All the other journals on the crank that I've felt are SMOOOOOOTH. The one with the rod knock (basically no bearing left in it) feels "scratchy" to the finger nail. Is this extremely bad or not so bad? There aren't any "grooves" or any specific trouble spots that I can see, the whole journal is just "scratchy." Do I need to get the journal resurfaced? Or can I just slap a new rod bearing on there and be ok?

not that i know anything about anything, but i was talking to my dad, and he would recommend that you resurface the journal, because if you install a new bearing without doing so, it may spin again and eat away at the crankshaft..?

Here are my attempt at some quality pics with my digital camera. Sorry, but tried my best. :(

http://www.sr20deforum.com/GRM/030202

Originally posted by Ben98SentraSE
Here are my attempt at some quality pics with my digital camera. Sorry, but tried my best. :(

http://www.sr20deforum.com/GRM/030202

Add more light, and use the macro setting of the camera.

Chris

I would get some VERY ligt sand paper and clean up the surface and get oversize bearing for that yournal. Been there done that on a 3.1L GM motor. Its at 240K miles now and no rod knocks since the bearing job 60K miles ago. Get some very light paper and clean it all up evenly.
Mike Jez
Did bearings on many cars from Audis to Nissans, GMs, Fords.

BEN98SENTRASE just a little advice do yourself a favor and take the crankshaft out and get that rod journal up to spec don't even think about throwing in new rod bearings before you resurface the crankshaft are chances are that you'll be doing this job all over again and you might not be as lucky you might actually throw a rod out your block. First off check all your rod bearing clearance useing plastigage to see what condition all the crankshaft rod bearings are in. Here are the specs you should be within STANDARD .020mm - .045mm LIMIT .090mm (you really don't want to be past .045mm) and your probably find that the other three rod bearing are just fine, if like you said they weren't scratched.

Mike- why need an oversize bearing? Just cleaning up the surface with emory paper will cause that much material to be taken off?

Originally posted by charlie2020
BEN98SENTRASE just a little advice do yourself a favor and take the crankshaft out and get that rod journal up to spec don't even think about throwing in new rod bearings before you resurface the crankshaft ....

Absolutely. There should be no question here. In fact, I would go so far as saying you just need to get a new crankshaft. The crank journals are hardened and grinding them will almost certainly screw that up.

Don't throw good money after bad.

Originally posted by SentraPLAYA
I would get some VERY ligt sand paper and clean up the surface and get oversize bearing for that yournal. Been there done that on a 3.1L GM motor. Its at 240K miles now and no rod knocks since the bearing job 60K miles ago. Get some very light paper and clean it all up evenly.
Mike Jez
Did bearings on many cars from Audis to Nissans, GMs, Fords.

Mike you monkey!!!

That is bad advice.

1) A GM motor has sloppy clearances. The SR20 clearances are a whole order of magnitude tighter (GM to thousandths, SR to ten-thousandths).

2) How quick you forget your DET. You did this with the DET to spun a bearing in at the Dallas convention. Didn't work for you then, and won't work for Ben now.

I was reading my Haynes manual and found a little trick:

"Rub a penny across each journal several times. If the journal picks up copper from the penny, it's too rough and must be reground."

A simple trick like that was JUST what I was looking for. :)

Originally posted by Ben98SentraSE
I was reading my Haynes manual and found a little trick:

"Rub a penny across each journal several times. If the journal picks up copper from the penny, it's too rough and must be reground."

A simple trick like that was JUST what I was looking for. :)

Ben....

If you can feel the scratches with your fingernail the journal is totally hosed. Think about this - if the bearing clearances are around 0.0005", don' t you think a scratch in the crank you can feel with your fingernail is larger than this?

Spend the $375 and get a new crank.

Please point me to where it is said that the journals are hardened.

FSM even states
"if clearance cannot be adjusted within the standard of any bearing, grind crankshaft journal and use undersized bearings."

The crank may be forged, but it isn't hardened (unlike camshafts).





Originally posted by Geo91SER

The crank journals are hardened and grinding them will almost certainly screw that up.

George, the crank is not hosed if one journal surface is messed up. It's called a MACHINE SHOP. The Haynes states to regrind (or whatever the correct term is) the journal and get oversize bearings.

