[PMI]

The bearings and balance chain finally got pulled today, and according to what I just heard, one bearing was in three pieces...

For some history, see

http://www.saabcentral.com/forums/showthread.php?t=51450

With any luck I will get the car back tomorrow, and see how it runs with new bearings and w/o the balance chain... this was the quick and dirty method of deleting the balance chain, from the bottom, while leaving thetensioner and sprockets in place.

So, now the question: I am wondering if anyone here removed the balance chain on a '94-98 900SE turbo, and anything to look for, besides a little more vibration at idle?

 

[earthworm]

IMO, not good idea to delete the balancer system .

It is driven by a short chain, should last forever, whatever that means...
At low RPMs, maybe no difference, but at over 4 grand - who knows...

 

[ragtopcav]

On the balance shaft subject, check out Adrian's quality contribution to this thread it'll make you want to have the shafts back in action.

 

[PMI]

At low RPMs, maybe no difference, but at over 4 grand - who knows...

Really? ... well, you would know... I thought the second order vibration was damped by the inertia of the engine at higher rpm. At 4500 rpm the second order component is 9 khz... I thought the engine and mounts would damp that, or not? At lower rpm the second order vibration frequency is too low compared to the mass of the engine... that is what the math would say, but I don't have that much practical experience in that area, and it would not be the first time I am wrong about this car :roll:

I wonder if there is a way to measure it, but I suppose I should have thought of that before and taken some kind of reading.

 

[PMI]

On the balance shaft subject, check out Adrian's quality contribution to this thread it'll make you want to have the shafts back in action.

I know theory, but thanks for the link... I have not closed the door on redoing it the right way, but I was not ready to pay to pull the engine... besides, I always thought simpler was better. The Lancaster/Mitsu shafts are great, otherwise Porsche would not use them. However I am afraid I think the implementation that depends on oil pressure and a plastic chain guide to make it work, and then makes you pull the engine to service the mess... well that just s**cks.

 

[PMI]

I know I am bumping my own thread here - but still looking for someone with any experience deleting the balance chain on a 2.0L ng900, and any possible problems to look for!

Car seems to run well w/o it. Engine has quieted down a bit since the new bearings were put in, but I am not revving it any higher than 2500 until they break in a little. One of the rod bearing shells was really cracked into pieces - never seen anything like it. I am REALLY relieved that was cought in time, the same shop was expecting a 9-5 with a hole in the block when I picked up my car...

Engine sound has changed, but that could be because the old chain and bearings were damaged. Still not a completely healthy sound at idle, but the timing chain has not been replaced. Engine sound is still well below the noise made by the AC fan when inside the car, or the radio at a low volume. Slight vibration in the shifter at idle, but none while moving.

 

[earthworm]

The balance chain and shafts system is one the the things that distinguishes, or should, a Ford from a Lincoln or a Saab from a VW Golf....

And its deletion does nothing for value.
Some other engines use the balance shafts - by now , some of their owners may have axed them..., but I do not know...

But, PMI, this is an interesting experiment..

 

[PMI]

The balance chain and shafts system is one the the things that distinguishes, or should, a Ford from a Lincoln or a Saab from a VW Golf.... And its deletion does nothing for value.

I agree, IF you are comparing new cars. I am not against balance shafts in these engines.

At worst, removing the balance chain will allow me to keep driving it for a few more months. At best, I may be able to stop worrying about the engine for a while and have some fun tinkering a little while replacing the rest of the worn parts in the car.

 

[G96nt]

I've driven(and owned) DSM/mitsubishis With and without balance-shafts in place.

not Sure how this is going to relate to our Saabs, but here goes a *short* pro/con

1: 1 less chain/belt running in the timing chain/belt area.
it was quite common for balance shaft belts to snap on DSM's and when they do, they wedge themselves into the sprokets of the crank pulley, and shred timing belts. instant motor-loss.

2: less rotating mass: although small, each balance-shat weighs about 3# they're actually heavier than a camshaft. the less rotating mass, the less power-loss.

3: (in DSM) when we pull the balance-shafts, we were forced to use dummy-bearings to block a few oil journals. doing this upped oil pressure by about 20Psi in high RPM. most guys LOVE this, as the oil-pressure in the head/turbo is disasterously low, and Any small mechanical failure has the potential of oil-starvation and excessive wear.

now, The bad:
mistu uses un-damped motor/trans mounts. removing the balance shafts usually meant you were reminded of it when the motor was spinning less than 3k/min. however, it was almost completely un-noticable in upper RPM. (except for the Extra ~20HP)

in some cases, with oil pressure So high, some people would experience somewhat Sooner oil break-down from shearing caused by the oil pressure relief valve working more often. the solution:
real synthetic, or more-frequent changes.


given the opportunity, I'd pull balance-shafts in a heart-beat.
in-fact. next time I go to "Bob, my saab guy" I'm asking him to replace the timing chain and delete the BS-chain.

my only question to PMI: you had to replace bearings; were you referring to the rod bearings? did you just leave the shafts in the motor, un-driven? or did you remove the shafts and replace/flip their bearings?

 

[PMI]

my only question to PMI: you had to replace bearings; were you referring to the rod bearings? did you just leave the shafts in the motor, un-driven? or did you remove the shafts and replace/flip their bearings?

Rod bearings. One was cracked in three pieces. Oddly the engine ran fine except for some chain noise, which may have masked any noise from the bearings. The main bearings were replaced also, but only because it seemed like a good idea to do both at the same time.

We left everything except the chain in place. The mechanic cracked the chain at the crank sprocket and pulled it out while the pan was off to replace the bearings.