket size of 54 teeth at 120 mph and 48 at 130 mph.

I was disappointed to hear your comments on the availibilty of "real" Renold 5/8 * 1/4 rear chain. We cannot get any Renold chain down here and therefore hunt out the lightest Japanese chain which is still heavier than we would like.

However I dont think I can agree with your statement "Only an idiot would run a 3/4 oitch rear chain on say a Triumph...lots do...... " unless you are meaning high speed competition machines only.

If I were using a bike in everyday use, poor conditions, average to low speeds I would very definitely look at heavier and more robust chain. On my calculations the data you supplied does not seem to indicate significant loss in efficiency for rear chains using sprockets and wheel sizes for typical British machines under average operating conditions up to at least 100mph.

This does assume however that the 6000 ft/ min figure quoted corresponds to the 90 mph figures in the Harley test. If it does not then my calcualtions are in error.Does the article support this assumption?

John

#196025 - 08/06/06 3:56 pm Re: belt drives  
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BSAPhill Offline
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Zzzzzzzzzzzzzzzzzzzzzzzzzz

Whoever "Beltdriveman" man is he needs to get out and get a life, not hang about with his so called "big bosses".

Name names, don't hide behind techno babble.

I deal with three different oil companies, and all three differ on what is right and what is wrong with differernt oils for different applications, thus i feel it will be the same for belts or whatever else you care to research, there is so much conflicting data out there that it really is a matter of suck it and see.

