Crank balancing

[Suprakeith]

I have had this going though mind for a while so thought would open a discussion about engine balancing as I currently doing forged na-t build and have been advised by a few to get the new crank balanced with the flywheel and clutch plate.

I am planning on running a lightened 4.6kg flywheel with the w58 gearbox and then in the future will upgrade the gearbox to either R154 or Getrag box which will require different flywheel.

So the thought going through mind is if get crank balanced with flywheel and clutch then when I upgrade gearbox my engine and gearbox will be unbalanced?

Plus have worked in engine building in the past and a crank was balanced as a crank and I am sure Toyota did the same when they made the supra, I can't imagine them balancing each one to the flywheel depending on box running, and another point going though mind is that can buy stock and forged built short blocks from different companies, so them engines would be unbalanced as they aren't balancing the crank with the flywheel or clutch customer going to be using??

[Axl]

When my crank was balanced it was done with flywheel and clutch I too wonder if changing my clutch for a twin or triple plate would affect the balancing

[markssupra]

You might mind this interesting, I have to balance the rotating cutting tools I make to enable them to run at up to 30,000 RPM.

http://www.irdbalancing.com/assets/balance_quality_requirements_of_rigid_rotors.pdf

[Suprakeith]

When my crank was balanced it was done with flywheel and clutch I too wonder if changing my clutch for a twin or triple plate would affect the balancing

 

It's good to know I not the only one thinking oblong these lines

[Suprakeith]

You might mind this interesting, I have to balance the rotating cutting tools I make to enable them to run at up to 30,000 RPM.

http://www.irdbalancing.com/assets/balance_quality_requirements_of_rigid_rotors.pdf

 

That was an interesting read as I understand using balanced tools as in my job as cnc programmer I have to make sure certain tools are balanced perfectly for the job needed,

 

But I still very confused over crank balancing as have been reading bits online all night while at work and am still unsure if it's best to balance crank with or without flywheel and clutch as the long term will be replacing gearbox and will require different flywheel and clutch and am I then going to have to pull engine apart again to get crank balance right.

 

Hopefully few more people will have bit of insight as there is a lot of upgraded and rebuilt engines on forum so they must of come across crank balancing situation.

 

Part of me is leaning towards just balancing the crank on its own as have noticed all the stroker kits for 2jz come with crank, rods and pistons which are all balanced of course but no flywheel, so in theory if one purchased a stoker kit and fitted it to an engine and then fitted new flywheel and clutch as you would, then would the engine be unbalanced

[Suprakeith]

Also forgot to mention that I have posted this question on different sites to try to find out the right answer if there is one, and been told by few people who work and run tuning companies that should get crank balanced with flywheel and clutch but when checked there websites they are selling rebuilt and new forged short block engines for fair few grand, but I don't understand how on one hand they say get crank balanced with flywheel then on other hand sell built short blocks with no flywheel or clutch so how is the engine balanced if they don't know what flywheel and clutch will be fitted.

[Chris Wilson]

When I get engines balanced I always suggest to the owner the individual items are balanced individually (crank damper, crankshaft, flywheel, clutch cover, clutch disc), then verified as an assembly. It's a lot dearer and means having mandrels made, which i have done for 2JZ and RB25 / RB26 engines, but enables you to swap in a different (balanced) flwheel or clutch at a later stage. If done the cheap way, as an assembly, changing a worn out clutch may unbalance the whole assembly. I balance new flywheels and clutches on a scrap, but balanced, crank, and dampers on a purpose made mandrel.

[Suprakeith]

When I get engines balanced I always suggest to the owner the individual items are balanced individually (crank damper, crankshaft, flywheel, clutch cover, clutch disc), then verified as an assembly. It's a lot dearer and means having mandrels made, which i have done for 2JZ and RB25 / RB26 engines, but enables you to swap in a different (balanced) flwheel or clutch at a later stage. If done the cheap way, as an assembly, changing a worn out clutch may unbalance the whole assembly. I balance new flywheels and clutches on a scrap, but balanced, crank, and dampers on a purpose made mandrel.

 

Thank you very much Chris for that answer that's exactly what needed to know, when I get the new flywheel, clutch and damper I will give you a call and get all the items balanced by yourself.