I like to try and SAVE MONEY when I do things by looking into all the alternatives. Spending $375 on a new crank is stupid. You can get a whole new JDM DE for that.

Here's the plan. Going to rebuild the whole bottom end. Do it right, everything in spec, clean clean clean, and take my time. I am so used to doing things in a hurry so you can drive the car again I must keep repeating the mantra "NO TIME LIMIT." :) New bearings, check all clearances, endplays, clean the block rings "while we're in there," everything. Blueprint it. Clean, correct, like new. And take my time. :cool: If the crank needs reground, we will had a shop reground it and use oversize bearings.

Dad has access to borrow this tool which can check the smoothness of a surface like this and show the amount of smoothness so we can see if it's in spec or not with the FSM. Sounds like a pretty advanced electronic doodad. :)

I need to get a better digital camera that takes videos...

Ben,
I seem to remember from a few engine's I've rebuilt that it isn't that expensive to get a crank reground (like $100). Some places have to send it out to get done though, others may try to sell you a 'rebuilt' (already reground) in exchange for yours.

If you do get yours reground, I think that they don't just regrind one journal, but all of them to the next serviceable size whether it needs it or not, unless you specify otherwise.

Check out the prices. Given the labor to do it all over if you don't do it right, you may want to have peace of mind and just get it done.

Lastly, you are looking for 'undersize' bearings. The crank journal is getting ground to a smaller diameter hence the undersize nomenclature. When boring a cylinder out to the next size, that's when you get oversize pistons and rings.


Is there a higher flowing oil pump avail for the SR20's? Seems that there are a lot of spun bearings for this motor when it see's high RPMS for a prolonged period of time.

Originally posted by Probedude
Please point me to where it is said that the journals are hardened.

FSM even states
"if clearance cannot be adjusted within the standard of any bearing, grind crankshaft journal and use undersized bearings."

The crank may be forged, but it isn't hardened (unlike camshafts).


I thought I had read that on the SE-R list. Perhaps not. I know there are undersize bearings available.

Still, I'd not be inclined to run a machined crank in an SR20. The clearances are just too tight.

Originally posted by Ben98SentraSE
George, the crank is not hosed if one journal surface is messed up. It's called a MACHINE SHOP. The Haynes states to regrind (or whatever the correct term is) the journal and get oversize bearings.

I like to try and SAVE MONEY when I do things by looking into all the alternatives. Spending $375 on a new crank is stupid. You can get a whole new JDM DE for that.

Whatever Ben. I don't think you can be a JDM for that anymore from what I've been hearing.

Geez, I just tried to help. Just throw that bearing in there.

George,
As long as a good quality machine shop does the job, there should be no problems. After all, the original crankshaft is machined to size and the OEM manuf was able to maintain proper tolerances. (ever see a crankshaft blank before machining?)

Lastly, don't you work for a major automotive parts chain? Don't they sell remanuf crankshafts for just about any car? Nissan can't be that technologically advanced to have a throw away crank design.

Originally posted by Geo91SER

Still, I'd not be inclined to run a machined crank in an SR20. The clearances are just too tight.

This is the $2003 challenge motor we're talking about here, right? Putting a new crank in the engine for that project truly would be stupid, since the whole name of the game is; as cheap a build as possible. I'm sure George doesn't know what you are using the motor for :).

Josh

Originally posted by MEclassic
This is the $2003 challenge motor we're talking about here, right? Putting a new crank in the engine for that project truly would be stupid, since the whole name of the game is; as cheap a build as possible. I'm sure George doesn't know what you are using the motor for :).

Josh

Thank you Josh. That was not at all clear to me. Actually it wasn't known at all to me

Now that I know what you are building the engine for, of course it's stupid. That's way too much out of your budget. But, be very very careful about who does the work. Most shops will not be anywhere near as careful as they should be with the SR20 crank. The guy that did all the measurements on my engine couldn't believe the tolerances were correct. He was sure I had to be nuts. I had to show him in the FSM. And this was a race shop building high quality, high dollar engines. Even if it is for this challenge competition, I'd be really picky about who does it.