Author Topic: New crankshaft/connecting rod design for 2021 V7/V9  (Read 7627 times)

Offline DaSwami

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New crankshaft/connecting rod design for 2021 V7/V9
« on: January 31, 2021, 11:01:20 PM »
Does this Cycleworld comment raise an eyebrow with anyone?

"An unexpected and fairly radical technical modification separating the V7/V9 V-twin engine from all previous editions, and from the V85 TT, is that the crankshaft here is of the press-fit type, with one-piece con-rods turning on plain bearings, rather than a forged one-piece unit. This follows the same engineering approach used on all Piaggio four-stroke scooter singles. Reducing production cost is the ultimate reason for the change. The more powerful, higher-revving V85 TT retains its solid forged crankshaft and cap-type rod."



Offline lucky phil

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #1 on: February 01, 2021, 12:18:47 AM »
Does this Cycleworld comment raise an eyebrow with anyone?

"An unexpected and fairly radical technical modification separating the V7/V9 V-twin engine from all previous editions, and from the V85 TT, is that the crankshaft here is of the press-fit type, with one-piece con-rods turning on plain bearings, rather than a forged one-piece unit. This follows the same engineering approach used on all Piaggio four-stroke scooter singles. Reducing production cost is the ultimate reason for the change. The more powerful, higher-revving V85 TT retains its solid forged crankshaft and cap-type rod."

Just like a roller big end but different. Doesn't sound appealing although if its bullet proof should be ok. Nobody's going to be rebuilding engines in 15 years time.

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Offline kirby1923

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #2 on: February 01, 2021, 07:57:23 AM »
Harley has been using press together cranks form its beginnings  to this day (on the big twins).
« Last Edit: February 01, 2021, 08:18:27 AM by kirby1923 »
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Offline moto-uno

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #3 on: February 01, 2021, 08:03:43 AM »
^ No they were  not ! Press fit cranks on Harleys didn't start until the Twin cam model ( FWIW) . The Laverda triples had press fit
cranks and were fairly durable . Not to forget most 2 strokes were also pressed together cranks !

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #3 on: February 01, 2021, 08:03:43 AM »

Offline acguzzi

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #4 on: February 01, 2021, 08:19:29 AM »
well there is the reason for not using the v9 engine in a performance twin.

Offline Tusayan

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #5 on: February 01, 2021, 09:29:48 AM »
The biggest benefit of the industry moving away from roller bearing bottom ends in the 70s and before was the elimination of pressed together crankshafts.  It’s an archaic concept that only survived as long as it did due to concerns about reliable oiling of plain bearings that themselves should should have been put aside in the 1940s or before.  Just because Piaggio has equipment to make built up crankshafts for scooters and apparently cuts cost of production using them does not make pressed together multi-piece crankshafts a good thing for the owner of a Guzzi.

Offline kirby1923

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #6 on: February 01, 2021, 09:57:00 AM »
Yes I agree very obsolescence in an engineering sense. Controlling run out during the manufacturing process is difficult, and HD keeps upping the tolerance.

A better way would be a one piece crank forging with an articulated  rod like a radial aircraft engine.
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Offline huub

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #7 on: February 01, 2021, 11:36:09 AM »
Should make rebuilding a engine easier !
for current smallblocks no oversize bearings are available so any wear means a scrap crankshaft.
With a pressed up crankshaft guzzi might actually provide the crankpin, making the crankshaft rebuildable.

Offline acguzzi

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #8 on: February 01, 2021, 12:21:49 PM »
also means you can't replace or inspect big ends without disassembling the crank

Offline Bulldog9

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #9 on: February 01, 2021, 02:28:53 PM »
I'd like to see pics of this, having a hard time picturing. I've never had a Guzzi motor apart, closest look I've had was when I dropped the pan on the Convert to change the oil filter Was surprised to not see a windage tray or much to keep oil from schloshing onto the crank.
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jwinwi

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #10 on: February 01, 2021, 02:56:05 PM »
Carlo Guzzi and Lino Tonti are rolling over in their graves... :cry:
« Last Edit: February 01, 2021, 03:07:19 PM by jwinwi »

oldbike54

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #11 on: February 01, 2021, 03:20:43 PM »
 Should help with dial indicator and large hide mallet sales .

 Dusty

Offline lucky phil

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #12 on: February 01, 2021, 04:23:44 PM »
Harley has been using press together cranks form its beginnings  to this day (on the big twins).

And thats a recommendation?

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Offline lucky phil

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #13 on: February 01, 2021, 04:35:31 PM »
The biggest benefit of the industry moving away from roller bearing bottom ends in the 70s and before was the elimination of pressed together crankshafts.  It’s an archaic concept that only survived as long as it did due to concerns about reliable oiling of plain bearings that themselves should should have been put aside in the 1940s or before.  Just because Piaggio has equipment to make built up crankshafts for scooters and apparently cuts cost of production using them does not make pressed together multi-piece crankshafts a good thing for the owner of a Guzzi.

