Balancing classic Mini flywheels

Here is the way I balance flywheel assemblies for classic minis.
A number of people have asked me about this so I put a video together on it. I hope you find it useful.

[@smallweights]

It's little Dave ac, looks like I'm sending my clutch n flywheel to you make my ex granny 998 a little sewing machine 👌 I'm actually enthralled, learning & understanding vaguely

[@MiniMattTV]

I found it interesting that you balance each flywheel individually and then together rather than straight to assembled, I was thinking if both were out you could potentially unbolt and turn it then assemble and check again. It makes sense to balance each part though. Great stuff 👍

[@ACDodd]

That’s done so you can change a part if needed and maintain the balance

[@thisisyourcaptainspeaking2259]

Nice work, bravo! ;)

[@ACDodd]

Thanks a lot!

[@mrnice30001]

Fantastic, so simple but effective.

[@ACDodd]

It works better than you think!

[@luismeixner2125]

very interesting video there! nice to see it be done without massive machinery

[@ACDodd]

It’s like a lot of things, you don’t always need massively expensive kit to do certain jobs.

[@paullorman8924]

Loved it, thank you. Just had mine balanced so now I know how its done.

[@ACDodd]

Glad you found it useful!

[@paullorman8924]

@@ACDodd Very much thank you. Love the precision when in balance.

[@kingkotkot2341]

best video for balancing

[@deangaryjames]

Very interesting 👌

[@jimthomas2459]

great video on balancing, , what is your thoughts on lightweight fly wheels, , eg: 1275 A series ,? i saw a video on Balancing a flywheel and cover plate and crank and front pully as one unit, what's your thoughts

[@ACDodd]

Yes dynamic balancing the while assembly is the correct way to do it. However those who simply wish to fit a flywheel or a new clutch to an existing engine this is more difficult, hence using this method of balancing for just the flywheel and clutch is ideal.

[@trevcessna1723]

This is the exact video I have been looking for and you explained it perfectly!! Question: is there a way to do the same thing to a new “stock” crankshaft? Thanks so much for sharing your knowledge!!! Subscribed!!

[@ACDodd]

No, as I mention in the video it’s not possible to statically balance a crankshaft.

[@trevcessna1723]

Thanks!

[@ah1472-u5h]

Thank you for your detailed explanation and demonstration. Bit by bit you are answering my remaining Mini mysteries! You casually mention “centring” the assembly when you put on the back plate. That I would like to see done. It seems to me that the balance would be VERY sensitive to this centring. So much so that I wonder if you disassembled your finished balanced assembly, then re-centred/assemble it, would it still be so perfectly balanced?

[@ACDodd]

Clearly it can only be as good as the location of the bolts in the holes they fit. Which it’s why it’s important to renew drive straps and bolts when overhauling the assembly to help maintain assembly accuracy.

[@arvacon]

In most Japanese manual gearboxes, such as Toyota's C52 (used with the 4AFE engine), the clutch disk and pressure plate are bolted directly to the flywheel. Do you need to balance the flywheel every time you change the disk and plate? Wouldn't this weaken the flywheel due to the numerous different holes being drilled in it?

[@ACDodd]

No the flywheel is only balanced once. Fitting a new clutch kit, means the back plate may require a light adjustment but it will be very small.

[@_UserUser_]

​​@@ACDoddso I should balance the flywheel without the pressure plate and then when I put it on the flywheel, I should just change positions on it, until I find the one that doesn't make the flywheel out of balance? Or do you mean that I should remove material from the pressure plate too?

[@ACDodd]

@@_UserUser_ balance the flywheel in its own, then add all the other parts and then balance the assembly again as clearly shown in the video.

[@peterduxbury927]

It was great to see just how much "Out of Balance" the Flywheels were! And your drilling corrected this. But do you think that the 'unbalance' cause was primarily the Ring Gear itself, during manufacture and fitting of that item? I am planning to completely remove the Ring Gear in order to lighten the Flywheel. The Flywheel (with Ring Gear and Clutch Assembly) is mounted to a 3-phase (perfectly-balanced) Electric Motor. My car is a '71 Beetle, and is running a Hyper 9 electric motor, so no crankshaft or engine to worry about. The electric motor revs to 8000 rpm, so the balance in the area of the Flywheel and also the Clutch Assembly is critical. Currently, there is a high degree of vibration, and (I believe) that to use Knives and balance the (lightened) Flywheel and Clutch Assembly will be a quantum leap forwards in achieving a successful balance. With Regen Braking on my car, it is important to remove as much reciprocating weight from the Flywheel (and Clutch Assembly) as is physically possible. To all persons who decide to go EV on a Classic Car, (and retaining the Flywheel and Clutch Assembly) this is so very important. Thanks and greetings from Australia.

[@ACDodd]

A lot of the out of balance moments are caused by the ring gear distorting the flywheel out of round as it shrinks on.

[@peterduxbury927]

@@ACDodd Thanks so much for your reply, which is fairly logical to me. Perhaps I used the wrong term (reciprocal weight). I should have written 'Rotational Mass'. Also, my understanding is that (the further that the out of balance distance is - from the axis), this will exacerbate the problem. And I can well-understand the great comments from those few people who have entrusted you with this work, in achieving a smoother-running (and better balanced engine). Finally, I was really pleased to see the 'stamping' on the securing bolts - and relative positions, following the balance procedure. This further demonstrates a very high degree of your knowledge and care.

[@4272005]

Very interesting video. I noticed a couple of welds, is it common practice to weld the ring gear to the flywheel?

[@ACDodd]

It is on aftermarket steel billet items

[@Sternhammer89]

Another informative video. I guess on the Verto Clutch assemblies the straps can cause and issue. Do you just make sure they are done up in the position that they should end up in as I guess any movement durning the balancing will result in starting again? If the Clutch and Flywheel have already been balanced, could adding another spring (RTS) and changing the Clutch to Flywheel bolts (8.8 - 10.9) throw the balance out by much?

[@ACDodd]

If the clutch is coming apart it should always be rebalanced as it will never go back together perfectly.

[@rogeronslow1498]

Is dynamic balancing more sensitive/accurate?

[@ACDodd]

That depends on how sensitive your static jig is, if you are using just a couple of small bearings to support the wheel on then it’s not very good. If you are using 4 inch or larger wheels, then accuracy is much better

[@rogeronslow1498]

@@ACDodd Thanks for the info. I may make my own one then.

[@66AGW]

If is not in perfect balance what is the problem?

[@ACDodd]

Engine vibration and harsh running.

[@66AGW]

@@ACDodd from the factory they are all perfectly balanced?

[@ACDodd]

@@66AGWno, and worse than that once you fit a new clutch kit the new parts available are not normally balanced from new.

[@66AGW]

@@ACDodd i understand. Thank you!

[@rogeronslow1498]

​@@ACDoddI fitted a new clutch and pressure plate to my Audi A3 (8L1) and it developed an annoying vibration. Still need to remove it and have it balanced.