Lightening a Turbo (240mm) Flywheel

[PalmettoZ]

This is from a website for lightening Datsun 510 flywheels. I think they are the same. Tony D can you confirm ?

 

 

[Tony D]

510's below the L20B use a five hole flywheel and smaller diameter clutch (200mm)

 

The L20B uses the same bolt pattern as all the six cylinder Z's and I put my old lightened L28 Flywheel on my son's wagon with an L20B.

 

I haven't looked into it further than that. The numbers look about right for the way they did it in Japan.

[EvilC]

I had the flywheel balanced with the rest of the rotating assy. You zero out the crank, then put the flywheel on and zero, then the front pulley and final balance to zero.

 

Based on this statement I have a few questions guys.

 

Is our L6 motor an internally or externally balanced motor? The reason I ask is: say I am building a motor, do I get the crank, piston/rods and flywheel all balanced together or just the internal components together only. My train of thought is, I would not get the flywheel balanced with the “motor†because say 5 yrs down the road I change flywheel and clutch setup, I would have to pull the motor apart. If I statically get the flywheel balanced alone each time, no mater how many changes I make…the motor itself will always be in balance. The flywheel is just the wild variable that will always change and only play a factor in the rotational mass that the motor has to over come.

 

Is my train of thought correct or does everything has to be balanced together?

 

Thanks guys!

 

 

Lots of good info here for newbies like me...lol

[Daeron]

Based on this statement I have a few questions guys.

 

Is our L6 motor an internally or externally balanced motor? The reason I ask is: say I am building a motor, do I get the crank, piston/rods and flywheel all balanced together or just the internal components together only. My train of thought is, I would not get the flywheel balanced with the “motor†because say 5 yrs down the road I change flywheel and clutch setup, I would have to pull the motor apart. If I statically get the flywheel balanced alone each time, no mater how many changes I make…the motor itself will always be in balance. The flywheel is just the wild variable that will always change and only play a factor in the rotational mass that the motor has to over come.

 

Is my train of thought correct or does everything has to be balanced together?

 

Thanks guys!

 

 

Lots of good info here for newbies like me...lol

 

It sounds to me like Doug did just what you described: zero the crank, put the flywheel on, zero the flywheel, front pulley on, zero the front pulley. Then, you're good to go. He started with the reciprocating assembly, balanced it, added the flywheel, balanced the flywheel, etc.. and I don't THINK anything in that order would be inherently "custom balanced" to that particular assembly. if at any point you changed the clutch, or put that flywheel on a different motor, or whatever.. you would need to rebalance either motor ANYhow..

[woldson]

The flywheel and pressure plate that I just had done, will not have to re-balenced afterwards. Ya the pressure plate will have to go, then I will have to pull the fly just to do another plate.

 

Anyhooo, I want to say internal balence, and yesterday I got mine in and running. I have not posted results yet due to loud exught that had to be cut to get the tranny out. I will get it welded up this weekend, in the mean time an old ford guy told me to cut up an old beer can and use that to bring the pipes back together and wrap it with wire.

 

Yes I will post a pic, cuse it is funny, and it worked! Probley in non tech stuff.

[Careless]

The flywheel and pressure plate that I just had done, will not have to re-balenced afterwards. Ya the pressure plate will have to go, then I will have to pull the fly just to do another plate.

 

Anyhooo, I want to say internal balence, and yesterday I got mine in and running. I have not posted results yet due to loud exught that had to be cut to get the tranny out. I will get it welded up this weekend, in the mean time an old ford guy told me to cut up an old beer can and use that to bring the pipes back together and wrap it with wire.

 

Yes I will post a pic, cuse it is funny, and it worked! Probley in non tech stuff.

 

metal tie straps or metal cv boot bands are awesome for that too. two long beer cans are wicked too. it will last a good couple of weeks if you're really really short on cash to get another exhaust if you're the type to "fix it right when you have money" but "this will do for now".

 

[Careless]

As stated in one of my building books (not word for word).

 

balancing the rotating assembly, and then the rotating assembly with the addition of the damper, and then with the addition of the flywheel will get you into a closely balanced range so that any flywheel or balancer you put on from thereafter will be closer to a completely balanced package than a balanced rotating assembly with a separately balanced damper and flywheel.

 

For the same reason, people balance with the disc and pressure plate bolted on too using the same procedure to install on an engine prior to installing the trans.

 

Balancing all these components at once will ensure that further changes of the same parts (if they are zero balanced from factory, like most performance parts... or if you have them re-balanced alone if your engine is already together) will not cause severe imbalance.

 

This is as close as you can get to having a rebalance of the entire rotating assembly (which is ridiculous for a hobbyist if you're changing just a flywheel or balancer) because you actually have something hanging off the ends of the crank that are closer to the finished weight/mass/balance than having nothing there at all.

 

 

Based on this statement I have a few questions guys.

 

Is our L6 motor an internally or externally balanced motor? The reason I ask is: say I am building a motor, do I get the crank, piston/rods and flywheel all balanced together or just the internal components together only. My train of thought is, I would not get the flywheel balanced with the “motor” because say 5 yrs down the road I change flywheel and clutch setup, I would have to pull the motor apart. If I statically get the flywheel balanced alone each time, no mater how many changes I make…the motor itself will always be in balance. The flywheel is just the wild variable that will always change and only play a factor in the rotational mass that the motor has to over come.