#196026 - 08/06/06 11:21 pm Re: belt drives  
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beltdriveman Offline
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Nice to see that one poor soul actually believed
Mr Haywards claims that his belts were designed to run with oil and bought a system to do just that. It proves yet again that bull**** baffles brains......
RACT. Mr Haywards Synchroflex AT10 belts UK agents were and still could be Power Transmissions down in Poole, Hampshire, UK. MANY years ago I checked up on this Hayward claim and was told in a letter from their Engineering Director that the AT10 belt was DESIGNED TO BE RUN DRY.( I believe the Gent is now Chairman of the Company.
FACT. Later on in the NOC mag Roadholder Mr Hayward told everyone that he recommended his dry belt users to keep their belts well greased!! AND i bet there were brain deads who did so!!! He also stated that the AT10 belt was more efficient when run with oil. Uniroyal had done testing of their belts with oil years previosly and found that H.P. were thrown away pumping oil out from between the belt and pulley ( In those days and probably even now Uniroyal belts could be bought for use submerged in commercial engine oil although why anyone would want to do so ......)... It was pointed out in Roadholder that Mr Hayward was wrong and he later changed his 'facts' stating that the power losses due to oil were so small they were difficult to measure...a YEAR later a letter from Power Transmission in reply to my questions I had sent to the German belt manufacturer who had told their UK agents to answer my questions stated that no testing with oil had been carried out so where the hell Mr Hayward was getting his 'facts' from........or was it just more bull**** knowing the average British Biker is so stupid they will believe anything ???
For info there were photos of a toothless AT10 belt from a 3 in Triple Echo a few years back (Iss 49 I believe) and a friend who used to build race 3s motors for people as his main business had had to rebuild at great expense a few motors where AT10 belts had stripped their teeth and steel worn from the tensile member had entered the engine oil supply and wrecked the motors. One gent with a BSA 3 who had this happen I know demanded and got back his money from a Derbk dealer who had sold him the Hayward belt system .
Now I am NOT saying the AT10 belt or its newer version is a bad belt but DONT believe the lies you are told about it. Some may of noticed that instead of stating that the AT10 belt is the highest revving and strongest belt.... he has now changed it to IN HIS OPINION theAT10 belt....... He was told to change his advert by the Advertising Standards Authority!! If ever you meet someone from the Norton Rotary race shop ask them if they ever tested Mr Haywards AT10 belt on a race bike and if so what happened...... Personally I would not use it because the modern belts are so good I would happily run a 20 mm wide belt on a 650/750/850 British twin both for road and race. For example if you were to rate an olde Uniroyal Powergrip 8mm pitch HTD belt of a given length and width running on given sized pulleys carrying Z amount of torque over 10 to the power 7 belt cycles at 25 Nm then a Uniroyal-now Gates Poergrip GT2 is rated ar around 53Nm and a Powergrip GT3 at 63 Nm with a Gates Polychain GT2 at 64 Mn and a Polychain GT3 at about 85Nm At10??? About that of the Powergrip HTD at a guess.
As for people stating that belts fail this is NOT normally a belt problem but the result of other problems. Hell chainf fail as well often the result of incorrect tension of incorrectly aligned sprockets or simply die to lack of lubrication and when they go they take your nice polished chhaincase with them!! .It is either the fact that the idiot who made the system has not made it correctly OR the user has fitted it incorrectly Its all toooo easy to blame the belt OR chain when it fails rather than investigate the problem to find out WHY it failed and thus LEARN as you do so.
If you go fit a belt to a std BSA or Tri clutch the pulleys wont even be parallel with each other.. the belt overhangs the rollers and with the clutch partly freed off the basket is being forced into the thrust faces and is not parallel with the engine pulley.Plus the poor old gearbox mainshaft is bending .......Even using a chain if you use the throtle as we used to do in our young days you need a gearbox mainshaft support bearing although to date I have never seen a well designed or made one commercially available
Today the Mead Brother and Sister were out again ploughing around on their 800cc plus A65 scrambles outfit and apart from throwing Miss Mead out of the chair once the 30 mm wide olde technology belt running on a four friction plate diaphragm spring clutch I cobbled together for them a while back has once again worked perfectly and I fully expect it to do so till the system gets its £10 Christmas present of a new belt for next years fun and games......so I would suggest that the gent having belt problems on an A65 should find out WHY he has these problems and LEARN.Personally I would NOT use a belt with a std BSA Triumph or AMC etc so called clutch. However there were people winning Vintage Championships in the USA on their Triumph using such clutches as part of their USA made QPD belt systems.. Mr Frank Shockley and Mr Robert Smith for example in the early 80s and Mr Jack Wuilson was also using QPD belt systems on his Triumphs to win National and Open championships as long ago as 78....... over 25 years ago......And lets NOT forget that the Norton Rotary won a TT using either a 25 or 30 mm wide belt(which apparently did the whole season without being changed) and NO it wasnt an AT10 belt but a Gates Polychain off the shelf 8mm pitch belt.....since then there have been the GT2 and GT3 versions.....
As for cush drives or shock load increasers(As Harley found out) I defy ANYONE to find any instance of shock absorber development by BSA, Triumph or Norton. I also defy any of you to find any published test results for a rear chains' efficiency when running at high chain speeds of, lets say,4000 ft per minute.
there you are, find out and tell mne some facts. Tritonsmashar or farter or whatever will naturally say he is far to busy to do such research.....lifting the phone is of course really hard work......as is learning.
No checks done.. Way past bed time!!

#196027 - 08/06/06 11:35 pm Re: belt drives  
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My head just exploded again!


,_o
_ -\_<,
(*)/'(*)

NOPGS #2
#196028 - 08/07/06 5:09 am Re: belt drives  
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johnm Online content
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A challenge I admit but some useful data is buried in there.

My take.

In general primary chains are operating outside their original industrial design envelope much of the time -and almost all the time under race conditions

The data above is the only test data I have seen which compares chain and belt performance.

Rear chain performance is not such an issue.

Rules permiting, belt drive is the norm for top level race competition and has been for nearly 20 years

Belts are not created equal and the original supplied article may not be the best available.

If you go to your local friendly belt supplier (as I have done) and ask to look at the manufacturers technical data specs you will find tables of recomended service conditions in rpm versus torque (or hp) for each belt size and type.

