Aircraft Wheel Balancing

Discussion in 'Maintenance Bay' started by Rob58, Dec 26, 2020.

  1. Rob58

    Rob58 Pre-takeoff checklist

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    After such success with a dynamic prop balance, I'm thinking about having my wheels dynamically balanced as well. Any shops on the west coast that can do this? I know there have been previous posts debating the value of this process... just looking for feedback. Thanks.
     
  2. Tom-D

    Tom-D Taxi to Parking

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    It is very easy to spin the tire wheel assembly to verify out of balance.
    replace the tire/wheel assembly and spin it. using a 1/4" drill motor, and a wire circular brush. If should not shake.
     
  3. Blatham489

    Blatham489 Pre-takeoff checklist

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    From what I know, dynamic balance is rare but if anywhere, try a motorcycle shop. Doing a static balance is relatively easy to rig up yourself and generally more than adequate.
     
  4. FastEddieB

    FastEddieB Touchdown! Greaser!

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  5. farmrjohn

    farmrjohn Pre-takeoff checklist

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  6. Jeff Oslick

    Jeff Oslick En-Route PoA Supporter

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    Another vote for a motorcycle shop. Just don't tell them it's from an airplane.

    Or, if you're near Fullerton, CA (KFUL), Ben's Motorworks on the southwest side of the field is a good A&P/IA and he also works on a lot of motorcycles in his shop.
     
  7. Dan Thomas

    Dan Thomas Final Approach

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    Static balancing is fine for main wheels. You can't attach weights on the inboard side of the wheel anyway, which is necessary for dynamic balance. The brake disc is in the way. The nosewheel should get the dynamic balance. A static balance on it can actually make shimmy worse. Or start it.
     
  8. Ravioli

    Ravioli Ejection Handle Pulled PoA Supporter

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    If in SoCal, call Anti-Splat Aero. He's an RV guy but he may have some thoughts for you. And he's really nice to work with. I f'd up some bolts he sent me and wanted to buy replacements, he replaced them all for free, free shipping, and threw in some extras so I could practice.

    ANTI SPLAT AERO LLC
    346 SOUTH I ST. SUITE 3 SAN BERNARDINO CA 92410 US
    TELEPHONE: +1.9098241020
    FAX: +1.9093815683
    E-MAIL: INFO@ANTISPLATAERO.COM
     
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  9. Jdm

    Jdm Line Up and Wait

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    I needed a new wheel balancer for a couple recent aircraft jobs. I finally broke down and purchased a horizontal type balancer that I’ve been interested in for some time. It’s extremely accurate. Couldn’t be happier with the results. Much better than the old vertical balancer we used in the shops I’ve worked.
     
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  10. Dan Thomas

    Dan Thomas Final Approach

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    If it's like this....
    [​IMG]

    .....it's still just a static balancer. A nosewheel really needs a dynamic balance, which is a totally different animal and the balancers cost far more. The wheel must be spinning to determine where the heavy spots are. They're not just radially located, they're axial as well. A static balancer can't find the axial imbalances. And it's those axial imbalances that cause nosewheel shimmy and nosegear component wear.

    A motorcycle dynamic balancer:

    [​IMG]

    Lots more money.

    When you get new tires on your car, they all get dynamically balanced. When I was young, static balancing was common and steering shake and shimmy was a headache and steering parts wore out all the time.
     
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  11. Jdm

    Jdm Line Up and Wait

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    My new balancer not like your first pic at all. Your first pick is the old vertical type we used back when I was a shop mechanic. I agree, they don’t work that well and can take a long time just to get it close.
    The new type that I purchased is a horizontal balancer. Mcfarlane makes one. There’s also knock offs that cost less. The wheel rests horizontally on a centered pivot point. It does a VERY nice job. Quick and easy. Definitely the best results I’ve had using a simple balancer. Probably not as perfect as a dynamic balancer but you can absolutely get the wheel balanced to an excellent standard. I have a guy who dynamically balances my motorcycle wheels. He can hook me up needed, but I doubt it’ll ever come down to that.
     
  12. Jdm

    Jdm Line Up and Wait

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    Also seems possible that you might run into limitations on weight placement, which would prevent a dynamic balancer from reaching its max accuracy. I don’t know, just seems likely.
    Here’s a wheel I recently finished. You’ll notice there’s only 6 indented areas that a standard weight can be placed. Unlike a automotive wheel most GA wheels are limited as to where you can properly place the weights. The horizontal balancer allows me to easily play around with various weight options prior to actually attaching the weight. Sometimes it’s best to split the weight into two of the indented areas rather than place too much weight into one area. The instructions address this issue and gives general guidelines of when to split weight.
    Unless you have another way to attach weight the accuracy of a high end dynamic balancer might be somewhat limited by the GA wheel design.


    CE4F6C97-7CE5-4008-96A2-DD3B009485A6.png
     
    Last edited: Dec 30, 2020
  13. Fly North

    Fly North Filing Flight Plan

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    JDM,

    Do you have a picture of the unit you purchased? Part number? Make&Model? I’m interested in getting one also. What did it cost?

