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20v crank re-grind - who's had failiures?
#1316255
13/02/2012 17:20
13/02/2012 17:20
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nedge2k
Unregistered
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nedge2k
Unregistered
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i see it advised against but has anyone actually experienced a failure? if so, what happened exactly?
(i don't need a new crank, i'm grinding for another reason)
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316261
13/02/2012 17:39
13/02/2012 17:39
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nedge2k
Unregistered
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nedge2k
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cheers mate, i'll leave it for him to see here in case anyone else wonders
Last edited by nedge2k; 13/02/2012 17:40.
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316262
13/02/2012 17:40
13/02/2012 17:40
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Marco20ValveT
Unregistered
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Marco20ValveT
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from memory, re-grinding take off the nitrate harding from the crank.
and i *THINK* it does not allow a propper oil film on the bearings which casuing the bottom end to fail.
i no of an engine which had a full re-build + New oil pump the lot.. and it failed due to bottom end knock.
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316342
13/02/2012 21:53
13/02/2012 21:53
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Joined: Oct 2010
Posts: 549 Bulgaria
Ferrarist
Enjoying the ride
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Enjoying the ride
Joined: Oct 2010
Posts: 549
Bulgaria
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Had one regrind on my 2.0TS, polishing on 2.5 and 20VT - no issues.....BTW at least 60% of our used cars here have some kind of regrind, i saw few times an crankshaft that was regrinded 3 times and used for long with no problems with appropriate bearings.......well most of it was daily cars, not driven hard......But hope you understand the reason for that - here in the price of one new 20VT crankshaft i can buy 2 used MK1 Punto's in full working order.
20VT - Alfa 156 2.0 - Alfa 156 Mid-Engined RWD - Locost 20VT
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316378
14/02/2012 00:00
14/02/2012 00:00
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1NRO
Unregistered
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1NRO
Unregistered
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316387
14/02/2012 00:45
14/02/2012 00:45
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TurboJ
Unregistered
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TurboJ
Unregistered
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It has come to my attention that somebody thinks my engine failure in my project thread is related to this thread, it is not. My failure was due to incorrect bore size for piston clearance. I have NEVER re-grinded my crank nor had a crankshaft issue.
I would strongly advise against re-grinding as suggested above.
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316394
14/02/2012 01:59
14/02/2012 01:59
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nedge2k
Unregistered
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nedge2k
Unregistered
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So, nobody has actually experienced a bottom end failure that has been 100% attributed to a re-grind? ...but then by the sounds, not many have actually tried it either so... the problem with the GC posts are a) I get the feeling he's mostly talking about the old skool twin cams which were probably subject to differing levels of nitriding depth and b)he's not said the failures he's seen are 100% attributed to a re-grind either. i would assume the nitiriding layer on a modern 20v crank would be a lot thicker, as much a 40 microns but that's just speculation - need to measure it really! thanks for the input
Last edited by nedge2k; 14/02/2012 02:04.
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316408
14/02/2012 09:10
14/02/2012 09:10
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Joined: Dec 2005
Posts: 12,295 Sandhurst
Begbie
Ex El Presidente
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Ex El Presidente
I AM a Coop
Joined: Dec 2005
Posts: 12,295
Sandhurst
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I went to GC's when my engine was being built with a new crankshaft. GC pointed out that this didn't have the nitridring on it and he demonstrated the difference between the 2.
He took a centre punch and a hammer and gently taped the non nitrated crank, this put a dent in it straight away, he then took an old crank with the nitrated layer, used the centre punch and used full force on the centre punch, the result? No dent.
For me, this was quite conclusive on which crank I should be using.
Your car is Usain Bolt with wellies
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316411
14/02/2012 09:18
14/02/2012 09:18
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Marco20ValveT
Unregistered
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Marco20ValveT
Unregistered
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can you get a crank nitrated harded after the skim?
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316419
14/02/2012 10:08
14/02/2012 10:08
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nedge2k
Unregistered
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nedge2k
Unregistered
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supposedly yes and as it's done at relatively low temps, shouldn't distort the crank or create stresses. however, GC has some warnings on it so some further investigation warranted me thinks.
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316436
14/02/2012 11:11
14/02/2012 11:11
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1NRO
Unregistered
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1NRO
Unregistered
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Are 20vt cranks that rare where you can't source a good used on?
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316437
14/02/2012 11:12
14/02/2012 11:12
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Joined: Dec 2005
Posts: 286 Germany
Stichl
Making a profit
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Making a profit
Joined: Dec 2005
Posts: 286
Germany
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Original 20V and 20VT crank is NOT nitrated! We did several investigations. Therefore regrinding is absolutely no problem at all.
Juergen
Last edited by Stichl; 14/02/2012 11:13.
20VT coupegrale 4x4
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316438
14/02/2012 11:13
14/02/2012 11:13
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tricky
Unregistered
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tricky
Unregistered
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You should ask Guy directly about the 20v cranks, this sort of thing is one of his pearls of wisdom.
I would like to suggest that the earlier cranks have a deeper nitride layer than the modern versions which would be a different procecss entirely. The original liquid nitriding I believe was banned due to some sort of harmfull chemical used.
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Re: 20v crank re-grind - who's had failiures?
[Re: Stichl]
#1316439
14/02/2012 11:15
14/02/2012 11:15
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tricky
Unregistered
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tricky
Unregistered
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Is there no treatment at all on 20v ?
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316446
14/02/2012 11:38
14/02/2012 11:38
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nedge2k
Unregistered
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nedge2k
Unregistered
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Are 20vt cranks that rare where you can't source a good used on? (i don't need a new crank, i'm grinding for another reason)
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Re: 20v crank re-grind - who's had failiures?