 

Is my train of thought correct or does everything has to be balanced together?

 

Thanks guys!

 

 

Lots of good info here for newbies like me...lol

[Doug71zt]

You're on the right track. It is harder to balance the damper and flywheel without the crank to mount them on. So, you zero out the crank to have a starting point, then add and balance the flywheel, then the damper. Everything can then be replaced down the road without having to worry that you are throwing the balance. If you mounted up all the components at once, would you drill the crank, flywheel or damper to zero the assy out?

The process I use to balance a new build is:

Match the piston/pin weight

Match the rod total weight/small end weight/big end weight.

Now the recip. components are done, on to the rotating components:

Zero balance the crank

Zero balance the flywheel

Zero balance the clutch housing

Zero balance the damper.

 

If you are rebuilding a factory-built Nissan motor with all the original parts, I have found that it is not really critical to balance the assy as they are very close from the factory. Worst I have seen is around 4 grams. They were correctly balanced from the factory, not thrown together like a GM V6..... If you are building something from scratch or a Frankenstein motor, then it is a good idea to balance it. I didn't do the clutch housing on this last engine because it was custom-built and balanced by the shop. They are internally balanced - to answer your first question. No external weights are required and the assy is at zero balance without damper or flywheel installed

 

 

Based on this statement I have a few questions guys.

 

Is our L6 motor an internally or externally balanced motor? The reason I ask is: say I am building a motor, do I get the crank, piston/rods and flywheel all balanced together or just the internal components together only. My train of thought is, I would not get the flywheel balanced with the “motor” because say 5 yrs down the road I change flywheel and clutch setup, I would have to pull the motor apart. If I statically get the flywheel balanced alone each time, no mater how many changes I make…the motor itself will always be in balance. The flywheel is just the wild variable that will always change and only play a factor in the rotational mass that the motor has to over come.

 

Is my train of thought correct or does everything has to be balanced together?

 

Thanks guys!

 

 

Lots of good info here for newbies like me...lol

[Daeron]

You're on the right track. It is harder to balance the damper and flywheel without the crank to mount them on. So, you zero out the crank to have a starting point, then add and balance the flywheel, then the damper. Everything can then be replaced down the road without having to worry that you are throwing the balance. If you mounted up all the components at once, would you drill the crank, flywheel or damper to zero the assy out?

The process I use to balance a new build is:

Match the piston/pin weight

Match the rod total weight/small end weight/big end weight.

Now the recip. components are done, on to the rotating components:

Zero balance the crank

Zero balance the flywheel

Zero balance the clutch housing

Zero balance the damper.

 

If you are rebuilding a factory-built Nissan motor with all the original parts, I have found that it is not really critical to balance the assy as they are very close from the factory. Worst I have seen is around 4 grams. They were correctly balanced from the factory, not thrown together like a GM V6..... If you are building something from scratch or a Frankenstein motor, then it is a good idea to balance it. I didn't do the clutch housing on this last engine because it was custom-built and balanced by the shop. They are internally balanced - to answer your first question. No external weights are required and the assy is at zero balance without damper or flywheel installed

 

That really says it best; sorry if I fudged anything up or didn't make this exact point in my last post, it was what I was shooting for. (I actually winced as I wrote "reciprocating" and thought "half of those parts are rotating, but I'm not going into all that")

[EvilC]

Thank you Doug71zt/Daeron/Carless!

 

I am in the process of building a 3.0 and wanted to make sure my train of thought had some validation. I would love to see exactly how the machine shop balances each part. If you guys don't mind I am going to start another thread with my question and your answers so it does not get lost in this great thread.

[Careless]

Thank you Doug71zt/Daeron/Carless!

 

I am in the process of building a 3.0 and wanted to make sure my train of thought had some validation. I would love to see exactly how the machine shop balances each part. If you guys don't mind I am going to start another thread with my question and your answers so it does not get lost in this great thread.

 

Flywheel balancing uses a cool type of light-strobe that identifies the out of balance area.

 

Crankshaft balancing uses pin-bobs that are filled with shot-peen balls to mimic the weight of your rotating assembly so that vibrations can be seen across the entire crankshaft and it's spun at the RPM you want it to be balanced to. The bob weights are static in that they do not rock back and forth like pistons on a wrist/gudgeon pin, which would throw off the weight in an atmospheric environment, whereas in an engine the rings add enough spring tension to brace them to the point where balancing with the bobs of equal rod/piston weight will closely or almost exactly mimic the weight of the engine assembled as a running unit, pistons/pins/locks/bearings and all. The latest machines use a washer/jam nut style two-sided clamp with threaded rods sticking out. Washers are stacked down onto the clamp outer face and jam-nut locked to the base. This method is supposed to be easier and quicker. If a machinist is working on time/hourly basis, it may be a good idea to check which machines they use. It makes a very noticeable difference in your bill.

 

Harmonic Damper balancing I would imagine is done using the light-strobe method with holes drilled in the back side of the damper.

 

All additional metal used to fill any holes if weight is to be added to a hole that has been drilled to accept a heavier metal than the host-metal is "mallory", which is expensive and is required to be a separate purchase from the machinist in most cases. It's got a good bite when press-fit and it's made of a bunch of alloys, notably tungsten in most mixtures.

[EvilC]

Thanks for the great info again.