Most manufacturers sell at least three different strenghts of belt for each size and you can get double the strenght for about 20 % extra money.

Setting up a belt isn't always easy and can be a challenge.

Do not bother to try and fit a belt drive to an AMC 1950s early 60s clutch (Dommie Atlas) with the 1/4 " rollers in a pressed steel cage. I promise you this will drive you to drink !! The belt overhang is too great and the belt will twist the drum and cause drag no matter how far you try to slacken the belt. Always use a proper sealed bearing in the middle as in a commando type cluch.

I use a beltdrive and Commando type on my Dommie 500 race bike and a standard normal chain and clutch on my street Mk 11 850 Commando. Both work.

#196029 - 08/07/06 11:48 am Re: belt drives  
Joined: Aug 2001
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Rich B Online happy
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So John RGS, how many times has your head exploded trying to absorb this stuff? Is it 2 or 3? laugh


Life is too short to drink cheap, bad beer.
#196030 - 08/07/06 12:20 pm Re: belt drives  
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belts are for pants

#196031 - 08/07/06 1:12 pm Re: belt drives  
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Britbodger R.I.P. Offline
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I can relate to bad experiences with Hayward belts when used in oil. I am one of those gullible idiots who swallowed the propaganda put out by Hayward before he had to retract it.

In my case I had retro-fitted a Hayward belt drive one of my road going BSA Rocket Threes. The teeth subsequently stripped leaving me with no drive. Worse though was that the belt slid off the pulleys bending the gearbox main shaft. Also oil pump gears ruined and bits of wire everywhere meaning a complete engine strip-down frown .

P.S. Iíve heard that having oneís head explode can be quite painful. Hope that you are on the way to recovery RGS after having had yours do that - again.

#196032 - 08/07/06 2:50 pm Re: belt drives  

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Is there any hint in the belt info about material composition? IIRC most rubber includes some petroleum (including tires) as a softening agent, which means that adding oil will decay the belt, only a question of time.
I'm perhaps not entirely logical here, but I instantly reject any product for which the manufacturer makes a demonstrably spurious claim.
I'm wresting with this for a different reason: trying to drive a blower, where minimizing shaft tension is a high priority and chain speed will be higher than I would like unless I fabricate the whole thing (many rows of tiny Japanese cam chain, etc.).

#196033 - 08/07/06 3:10 pm Re: belt drives  
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So if you've got a Hayward Belt on your bike (T140 and there when I bought it) should you swap back to chain?

I could have walked the 30 yards over to see the Meads and asked them about their Sidecar's belt drive in the pits yesterday but it was too hot!

