Author Topic: Convert issue  (Read 510 times)

Offline jjoking

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Convert issue
« on: March 24, 2019, 08:21:23 AM »
Good day, 1st post here and thanks for the venue!
A week ago I was doing some at speed panic stops on my 76 Convert after the rebuild in my rear brake master brake cylinder. All went well with the great brake performance, but on the return trip I was feeling like a more spirited ride and accelerated to a little over 90mph. At that pint I lost all forward power and did a very long coast to a stop, engine idling, running well. A friend rescued the Guzzi and me  on his trailer and brought us home. I had originally assumed the hex shaft/atf pump had failed and in the next day or so pulled the front timing cover to find all was well. Oh well, I thought, I cleaned all of it and buttoned it back up. New gaskets on the cover & sumptuously , oil filter as well. So yesterday I turned the gas back on...hit the starter, and the starter spun, freely without turning the crankshaft to start it.
 I hadnít tried to start the Guzzi previously after being hauled home as I had the thought of the hex shaft issue on my mind as the problem.
Anyway now it looks like I am pulling the trans/bell housing/motor from the frame to find a failed early stamped flywheel!
Also when the Convert lost power, no racket/bad noises of any kind were heard. I can freely /smoothly turn the flywheel thru the timing inspection hole with a screwdriver, so am assuming the flywheel inner mounting flange has separated with a clean break???
Any input would be helpful and thanks again for the forum!
jjoking


Offline jjoking

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Re: Convert issue
« Reply #1 on: March 24, 2019, 08:28:29 AM »
More info on the Convert 1976
Very low mileage unit 9,000 original miles
Sat in a museum for close to 40 years


Online fotoguzzi

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Re: Convert issue
« Reply #2 on: March 24, 2019, 08:31:07 AM »
Your  diagnosis sounds spot on.  Sorry about that. Finding a new flywheel might be a challenge.

I can freely /smoothly turn the flywheel. Assume the crank not turning when you do that?
« Last Edit: March 24, 2019, 08:34:42 AM by fotoguzzi »
2013 Hyperstrada
many Guzzi's loved,  (then sold)
72 Honda Trail 90 my first real motorcycle
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Offline jjoking

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Re: Convert issue
« Reply #3 on: March 24, 2019, 09:11:17 AM »
Correct! Crank is not turning...what puzzles me is that when I rotate the flywheel manually, it is so smooth.
I just didnít thing that if the flywheel center flange had let go it would have a smooth break. I guess maybe the assembly may have moved to the rear enough to be off the break? I soon will know about it for sure
When it is pulled down & apart

Online fotoguzzi

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Re: Convert issue
« Reply #4 on: March 24, 2019, 10:45:49 AM »
That is a little puzzle, let us know with pics if possible.

Are you aware of the yahoo group MGconvert? Join here,
mailto:mgconvert-subscribe@yahoogroups.com
2013 Hyperstrada
many Guzzi's loved,  (then sold)
72 Honda Trail 90 my first real motorcycle
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Online Bulldog9

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Re: Convert issue
« Reply #5 on: March 24, 2019, 10:47:36 AM »
I'm by no means an expert on the convert, but I've been researching them as I'm considering buying one. Seems that some of them came with a pressed steel flywheel. they are known to fail in the exact manner you're describing, and the recommendation is to swap out to a cast-iron one. From what I understand, they are hard to come by but not unobtainable.

Not for nothing, but taking a 40-year museum piece and beating on it might not be the best course of action. Beautiful Bike by the way.
« Last Edit: March 24, 2019, 10:49:29 AM by Bulldog9 »
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Offline jjoking

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Re: Convert issue
« Reply #6 on: March 24, 2019, 11:08:07 AM »
My history with this, my 2nd Convert has been measured
Short 50 mile or so rides over the past 6 months, varying speeds with
A max of 73 mph checking the speedo with GPS speed
Readings...amazingl y accurate within 2-3 mph.
So with less than 10 of those 50 mile rides and confidence growing in the bike/reliability, that one nice
Late winter/early cool spring morning 😎 I upped the throttle that one time with 90 mph being the max!
It was the max alright...thatís when the low mileage old girl let go. Anyway after many Guzzis owned in the last
40 yrs, itís the first time I had ever been hauled home
For a 90mph ride...so I guess, I will take it like a man
And just accept a ďShame on meĒ for it!

