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Failed alternator rotor - obvious? #217036
10/04/08 11:10 pm
10/04/08 11:10 pm
Joined: Sep 2008
Posts: 117
Norfolk, UK
L
Lorenzo Offline OP
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Lorenzo  Offline OP
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L
Joined: Sep 2008
Posts: 117
Norfolk, UK
My recently-purchased T140E was making rumbling/clonking noises, and suspecting a loose or faulty alt. rotor that I'd read so much about, I stripped the primary drive, and found, well..........nothing!
If the rotor had failed, wouldn't it be obvious?
Reason for asking is that a former local Triumph engine guru mentioned in his "services offered" list having a special jig for checking a loose centre.
The rotor is a Lucas item, part #54212006, and the date code is stamped 12 78, leading me to believe it's the original.


1978 T140E
1979 TR7V
1960 Royal Enfield Bullet 350
Waste not, want not.........Thrift is a virtue.
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Re: Failed alternator rotor - obvious? [Re: Lorenzo] #217051
10/05/08 12:08 am
10/05/08 12:08 am
Joined: Jan 2004
Posts: 3,727
ca, us
D
DMadigan Offline
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D
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ca, us
You will not necessarily see a loose rotor. Remember, the engine is giving it a good wack with each power pulse. If you take off the stator and grab the rotor a good twist you mighth feel it move. Generally you hear a knocking sound in the primary at idle and it goes away at higher RPM. If you have a strobe light you could try lighting up the rotor at idle to see if it moves.

Re: Failed alternator rotor - obvious? [Re: DMadigan] #217061
10/05/08 1:00 am
10/05/08 1:00 am
Joined: Jun 2002
Posts: 9,965
Scotland
S
Stuart Offline
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Stuart  Offline
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S
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Scotland
Hi,

I'm almost certain the alternator rotor isn't your problem, simply because one made in December '78 and fitted to a T140E is years after Lucas introduced rotors with a welded centre.

However, to be absolutely sure, whip off either stator or rotor and check the inside of the stator - damage from touching will be obvious.

Hth.

Regards,

Re: Failed alternator rotor - obvious? [Re: Stuart] #217066
10/05/08 1:27 am
10/05/08 1:27 am
Joined: Jan 2008
Posts: 1,114
Noblesville, IN
Jack Adams Offline
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Noblesville, IN
Lorenzo,I've had more than one broken rotor over the years and what I learned is this. Take off the stator and grab the rotor with your hand and try to turn it back and forth,if you can feel any looseness at all between the rotor and crank it is bad. While you are at it,you can give the main bearing(drive side) a quick check by clamping a pair of vise-grips on the rotor nut and lifting, there should not be any play that you can feel. Good Luck. Jack

Re: Failed alternator rotor - obvious? [Re: Jack Adams] #217067
10/05/08 1:42 am
10/05/08 1:42 am
Joined: Jan 2003
Posts: 554
west central ohio where all be...
D
drp Offline
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drp  Offline
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Posts: 554
west central ohio where all be...
Clamp the center (hub) in a vise (may need some washer so you don't clamp the magnet too) and try to turn the outside. Any movement is an indication the the magnet is loose.

Dave

Re: Failed alternator rotor - obvious? [Re: Jack Adams] #217069
10/05/08 1:50 am
10/05/08 1:50 am
Joined: Mar 2005
Posts: 10,158
Boston, Massachusetts
J
John Healy Offline

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J
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Posts: 10,158
Boston, Massachusetts
"I'm almost certain the alternator rotor isn't your problem, simply because one made in December '78 and fitted to a T140E is years after Lucas introduced rotors with a welded centre."

Stuart have you ever taken one of the quote "welded" rotors apart? I am curious by nature and always suspect of engineering done by the sale department. I have taken several production runs of brand new "welded" rotors apart on my lathe.

I was curious because "welding" would most certainly effect the magnetism. The "welding" does not refer to securing the magnets to the steel center - the magnet blocks are held in place by their magnetism, not welding or any other form of adhesion.

