harmonic balancer ??? !!!!!

[1jzracing]

who knows anything about the harmonic balancer on the front of sixes like the 1&2J ?

1) what is it do apart from the obvious removing harmonic vibration - but what is that and what is the end result of having hamonic vibration?

2) what happens if ther balancer is removed? such as fitting one of those alloy underdrive pulleys from US

3) why do only 6s and V8s have them, and they all do i think?

any ideas??

[love ke70]

can i tack another question on?
well i will, tell me to get rif of it if you dont want it. but what happens if your harmonic balancer is ground down like this...

that back "Wall" closest to my hand, should be same size as the front one. has now been replaced but wondering what damage i may have done?


and 1jzracing, i believe the damage of having harmonic vibrations is it upsets the crank and wears out clearances on bearing and sturf....

[Norbie]

Harmonic vibrations can lead to broken crankshafts. Just ask anyone with a 202 who tried revving it past 5000rpm!

[RWDboy]

How exactly does a harmonic balancer reduce vibrations though ? I presume it's stopping harmonics/standing waves going from flywheel end to pulley end, right ?

[30psi 4agte]

For starters all motors have some sort of balancer at the front of the engine not just 6s/8s.

Loveke70:
Grindng down the balancer will have no effect on how the engine performs as long as the balancer is balanced after modification(could cause vibration otherwise). I have actually machined the front half of mine off so that I am just left with the one pulley to run the alternator and waterpump (I had my balancer re-balanced).

Rwdboy:
Yep, your pretty much right. It can also help to take out the rotational harmonics plus the horizontal harmonics you mentioned.

There is a much more in depth answer than this but would take forever to explain. You are best off doing a google search on engine balancing/ harmonics for a good run down.

[stradlater]

Loveke70: As I had already discussed with you, if the thing is out of balance, it will damage your crank. Do you not listen to anything I tell you?


1jzracing: The underdrive pulleys from the US or whereever else, are still harmonic balancers. Atleast they should be if they are a replacement for your present harmonic balancer. They will still have an effect on the harmonic balance of the crank, but they will also have a smaller diameter(Or larger if that's what your after) that will drive your ancillaries at a different rate.

[love ke70]

stradlater of course i listen to what you say! shit man you are helping me out so much at the moment its awesome
but this came up and a second opinion can never hurt, i wasnt doubting you, just threw it up here as a spur of the moment thing...
do you still love me master?

[1jzracing]

I know the function of an underdrive pulley .... circuit car at constant high rpm needs one!

They are not a balencer at all just a small alloy pulley replacing the balancer check the picture

ive gon with machining down the grooved section to a smaller diameter on my factory one which will pull just over 1000 rpm out of my water pump at redline

[stradlater]

No, I think you'll find they still balance, even despite the fact that they appear to be nothing other than a pulley....

[ra_28]

My opion is don't touch the harmonic blancer there are set at a certain weight the counter act the fly wheel. Talk to Romac Engineering They make custom Harmonic Balancers.

[Joshstix]

The underdrive pulleys are just that a pulley. They have no rubber centre like a standard Toyota balancer.

As to whether the toyota balancer is doing a useful job or not, who can tell. The balancer was designed to work with the standard components in the standard operating window. I don't think my balancer is optimal in an engine where the pistons are lighter than standard the conrods are 250g lighter than standard for each rod and I have a billet steel flywheel with twin plate clutch and alloy clutch cover. All of those rotating/recipricating components are lighter than standard. The only bits that are standard weight down there are the crank timing pulley and the balancer.

Having said that I am sticking with the standard balancer because in my opinion a damper pulley is better than a solid one even if it's not completely optimal for the combination.

[wilbo666]

What about the fact that straight 6's are inherently balanced?
(that was my understanding at any rate).

Cheers
Wilbo

[Joshstix]

It's about harmonics not actual balancing. The crank flexs when each combustion event occurs and this dynamically puts the crank out of balance and sets up vibration waves in the length of the crank. The damper is there to stop these vibrations as quickly as possible. At least that's my understanding.

[Norbie]

There are reports on SupraForums of problems with 2JZ's after replacing the stock harmonic balancer with shiny underdrive pulleys. Apparently Toyota knew what they were doing when they designed the engine - who would have thought?

[takai]

And yet you have people driving and racing with Johns (Nevo) pulleys with no adverse effects whatsoever.
The only bit which springs to mind is maybe that the 6cylinder crank flexes somewhat more than the little 4A crank.