Flywheel Advice Please

[454]

Hi All,

I have a rather pressing question regarding flywheels for those of you out there who are technically minded.

My car is now finished and ready to roll but I have just discovered that as my engine is based on a 400CI unit it requires an 'externally balanced' flywheel rather than the standard Ultima 'zero balance' unit.

I currently have the standard Ultima flywheel which, as you can imagine, is causing much vibration on running the engine so I need to get this sorted to avoid destroying drivetrain and many other expensive parts.


What I need to do is take my Ultima flywheel and get it rebalanced to the same specifications as a chevy 400CI externally balanced flywheel, then put it back on the car.

Sounds simple but I need to find out what the specific figures are for the balance of the flywheel and where I can get it done to a very high standard.

Have spoken to the factory who helped diagnose the issue and they have been vey helpful, offering to send the flywheel off to American Speed who can perform the work and send it back.
This is an option I may persue but thought I would check in here first to see if any of you boys had any bright ideas.

Thanks

[Bowm4n]

Wouldnt it be easier to get the crank balanced then use the Zero-balance flywheel. Then you dont need to go through this again if/when you need to change the flywheel?
Also I thought the flywheel needed balancing whilst on the engine (not sure about that though)

[CanAm Dave]

Hi Jeremy

I had the bottom end of my engine balanced at Real Steel (01895 440505). Both the two engine builders Pete and Murrey know what they are doing. They have there own in house balancer. If you know what needs to be done then give them the details. I'm sure they could help!

Regards Dave

[Paul.B]

Drop Pete Knight an email. He is known as pi5ton on here. He did my 400cid engine in my last car. (I had the original fly wheel to go with my crank!!!)

Good luck

Paul.B

[Steve_D]

Are you sure the crank is the original 400 crank?

If it is an aftermarket replacement or a 350 crank it may be internally balanced.

It is not possible to just machine and balance the original crank as its design is inherently out of balance which is why you will not only need a balance weight in the flywheel you also need a counterbalance type front harmonic damper.
If you are going to get the flywheel balanced they will need to do the whole bottom end.
There is a lot of weight that will need adding to the flywheel rather than machining weight off.

Steve

[Davrianman]

I'm not an expert, but on my 434, my engine builder Pete Knight is using a high quality harmonic damper. I believe that these are essential of the larger engines to help eliminate the crank harmonics. Speak to Pete, he's the expert...

Mart

[Steve_D]

Davrianman said:

I'm not an expert, but on my 434, my engine builder Pete Knight is using a high quality harmonic damper. I believe that these are essential of the larger engines to help eliminate the crank harmonics. Speak to Pete, he's the expert...

Mart

It all depends on the crank.
If Pete is using an aftermarket crank then it will be internally balanced. The original crank for a 400 has to have balance weights in both the flywheel and the harmonic damper.

Steve

[454]

Thanks all for your advice

Have spoken to Mr Knight who was very helpful, my flywheel will be arriving there tomorrow.

The block is a 400CI 4 bolt mains unit and the crank is standard so what Steve is saying is correct, it will need the counterbalanced flywheel and damper.

Good news is I already have the damper in place so it's just the flywheel that needs rebalancing to 400CI spec.

Flywheel should be back in a few days so I will know how well this worked soon enough.