If the magnets are not welded do you know what "welded" means?
John

Lorenzo when the drive side main bearing fails it typicall makes a rumbling/clonking sound that makes the hair stand up on the back of my neck.


Re: Failed alternator rotor - obvious? [Re: John Healy] #217081
10/05/08 2:46 am
10/05/08 2:46 am
Joined: Jun 2002
Posts: 9,965
Scotland
S
Stuart Offline
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Stuart  Offline
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S
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Scotland
Hi John,

I'm not quite sure of the point you're trying to make.

Aiui, Lucas made a design change to the rotor, that differentiates those where the rest of the rotor might come loose from the centre from those that don't. Aiui, the latter is known, certainly in GB, as a 'welded rotor' and has a different number to earlier rotors, although Lorenzo's does not appear to have the latest number I know of (54202298).

If there are other differences or differentiations that you know of, like many other readers, I'd be pleased to be enlightened.

Regards,

Re: Failed alternator rotor - obvious? [Re: Stuart] #217085
10/05/08 3:29 am
10/05/08 3:29 am
Joined: Jan 2004
Posts: 3,727
ca, us
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DMadigan Offline
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ca, us
Of course the simple test would be to remove the rotor and run the engine to see if the noise goes away.

Re: Failed alternator rotor - obvious? [Re: DMadigan] #217089
10/05/08 4:04 am
10/05/08 4:04 am
Joined: Mar 2005
Posts: 10,158
Boston, Massachusetts
J
John Healy Offline

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John Healy  Offline

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J
Joined: Mar 2005
Posts: 10,158
Boston, Massachusetts
Stu... They are NOT welded! Once you remove a small amount of the metal from the side the magnets are free to move or be removed! So the point is: "What does "welding" mean?
John


Re: Failed alternator rotor - obvious? [Re: Stuart] #217094
10/05/08 8:00 am
10/05/08 8:00 am
Joined: Mar 2006
Posts: 3,690
Norfolk, UK
L.A.B. Online content
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L.A.B.  Online Content
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Posts: 3,690
Norfolk, UK
Originally Posted By: Stuart
I'm almost certain the alternator rotor isn't your problem, simply because one made in December '78 and fitted to a T140E is years after Lucas introduced rotors with a welded centre.



Stuart, I think you will find that "12 78" is week 12 1978, and not month 12, (as you can find the Lucas date stamps on their parts far higher than '12').

Obviously, if the rotor had been manufactured by Lucas in December 1978 it would not have been the original, as Lorenzo says it's a '78E model, and a "Dec" '78 manufacture date would have been well inside the '79 production year, (from late/July-Aug. '78?) - even without allowing for the time between manufacture and when it was actually fitted to a bike on the production line.

It's also worth noting that the rotor commonly used for the OIF twins is the 54212006 one (which is what my own late-'78 T140V has, - with a date stamp of '18' 78), yet that number doesn't match any of the Lucas rotor numbers given in the OIF parts lists?

Last edited by L.A.B.; 10/05/08 8:19 am.
Re: Failed alternator rotor - obvious? [Re: L.A.B.] #217098
10/05/08 9:25 am
10/05/08 9:25 am
Joined: Aug 2007
Posts: 4,542
Kent UK
Blapper Offline
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Blapper  Offline
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I have an Aug '78 E which had a loose rotor. Like Jack said earlier, take off the stator and turn the rotor and you will find the play.

Blapper redwine

Re: Failed alternator rotor - obvious? [Re: Blapper] #217100
10/05/08 10:09 am
10/05/08 10:09 am
Joined: Sep 2008
Posts: 117
Norfolk, UK
L
Lorenzo Offline OP
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Lorenzo  Offline OP
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Posts: 117
Norfolk, UK
Thanks guys.
I'd already carried out the tests mentioned for checking the rotor, and found nothing.
I also tugged at the crankshaft end and found nothing.
I was just trying to convince myself it wasn't what I most feared - main bearings! (The bike had spent almost 20 years of its life in storage, so this is the most likely cause of the noise). To my ears, it sounds quite rough at tickover, although out on the road at 60mph you wouldn't know there was anything wrong at all. A full engine strip would have to be a job for later, when I have more time (and money).
Both my Triumphs have "NA" prefixes, which you experts already know means an October '78 build date/'79 model; L.A.B. is correct about Lucas date codes - the first figure refers to the week no., not the month.


