# Correcting runout?



## njloof (Nov 21, 2011)

So I mounted the adapter plate and flywheel onto my motor (an AC24) and spun the flywheel to measure runout. I saw .004" from lowest to highest point, and saw some vibration at low RPM.

Because it's an AC motor, a lot of motor shops don't know what to do with it, and typically can't test it. Can they correct the problem by just spinning mechanically? I worked with an industrial machine shop on the adapter plate but they really don't know much about automotive applications. Any suggestions? I'm in Los Angeles for what that's worth...


----------



## major (Apr 4, 2008)

njloof said:


> So I mounted the adapter plate and flywheel onto my motor (an AC24) and spun the flywheel to measure runout. I saw .004" from lowest to highest point, and saw some vibration at low RPM.
> 
> Because it's an AC motor, a lot of motor shops don't know what to do with it, and typically can't test it. Can they correct the problem by just spinning mechanically? I worked with an industrial machine shop on the adapter plate but they really don't know much about automotive applications. Any suggestions? I'm in Los Angeles for what that's worth...


So what does that mean? Was this on the output shaft relative to the housing? Like the shaft is bent? And runout is not necessarily related to balance. Positional tolerance and balance is independent to the type of motor or if it is a motor at all. A machinist should be be able to work with rotating equipment regardless. And motor shops are more familiar with AC motors. Yes, an EV motor can be tough for them to deal with because it won't simply run on 60 Hz from the mains. But you don't power it to take runout and balance is done on the rotor alone.


----------



## njloof (Nov 21, 2011)

major said:


> So what does that mean? Was this on the output shaft relative to the housing? Like the shaft is bent? And runout is not necessarily related to balance. Positional tolerance and balance is independent to the type of motor or if it is a motor at all. A machinist should be be able to work with rotating equipment regardless. And motor shops are more familiar with AC motors. Yes, an EV motor can be tough for them to deal with because it won't simply run on 60 Hz from the mains. But you don't power it to take runout and balance is done on the rotor alone.


That's runout measured on the outer rim of the flywheel relative to the housing. I did not measure runout at the shaft, but I can if needed. It did not occur to me that the shaft might be bent in my early testing.

The motor shop I went to (Littlejohn-Reuland) referred to it as a "servo motor". But in theory it should run just fine on three phase power, right?

If they don't need to run it I can take it back to them to try to balance it. I just felt that they hadn't ever worked with automotive parts in their shop. If there is a particular kind of motor/machine shop to look for, I can...


----------



## major (Apr 4, 2008)

njloof said:


> That's runout measured on the outer rim of the flywheel relative to the housing. I did not measure runout at the shaft, but I can if needed. It did not occur to me that the shaft might be bent in my early testing.
> 
> The motor shop I went to (Littlejohn-Reuland) referred to it as a "servo motor". But in theory it should run just fine on three phase power, right?
> 
> If they don't need to run it I can take it back to them to try to balance it. I just felt that they hadn't ever worked with automotive parts in their shop. If there is a particular kind of motor/machine shop to look for, I can...


0.004" TIR on a 5 inch radius for an assembly sounds pretty close to me. That's less than 0.001 inch/inch. I didn't realize you were working with the flywheel attached. Maybe you'll have to work with an automotive guy in that case. Motor shops either routinely do or have a go-to-place for balance of rotors. They also should be able to check straightness of the shaft as well as a machine shop. For motor work I recommend an EASA shop. Not sure what you (or they) mean by servo. If it a 3 phase induction motor or PMAC, it will work on 3 phase. Servo is more of an application term than a type of motor.


----------



## njloof (Nov 21, 2011)

major said:


> 0.004" TIR on a 5 inch radius for an assembly sounds pretty close to me. That's less than 0.001 inch/inch. I didn't realize you were working with the flywheel attached. Maybe you'll have to work with an automotive guy in that case. Motor shops either routinely do or have a go-to-place for balance of rotors. They also should be able to check straightness of the shaft as well as a machine shop. For motor work I recommend an EASA shop. Not sure what you (or they) mean by servo. If it a 3 phase induction motor or PMAC, it will work on 3 phase. Servo is more of an application term than a type of motor.


If 0.004" is close enough, I'm happy to not bother 

They're an EASA shop; I'll take it back to them with the flywheel and see what they say. They did a really nice job on the adapter.

No idea why they called it a servo motor; they just knew it wasn't like the other motors they worked on there. Most of them were much bigger!


----------



## electro wrks (Mar 5, 2012)

I don't know what AC motor you have-some pics would help. Some of the OEM AC motors out of EVs can run at 10-12k or more RPM. This might be too high for a stock ICE flywheel. Check with a pro, an exploding flywheel is very dangerous. 