    Thanks

    Kurt
     
  14. Larry Korona

    Larry Korona Pre-Flight

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    Also interested, does the kit come with the weights? If not where did you get them from? How does the weight attach and remain in place?
     
  15. Dan Thomas

    Dan Thomas Final Approach

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    That horizontal balancer is just a cheaper version of this:

    [​IMG]

    I used one just like it 50 years ago as a teenager working in a service station. It's still a static balancer, and no tire shop has used one of these things for at least 40 years now. All use electronic dynamic balancers, Much later, I had a vintage mechanical dynamic balancer that I used on the Cessna nosewheels, and it worked like a charm but took longer than the electronic balancers. When I left I missed it, so I built my own using the same principles. With either machine I was able to eliminate nosewheel shimmy, often without even touching the loose and worn nosegear stuff.

    Yes, getting enough weight in those old McCauley wheels can be a challenge. You have no choice, really, if you're going to get it balanced. Most aircraft now have Clevelands, which are no problem at all.

    Aircraft technology is way behind in this area, as it is in some others. Cars haven't had static balancing for 40 years or more, yet we're somehow satisfied with static balancing of nosewheels, and put up with the resultant shimmy, "because that's what Cessnas do." Yes, the smaller Cessna singles are prone to shimmy because their nosegears are rather light and flexible, but the real problem lies with the sloppy manufacture of the tires, and those tires are still bias-ply (gone from cars 40 years ago), tube-type (gone from cars more than 50 years ago) and have more radial and axial runout than the cheapest car tires. So most mechanics spend lots of time and customer's money replacing torque links and steering collar shims and shimmy damper stuff, while the imbalanced tire just rips it all up after a few more hours of a wobbling nosewheel.

    I dynamically balanced the flight school's nosewheels for years and NEVER had shimmy issues.
     
    Last edited: Dec 30, 2020
  16. Dan Thomas

    Dan Thomas Final Approach

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    Aviall sells them and tire shops have them, too. They're a peel-and-stick lead weight. They come in strips and you cut off what you need. One must get the wheel surface absolutely clean so they'll stay put. They go on the inside surface of the wheel so that centrifugal force presses them hard into place and they don't get flung off. It also helps to bend them to the wheel contour for maximum contact area.

    Some mechanics are hesitant to balance wheels. One can cite Cessna service bulletin SE84-21 as data.
     
  17. Jdm

    Jdm Line Up and Wait

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    DA42CAEC-6F57-494E-B311-73373DDFC310.png A91628D7-A608-45DE-B073-F7ADE9B23BCC.png DA42CAEC-6F57-494E-B311-73373DDFC310.png A91628D7-A608-45DE-B073-F7ADE9B23BCC.png
    There’s only 2 options that I know of. Pics of both are attached. McFarlane is the popular choice. It hangs from a cable. Really cool idea. Problem it’s ridiculously expensive and there’s 2 different sizes to choose depending on axle size.

    After doing more research I found a table top model at Desser Tire for $100.

    Desser experience: I’ve used Desser for years and have always been super happy, but this purchase didn’t go smoothly. The balancer had a missing part. Not knowing what the missing part was I had a very difficult time figuring out what I needed. Desser decided to send me another balancer but somehow the communication got crossed up and the package didn’t ship. I had to call back and repay for the 2nd balancer. The 2nd balancer arrived with the box totally destroyed. Huge rip in the box allowing small items to fall right out. Some of the weights had actually fallen out and were missing. Then it took forever to get refunded for the first item which had to be returned before they credited. We finally got everything straight. They were always easy to talk with, easy to contact, and tried super hard to make everything right. Based on our last conversation I think they’ve probably addressed the packaging issue of this item.
     
  18. Jdm

    Jdm Line Up and Wait

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    Yes it comes with weights. The Desser one does anyway. I don’t know about the McFarlane. You can purchase extra weights at aircraft spruce. Desser might sell them as well. Most mechanics clean the area well before sticking them in place with the self-adhesive backing and then smear a little RTV around the edges. Check with your mechanic on that.
     
  19. Fly North

    Fly North Filing Flight Plan

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    JDM,

    Thank you very much for the info!

    Kurt
     
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  20. MBDiagMan

    MBDiagMan En-Route

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    I have an old Coats dynamic balancer and I’m quite sure I could fit any of my airplane wheels onto it and balance them. They are too small for the read outs indicating how much weight is needed, but with a little trial and error I could get them dynamically balanced to within a gnats eyelash. I expect there’s a tire store kid near you that could get the job done.

    BTW, where ARE you? It’s times like this when having your general location in your profile could pay off. If it turned out you were near me I would be happy to balance them for you free gratis.
     
  21. MBDiagMan

    MBDiagMan En-Route

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    There are PLENTY of locations on that wheel for someone with dynamic wheel balance experience and willing to spend a few extra minutes.
     
