PDA

View Full Version : Crank bearing question....



87preludeA20A3
02-22-2006, 06:40 PM
If i'm going to boost, what is the most that you should re-grind the journals. i know that it probably has to be ground down like .010 minimum. Would this be good or should i be better off with a good std. crank.... let me know. Thanks alot...

bobafett
02-23-2006, 09:49 AM
i dont recall the service limit, but....

i would suggest taking the crank and bearings that came off of it to a machine shop. they will let you know how bad your wear is, and whether or not you need to go to an oversized bearing. its possible that std size would work fine, but it all depends how happy your engine has been over its lifetime.

i had a low mileage motor to rebuild, and i used oem sized bearings IIRC

87preludeA20A3
02-23-2006, 03:19 PM
The crank that i have now has a baddly scorred main journal that is why i asked if i should just replace or used oversized bearings for my boost engine.... do you get that? does that make sense?

smufguy
02-23-2006, 04:04 PM
i dont know what you mean grind off, but here are the specs you are looking for http://www.accordproject.com/engineblock.htm 49.99mm is the max for the journal diameter

88Accord-DX
02-28-2006, 05:33 PM
The biggest undersized bearings your probably going to find are .030 thousandths of an inch. That is the farthest you want the crank turned. An automotive machine shop will only turn the crank untill it is past the scoring. Anything past .030, your more than likely need a new crankshaft.

Edit- I forgot to add, the automotive machine shop will turn your crank to .010, .020 or .030 thousandths of an inch. Which ever one brings it to where the scoring is gone. They will tell what size they turned it & what size undersized bearings to buy.

87preludeA20A3
03-01-2006, 10:51 PM
I realize all that but my actual concern was the reliability and strenght of using a .030 oversized bearing on a boosted engine... Do you thing the smaller crank journal(.030 smaller than std) will be weaker than the std journal for boost....? Does that make sense...

88Accord-DX
03-02-2006, 06:18 PM
I'm not an automotive machinist, but being that .030 is little less than a millimeter. I doubt there is anything to worry about. These crankshafts are pretty solid & haven't heard of anyone breaking one with or without boost.

bobafett
03-02-2006, 06:40 PM
darkside is a user on the board here, and he messed up a crank, but he spent a lot of time at 7k+ (daily i think). but yeah these cranks are really tough AFAIK

Accordtheory
03-02-2006, 06:40 PM
I would strongly recommend getting another stock crank. I was just reading a thread on h-t where a guy with a boosted d series had a crank ground, and his engine developed rod knock right after the break in, on his first trip to the dyno. Several people wrote that honda cranks have a surface treatment that has different wear characteristics than the underlying metal..but I don't know if that really matters, I'm sure it is still harder than the bearings..lol. But still, use a factory crank and be within spec, why f around, especially with forced induction?

shit, I Might have a crank for you, actually..I'll have to check..time to bust out the micrometer

smufguy
03-03-2006, 08:35 AM
as far as i know, our cranks were forged and were nitrated from the factory like the VR4 3000gts. NOt positive on the nitrated, but our cranks are one of the solid ones out there for a stock passenger economy car.

87preludeA20A3
03-03-2006, 09:30 PM
Accordtheory if that crank mics out and looks usable with just a polish than i will buy... PM me about it...

88Accord-DX
03-03-2006, 10:09 PM
Have you plastigauged your main & rod bearings yet? Anything but a new crankshaft is going to have some wear. Anyway, as solid as this crankshaft is, I don't see nothing to worry about if you get it turned to less then .030 .....
Even if you do get a "used" crankshaft. You still need to plastigauge it & see if it needs turned & polished. Look at the price of shipping a crankshaft & if it will meet specifications compaired to having your crankshaft turned & the right size bearings......
Just my $.02

smufguy
03-04-2006, 12:41 PM
If you're that worried about it, you could always get a new one for $575.

xD

:lol:

87preludeA20A3
03-04-2006, 01:01 PM
Well i micked the journals and they are all std... But because of the one main that spun i have to turn the crank to who knows how much and i also have to line hone the block. So if the crank needs .030 and the block gets .010 than i'm already out of spec bearing size... right because you cant get .040 over bearing sizes...

Accordtheory
03-04-2006, 04:25 PM
How much can you get another engine for? I didn't realize the block was damaged too..

87preludeA20A3
03-04-2006, 07:33 PM
Well i only paid like 150 for the whole engine in the junk yard... so yeah that might be the way to go. And this time i'll check it before i buy it....