I recently ordered a piston ring set from Andover Norton and they sent rings made in Italy by Gandini. These are unlike the OEMs I'm replacing in that they have a different design for the oil scraper, and there's a small bevel on the inside edge of the two top rings. Anyone have any experience with these rings and can tell me if the bevel should be positioned up or down or whether it even matters? Thanks.
Gandini Piston Rings?
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I just deleted the text of this post. If you already read it,
DISREGARD . My rings were Italian but NOT GANDINI, they were GPM rings. So Disregard my comments about ring type and orientation that were in this post previously.
DISREGARD . My rings were Italian but NOT GANDINI, they were GPM rings. So Disregard my comments about ring type and orientation that were in this post previously.
Not sure if you answered your own question but I just installed a set of GPM rings. My compression rings had a "top" marking - and there was a bevel/chamfer on the INNER diameter - it faces UP.
Oil scrapers were one two-edged ring with a spring that fits inside. Apparently, both sides the same, so doesn't matter which side faces up.
EDIT: How quickly we forget. The oil rings had a "top" marking also. Sorry, this was so long ago....yesterday!
I used .010 gap on top ring and .011 on 2nd and oil rings. So far, so good.
Best of luck.
Oil scrapers were one two-edged ring with a spring that fits inside. Apparently, both sides the same, so doesn't matter which side faces up.
EDIT: How quickly we forget. The oil rings had a "top" marking also. Sorry, this was so long ago....yesterday!
I used .010 gap on top ring and .011 on 2nd and oil rings. So far, so good.
Best of luck.
Sounds like GPM and Gandini rings are identical...
I was interested when I received my GPM to see they used a one piece oil scraper (with spring behind) and that both 1 and 2 ring were identical cast iron. I wonder if they have found that to be a better design choice for the engine than the original style rings with a 3 piece oil ring, a chrome top ring and a cast iron 2nd ring. Or did they just figure the "new" setup is "good enough" and cheaper?
I was interested when I received my GPM to see they used a one piece oil scraper (with spring behind) and that both 1 and 2 ring were identical cast iron. I wonder if they have found that to be a better design choice for the engine than the original style rings with a 3 piece oil ring, a chrome top ring and a cast iron 2nd ring. Or did they just figure the "new" setup is "good enough" and cheaper?
MexicoMike said:
I expect different piston/ring manufacturers have their own ideas about which designs and materials are best suited to particular application? Also I'd hope that piston ring technology has actually advanced a little since our bikes were new, however no doubt manufacturing cost is also likely to be a consideration?
The set of original Hepolite/AE Commando pistons in my spares collection have the cast iron 1st. & 2nd. rings, (as are the ones currently fitted to my Commando's pistons) these have the top inner bevel edge (as the rings are marked "TOP") with three-piece oil scraper rings, however I do remember the last set of Federal Mogul boxed "AE" rings I bought for my T140V Bonneville had one-piece oil scrapers.
That's interesting...per the '73 Norton service manual, the top ring was chrome. So there must have been a service change at some point (or the manual is wrong - certainly not unheard of). This is the only set of rings I have ever installed in a Commando so I have no experience with the actual parts from "back in the day". Nothing at all wrong with cast iron rings; they have proven very effective over the years and can tolerate a wider range of less than ideal cyl wall surface and still seat properly than can "better" rings. That could be precisely why the chrome top ring was eliminated.
The NOC Service Notes (published in 1979) say this:
"Rings last, on average, 25,000 - 30,000 miles. At this mileage the bores shouldn’t be worn significantly and
new rings will restore your oil consumption. If the bores are worn enough at this mileage to need boring
then change your brand of oil (or, dare I say it, change your oil).
Greater ring wear will occur without air cleaners and also not having chrome top rings (often two cast
rings are supplied). In these cases oil consumption can get as high as 100 mpp when the handle is "well
wrung". Only up to 20,000 before new rings and 40,000 between rebores."
"Rings last, on average, 25,000 - 30,000 miles. At this mileage the bores shouldn’t be worn significantly and
new rings will restore your oil consumption. If the bores are worn enough at this mileage to need boring
then change your brand of oil (or, dare I say it, change your oil).
Greater ring wear will occur without air cleaners and also not having chrome top rings (often two cast
rings are supplied). In these cases oil consumption can get as high as 100 mpp when the handle is "well
wrung". Only up to 20,000 before new rings and 40,000 between rebores."
Re the Norton owners service notes
If you go here, it will open as the service book in PDF; you can save it from there to a folder on your computer.
http://archives.jampot.dk/Book/Workshop ... _Notes.pdf
If you go here, it will open as the service book in PDF; you can save it from there to a folder on your computer.
http://archives.jampot.dk/Book/Workshop ... _Notes.pdf
BrianK said:
Just be aware that the online pdf copy of the NOC Service Notes contains a lot of typing errors! If you read something that doesn't make sense please let me know and I will check the pdf text against the paper copy and point out any errors.
The paper copy is no longer available from the NOC unfortunately.
I have Total seal piston rings in my MKIII, they consist of a chrome top ring, a 2 piece 2nd ring, and a 3 piece oil ring. They are easy on the bores and reduce oil use. I've used these rings on verious other vintage projects all with goog luck.
I installed a set in a 3ltr. 911 Porsche I use to own, and it cut the oil use by half. Porsche didn't find out about 3 piece oil rings untill the 90's. Take apart any modern engine, car or motorcycle, you will find 3 piece oil rings, cast iron rings are just cheeper to make. I have used JE pistons (they are in So. California) for several years, they will make you anything you want, you have to order 4 at a time, they are beautifuly machined and come with modern rings, at around $200 ea.
Compared with GPM, and NOS Hepolite they are not a bad deal.
Ken G.
I installed a set in a 3ltr. 911 Porsche I use to own, and it cut the oil use by half. Porsche didn't find out about 3 piece oil rings untill the 90's. Take apart any modern engine, car or motorcycle, you will find 3 piece oil rings, cast iron rings are just cheeper to make. I have used JE pistons (they are in So. California) for several years, they will make you anything you want, you have to order 4 at a time, they are beautifuly machined and come with modern rings, at around $200 ea.
Compared with GPM, and NOS Hepolite they are not a bad deal.
Ken G.
motoracer8 said:
Wish I'd thought of that before re-ringing this time around, but I'll store it away for next time. I have used JE pistons (have a set in a Duck) and agree they're quality items. Can no longer remember what rings they came with but they weren't Total Seal. JE pistons with Total Seal rings sounds like a superb setup.
MexicoMike said:
I was dipping into "Modern Motorcycle Mechanics" on an unrelated topic (my newly popping on overrun fueling issue) today and noticed a bit where Nicholson lauds chrome plated rings as the advance of the century, or some such, and decries the fact that not all manufacturers have yet made the switch.
This from the seventh edition, ca 1974.
It seems the notion that rings last about 25k miles and the bores shouldn't be very worn at this mileage are both spot on in my case. My bike had about 25k miles when I acquired it two years ago (in nice condition for the mileage). Since then, I've decided on a complete restoration. Recently, when I miked my bores with a bore gaugeaccurate to .0001, there was no discernible wear anywhere along the bores. In fact, you can still see faint cross hatching from the factory honing on the ring contact portion of both bores. Pretty amazing. The previous owners evidently took care of her. But the rings...they needed replacing, though not by much.
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