  22. Jdm

    Jdm Line Up and Wait

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    I think you’ll find that most A&Ps will be reluctant to adhere weight anywhere other than well inside one, or possibly two of the six indented locations shown in the pic. It’s likely to fall off if placed at any other location. If you see one done differently I’d be interested to know how.
     
    Last edited: Dec 31, 2020
  23. Dan Thomas

    Dan Thomas Final Approach

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    That's where they go. Sometimes you have to stack the weights a bit. Whenever changed a tire on a wheel I'd balanced some time before, I had to pry the weights off with a screwdriver. The self-stick stuff has a serious grip on a clean surface. Stacking the weights just means that the surface of the first weight has to be really clean and oil-free.

    The weight needs to go inside the well but near the outer edge. If it's farther in it takes more weight to achieve a dynamic balance., And like I said earlier, the weight has to go on the rim, where centrifugal force will hold it down tight, not on any other surface where the force will try to shear or peel it off.
     
  24. Jdm

    Jdm Line Up and Wait

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    Exactly, thanks Dan.
     
  25. MBDiagMan

    MBDiagMan En-Route

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    No offense, but apparently you’ve never balanced wheels and monitored the long term reliability of the weights staying in place. First of all those six locations are quite adequate for someone who knows how to use a dynamic balancer. If the need for a weight between two of those positions arises, you split weight between the two positions. If the point needing weight is not exactly centered between positions, you will have to put more weight on one position than the other. No sweat, just a little time consuming.

    Secondly it is amazing how well the adhesive on current tape weights adheres. Much of the reason for that is that centrifugal force keeps them planted against the surface.
     
  26. Lycosaurus

    Lycosaurus Pattern Altitude

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  27. Jdm

    Jdm Line Up and Wait

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    We might be saying the same thing about the location. I thought you were talking about putting the weights someplace other than the six locations, in which case they could possibly come off. I’ve never have one come off, but I’ve never tried to place one anywhere other than the six normal locations.

    The avatar pic is of me working on my Stinson after graduating A&P school in 1986. Not saying I’m a balance expert in anyway, but being you brought it up..I’m pretty sure I’ve balanced an airplane wheel or two over the past 35 years.
     
    Last edited: Jan 1, 2021
  28. ktup-flyer

    ktup-flyer En-Route

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    Unnecessary on our little airplanes
     
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  29. MBDiagMan

    MBDiagMan En-Route

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    Unnecessary? Yes and no. Although there is a small amount of mass as opposed to a car or truck tire, due to the rotational speed, they can work up a pretty good vibration. If they are not vibrating so much when you lift off that you have to hit the brakes to stop the vibration, there’s no real need to balance them.

    Years ago, my 140 required brake application on lift off. I pulled the mains and balanced them. Smooth as silk after that. No need to tap the brakes is eliminated. Tire vibration is just one more potential distraction.

    Vibration applies impact stresses that are not only irritating, but can prematurely wear bearings and in odd situations cause various problems.
     
  30. MBDiagMan

    MBDiagMan En-Route

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    Then you know that wheel imbalance is not something to ignore.
     
  31. Jdm

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    Obviously, I chimed in to provide information about a new wheel balancer that’s working very well for me.
     
  32. donjohnston

    donjohnston Pattern Altitude

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    One of the things that surprised me when I was balancing my ailerons is that getting lead is difficult now days. After going to a bunch of different tire shops, I found one that was willing to part with some of their stash.
     
  33. thomasdr72

    thomasdr72 Pre-takeoff checklist

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  34. YKA

    YKA Pre-takeoff checklist

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    That needs to be cleaned up before balancing, all that dirt would throw off the balance. Then just use stick on weights.

    Most auto shops have a balancer, and many different sizes of the tapered cones they use on the shaft to center it. I worked at a Honda dealership, and balanced hundreds of tires, from motorcycles to pickups, and yes aircraft tires on their wheels. Spin balancing is really the only way to go. I recently mounted my own motorcycle tires, which I always do, then took them to the ford dealer and had them balanced. They did my new airplane tires a few years ago to. They justngrab the right size cone to put the wheel on the shaft, brab the big plastic calipers hanging on the side of the machine, a could quick measurements, punch them into the machines digital keyboard, close the cover that stops flying dirt, and hit start. When it stops, open the cover, and turn the tire by hand till the 2 arrows line up, then at the exact bottom of the wheel, add the amount of weight it tells you to. Couldn't be simpler!
    Then spin it up again and see if you need to adjust it a bit more, or if it is good.
     
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  35. Snowmass

    Snowmass Line Up and Wait

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    Are you sure you had true dynamic prop balance? Dynamic balance usually requires adding weights at both ends of a shaft and the prop and crankshaft are essentially one unit . A prop is basically a disk where dynamic and static balance are the same. Probably you just had a better static balance.

    Of course since the balancing operation involved motion it could be called dynamic but that is not how the term is normally used.
     
  36. flyingbrit

    flyingbrit Pre-takeoff checklist

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    That depends on whether you're a salesman or an engineer!
     
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