Oversize Bearings SR20

[AznXstazy]

hey guys, trying to find people's input on oversize bearings for the sr20. mine started knocking tore it down and found the crank is semi done... could be cut and use oversize bearings, but my machinist doesn't recommend it to much.

i know most import has special coating on them and shouldn't be cut etc etc, but trying to see if anyone has cut them and used oversized bearings. if so how long have you driven on it for and have ya'll had any problems.

[Sileighty_85]

theres no special coating just polished after being turned.


If your worried buy a new one
Nissan OEM Crankshaft S13 S14 S15 SR20DE(T) **Open Box Return** (http://www.frsport.com/Nissan-OEM-Crankshaft-S13-S14-S15-SR20DE-T----Open-Box-Return--_p_21525.html)

[AznXstazy]

theres no special coating just polished after being turned.


If your worried buy a new one
Nissan OEM Crankshaft S13 S14 S15 SR20DE(T) **Open Box Return** (http://www.frsport.com/Nissan-OEM-Crankshaft-S13-S14-S15-SR20DE-T----Open-Box-Return--_p_21525.html)

i know there won't be a special coating after i turn it, but from factory there suppose to be a special "nitride" coating on the journals of the crank. without the coating my machinist said it would most likely spin a bearing again in no time...

and i would order a new crankshaft, but i'm broke DX

[240sxluver4life]

Get a new machinist cuz either 1, he's a moron, or 2, he's an asshole and trying to screw you out of money. There is no nitride coating on cranks. I work at a machine shop and we build like one engine a week with a machined crank, never any issues. Nitride coatings are only on cams, and only on the cam lobes, not the journals. Thus cam lobes cannot be polished like the crankshaft can be.

[AznXstazy]

i'll go ask around a few other shops and get their opinions on this. i trust the guy who i'm bringing the crank to. he's done a few of my other machine work and a lot of other local guys here. he's not here to screw me, cause he doesn't recommend doing it. he never said he couldn't do it or charge me a lot. he just said it would most likely spin another bearing in no time.

soooo, i started this tread trying to see who is running oversize bearings and for how long etc. and what size over are you. thanks

[KaminaSan]

i know there won't be a special coating after i turn it, but from factory there suppose to be a special "nitride" coating on the journals of the crank. without the coating my machinist said it would most likely spin a bearing again in no time...

and i would order a new crankshaft, but i'm broke DX

What a bunch of bullshit.

Look, a lot of machine shops warranty their work. Do you think they would warranty something if they knew that turning or polishing a crank would cause it to spin bearings?

Think about it. Do you know what the point of oil is? It's to keep the metal on your crank, and the bearing materials from hitting eachother and denting/scratching the surfaces... If your crank and rods and everything had metal on metal contact, you would go through bearings in a matter of seconds. Can you imagine metal rubbing against metal at 7,000 rpms?

Let's put it this way. When people go to get built engines, or engine rebuilds, do you think they would get their cranks polished knowing that it will cause a spun bearing in no time?

[AznXstazy]

not here to argue if that is true or not, but that's what he's telling me. making me skeptical bout getting the crank cut.

trying to see who out here uses oversize bearings with a cut crank and ever run into problems etc.

i was trying to search more and someone on the dsm forum had their crank turned and cut through the coating and spun there rebuilt motor less than 200 miles into break in...

[Sileighty_85]

Seriously call another machine shop and ask them about it.

[brian3676]

SOME manufactures use the nitrite treated cranks. NISSAN DOES NOT. You can grind the cranks if you want to and as long as it is grinded RIGHT it will be 100% fine. Subaru, for example used nitrite treated cranks, there for is NOT grindable. However, brand new OEM Subaru crank=$350. Brand new Nissan crank=550-600.

I have rebuilt 20+ SR's for people, 50% of them have ground cranks, a few pushing upwords of 400-500HP, every one of them is still running.