Re: Std size new big end bearings + std crank => can't turn over by hand *conrod bent?*
you dont need to ghave adjustments to calibrate your torque wrench.
even if they fit an adjustment table which tells you by how many ft-lbs it is off at each reading then you can compensate
MX83 2JZ-GTE!!
#YOLO.
Re: Std size new big end bearings + std crank => can't turn over by hand *conrod bent?*
OC - you're right the rods/caps are a matched item and its not the perfect solution however, it is better than running with a stuffed bearing and wrecking the crank completely.
Rob - i'd say that the crank is out and the block may need a line bore. When you rebuild make sure you get everything done properly (and dont forget to add forged, lightened and balanced goodies)
How did this go with new oil etc anyway? has the orignial noise lessened at all?
Re: Std size new big end bearings + std crank => can't turn over by hand *conrod bent
Rob, if you have mixed caps around, i will estimate your engine will last no longer then 5 minutes running.
One of the most important points in ANY piston engine bottom end rebuild is that the caps of both main and conrod big ends belong with their other side for their entire lifespan. They should never be swapped EVER. Factory Toyota rods are marked on the cap sides and rod sides to identify which cap belongs with which rod.
If it was "err maybe it will work" scenario it may pass. But its not, engines with mixed caps dont last 20 seconds, Iv recently seen an engine that had ONE cam cap in the wrong place and it destroyed the head and camshaft in 5 minutes of running idle.
OK, perhaps it turns over and you've got clearance, You may have fluked it. Yes it all depends on the casting, machining process and overall consistency of the rod manufacturing process. But im suggesting that this engine will not last very long at all and you may have been better not touching them at all if you have swapped caps.
Please visit your local engine reco shop and ask them if you can swap caps. Then, observe their facial expression very closely and you will see how f'd up swapping caps really is.
P.S. Im not trying to have a go at you. Id just like yourself and any others to realize that this practice truly is unacceptable and 90 percent of the time unsuccessfully on all playing fields. If it works tho, you seriously have fluked it.
EDIT: oh btw, .0028" is way to much.
Last edited by jeffro ra28; 25-03-2009 at 09:31 PM.
Re: Std size new big end bearings + std crank => can't turn over by hand *conrod bent?*
Jeffro - you are absolutely correct. When i did my 3s rebuild the caps/rods had no markings on them whatsoever and had to be done by myself. I suspect that after all of the swapping and changing the original order may be impossible to revert back to and may have to run as is.
rob - you need to get back to us ASAP!
Re: Std size new big end bearings + std crank => can't turn over by hand *conrod bent
If there are NO markings whatsoever they can still be matched with their correct part with the use of a bore gauge. If this is unobtainable much simpler methods can be used. Although its very hard when there is a crank in the way and the engine is still in the car!
Rob, it may benefit you before going any further to blue check every cap and rod until a consistent match is found. I would remove the bearing shells from the rod and cap and blue check each rod and cap until a definant match is found. I can explain blue checking rods if you are un familiar.
Re: Std size new big end bearings + std crank => can't turn over by hand *conrod bent?*
So whats the problem with swapping bearing caps? If theyre all cast the same and it's the bearings that wear then whats the problem?
Daily Driver: Red Ae93 Project: My TA22 - now with 3s-gteD is for Disco, E is for Dancing
Re: Std size new big end bearings + std crank => can't turn over by hand *conrod bent
You basically end up with a hole that isnt round. All things working perfectly how they should, engine bearings wont wear. The oil if doing its job will never allow the crank to contact the bearing shell.
The thing is, its impossible to control the casting and manufacturing process to a degree where caps can be mismatched, they will all be different. Even billet machined CNC items require their caps to remain with the other half regardless. They will always differ some amount.
Re: Std size new big end bearings + std crank => can't turn over by hand *conrod bent?*
If the rod and cap combo was removed and professionally resized and honed etc it should be OK. But he is not doing that anyway.