Tom

#196034 - 08/07/06 3:51 pm Re: belt drives  
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beltdriveman Offline
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As the gent said in this Classic Motorcycle test of a friends Triumph Saint not long ago with its 4 friction plate diaphragm spring clutch fitted along with a very olde technology 30mm wide Gates HTD belt...the primary transmission was 'a revelation'.
And thats the real benifit of belts....you and I can ride our British Iron with a clutch that works CORRECTLY just like every car clutch.
Just in case you have never seen the litle survay I did about 25 years ago..when people used to ride their BSA Triumph and Norton motorcycles and wear them out so wrere always visiting spares emporiums......!!!!
Done one Saturday afternoon in Motor Cycle Shop in London. Customers were asked if they would PLEASE fill in a questionaire answering yes or no to a few questions. It was one of those days when few BSA owners appeared so only Triumph and Norton results are shown...
TRIUMPH. 5 x T140 1 x TR7 2 x 6T 1 x T120
2 x T100 2 x T90.
NORTON. 2 x 820 & 2 x750 Commando. 2 x 99
1 x 650SS.
Answers listed... Triumph YES/NO Norton YES/NO.
1. Are you happy with your primary system?
10/3 6/1
DOES IT SURFFER FROM......
2. Clutch slip due to oil on the clutch plates cured by removing the oil from the clutch plates?
4/9 5/2
3. Clutch drag that requires the clutch to be fred 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 after a journey?
7/6 2/5.
IF YOU HAVE ANSWERED YES TO ANY OF QUESTIONS 2 - DO YOU....
7. regard them as a problem that is annoying?
11/2 6/1
8. regard them as a problem but one that is 'normal'?
12/1 5/2
9 If you bought a new motor car and had any of these clutch problems occur would you consider them to be 'normal'?
0/13 0/7/
None of the owners answered YES to less than 2 of questions 2 - 6. Of the T140 owners 4 reported slip due to oil and all 5 reported wrist ache a problem. All 4 Commando owners reported clutch slip due to oil a problem and both 820 owners reported wrist ache a problem.
Might I suggest you NOT become a car salesman for any car company whose clutches are as bad as the **** fitted to our old British Iron. A car parked sideways up your **** by an irate customer could be painful and believe me that would happen and there would be a LONG queue of customers waithing to do it!!!!!!! Guess it shows how stupid the average Brit owner was in putting up with such crap. AND dont think people like Bert Hopwood were not FULLY aware of the problems. In reply to my question of what were his thoughts regarding the Triumph wet clutch idea he replied....'In my opinion it is a perfectly acceptable idea for smaller capacity lower powered motorcycles, but, had I of had my way all the larger capacity higher powered motorcycles for which I was oersonally resonsible would of had dry clutches'.Of course by DRY clutches he did NOT mean as Norton did it, NOr did he mean as he did it on his BSA twin design where it ran in a cover within the oil bath chaincase...he meant as ARIEL did it... correctly. Or as the staff of The Motor Cycle put it in Speed and How to Obtain it' ..'a much better idea'.
Thats the beauty of belts on our olde British Iron road bikes IF you select the belt system and the belt system maker correctly and IF you fit it correctly you can have a clutch that...
1. does NOT slip when fully engaged, even when hot.
2. frees off INSYTANTLY WITHOUT DRAG WHENEVER REQUIRED, even when hot.
3. is EASILY operated by the rider at all times
4. possesses the LIGHTEST rotating weight rather than the heaviest unbalanced gearbox breaking flywheels BSA, Triumph anfd Norton gave us.
5. will perform with litle or no maintenance for many tens of thousands of miles usage.
I think you will find 1 to 4 listed in a Phil Irving book......Clearly unread by British motorcycle acc'o'untants..
As the gent said of Mr Shillings' Saints primary with its dry running one finger operated 4 friction plate diaphragm spring clutch..it was a revelation .Triumph were offered a fully working belt system already developed and tested in 78....Bob Oswald of Qpd in the USA wasted a lot of his time trying to get them interested.
TRUE TALE. As Mr Owsald and his wife walked out of the Triumph factory during one of their visits to Triumph she turned to him asking two questions....
1 What was that man doing poking that long stick into the roof? to which the answer was... changing the flat belt over onto a different pulley to alter his machines speed .
2 OK that was the industrial museum where is the factory!!!!!Bet that pissed off the Triumph guys escorting them round!!! Ever go round AMC at Plumstead?? What a total **** hole. Of course it was them at Plumstead who nicked the dosh Mr Hopwood had put aside out of Nortons profits for a new Norton factory wasnt it.......Bet Bracebridge Street was even worse than Plumstead.

The only reason for the survay and the questions I ask of owners to this day is to confirm that what I say is correct.Oh sure you will never get Joe Bloggs to ever apply enough grunt to his clutch for it to suffer from slip for example so he never suffers from it and swears there is not a slip problem... and there may well be people who realise how to correctly fill their Norton oil bath chain case but such are rather rare beasts.I know of several and Mr Phil Heath departed this earth long ago which gives one less than several....
Trust all research Triton thrasher etc are doing into so called clutch shock ansorber development in the British motorcycle industry from 1900 to 1980 is going well..........I await with interest hearing from anyone who can actually find some........Any bets on your so called shock absorber actually doing more harm than good????
NO checks done.

