I've seen these marks too, the bearings on those will not last long....
- Thread starter carl0s
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Melvyn Best
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Had one that lasted a week, that must have been a good one. I watched when the original replacement was stripped, it had loads of swarf inside .
Trevorleach
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It became a standing joke in the end, the customer supplied the engines which I guess they bought as they were the cheapest, our guys fitted them, and it was pot luck to how long they ran for.
I always smile when I see that companies name mentioned anywhere.
Cracks when re-nitrided. You have to grind after nitriding to remove the white layer and bring it back to tolerance - exposing the cracks.
And of course, any heat treatment, stress relieving etc can cause it to distort - requiring even more grinding.
You do need to know exactly what the crank is made of too.
Stueeee
Old git
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Not sure where you're based... Jason Howes at South Kilworth near Leicester does quality work at reasonable prices. He uses a stroke corrective indexing grinder rather than the Prince style machines that follow the existing (worn) journals. if the crank is Nitrided, it should be possible to grind it once more; the main thing is to preserve the original fillet radius as changing (reducing it) will guarantee a broken crank.
The usual process for new nitrided cranks is to initially grind them .005 oversize, nitride, and then grind to size, the hardest layer of nitriding is below the surface of the heat treatment, also if there has been any distortion, the crank will be 'ground straight'
The usual process for new nitrided cranks is to initially grind them .005 oversize, nitride, and then grind to size, the hardest layer of nitriding is below the surface of the heat treatment, also if there has been any distortion, the crank will be 'ground straight'
Smallfry
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Another vote for Gosnays at Romford. I have always been happy with their work, and they will grind single journal if you wish.
Wouldn't like to say anything about hardening though, Surely must be able to get a used crankshaft or an engine with another problem and take the crank out ?
Wouldn't like to say anything about hardening though, Surely must be able to get a used crankshaft or an engine with another problem and take the crank out ?
Erie Fred
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Does anyone do weld & regrind ?
www.gleasonengineering.com
Gleason Engineering Industries, Inc. - Simple, Reliable Crankshaft Rebuilding
Simple Reliable Crankshaft Rebuilding. Gleason Engineering Industries, Inc., a supplier of crankshaft rebuilding machinery and journal buildup materials.
www.gleasonengineering.com
carl0s
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Thanks all for the responses so far. Given the variety of thoughts on this, I am still most convinced of the brand-new OEM route. Yes a good-used would be an option, but a quick search of eBay for 'n57 engine' or 'n57 block' or 'n57 crankshaft' shows that most being sold are knackered - a sign of how relatively common this failure is.
Somebody queried why I ruled-out aftermarket cranks. The reason is: I am only aware of Chinese stuff, and then Motus, and Genmot both of Turkey. I thought IPSA (through Autodoc) was an option, especially as they specifically list about 3 variations, with 4-counterweight, 8-counterweight, cast iron, cast steel, and forged all as options (which is good - properly specified rather than just labelled as 'good quality'), but upon closer inspection I can see they are reboxing Motus crankshafts. More research into both Motus and Genmot has revealed enough dissatisfied punters to put me off.
Somebody queried why I ruled-out aftermarket cranks. The reason is: I am only aware of Chinese stuff, and then Motus, and Genmot both of Turkey. I thought IPSA (through Autodoc) was an option, especially as they specifically list about 3 variations, with 4-counterweight, 8-counterweight, cast iron, cast steel, and forged all as options (which is good - properly specified rather than just labelled as 'good quality'), but upon closer inspection I can see they are reboxing Motus crankshafts. More research into both Motus and Genmot has revealed enough dissatisfied punters to put me off.
carl0s
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What about sticking something else in it, like a LS5
There was a suggestion from my father-in-law to shove a 2L (N47) in it or a lower tuned less-crankshaft-eaty ~200hp variant of the N57.
I am not up for the complications of an engine swap though.
I did put an LS2 in an RX7 a few years ago. That thing was too much. I would love another non-turbo big V8 car, and that might end up being something American since there are no more supercharged 5L Jags. Anyway this is the missus' car and she just wants it back on the road. She's driving my 125d and it's a bit crap in comparison to her '35d x4 I suppose (each to their own.. the 125d suspension is harsh though despite an expensive swap to Koni Special active dampers, and it's more cramped.)
pressbrake1
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chris pruteanu
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Not read your thread entirely but I would have gotten another engine given that they are not that much money anymore ! Grinding oversize it’s a hit and miss job and in most cases oversize bearings are not available aftermarket don’t know in your particular case ! My 2 cents, save yourself the grief and get another engine to work with !
carl0s
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Where's the fun in that!! :-) No seriously though a 2nd hand engine would still need timing chain doing (since it's sandwiched between engine and gearbox on these), and the rod bearings checking and changing anyway. and I really don't fancy the confrontation of buying a used engine, opening it up and then having to try to return it if it turns out to be in poor condition.
Stueeee
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The last time I was there, Jason (he, as above) had a batch of part machined billet cranks to grind for Arrow Precision. Arrow's prices have been eye watering when I've got quotes for one off billet cranks in the past.