Offline Yeahoo Whoyah

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Re: Convert issue
« Reply #7 on: March 24, 2019, 11:11:21 AM »
They show up on eBay, in late February a used heavy flywheel sold for just over $100 and $13 shipping.  Maybe call Harper's?  Are you on the Convert Yahoo Group? Maybe someone in the group has a spare to sell. 
Mark is selling a good early version, these can be modified (reinforced) so they're reliable. Here is a link.
https://www.ebay.com/itm/Moto-guzzi-parts-convert-flywheel-ring-gear/222252378610?hash=item33bf4629f2:g:x8MAAOSwNRdX3FlG
« Last Edit: March 24, 2019, 11:57:38 AM by Yeahoo Whoyah »
Good advice is something a man gives when he is too old to set a bad example.

Offline jjoking

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Re: Convert issue
« Reply #8 on: March 24, 2019, 11:45:14 AM »
Thanks for the info...I had seen this on eBay
Also a couple from Germany for approx $160
For a later model heavy flywheel.
Will call Curtis @ Harpers tomorrow to see what he might
Have available. Iím in no hurry, havenít disassembled it yet
But will do so soon. Then will know for sure about what I am dealing with.
So tomorrow I am going fishing! Relax and contimplate on the next convert project issue at hand.


Offline fubar guzzi

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Re: Convert issue
« Reply #9 on: March 24, 2019, 12:09:09 PM »
 :popcorn:  Welcome to the club(club of broken Guzzi')--what your guessin is just what happened to it!!! One of mine(I have 3)did that 80 miles after I brought it home! You can weld it if it's not all buggered up,make sure it;s balanced well   :thumb:    When replacing the torque converter be religious about alignment,if not it will vibrate like an old EV     :boozing:

Offline jjoking

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Re: Convert issue
« Reply #10 on: March 24, 2019, 12:25:47 PM »
Thanks for the info!
I have my dial indicator all ready to get the Converter
Spot on @ assembly.
A smooth ride will had by all

Offline Texas Turnip

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Re: Convert issue
« Reply #11 on: March 24, 2019, 02:47:12 PM »
I sent Mr. King to this list when he called me wanting info. Thanks to y'all for helping a fellow East Texas Guzzi rider.

Tex
Nothing beats a goodnight kiss...unless you are in prison.

Offline jjoking

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Re: Convert issue
« Reply #12 on: March 24, 2019, 03:49:38 PM »
👋 Tex!
Good quote on the goodnite kiss... although the prison angle gave me a bit of a chill!!!!
Thanks again!
JK

Offline Aldo

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Re: Convert issue
« Reply #13 on: March 24, 2019, 04:31:08 PM »
Happened to me last week, this is probably what it will look like once you open it up. I have a spare stamped one in good shape that I am going to have reinforced on both sides by a good welder. My torque converter has a little nub at the end; seems as though a small tip of that nub broke off in the end of the crank.  Don't think its a big issue and it doesn't look like there is any other damage, so I plan to button it back up once I get my flywheel done up....











'72 Eldorado, '75 Convert, '04 Thruxton
GONE: '89 Guzzi Cafe, '99 Duc 900SS, Guzzi '79 1000 'SP'ort,'14 Harley '48','12 V7 Stone,  '72 Benelli 650S, '82 Guzzi 1000SP,'72 N. Falcone 500, '75 T3 850, '00 V11 Sport, '78 LeMans 1, '89 LeMans CI, '76 Morini 350S, '89 Duc 750S, 01 Kaw W650,'72 Rizzato 50

Offline Yeahoo Whoyah

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Re: Convert issue
« Reply #14 on: March 24, 2019, 05:14:49 PM »
Aldo: How many miles on your Convert when the flywheel failed?  What is your best guess on the speed (or RPM) when the failure occurred?
Good advice is something a man gives when he is too old to set a bad example.