1978 T140E
1979 TR7V
1960 Royal Enfield Bullet 350
Waste not, want not.........Thrift is a virtue.
Re: Failed alternator rotor - obvious? [Re: Blapper] #217101
10/05/08 10:22 am
10/05/08 10:22 am
Joined: Mar 2006
Posts: 3,690
Norfolk, UK
L.A.B. Online content
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L.A.B.  Online Content
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Posts: 3,690
Norfolk, UK
Originally Posted By: Blapper
I have an Aug '78 E

1978 T140E coming along...any day now...


So it's really a '79 model? (from HA11001-on)

Re: Failed alternator rotor - obvious? [Re: L.A.B.] #217104
10/05/08 10:30 am
10/05/08 10:30 am
Joined: Aug 2007
Posts: 4,542
Kent UK
Blapper Offline
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Blapper  Offline
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CX so it was made in March '78 - first reg August '78.

I like D Mads idea of taking it off and starting it to hear (don't forget to put the case on or yuk!).

Blapper redwine

Last edited by Blapper; 10/05/08 10:53 am.
Re: Failed alternator rotor - obvious? [Re: Blapper] #217121
10/05/08 1:01 pm
10/05/08 1:01 pm
Joined: Sep 2006
Posts: 205
Rhode Island
cabletech Offline
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cabletech  Offline
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Posts: 205
Rhode Island
idea of taking it off and starting it to hear


This is probally obvious and goes without saying but .....
Wouldn't you need to install a spacer on the crankshaft so you could re install the crank nut to hold the front primary sprocket in place wile running? I know it is pressed on but if it comes loose wile running it too may make allot of noise.

Mike

Last edited by cabletech; 10/05/08 1:07 pm.

1983 Husqvarna WR430
1973 T150
1974 T150
1975 T160
1975 T160
I'm now a triple Freak!
Re: Failed alternator rotor - obvious? [Re: L.A.B.] #217138
10/05/08 2:32 pm
10/05/08 2:32 pm
Joined: Mar 2005
Posts: 10,158
Boston, Massachusetts
J
John Healy Offline

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Boston, Massachusetts
A stethoscope or screw driver held against the ear can locate and identify the source of the noise from a failed main bearing on a Triumph. A confusion can result from listening to general noises coming from the motor as one stands near it. The primary cover often amplfies sounds and makes it appear the noise is coming from the primary or drive side.

In my experience Triumph timing side main bearing failures can often be miss diagnosed because the primary noise seems to be coming from the primary cover near the clutch. A stethoscope probe placed near the crankcase area that supports the timing side bearing will re-direct your attention to the timing side bearing.
John


Re: Failed alternator rotor - obvious? [Re: John Healy] #217161
10/05/08 4:39 pm
10/05/08 4:39 pm
Joined: Jan 2004
Posts: 3,727
ca, us
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DMadigan Offline
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I do not see how 20 years of storage can cause main bearing problems unless they have rust pits. The other possible cause of low speed rumbling/knocking is the clutch damper. First check the mainshaft nut then remove the cover plate and check the rubber cushions. If the damper hub comes off the mainshaft adapter without a puller then the splines are worn.