#196035 - 08/07/06 4:07 pm Re: belt drives  
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kommando Online content
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Scotland
I'll wait for the executive summary, head bursting is not recommended eek .

#196036 - 08/08/06 3:40 am Re: belt drives  
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Preunittrump Offline
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Baltimore, Md.
OK I just read all posts on Belt Drives. I've been riding my generator (solid crank gear) '55 T110 for almost 30 years - lots of miles. The 2nd time I broke a #28 single row chain...after I assembled all necessary parts for rebuild, I saw it gleeming at me from Frank Dehil's back shelf - even though I couldn't afford it...I bought the BNR belt drive. I've been running it for 2-/12 years now, (10K miles probably) - it's been good for all the reasons everyone else mentioned, BUT - I have a problem that just started: My drivetrain is making a slapping box of rocks noise in 2nd and 3rd gear (when in-gear) when I close the throttle (no load on engine). No noise from drivetrain when accelerating or when coasting with clutch disengaged. No noise in 1st or 4th.
I removed the clutch plates to see what I could find. The G-box mainshaft and the clutch inner basket have over an inch of rotational slop (back & forth play on the shaft) in 2nd and a little less in third. I am guessing I will have to take the gear cluster out and I might even build up a spare box I have from a '61 Bonne.
Can I ask a few questions? 1. Did this happen because of "no cush"? 2. How bad is it? 3. If I go to the trouble of building up the new box, should I go back to the cursed pre-unit primary set up I ran for so many years to prevent similar damage to my new box?


"still crazy after all these years"
#196037 - 08/08/06 6:42 am Re: belt drives  
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Redman Offline
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Redman  Offline
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San Francisco
I'm in Beta stage testing myself.....'66 A65, stock engine, 10:1 comp. QPD belt primary...no cush. Maiden voyages...clutch works wonderfully although a fairly stiff lever. Took off Pcover yesterday...everything inside looks like new.
I will keep everyone posted as time goes by. BTW, I ride in a spirited manner...shall we say.
One thing more...I'm running a 20tooth and 47tooth. My QPD is one of the older models that has a slightly taller primary ratio than stock so my final is pretty tall. 2nd is 35mph to maybe 60 or so...I'm guessing 'cuz I don't need no stinkin' speedo, no tach either...I know when to shift.
I'll keep posting......


Life is short but very wide.
#196038 - 08/08/06 11:09 am Re: belt drives  
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Posts: 4,950
Rich B Online happy
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Stone Creek OH USA
Gee Redman, why such low gearing laugh . My LC is geared 28/58 - 20/42.....55 is not a problem in 1st. 2nd really doesn't start to work until 40 - 45. But with close ratio, it's lots of fun.

Oh, there is a down side, slipping the clutch to 15 is a bit of a drag laugh But fun.


Life is too short to drink cheap, bad beer.
#196039 - 08/08/06 5:49 pm Re: belt drives  

**DONOTDELETE**
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This is one of those cases where more flywheel weight makes the bike easier to ride. The amount of throttle needed to slip the clutch (after the first blip), the RPM, and the speed at which the clutch can be fully released will all be lower without chain-snatch, bucking, etc. The power lost is also not as bad due to taller gearing, since the inertia of speeding up the crank varies as the square of the RPM, so (for example) 10% taller gearing means 21% lower loss in each gear.

#196040 - 06/25/07 1:20 am Re: belt drives  
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Gary Ramey Offline
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Atlanta, GA
I have a Norvil belt drive on my Commando and have been struggling with it.
The belt doesn't run completely "true" and I've been stranded in the Georgia mountains.
Belt manufacturers fail to tell you that the alignment must be perfect or the belt will frag....
Time for another adjuster for the left side of the engine cradle....

