Rb30 Crank Work

[a31gtst]

Guys, yes I've tried the search option and cant find what I need so here goes...

I'm on the journey of a 25/30 build and in a dilemma on whether to balance the crank or not. I know the RB30 crank is already nitrated and am looking for 350+rwkw so aside of all other mods to achieve this, should the crank in stock form suffice or at minimal do I need to at least balance it? I don't plan to rev the motor past 7k rpm.

Your kind advice is much appreciated!

Cheers!

[TiTAN]

the stock crank as is will be up to the task but for the small amount it costs to have everything ballanced why wouldnt you get it done.

[relic21]

definitely worth getting all your up and down and around and around bits balanced, including ur clutch and harmonic balancer, which gets bolted to your crank... i know sydneykid recommends it.. and thats good enough for me

[Swiper the Fox]

All reciprocating engine internals should be balanced before assembly.

[James_03]

Personally I would check the tolerances against factory minimum spec before you use it.

I picked up a rb30 crank with 100,000ks on it, and the front main journal + no6 were both just out of spec.

If they all measure in sort of mid range, then I would have a collar fitted then cleaned and grub screwed + balanced. You can find the journal minimum spec in the VL/R31 gregories service manual. That's my 2c anyway.

Edited May 19, 2010 by James_03

[a31gtst]

Thanks guys!

It puts things into a clearer perspective now. I had a mate tell me to just leave the crank and balance the rest as the crank is good enough "as is" so better not mess with it.

I've already got a crank collar fitted and will check the tolerances...I guess with all the bits a part now it just makes perfect sense to balance everything up.

Cheers!

[bubba]

Definitely check clearances, I didn't the first time and it cost me a new oil pump and almost a new block (and probably everything else if I didn't catch it in time).

[a31gtst]

Hi bubba,

I've been trying to find the clearance values, do you by any chance have them off you or perhaps be able to advice me how I can check them myself?

Cheers!

[zebra]

There is some discussion about clearances in here

http://www.skylinesaustralia.com/forums/Ma...gs-t319454.html

[bubba]

Very good info in that thread^^^

[a31gtst]

awesome...just read the thread...invaluable I must say.

Thanks!

[Gerg_R31]

rb30 blocks are getting a bit old so best to

measure bores - rebore if needed

measure big end journals on crank - grind if needed

measure main journals on crank - grind if needed

if using standard conrods measure the big end tunnel - close and hone if needed

with rb30 cranks they are nitrated from factory, if it has to be reground it should be re nitrated

after nitrating it should be balanced as the bare crank, then the flywheel, flywheel and the pressure plate, then with harmonic balancer flywheel and pressure plate that will be used

if new conrods and pistons are used have them weight balanced (little end big end and over-all)

only use ACL bearings if its a standard rebuild, "ACL Race Series" if its a factory turbo, I recommend "king" bearings as they are a better quality bearing and wont shit themselves as quick

[Bl4cK32]

only use ACL bearings if its a standard rebuild, "ACL Race Series" if its a factory turbo, I recommend "king" bearings as they are a better quality bearing and wont shit themselves as quick

Depends whose building it, and what they are comfortable / have some experience with. Cubes/Slaps and I, when our motors were built, went with the King trimetal bearings as thats what our builder had used and recommended.