Yep all true but 99% of todays buyers wont understand and will never need to. More interested in connectivity than engineering. I personally hate the way modern engines are designed around cheapness to manufacture and fast assembly on a production line, makes insitu maintenance very difficult. Both my cars as do many other engines now utilise friction drive for the OHC's so no keyed crank or camshafts. If you loosen off the front pulley bolt to remove it for a seal replacement for instance then its re do the valve timing which isn't as easy as it sounds with the dismantling of half the top end to fit the timing tools and removing accessories like the HP fuel pump and vacuum pump. Painful and many amatures have been caught out by this alone.

Ciao  e
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Offline LowRyter

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #14 on: February 01, 2021, 04:40:30 PM »
Wait, I always thought that pressed cranks were quite a bit more labor intensive and expensive to build.  This is the first time I've ever read the opposite.   I don't know why two piece rods could be revved at higher RPMs and more stress than one piece rods; if there is a difference, I'd think would be the other way around. 

OK, since I'm the least mechanically inclined person on the Board, someone please educate me.

Thanks. 
« Last Edit: February 01, 2021, 04:48:18 PM by LowRyter »
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Offline kirby1923

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #15 on: February 01, 2021, 04:41:47 PM »
And thats a recommendation?

Ciao


In a word no.
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Offline LowRyter

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #16 on: February 01, 2021, 04:46:05 PM »
^ No they were  not ! Press fit cranks on Harleys didn't start until the Twin cam model ( FWIW) . The Laverda triples had press fit
cranks and were fairly durable . Not to forget most 2 strokes were also pressed together cranks !

I thought all Harleys had press fit cranks. 

Isn't that how they installed those "knife and fork" rods? 
John L 
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Offline lucky phil

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #17 on: February 01, 2021, 04:51:13 PM »
I thought all Harleys had press fit cranks. 

Isn't that how they installed those "knife and fork" rods?

Like older British bikes some were a tapered pin with a nut to hold in place from memory.
The side by side rods on a common pin like a Ducati has is the best option unless crank width/length is an issue. Articulated rods in all there forms whether a "master rod" situation or a forked arrangement like a Merlin engine uses are less desirable and generally for low rpm applications only.

Ciao
« Last Edit: February 01, 2021, 04:55:12 PM by lucky phil »
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Offline kirby1923

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #18 on: February 01, 2021, 04:58:22 PM »
Wait, I always thought that pressed cranks were quite bit more labor intensive and expensive to build.  This is the first time I've ever read the opposite.   I don't know why two piece rods could be revved at higher RPMs and more stress than one piece rods; if there is a difference, I'd think would be the other way around. 

OK, since I'm the least mechanically inclined person on the Board, someone please educate me.

Thanks.

The factory (HD) does not sell parts for the crank but you can pull them apart and put them back together in your shop if you have the right equipment, Most of the people that do this send them to someone (only one place really) and they will refresh the crank, balance and weld the pin up if requested.

The rods are blade and fork. You can get away with a bit more RPM 'cause w/the blade and fork rod (
s) there is no offset of the cylinders thus no shaking order side to side like a Guzzi twin of a BMW.

The first press together crank from the factory was the XR, then  later the twin cam (which I used to always call the big twin)

If they, HD machines, are not too abused with big after market cylinders and other hop up stuff they do OK more or less. For me the 45 deg cylinders are only good for the unique sound and produce surprisingly good traction, much like a big single.

Still a bad way to do it in my opinion.
« Last Edit: February 01, 2021, 05:01:38 PM by kirby1923 »
'81 CX100


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Offline Tusayan

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #19 on: February 01, 2021, 07:45:24 PM »
I always thought that pressed cranks were quite a bit more labor intensive and expensive to build.  This is the first time I've ever read the opposite.   I don't know why two piece rods could be revved at higher RPMs and more stress than one piece rods; if there is a difference, I'd think would be the other way around. 

OK, since I'm the least mechanically inclined person on the Board, someone please educate me.

Pressed together cranks with roller bearing rods, assembled by hand are more expensive to build.  Apparently pressed together single throw V-twin cranks with simple one piece rods/bearings assembled on the same machine that does the same for single single scooter engines is cheaper, or so believes Piaggio.

One piece rods may well be stronger and better for high RPM, when fitted with a plain bearing as in this case.  But it imposes a burden on anybody who ever has to work on the engine, and this engine doesn’t rev high enough for it to matter, or close, because pushrods prevent high RPM.

