? on balancing..

[Rodney87GN]

Quick question, sorry if it sounds dumb.

But does the machine shop need the balancer and flexplate to balance an internal balance rotating assembly?

 

[turbodave231]

Not if the balancer and flexplate are already neutral balanced. BTW, The production parts are external balance (not neutral). If your machinist can spin the crank with the flywheel and balancer installed, that makes sure everything is good.

Understand that each part was balanced by itself and to an acceptable tolerance. (Kinda like balancing tires, they are never absolutely perfect) Balancing the crank with the harmonic balancer and flywheel installed will help eliminate the stack up of small errors that could occur.

 

[Rodney87GN]

I forgot to mention that I will be using a BHJ balancer and JW flexplate, both internal balance. Also I'll be using a CAT internal balance crank. Thanks for the response.

 

[87GNSteve]

If I remember correctly the BHJ balance doesnt slide on easily like the factory one does.
It needs to be "fitted" so it might need the hub to be honed out.

 

[Nick Micale]

......But does the machine shop need the balancer and flexplate to balance an internal balance rotating assembly?

We will never balance a rotating assembly unless ALL the parts are included.

Taking a chance and assuming the flexplate and balancer will match exactly is not one we are will to take for our customer.

You are going to pay for the entire assembly to be balanced, do it right.

Also, do not hone the BHJ as it is made to work properly with its press fit, NOT slide on and off like the stock piece.

 

[87GNSteve]

OK, I did remeber correctly.
BHJ Instruction sheet states:

Internal diameter has been honed to minimum OEM tolerance. In many instances this will create an excessivley tight press fit. Carefully measure your crankshaft snout diameter and hone the bore of the dampner to give a .001/.0015 press fit. This operation must be performed with the utmost care as too loose a fit will cause the dampner to move and damage the keyway and too tight a fit may cause the dampner to gall and weld itself to the crank. We highly recommend the use of anti-seize compound since a steel hub is not as forgiving as a stock cast iron hub.

All neutral balance dampners have been factory balanced. However we higly recommend that you have YOUR balance shop check the BHJ dampner against your existing dampner since some balance shops have been known to utilize an out of balance dampner as part of a balanced assembly. If any additional balance holes are requrired the should be drilled as follows:


MAX drill diameter: 3/8"
MAX hole depth: 1/4 "

Taken directly from The BHJ installation instructions.

 

[Blown&Injected]

My machinest drilled 4 holes in my BHJ and honed it to fit the crank.

I believe the JW Flex Plate was also drilled in a few places too.

 

[Rodney87GN]

Thanks for the info guys. I guess I will have EVERYTHING at the machine shop for balancing.