#196041 - 06/25/07 12:00 pm Re: belt drives  
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triton thrasher Online content
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triton thrasher  Online Content
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Quote:
Originally posted by beltdriveman:

Trust all research Triton thrasher etc are doing
I am expressly forbidden by mods to tell the forum what I think of you. Please be a good loony and leave me out of your novellas.


Amateur Loctite enthusiast.
#196042 - 06/27/07 3:33 pm Re: belt drives  
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Ron - in California R.I.P. Offline
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Ron - in California R.I.P.  Offline
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Oh my.. OK, so let's take a "real world" look see.. Folks have had good luck with chains, folks have had bad luck with chains... yadda yadda.. same with belts.

One thing for sure, if a chain breaks, it will (almost always..?) break something. If a belt breaks, it (almost always) does not break something.

Then there is the oil thing... I resisted a belt until I had one of my Goldies that would NOT stay dry... I hate oil leaks.!

I now have 3 bikes with the Hayward set up.. yup my new racer is a Hayward too.. Yup, I did modify all of them to run a sealed ball bearing, a change that Hayward has yet to make, although he is not against making the design change..

I did have (past tense) two of my bikes like to leak oil from the engine drive side bearing on to the belts, no damage there either.. just the mess that I was trying to avoid..! (the diapers on my racer stay real clean now..!!)

The only belt failure I had was on a brand new belt, I take that as a Manufacturing defect... no damage, just a bit inconvenient. That belt got replaced as the original one got damaged soon after I got that bike running again after a bad accident.. turned out the frame is not in the same plane as it was before the accident and thus the belt was not running true. I just reshimmed the engine and all is well.

So, my take is that some applications are better suited to a belt than others. I know enough about those pesky triples to know they are a challenge, period..! My hats off to those that wrestle I mean ride those beasts.! On singles, well, they are a treat.. and I know many a redundant cylinder rider than say the same.

The bottom line, is (as always) up to each person... do what ya think is best and have fun.

On a race bike, a belt is almost a requirement... oil on the rear tire can put you down darn fast... Oh WAIT... even on a street bike oil on your rear tire can hurt you even more than on a racer... Hmmm running a dry primary is good thing..!

Ron

#196043 - 06/27/07 7:44 pm Re: belt drives  
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Alex Offline
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Alex  Offline

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Seattle
So Ron, the Hayward drives have been good to you? Is that what the Norbsa racer is running? I'm considering pulling the trigger on one, but woo-hee have they gotten expensive. The exchange rate's just killing me on this one.


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
#196044 - 06/30/07 3:23 pm Re: belt drives  
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beltdriveman Offline
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A few friends have said to me of late that the reason people get upset with my posts is because I tell the truth and give them facts rather than fiction like so many others...which they have then believed to be facts. I suspect its true after all no one likes to realise they have ben stupid enough to believe fiction to be fact do they.As for those who get upset by me ...Well tough titty is all i can say!!

Go for example into any motor cycle shop and look at the second hand cranks and crankcases... many cranks will have knackered splines or tapers/keyways because many owners dont even know how to use a torque wrench correctly and there will be chain grooves in the cases because many owners are incapable of tensioning a chain correctly... let alone aligning the sprockets correctly.
As for a belt system for a Vincent with a Norton box I have never made such a system and unless one gent gets his arse into gear and supplies me with the lump to study I wont ever be making one ..and I was only going to do it because a very good friend asked me if I would help out one of his customers and I thoought the job might keep the brain cell working and amused. I dont need to flog belt systems to the public to earn a crust of bread. Thank GOD. There are some Vincent systems shown on the web and I believe Mr Newby might of done the odd one but dont quote me on that .....

