Jabiru wheels / rims

[TechMan]

Just wanting to see how many on this forum know of / have / or do experience vibration from the wheels on T/O and landing. I have had a report and have been sent some pictures of the cast rims being out of roundness. Any one else know of others with this problem?

 

 

[Guest DonC]

I experience it after take off for a few seconds

 

 

[Ultralights]

i experience the same problem every time just after liftoff, a quick pull on the brakes after liftoff will fix it, as for the cause, i have no idea, i have flown 3 different jabs, 2 factory built and one amature built, and all have the same problem.

 

 

[TechMan]

Thanks. If you believe that it is caused by the rims being 'out of roundness', can I please ask you to submit a defect report to the RA-Aus office by fax or email.

 

I only have one report of this happening so far, so if it is a concern for others, I will need more info from the field to take back to Jabiru.

 

Thanks

 

Chris

 

 

[Geoff]

I experience the same problem every time just after take off so did most of other Jabs in Sunraysia, got a wheel balance done no more problems, need to do every time you change tyers, just like a car.

 

 

[Guest ozzie]

just a note on using the brakes to stop the wheel rotation after takeoff.

 

my experience with GA aircraft has shown that this method can damage the calipers or weaken and snap the bolts holding the disc on. in many applications these bolts hold the wheel halves together. this can be agrivated by increasing the wheel mass with bigger(heavier) tyres ect. the breaking of the bolt in some instances was accelerated by the disc/ wheel bolt holes not being shamfered and having a razor sharp edge in contact with the bolt.

 

best just to let the wheel spin to a stop. steve

 

 

[pylon500]

I've noticed this as a harmonics thing in a few aircraft.The first time I flew a sapphire it did a wheel shake as I was going up through about 100 feet.I was sure something was about to fall off.

 

I've since noticed it in Drifters, Jabirus, Cessnas and other aircraft that use a common leaf spring gear, or any other type of single cantilevered gear leg.

 

Arthur.

 

 

[Student Pilot]

Most GA stuff will do it, especially if you hold it on for a while, if you get the Aircraft flying when it can instead of holding down then pulling off with some "margin". Pull the Aircraft off at minimun speed and let it accelerate in ground effect.

 

Using brakes is no big problem as long as you don't stomp hard, just stop the wheel rotation. Sometimes too if the bearing is on the looser side with not much greese it will make it spin up as well. I do probably 900 take offs and landings a 100 hourly, no ill effects stoping the wheels after lift off. The front wheel however has no brakes (not a Mig) and does spin up and vibrate towards the end off the 100 sometimes.

 

 

[PaulN]

OurCT2K used to give the trembles on lift off. On checking the gear we discovered the nose wheel hub assembly was manufactured with the axle hole eccentric to the outer rim so ordered a replacement from Flightdesign. Alas, the replacement arrived in the same state as the original ... must be purpose built.

 

Took it to the local engineering shop and had them rework it and all was well. At a later date we changed the front tyre only to get a new wheel vibration. Took it to the local bike shop and had it balanced for $5 and all is well again. I guess these things happen just to keep us on the ball.

 

Paul

 

 

[Guest Guest]

I 've too have noticed this "wheel wobble" paricularly on take off in Jabs . I was also advised to apply a little brake to stop the rotation and hence the vibration . It has also occured whilst cruising along in the Jab , but only on models with wheel spats . I concluded that this must be a result of unbalanced wind flow around the wheel , but the first time it happened it had me a little worried !!

 

 

[Guest aaronb]

I NOTICE THIS IN THE JAB I TRAIN IN, THE IDEA IS AFTER YOU TAKE OFF TAP THE BRAKES TWICE AND IT SEEMS TO FIX IT :p

 

shifty06

 

 

[Guest Ken deVos]

During my training in LSA55s, I was curious as to why, just after takeoff, my instructor always put his hand on the brake handle - At the time I thought it was some form of nervous reaction at my limited flying ability.

 

With tongue in cheek, I explained my thoughts but was immediately advised that, 'my limited flying abilitydid not cause a nervous reaction and the reason was to stop the main wheelrotation which would otherwise vibrate once the weight is removed after lift off'.

 

Note thatthe nose wheel is still able to rotate freely butthis didn't seem to cause much vibration in the LSA55. Bycomparison, expect more vibration after takeoff in the J160 and application of brake will not cure the problem as the nose wheel is larger.

 

Cheers

 

Ken. Ken deVos

 

 

[Guest Ken deVos]

Hi Shifty

 

I have worn a track between Ringwood and Tooradin over the last two and a half years but with about a two month stint at Point Cook.Only ever flown Jabs and think they are great aircraft for what we do in them. However, would love to fly the CT2K/SW if only I could find the extra time, extra money, operatoretc etc....

 

How about you?

 

Cheers

 

Ken.

 

 

[Admin]

Hi Ken

 

Have you been up in a CT yet? If not then remind me around Nov when my new one arrives and we can go up for a couple of hours.

 

 

[Guest Ken deVos]

Thanks Ian for your very kind offer. Certainly I would love to go flying in a CT. My only experience was to sit in the CT2k at Penfield and marvel at the roomy interior, thequality of the build and overall finish of the aircraft.

 

I didn't pursue any further due to cost, distance from home etc. I also got a little concerned atthe rumour that the long wing was 'twitchy' in the landing configuration - but then I've heard the same said (by a GA operator of Piper Warriors and Archers) of the small Jab.

 

BTW, good luck in the RAA-us elections. It seems that interesting times are ahead in aviation for us all.

 

Cheers

 

Ken.

 

 

[BigPete]

Where do I go?

 

OK I've balanced the front wheel of my J160C - by spinning and marking the rim when it stops. (It stopped in the same place most of the time).

 

I then stuck on a small self adhesive weight to the inside of the rim.

 

Although the vibrations is now less, it is still quitesevere.

 

They can't balance it at the local auto tyre place as it won't fit on their machine.

 

Its been suggested that the go kart people might balance their wheels and have the means to do it. or - maybe the local motor bike shop.

 

any suggestions, please?

 

regards

 

 

[S.Drifter]

This may cause laughter, but I think it has little to do with balance, but more to do with how long the plane has been sitting in the one spot ie. weeks or longer and not being moved. I find that after sitting for a period of time you get a flat spot and that is the cause . The reason I say this is because I only get this if one of the planes has been sitting for awhile, if it was balanceI would have thought it would happen every time you took off. I've never owned a Jab so I may be off track although I have the same flat spot thing with my grader.

 

 

[Geoff]

Pete Find some one with a old on car wheel balancer it has a flashing light they spin the wheel with a electric motor, can do any wheels

 

 

[Guest P.A.]

When a tyre sits for an extended period it will go out of round due to the weight sitting on it. Is there some way to store the plan on blocks for a week when you are not using it then see if the problem is as pronounced?

 

 

[blueline]

What about putting a small piece of rubber lightly against the tyre to stop it spinning in flight?

 

An out of balance wheel wouldn't matter then.

 

 

[theoy]

Every timewe take off withour J160C vibrations on all rims. Yes the front one too. theoy