Author Topic: Rings Matched to Piston  (Read 1078 times)

Offline Colsbeeza

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Re: Rings Matched to Piston
« Reply #15 on: 03.09. 2018 14:51 »
Richard, No. I emailed SRM a few days ago for dimensional details. Their reputation is superb. Awaiting a reply.
Musky - British Austria's are Gandini. The Oil ring depth is 2.85. My Piston Oil ring depth is 2.80mm. I think they are the same as the Gandini rings I got from Classic Allparts.
I am trying to avoid having to machine my piston grooves.
Col
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Online RichardL

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Re: Rings Matched to Piston
« Reply #16 on: 03.09. 2018 16:35 »
Col,

Maybe I'm confused here (never happened before ;) *whistle*) but it seems to me that if you have 0.004" clearance wall-to-piston (0.002" radially) the 2.85mm-deep Gandini ring will never bottom in the 2.80mm-deep groove. Open to education if I need it.

Richard L
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Online Triton Thrasher

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Re: Rings Matched to Piston
« Reply #17 on: 03.09. 2018 19:32 »
it seems to me that if you have 0.004" clearance wall-to-piston (0.002" radially) the 2.85mm-deep Gandini ring will never bottom in the 2.80mm-deep groove.

It seems otherwise, to the Hastings Rings people.

https://www.hastingspistonrings.com/tech-tips-faqs/ring-groove-depths-of-piston-rings

 
Quote from: Hastings
Place the O.D. of the piston ring fully into the piston groove as illustrated.


No portion of the inside diameter (I.D.) should protrude beyond the piston land.

Online RichardL

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Re: Rings Matched to Piston
« Reply #18 on: 03.09. 2018 20:40 »
OK THEN

Col,

Obviously I was wrong about the clearance. TT has done a service and educated me on the topic. Thanks, TT. Though, I wish they had gone on to describe why there would be damage. I suppose you know why and will describe. 

When working on my bike, I sometimes think of the movie Flight of the Phoenix. In it, the crew of a crashed plane in the Gobi desert must make their aircraft flyable to survive. I guess you could say that if using rings that didn't have enough inside clearance meant you got to fly out of the desert, you'd probably go with 'em.  Col, you're not stuck in the desert, right?

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Online Triton Thrasher

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Re: Rings Matched to Piston
« Reply #19 on: 03.09. 2018 20:59 »
Thanks, TT. Though, I wish they had gone on to describe why there would be damage. I suppose you know why and will describe. 

I don’t know nuffin.  I’m handing Google over to you now.

Online muskrat

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Re: Rings Matched to Piston
« Reply #20 on: 04.09. 2018 00:38 »
G'day Col.
0.05mm = less than 2 thou". If the rings pass the "Hastings" test they'd be OK, as the ring once in the bore is a fair bit bigger OD than the piston meaning the ID is also bigger.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online RichardL

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Re: Rings Matched to Piston
« Reply #21 on: 04.09. 2018 02:04 »
Y'y'yahbut, isn't the Hastings test asking for oil ring depth to be 0.015" less than groove depth? The arithmetic I played with had the backside of the oil ring about 0.001" from the groove depth when 0.004" is the piston/bore clearance. Is there something here the Hastings test is not telling us, or I just flat-out don't understand (again)?

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Offline Colsbeeza

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Re: Rings Matched to Piston
« Reply #22 on: 04.09. 2018 02:29 »
That is a great find TT. Explains perfectly. I suspect the damage would occur because the ring may hold the piston off the cylinder wall - doesn't bear thinking about.! Muskrat you're scaring me with the logic - I am wavering.!!
Richard, it is like a desert here - makes everyone desperate. NSW is in 100% drought, We expect 80% of cattle won't survive. One farmer was asked by a city mate what he needed. He said "Bring me some bullets - I've only got 5 left". Oz is running out of hay - truckloads coming from Western Australia and Western Victoria. Newcastle port is trying to figure out how to unload grain - never done that before, always exported. Maybe I should stick in the oversize rings and carry some hay over.
Blow me down - it's raining outside as I type.!!
Anyway, I have ordered the Hepolite rings from SRM - if I have to machine the grooves so be it!.
Col
Colsbeeza
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