It’s just a cost saving thing, squeezing pennies out of something in exchange for reducing its practical lifespan.  Fine for the first buyer who likely never knows, fine for Piaggio because there won’t be as many multi-resale used bikes for them to compete with in selling new bikes.  Not so good for anybody who thinks long life is a measure of quality.
« Last Edit: February 01, 2021, 07:55:10 PM by Tusayan »

Offline LowRyter

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #20 on: February 01, 2021, 08:26:36 PM »
thanks for the replies, more confused than even.    :shocked:

are Harley cranks solid or pressed?  are pressed cranks really cheaper?  how would one piece rods fit on a solid crank? 

still confused.

don't worry about answering because I probably won't understand.   :sad:
« Last Edit: February 01, 2021, 08:31:55 PM by LowRyter »
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Offline moto-uno

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #21 on: February 01, 2021, 08:28:11 PM »
Keep in mind when making references to HD , they sell more bikes with pressed together cranks in a couple of months than Guzzi does in a decade  :popcorn:.
I worked on them at dealerships for decades and of course went to their factory for specialty training , so kinda familiar with them . And owned and ridden
Guzzi's for 38 years . I definitely prefer my Guzzi's , but that doesn't make H-D's bad bikes , just not my style ( and my pockets aren't that deep either :) ).
Peter

Offline DaSwami

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #22 on: February 01, 2021, 09:58:22 PM »

It’s just a cost saving thing, squeezing pennies out of something in exchange for reducing its practical lifespan.  Fine for the first buyer who likely never knows, fine for Piaggio because there won’t be as many multi-resale used bikes for them to compete with in selling new bikes.  Not so good for anybody who thinks long life is a measure of quality.

This was my initial thought, that this move may save them a few $$ at the cost of a more robust unit longterm.  Glad I have my V7III's.

However, I know just enough to be dangerous.

Most interesting to me, was that Cycleworld even bothered to mention it.  Seems like a detail that could just as well be left unsaid with no skin off their nose.


Offline voncrump

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #23 on: February 02, 2021, 12:24:35 AM »
The way I see it is;
If the crank pin is the same size then it should be as strong as the existing big end.
It will allow them to use very hard material in the pin.
The rods will be lighter thus allowing a better balance situation.
If the big ends fail in either type (seems to be very rare on modern V7s) then the crank has to be removed, repaired if possible or replaced.
What is the problem?
As long as the the crank doesn’t slip in the press fit all will be as normal.
Plus they are still making the V85 in the normal way so they could use that bottom end in the long awaited V85 Lemans.
Maybe even have another try at 4V per cylinder as some people have suggested might happen after they looked at the
Castings on the hemi motors.
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Offline Murray

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #24 on: February 02, 2021, 12:35:28 AM »
The question are the fittings a Hirth sp? style firrting similar used on old Porseche's and eventually the V8 gp racer or are they some dodgy tappered fitting i'm thinking the latter.

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #25 on: February 02, 2021, 05:37:08 AM »
Like older British bikes some were a tapered pin with a nut to hold in place from memory.
The side by side rods on a common pin like a Ducati has is the best option unless crank width/length is an issue. Articulated rods in all there forms whether a "master rod" situation or a forked arrangement like a Merlin engine uses are less desirable and generally for low rpm applications only.

Ciao
Yes, the large threaded nut provides the "press" onto the tapered joint.....Kawasaki 900 was a multi piece crank along with a few other Japanese 4 strokes..I believe they were pressed..
 WW2 Merlin and Allison used  knife and fork bolted rods with a one piece crank . The Dailmer Benz used both side by side and knife and fork with one piece cranks...
  When Allison dominated unlimited hydro plane racing the 1710 cube engines crowded 4500  rpm and made over 4000 hp...

Online twowheeladdict

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #26 on: February 02, 2021, 06:37:29 AM »
So, I've read a lot of opinions here.

What are the real world consequences of this design change? 

The engine will last less miles?

The new crankshaft will now be the first point of failure?

Does any of this matter to someone who might put 2000 miles a year average on a small block? 

What percentage of motorcycles, other than touring models, ever see 80,000 miles? 

How many 1998 - 2003 bikes have we seen on this forum recently purchased with under 35,000 miles on them?

Maybe we need a survey for just Moto Guzzis on this forum with Year, Model, Mileage so we know if this design change will have real world affects on future Guzzi riders. 

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Offline Chuck in Indiana

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #27 on: February 02, 2021, 06:52:22 AM »
Much ado about not much, as far as I'm concerned.  :smiley: I've never managed to wear out a motorcycle engine yet..
Chuck in (Elwood) Indiana/sometimes SoCal
 
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Offline Aaron D.

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #28 on: February 02, 2021, 07:00:13 AM »
Crazy panic time!

Thinking of all the older sports and racing cars with built-up cranks.  Not to mention my Laverda triple.

Like Chuck I have never worn out an engine. I suspect this will be a big savings for Piaggio.

To help with the angst, I should point out that you can't buy main bearing inserts for Vespa engines-they are sold as part of the case.

jwinwi

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Re: New crankshaft/connecting rod design for 2021 V7/V9
« Reply #29 on: February 02, 2021, 07:58:48 AM »
Crazy panic time!

Thinking of all the older sports and racing cars with built-up cranks.  Not to mention my Laverda triple.

Like Chuck I have never worn out an engine. I suspect this will be a big savings for Piaggio.

To help with the angst, I should point out that you can't buy main bearing inserts for Vespa engines-they are sold as part of the case.

Um, no. Just another example of how the cheapest solution is the way Guzzi is run now. If the pressed together crank is a better solution, why are they still using the forged crank on the V85?

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