Offline Aldo

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Re: Convert issue
« Reply #15 on: March 24, 2019, 05:22:32 PM »
Aldo: How many miles on your Convert when the flywheel failed?  What is your best guess on the speed (or RPM) when the failure occurred?

Mine has just over 17300 miles...I bought it with just over 17000 last month. I knew what I was getting into and that's why I ended up getting a spare flywheel.  It's original and a very nice example.  Not sure the RPM range at the time it occurred, but was in High gear and about 40 mph or so when I felt it let go. No real banging noises, just sudden loss of drive, so I just coasted to the side of the road and into a parking lot.
'72 Eldorado, '75 Convert, '04 Thruxton
GONE: '89 Guzzi Cafe, '99 Duc 900SS, Guzzi '79 1000 'SP'ort,'14 Harley '48','12 V7 Stone,  '72 Benelli 650S, '82 Guzzi 1000SP,'72 N. Falcone 500, '75 T3 850, '00 V11 Sport, '78 LeMans 1, '89 LeMans CI, '76 Morini 350S, '89 Duc 750S, 01 Kaw W650,'72 Rizzato 50

Offline jjoking

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Re: Convert issue
« Reply #16 on: March 24, 2019, 07:27:40 PM »
Hey 👋
Thanks so much for the pics, sorry about your issue as well. Mine was spooled up and pulling hard @ just over 90 mph when it let go.
Also am puzzled as to why mine turns so smooth with out noise when I turn it.
It sure seems like I should be hearing scraping going on. I guess I will know when I get it apart!
Thanks again

Offline brider

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Re: Convert issue
« Reply #17 on: March 25, 2019, 09:16:39 AM »
Mine has just over 17300 miles...I bought it with just over 17000 last month.

Been there, done that, too, on a '76, and it failed somewhere in the 17,000-range, highway speed, no other grinding or crunching, as the OP reported.

I don't recall trying to spin the flywheel thru the inspection window, and the lack of "grinding" noise in this case IS puzzling.

I went the reinforced sheet-metal route because I couldn't find the later version. Simple reinforcement, an after installing it and ensuring proper runout, it worked like a charm for many more miles until I sold it.

I am MORE amazed that you got to 90 mph on that thing. Must've been with no fairing.
'85 Cal II Auto
'86 LM IV (sold)
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Wish'd I'd never sold:
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Offline mtiberio

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Re: Convert issue
« Reply #18 on: March 25, 2019, 09:17:39 AM »
I'm by no means an expert on the convert, but I've been researching them as I'm considering buying one. Seems that some of them came with a pressed steel flywheel. they are known to fail in the exact manner you're describing, and the recommendation is to swap out to a cast-iron one. From what I understand, they are hard to come by but not unobtainable.

Not for nothing, but taking a 40-year museum piece and beating on it might not be the best course of action. Beautiful Bike by the way.

Rubbish. I have the "Worlds Fastest Guzzi Automatic" (TM) and it has been clocked at 114 at El Mirage dry lake by the SCTA. When I have it in street trim, I am always checking the top speed, it gets the stick, a lot. The old sheet metal flywheels fatigue, no telling when they will let go. It could just as easily be due to low RPM running as high. I have had one sheet metal flywheel fail, that was years ago, and I can't remember the circumstances.

For my current automatic, I have a heavy flywheel that I had lightened. Never thought much of having a light one welded up to reinforce it, I suppose if you had it trued afterwards it would be OK. I'd be concerned about distortion due to welding. It is hard enough to indicate the torque converter boss to within +/- .001" with an un-welded one.

Offline mtiberio

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Re: Convert issue
« Reply #19 on: March 25, 2019, 09:21:00 AM »
Happened to me last week, this is probably what it will look like once you open it up. I have a spare stamped one in good shape that I am going to have reinforced on both sides by a good welder. My torque converter has a little nub at the end; seems as though a small tip of that nub broke off in the end of the crank.  Don't think its a big issue and it doesn't look like there is any other damage, so I plan to button it back up once I get my flywheel done up....













I would be real concerned about that missing nub. It locates the flywheel, and it will wag more without it. It is broken either due to your flywheel breaking, or it being broken was the cause of your flywheel breaking. Either way, I'd get a new torque converter.

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