[Re: Stichl]
#1316447
14/02/2012 11:39
14/02/2012 11:39
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nedge2k
Unregistered
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nedge2k
Unregistered
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Original 20V and 20VT crank is NOT nitrated! We did several investigations. Therefore regrinding is absolutely no problem at all.
Juergen now that's very interesting! would you mind sharing a few more details of the investigations?
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316457
14/02/2012 12:40
14/02/2012 12:40
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Marco20ValveT
Unregistered
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Marco20ValveT
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Please do.. im interested... i wounder if Guy Croft will come on here to explain a bit more..
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Re: 20v crank re-grind - who's had failiures?
[Re: Begbie]
#1316471
14/02/2012 13:51
14/02/2012 13:51
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nedge2k
Unregistered
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nedge2k
Unregistered
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I went to GC's when my engine was being built with a new crankshaft. GC pointed out that this didn't have the nitridring on Apologies, appear to have totally missed that. So that's two saying no nitride layer on the 20v cranks. Don't know about the rest of you but after 70k, my crank was still within std OE diameters - so if they're not nitrided, what's the deal?
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316483
14/02/2012 15:07
14/02/2012 15:07
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Joined: Dec 2005
Posts: 286 Germany
Stichl
Making a profit
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Making a profit
Joined: Dec 2005
Posts: 286
Germany
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Very simple test - make a hardness test (I think we did Vickers) with original crank, take a file and grind a bit of surface, repeat test. If there are no changes in the result, there cannot be any nitride on it. We did not find any change. Moreover I am quite sure that a grinding shop would realize a hardened crank, when trying to regrind it... It is very very hard to regrind a nitride surface... Juergen
20VT coupegrale 4x4
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316484
14/02/2012 15:13
14/02/2012 15:13
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Joined: Dec 2005
Posts: 12,295 Sandhurst
Begbie
Ex El Presidente
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Ex El Presidente
I AM a Coop
Joined: Dec 2005
Posts: 12,295
Sandhurst
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I went to GC's when my engine was being built with a new crankshaft. GC pointed out that this didn't have the nitridring on Apologies, appear to have totally missed that. So that's two saying no nitride layer on the 20v cranks. Maybe if you look at my signature, you will notice that I don't have a 20vt and was talking about 16v cranks
Your car is Usain Bolt with wellies
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Re: 20v crank re-grind - who's had failiures?
[Re: Begbie]
#1316486
14/02/2012 15:24
14/02/2012 15:24
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nedge2k
Unregistered
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nedge2k
Unregistered
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I went to GC's when my engine was being built with a new crankshaft. GC pointed out that this didn't have the nitridring on Apologies, appear to have totally missed that. So that's two saying no nitride layer on the 20v cranks. Maybe if you look at my signature, you will notice that I don't have a 20vt and was talking about 16v cranks what kind of arsey response is that? you're the one talking about 16v cranks in a 20v crank thread!
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Re: 20v crank re-grind - who's had failiures?
[Re: Stichl]
#1316488
14/02/2012 15:27
14/02/2012 15:27
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nedge2k
Unregistered
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nedge2k
Unregistered
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Very simple test - make a hardness test (I think we did Vickers) with original crank, take a file and grind a bit of surface, repeat test. If there are no changes in the result, there cannot be any nitride on it. We did not find any change. Moreover I am quite sure that a grinding shop would realize a hardened crank, when trying to regrind it... It is very very hard to regrind a nitride surface... Juergen and you checked the journal diameters first to make sure they had not been ground already? did you test more than one crank?
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316492
14/02/2012 15:49
14/02/2012 15:49
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Marco20ValveT
Unregistered
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Marco20ValveT
Unregistered
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I went to GC's when my engine was being built with a new crankshaft. GC pointed out that this didn't have the nitridring on Apologies, appear to have totally missed that. So that's two saying no nitride layer on the 20v cranks. Maybe if you look at my signature, you will notice that I don't have a 20vt and was talking about 16v cranks what kind of arsey response is that? you're the one talking about 16v cranks in a 20v crank thread! Begbie is Mr Cranky
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316494
14/02/2012 16:05
14/02/2012 16:05
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nedge2k
Unregistered
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nedge2k
Unregistered
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Begbie is Mr Cranky Pun intended?
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316511
14/02/2012 16:55
14/02/2012 16:55
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Joined: Dec 2005
Posts: 12,295 Sandhurst
Begbie
Ex El Presidente
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Ex El Presidente
I AM a Coop
Joined: Dec 2005
Posts: 12,295
Sandhurst
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I went to GC's when my engine was being built with a new crankshaft. GC pointed out that this didn't have the nitridring on Apologies, appear to have totally missed that. So that's two saying no nitride layer on the 20v cranks. Maybe if you look at my signature, you will notice that I don't have a 20vt and was talking about 16v cranks what kind of arsey response is that? you're the one talking about 16v cranks in a 20v crank thread! Maybe take the time to re-read your own thread. People were discussing about regrinds and the topic went onto nitrate on the crank. I was giving a real life example of the difference between a nitrated crank and a non nitrated crank.
Your car is Usain Bolt with wellies
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Re: 20v crank re-grind - who's had failiures?
[Re: ]
#1316517
14/02/2012 17:03
14/02/2012 17:03
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Marco20ValveT
Unregistered
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Marco20ValveT
Unregistered
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Begbie is Mr Cranky Pun intended? well, might as well! it was not ment to be.. but Yer..
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