Re: Std size new big end bearings + std crank => can't turn over by hand *conrod bent?*
that cap is ground and resized to its designated journal. when you mix them up the caps dont align with crank and the caps to the block or rod, so you can see how this can not be a good thing.
i dont have a funny or cool signature.
Re: Std size new big end bearings + std crank => can't turn over by hand *conrod bent
Originally Posted by amichie
Depending on the actual rod determines the scale and accuracy of my following comments of course. But the problem with doing this is that areas of the rod will end up thinner then they are meant to be, the rod may end up longer or shorter then its ment to be and distance between the bearing surfaces and rod bolts will be uneven from side to side. All of these things affecting the overall integrity of the conrod.
It really just ISNT meant to be done regardless. Yes getting the mismatched caps with conrods machined is a bit more acceptable and in most cases will work. But it is technical incorrect practice full stop.
Re: Std size new big end bearings + std crank => can't turn over by hand *conrod bent?*
Why would they be ground and resized from factory when the bearings they are using are all the same? So if rods start as one piece then are they cut in half after having the big ends bored? Then doesn't this pose a problem in itself.
I'm not doubting that keeping 1 with 1 is best practice, I just fail to see how mixing them up actually makes a difference, especially when your putting new bearing in there anyways, and if theyre not round then isn't that a problem in it's own right?
Apologies for making you guys cover the basics
Daily Driver: Red Ae93 Project: My TA22 - now with 3s-gteD is for Disco, E is for Dancing
Re: Std size new big end bearings + std crank => can't turn over by hand *conrod bent
The objective of a conrod big end bore is to provide a perfectly round hole for which to house the bearing shells, so that the bearing shells can provide a near perfectly round space for the oil ( the oil clearance is technical not perfectly round but no need to cover this here) If caps are mismatched this hole will no longer be perfectly round and the two halves will not match to make a perfect circle. Because of what a rod consists of, from accurate machining practices and clearances the rod bolts usually locate the two halves together to make a circle. If either or is shifted from its original machining in the factory, there will be some degree of mismatch of the two halves. Some conrods made nowadays are actually fractured on their cap face and not machined, these are not possible to mismatch caps.
The best way for you to understand this is to sit down with a few rods, knowing the basics of how a crank, bearing shells and oil work together. And swap the caps around. Id suggest first learning how oil, bearings and crankshafts work first tho. Its very simple once you understand how it all works and how basic machining practices are carried out.
P.S. I hope someone can explain this better then i have
Last edited by jeffro ra28; 25-03-2009 at 10:31 PM.
Re: Std size new big end bearings + std crank => can't turn over by hand *conrod bent?*
"P.S. I hope someone can explain this better then i have "
haha i dont think so man.
line boring is only at its straightest when all the caps are matching, the machine isnt 1000% dead on smack centered so when you start mixing caps that tiny % differance from this cap to another is enough to cause problems.
i dont have a funny or cool signature.
Re: Std size new big end bearings + std crank => can't turn over by hand *conrod bent?*
usually toyota has 3 or 4 different sizes of bearings depending on tolerance.
there is an explanation in most factory manuals... the difference in size is small, but is to allow for variations during manufacturing.
aftermarket bearings are usually "one size fits all" but they will not have the same tolerances as when it left the factory.
most rods don't start as one piece... or at least not with the fracture type.. they are kinda a bit special...
"I'm a Teaspoon, not a mechanic"
"There is hardly anything in the world that a man can not make a little worse and sell a little cheaper" - John Ruskin (1819 - 1900)
AU$TRALIA... come and stay and PAY and PAY!!! The moral high horse of the world!
Re: Std size new big end bearings + std crank => can't turn over by hand *conrod bent?*
yeh thats why toyota have numbers stamped on the block E.G 2242 (4cyl)
fracture type are cool
i dont have a funny or cool signature.
Posting Permissions
Reply With Quote
Bookmarks