Re: Failed alternator rotor - obvious? [Re: DMadigan] #217168
10/05/08 5:21 pm
10/05/08 5:21 pm
Joined: Mar 2005
Posts: 10,158
Boston, Massachusetts
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John Healy Offline

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John Healy  Offline

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Boston, Massachusetts
In the Northeast we see a lot of timing side main bearing failure in the first few weeks of spring. It typically seen after 900 to 1,000 miles after the bike is taken out of storage. Contact pressure of the ball is more concentrated in the bottom of the track than a roller and small, microscopic rust damage to the steel from moisutre collecting at the bottom are perfect places for hardened surface of the bearing to begin to fail.

Triumphs improperly stored have a lot of internal surfaces to collect condensation. One good example is storing a Triumph near a heating furnace or a heated garage that is in daily use. This constant change in temperature in what is typically a damp climate creates quite a bit of condensation. Find a place to store your Triumph where the temperature, no matter what it is, remains constant. The heat from the sun beating through a window on your cold stored bike will encourage condensation to form inside the motor.

Add this to the common practice of putting the bike away without changing the oil (don't forget the gearbox). Oil itself doesn'y prevent rust. Anti-oxidants need to be added to prevent rust. These have an effective life and their protection is renwed with the change of oil (when buying a break-in oil it is important that the oil has these additives as many of these motors are stored for months before being started. These additives are commonly left out of break-in oil as it is assumed the motor will be started and the oil changed in a short period of time.

In the Fall in the Northern climes the trips are short and the condensation created by combustion is never fully evaporated out of the motor as it would be on a long trip. Add some condensation due to improper storage and rusted crankshafts, bearings and other motor parts are common. How many of us have taken one more blast short around the neighberhood just before putting the bike away for the winter?
Dave, the low speed clutch damper rumble is typical to a Trident as is the rumble from the missalignment of the transmission mainshaft and primary chain wheel bearing housings which trys to turn the clutch plate into a universal joint and puts terrible loads on the primary radial needle bearing. The twin doesn't seem to suffer from damper rumble as such.
John


Re: Failed alternator rotor - obvious? [Re: DMadigan] #217179
10/05/08 5:58 pm
10/05/08 5:58 pm
Joined: Sep 2008
Posts: 117
Norfolk, UK
L
Lorenzo Offline OP
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Lorenzo  Offline OP
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Posts: 117
Norfolk, UK
Condensation may not matter too much in sunny California, but believe me, it's definitely an issue here in damp ol' UK.
(As an example, some places within 50 miles of my home town had a month's worth of rain today).
Additionally, few owners can afford heating/dehumidification for their storage area.
I know from personal experience that damp storage can eat 2-stroke main bearings in less than 5 years, let alone 20, and the problem seldom manifests itself immediately, but a relatively short time after re-commissioning.


1978 T140E
1979 TR7V
1960 Royal Enfield Bullet 350
Waste not, want not.........Thrift is a virtue.
Re: Failed alternator rotor - obvious? [Re: DMadigan] #217226
10/06/08 1:24 am
10/06/08 1:24 am
Joined: Oct 2003
Posts: 11,222
North Georgia, USA
RF Whatley Offline
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RF Whatley  Offline
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North Georgia, USA
Originally Posted By: DMadigan
You will not necessarily see a loose rotor. Remember, the engine is giving it a good wack with each power pulse. If you take off the stator and grab the rotor a good twist you might feel it move.


1) You might, but you probably won't. I just tested one for "Atlanta Bonnie" on a sub-standard Smallheath model, so he can vouch for what I say. The very strong magnets are highly attracted to the steel core of the rotor. Therefore, they won't move unless forced to move. Use a giant set of "slip joint" pliers to get some leverage.

2) I agree with John. TS main bearing has got to be considered. Both give about the same rumbling sound, just on different sides.

bigt


Don't hide 'em, Ride 'em !!

RF Whatley
Cornelia, GA
Re: Failed alternator rotor - obvious? [Re: RF Whatley] #217231
10/06/08 1:44 am
10/06/08 1:44 am
Joined: Jan 2008
Posts: 1,114
Noblesville, IN
Jack Adams Offline
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Jack Adams  Offline
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Noblesville, IN
What RF? No "kung fu grip"? Jack


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