hello all, im soon to be building my evo 6 engine up and ive stripped it down to the block , now i was going to put new acl full race bearings in but the bearings that came out look very good, when i say good you can see some wear but the cranks absolutely mint! my dilemma is if i use new bearings they might cause trouble as in new bearings really need new crank? whats peeps thoughts on new bearings with used cranks

andy

 

Measure up first of all, going by eye will more than likly lead to a failure of some description. If within tolerance of std size bearing then bang in a new set, if not then crank out and send it for a regrind and get the appropriate sized bearings.

 

The the crank is out, why not put it into a machiners and get it properly checked, then run new bearings? Seems silly to have come this far and fall down on something that easily be given a better chance.

 

Never heard that one before ... As long as the crank journals are within tolerance .. And u have correct size bearings ... They will be fine

 

hi christian i now you deal in 4g63t engines, you mean just get the machine shop to check journal sizes?

thanks
andy

 

+1

If you cant measure it then you need to get someone how can too

 

see what ya say about if in tolrences then use standard bearings but as for regrind this is abit of a no no for these cranks it seems that Mitsubishi put a special coating on and as soon as you grind it off the cranks dont last very long

thanks
andy

 

At the very least get the machine shop to check the crank and polish the bearing faces if within tolerance.

 

I use only stock bearings or Cosworth ones.

Mark

 

in a mitsubishi?

 

Yes Cosworth sell engine bearings for the evo range.

Mark

 

I'd get the crank/bearing clearance measured to see if its within spec, then get it machined if necessary and new bearings to suit.

I personally doubt theres a special coating on the crank, the crank runs on a thin film of oil between the crank/bearing assembly, so special coatings etc need not be applied, the only time the crank comes into contact with the bearings is when oil pressure is lost.

In what way do the cranks not last long, do they wear prematurely or do they shear/snap?

 

No special coating. There case hardened, therefore if you remove material, you will weaken the crank a little.

John

 

hi, this was said to me on mlr and ive talked to dave ears motorsport who used to rally them and constantly rebuild them he said regrinds just dont seem to last very long and mitzy put this coating on them, you can say one thing the oem ones are very strong , they have been known to take well over 700bhp, and yes cosworth do make the bearings and the full block, pistons and rods the lot...

http://www.grdstore.com/cosworth-sho...2l-p-2671.html

seen the price tho

 

howz it goin mate long time no see

andy

 

Yeah not bad ta Andy, yourself??

 

Get the crank checked and polished, and crack on with building it up properly, once bearings start to show wear, its generally downhill from there.

 

thanks all, if anyone is interested aim doing this full rebuild in the restorations


evo 6 block 4g63t


evo 8 mr pistons


uprated excedy clutch


tommi multilayer headgasket


evo 4 gearbox


every single nut and bolt has been bagged and noted

 

Those rods look weak when you see them like that!

 

Put a YB rod next to one and the YB rod looks like a girder.

IMHO Exedy clutchs are rubbish but that might be to do with my driving style more than anything else (they don't like clutch kicking).

 

chip thats been said before mate and stu came on and told us all why they dont need to be any stronger but theirs still people running 500bhp thru these, my mates only just changed his and he was running 510bhp


andy

 

I know of loads of people who have had rod problems at more like 400bhp.

Have you got a link to where stu explained otherwise as that sounds interesting?

 

the weakest point in deff the rod, the oem pistons can take well over 500hp with norris rods
but stu explained about over engineering your talking a 220bhp cosworth with massively over engineered rods , i will try and find the post pal

 

Oh, if you mean for standard use then I am already FULLY aware of the fact that parts that over engineered (like YB ones) are shocking for production costs with no payback and not to mention heavier which actually loses a small amount of power an economy too.

I though you meant why he says they are fine for 500bhp!

 

Andy, bin that clutch mate and get a twin plate. A couple of full bore launches and that exedy will be toast Whereas the twin on mine gets launched seriously hard at every opportunity (at least 50 so far) and is still mint