Check in a service manual for your ICE for the max. allowable flywheel edge and face runout. Sometimes you can move the flywheel/ shaft coupler to different positions on the motor shaft to correct too much runout. This is called "indexing". Don't forget to mark the position! Sometimes a piece of metal, dirt, or a burr on a sharp machined edge can mess up the alignment. Keep it clean and deburred. As a last resort, a good machinist can scrape the parts for the correct fit. The process uses very simple, basic tools but requires a lot of skill and patience.

Some ICE flywheels are used in a external balance system with a lump of metal near one edge of the flywheel and not the other. It will be an obvious asymmetry. Do not run the motor if the flywheel has it. You need to check for this. Again, a pro can help. You might be able to machine it out. Minor imbalances sometimes can be corrected with an extra washer under a clutch pressure plate bolt.


----------



## njloof (Nov 21, 2011)

electro wrks said:


> I don't know what AC motor you have-some pics would help. Some of the OEM AC motors out of EVs can run at 10-12k or more RPM. This might be too high for a stock ICE flywheel. Check with a pro, an exploding flywheel is very dangerous.


This is not my motor, but my motor is identical to this:









This motor can go up to 10k, but I can limit that on the controller closer to the ICE redline (7k). Also, I have an aluminum aftermarket flywheel, not the stock one (at least 10 pounds lighter!)


----------



## mizlplix (May 1, 2011)

> I saw .004" from lowest to highest point,


If you are talking radial runout and you are using a factory made flywheel and a machineshop made adapter, it can not be "repaired". 

(Now, axial runout can be trued and the flywheel made to run smoothly.)

If I am understanding you correctly, it sounds like radial and that is machined into the adapter, you will need another one.

You can remove the ring gear and true the outside of the flywheel and make it run smooth, but the clutch assembly will throw it out of balance. That can be bandaided by rebalancing and match marking it to assure correct assembly.....But you are just playing with disappointment.

The radial runout should not be more than .0005" max. (or less)

If there is one part that is really the "heart" of your conversion, it is the hub.

Miz


----------



## major (Apr 4, 2008)

mizlplix said:


> The radial runout should not be more than .0005" max. (or less)


0.0005" on an assembly of like 5 components  That's tough to hold on 2 diameters on the same piece.


----------



## njloof (Nov 21, 2011)

mizlplix said:


> If you are talking radial runout and you are using a factory made flywheel and a machineshop made adapter, it can not be "repaired".
> 
> (Now, axial runout can be trued and the flywheel made to run smoothly.)
> 
> If I am understanding you correctly, it sounds like radial and that is machined into the adapter, you will need another one.


Yes, it's radial. I have not even tested axial runout, but now I know to do so as well.

Ahhhhh, but this is when it gets interesting. The actual hub adapter is a Rebirth Auto adapter plate. The machine shop made me a piece in between to match my 13cm bolt pattern on the motor to the 15cm bolt pattern on the plate. It sounds like that piece can be remachined to better center the shaft (assuming the flywheel is true). Does that make sense?

Thanks, guys, your caution says I was right not to just shrug and mount the motor as is


----------



## mizlplix (May 1, 2011)

Oh, a three piece mounting...that is a difficult thing to do with a flywheel. 


A radial mistake when you use a stepped type mounting probably will require a new piece because, you naturally assume the manufactured hub is OK and the factory flywheel is ok too. 

Miz


----------



## njloof (Nov 21, 2011)

Ok. I'm taking it back to the shop that made it, so worst case they may have to make me a new piece.


----------



## mizlplix (May 1, 2011)

If you can. Take everything for them to look at and work with. 

Miz


----------



## njloof (Nov 21, 2011)

Well, we measured the radial runout at the Rebirth Auto adapter and got 0.0025". That reached 0.007" at the flywheel.

So the guys at the shop are both trimming and rebalancing the flywheel. They said that since the clutch and pressure plate are wearing components they should be replaced if out of balance.


----------



## electro wrks (Mar 5, 2012)

njloof said:


> Well, we measured the radial runout at the Rebirth Auto adapter and got 0.0025". That reached 0.007" at the flywheel.
> 
> So the guys at the shop are both trimming and rebalancing the flywheel. They said that since the clutch and pressure plate are wearing components they should be replaced if out of balance.


What kind of coupler is this? Is it a set screw over a key type or is it a tapered bushing type? Again, pics would help. If the flywheel is modified, the locating registers and/or locating dowel positions may need to be remachined. If they're not, the whole flywheel/clutch assembly may need to be rebalanced- and could be a real PITA. Doubly so in the future when the clutch and pressure plate need to be changed. 

It seems to me if the RA adapter is off, they should take care of the problem.


----------