Regarding the Gates Polychain belt that failed at 6500 RPM. Just think of the damage had it been a much heavier chain with all its much greater mass!!!Could of severed your head as one did to a gent at Pendine Sands all those years ago....
Suggest that people try to remember that the TT winning rotary Norton of many years ago employed a bog std off the shelf Gates 8mm pitch Polychain belt on the primary. I was told by the race shop it was 25mm wide but many years later I measured the one in the National museum and it measured 30mm. The race shop gent also told me that the belt did the whole season including the TT without being changed and as I suspect the bike revved a tad above 6500 RPM I would suggest that you were running the belt incorrectly which caused the failure. Was the system designed correctly for the grunt it was carrying? Did you tension it correctly with the correct load being applied to the belt as recommended? Were the pulleys correctly toothed? Were the shafts parallel? Did you send the belt to Gates and ask them to report on why it failed????? Thats an interesting thing to do...amazing what one can learn about why a belt failed prematurely. Nearly each cause gives a different looking failure and in my case where the belt had broken cleanly in the root of a tooth it was a CRIMP failure. I NOW know what belt manufactures mean when they print on the backs of their belt products 'DO NOT CRIMP'. For years I had wondered why one would want to crimp a bit of electrical string to a belt!!

As for belt systems on Norton MK3s DONT phone Bob Oswald to ask him if primary belt systems on them need tensioners!!! He might be in a bad mood and about half as impolite as I would be telling you to stop listening to idiots who could not even be refered to as EX SPURTS.
The problem with MK3s is the differnces that one can get between shaft centres due to the cradle variations and fixings.Thus a belt system on one bike will employ the belt toooo tight and on another too loose both of which will lead to premature failure. Correctly manufactured tensioners are not a good economically viable as they would have to be similar to the olde double chain tension device but employing correctly toothed pulleys.Of courset if you made your own and didnt care about cost. Suggest that as one thing one has to do to ensure good belt life is ensure the pulleys are 100% parallel then I would fit some double sided adjusters to the box and file the plates to give plus and minus say 1/8 inch thus allowing the shafts to be correctly parallel and belt tension to be adjusted to be correct...for which its not a bad idea to make ones own tension checker OR as I did blagg a couple but I did ask on bended knees and whilst pulling forelack of a BIG BOSS/GOD. Of course they are commercially available. I would also fit a correctly made gearbox support bearing behind the clutch mountedoff of the engine plates and dowed in position. But I am well known for over engineeing things...but if one is going to do something why not get it right first time? Tisnt as if its a UK MOD cost plus contract where one can take decades modifying modifications to try to get it right all at the taxpayers expense!!

Quickly thinking about it I would be more than happy to try a 20mm wide Polychain GT2 or whatever the latest version is on a MK3 Commando. Hell it has about 3 times the torque carrying capacity of the old late 1970s original HTD belt and I would happily run a 30mm wide one of them on a MK3. Or even A GT2 or GT3 version of 25mm width or even a .....but I aint going to mention that version.!!
NO spell or grammer checks.

#196045 - 06/30/07 3:43 pm Re: belt drives  
Joined: Oct 2006
Posts: 3,017
Bob S Offline
BritBike Forum member
Bob S  Offline
BritBike Forum member

Joined: Oct 2006
Posts: 3,017
, Lower -Lower michigan
hey everybody , run for the hills,if your unfortunate enough to be uninformed. :rolleyes: cool


Bob S
Street Rods, Kustom Kars,A BSA,Cushmans,H.Shadow ACE, Now a 2004 triumph america . "More than enough!!!!
#196046 - 06/30/07 5:29 pm Re: belt drives  
Joined: Aug 2001
Posts: 1,839
hh Offline
BritBike Forum member
hh  Offline
BritBike Forum member

Joined: Aug 2001
Posts: 1,839
British Columbia
It's amusing that one who feels the need to communicate in large diatribes and continually rants about how others are such "stupid people" won't go to the trouble to learn his own language and stop using "of" as a verb.


"Beer is proof that God loves us and wants us to be happy" - Benjamin Franklin
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