Is your Barra out of balance too?

Swedishmoose · 20-07-2011, 05:14 PM

Hi there,

the Barra is like most straight 6 a very well balanced engine.
However, i have recently discovered that there are some areas within the rev-range, where it is slightly out of balance.
If I keep the RPM at 1700 when the car is parked in the garage, the engine develops some sort of slight vibrations that can be felt in the steering wheel and when holding/touching the open drivers door. The vibrations basically flow through the whole car although they are not extreme but noticeable.
It is a 2000 AU Falcon Futura (4 speed auto , 151000 km).

Is there anything that can be done to eliminate the vibrations at 1700 RPM so it can't be felt anymore?

I mean it is not that a tiny weight can be put onto the crankshaft to counterbalance it like you do when a wheel is out of balance.
I also checked the vibration absorbers that are used to keep engine and frame apart. They seem to be ok.

However, if it is normal that the Barra develops some sort of light vibrations in some areas throughout the rev-range (every engine is different), I'd like to ask you guys at what RPM your Barra is slightly out of balance and if anything can be done about it.

Thanks for any info....

cheers

The Moose

You Yangs · 20-07-2011, 05:32 PM

Barra is the code name for the DOHC from BA onwards.

FGII-XR6 · 20-07-2011, 05:35 PM

Firstly the barra is from B series on the AU engine was not a barra. the problem ( if you could call it a problem) you mention sounds more like a slight out of balance situation in an ancillary item rather than in the engine itself , harmonic balancer, PS pump, Alternator, AC compressor, torque convertor or fly wheel to name a few

Donny · 20-07-2011, 06:03 PM

All mass produced engines have spots in their rev cycle where they can be a bit harmonic and resonate some. The cranks were basically balanced to an acceptable factory standard, but not all the reciprocating parts are balanced as in a properly prepped and balanced motor.
Add age, klms done and how its lived its life and your likely to have a few harmonics here and there. The Ford straight 6's are pretty good, you should see how some older V6's are.. The Old V6 Capri engines were shocking things..
Some can be caused by exhaust systems too, or tune out of whack a bit, crap in the fuel or partly blocked or leaking injectors etc.. The possibilities of what it could be are nearly endless..

Unless its excessive, I wouldnt worry about it. The later B series on barra DOHC engines quite reqularly bumped and shimmied around idle..

Swedishmoose · 20-07-2011, 06:38 PM

Hi guys...

thanks for the replies...

i guess I made a fool out of myself by calling an AU straight six Barra....well....some of my Ford buddies do too..I guess I have to let them know

It is not excessive but you know how it is if you find something new and unusual....although I am not even sure if it has always been like that and I haven"t just noticed it.

It is a very light vibration that can be felt in the steering wheel.

I don't have any upgrades except a cat back exhaust and muffler. I don't drive it much and I haven't put any fuel injector cleaner in it for a while.

That could be a start then...

The Moose