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Old Aug 22, 2013 | 07:14 PM
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Default Crankshaft Question

Hi folks, in need of some advice if possible.

Having had no.4 shell spin on a Cossie engine I sent it off to be checked and rebuilt. They found the crank to still be on standard grind but now has a 17thou bend from the shell going.

I then sourced a second hand crank on a 0.5 grind that I was informed was ready to go however once the engine builder measured it it appears no.4 on that one too is fooked and would need a grind to 0.75, but this crank is straight and always has been.

Has anyone had a crank straightened and how has the car been with it?

My options now are:
1) Straighten the 0.25 grind the std original crank
2) 0.75 grind the 2nd hand one
3) Chuck a gallon of V Power and a match at the car and torch the fecking thing!!

Cheers in advance for any advice/opinions
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Old Aug 22, 2013 | 07:36 PM
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I'd personally go with option 2 as its a lot safer to get oversized bearings than have the crank straightend,
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Old Aug 22, 2013 | 07:37 PM
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how much power you looking to run dude? Not sure I'd want to be risking an expensive big hp engine on a bodged crank
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Old Aug 22, 2013 | 07:39 PM
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Im not chasing big power, it will be running stage 3 on a t34.48 with no plans to start chasing numbers
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Old Aug 22, 2013 | 07:57 PM
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Would think crank would be fine at that power on a .75 grind
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Old Aug 22, 2013 | 09:05 PM
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Get a second opinion on the crank ?

I'd really struggle to believe a Cossie crank would bend
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Old Aug 22, 2013 | 09:11 PM
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Originally Posted by stevieturbo
Get a second opinion on the crank ?

I'd really struggle to believe a Cossie crank would bend
I've had two machine shops check it and have seen them test it for myself.

They run the gauge round the journals and each one from 1-4 is showing a greater reading than the last so it does have a bend, as said its about 19thou
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Old Aug 22, 2013 | 09:17 PM
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Wow.

It must take some effort to do that, and even more for them to be able to straighten it.

Ive seen Subaru cranks bend, although their webbing between the journals is pretty thin. Although even that is rare
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Old Aug 22, 2013 | 09:22 PM
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Originally Posted by stevieturbo
Wow.

It must take some effort to do that, and even more for them to be able to straighten it.

Ive seen Subaru cranks bend, although their webbing between the journals is pretty thin. Although even that is rare
It barely done 300 yards from when the noise was heard til it was stopped

I've been told its when the shell spins it locks and the crank bends/twists as it frees off

Shit happens I guess
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Old Aug 23, 2013 | 12:02 AM
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My brother built his VR-4 motor (4g63t) evo etc round a crank that the engine recon shop straightened for him. running approx 320 hp at the wheels does 12.5 quarter miles and when the front axels are out enters most of the local burnout comps. So far engine has performed faultlessly, have they straightened any in the past?
(search you tube VR4 rwd Levin or Masterton, if you wana see an old VR do so sum burnouts its the yellow one, from NZ lol)
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Old Aug 23, 2013 | 12:05 AM
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should be fine once straightened, as long as it's done properly.
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Old Aug 23, 2013 | 09:47 AM
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Originally Posted by CZWRTH NZ
My brother built his VR-4 motor (4g63t) evo etc round a crank that the engine recon shop straightened for him. running approx 320 hp at the wheels does 12.5 quarter miles and when the front axels are out enters most of the local burnout comps. So far engine has performed faultlessly, have they straightened any in the past?
(search you tube VR4 rwd Levin or Masterton, if you wana see an old VR do so sum burnouts its the yellow one, from NZ lol)
Yeah they have done cranks in the past but usually they find the bend in the middle which is easier to sort. Mine is bent towards one end
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Old Aug 23, 2013 | 07:05 PM
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as i mentioned to you on facebook, TM Smiths in coatbridge straightened mine 2 years ago, its been running over 400bhp since and has been fine
but i cant remember where mine was bent, might have been the middle, but it was out as it had run no.4 big end shell thru to the copper so i assumed it was there but not sure
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Old Aug 23, 2013 | 07:24 PM
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ive had one straightened before and worked fine for 10000 miles running 380 bhp still have the moter but its my spare one now
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Old Aug 23, 2013 | 10:38 PM
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Cheers folks, seems a split opinion lol

I have left both cranks with the engine builder and said I shall phone them Monday with a decision
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