Undercarriage leg adjustment

[biggles5128]

I have a J230 which seems to have excessive positive camber set. The aircraft sits on the outer edges of the tyre and always wears that way, with the centre of the tyre tread hardly wearing. I had believed from new that this was a deliberate pre set to accommodate for loads on landing. I have ordered spacers and longer bolts from the factory which replace original to allow the inner most part of the leg to be positioned further from the belly of the aircraft thus resulting in a slightly wider stance and less camber on wheels.

 

My question here is has anyone else performed a similar adjustment and if so were there any notable differences other than visual and what did you find was the best way to hold the aircraft up as each leg is removed?

 

 

[frank marriott]

 

This is what I use if it is any help. It is a copy of what they use at the factory.

 

FrankM

 

 

[biggles]

I have a J230 which seems to have excessive positive camber set. The aircraft sits on the outer edges of the tyre and always wears that way, with the centre of the tyre tread hardly wearing. I had believed from new that this was a deliberate pre set to accommodate for loads on landing. I have ordered spacers and longer bolts from the factory which replace original to allow the inner most part of the leg to be positioned further from the belly of the aircraft thus resulting in a slightly wider stance and less camber on wheels.My question here is has anyone else performed a similar adjustment and if so were there any notable differences other than visual and what did you find was the best way to hold the aircraft up as each leg is removed?[/quote

I adjusted the camber on my J160 by making aluminium wedges to pack out the lower section of stub axle . No need to interfere with undercarriage leg that way .

 

Bob

[biggles5128]

Thank you both, Bob my concern there would be that the parts I have ordered are supplied by J for this adjustment, they did not suggest your mod, is that something that has been done before or your design?

 

Danny

 

 

[biggles]

Thank you both, Bob my concern there would be that the parts I have ordered are supplied by J for this adjustment, they did not suggest your mod, is that something that has been done before or your design?Danny[/

Danny it was a mod I had seen done on another Jab . If your 230 is a factory aircraft , you would be well advised to stick with their recommendations . I was'nt aware that the factory had an alternative way of correcting this problem .

 

Bob

[jetjr]

Theres a section in the builders manuals on alignment and adjusting the camber

 

Washers are used under stub axle and whole thing flocked back into place

 

Alignment is quite hard to get right and if your getting no shuddering or vibration on landing and TO Id possibly leave it alone.

 

 

[biggles5128]

I do get some vibration on take off which I eliminate by applying brakes. Other than excessive tyre wear, the thing looks cr@ppy that way as well.

 

Thanks for the replies....

 

 

[JabSP6]

Biggles

 

The Shudder you feel is from the main wheels being out of balance just like when your car tyres are out of balance. If it goes away when you apply the brake then your Nose wheel must be fairly close to being balanced. This shudder can be felt on planes with no camber issues as mine was. The excess Camber doesn't cause the shudder, the balance of the wheel does. My situation was that the shudder improved by hitting the brakes but i still had a slight shudder after this which turned out to be the nose wheelout as well as the main wheels out of balance.

 

The shudder can be eliminated quite easily by simply balancing the wheels. You can statically balance them by fitting the stick on weights to the rim while balancing on an appropriate size shaft in a vice or you can take them to a tyre shop for this to be done. You will be surprised what a differance this makes. Be sure to have all 3 wheels done.

 

As for the Camber issue and uneven tyre wear, the factory is well aware of this and the procedure that JetJR has mentioned is something i have seen done at the factory but does require time for flock to dry. The method you have mentioned can be done quicker and the plane flown straight away and doesn't require messing around with flock. Both work but niether will eliminate the shudder you describe.

 

Both are factory rectifications so it is your choice how to go about it.

 

Safe Flying

 

JabSP6

 

 

[biggles5128]

BigglesThe Shudder you feel is from the main wheels being out of balance just like when your car tyres are out of balance. If it goes away when you apply the brake then your Nose wheel must be fairly close to being balanced. This shudder can be felt on planes with no camber issues as mine was. The excess Camber doesn't cause the shudder, the balance of the wheel does. My situation was that the shudder improved by hitting the brakes but i still had a slight shudder after this which turned out to be the nose wheelout as well as the main wheels out of balance.

The shudder can be eliminated quite easily by simply balancing the wheels. You can statically balance them by fitting the stick on weights to the rim while balancing on an appropriate size shaft in a vice or you can take them to a tyre shop for this to be done. You will be surprised what a differance this makes. Be sure to have all 3 wheels done.

 

As for the Camber issue and uneven tyre wear, the factory is well aware of this and the procedure that JetJR has mentioned is something i have seen done at the factory but does require time for flock to dry. The method you have mentioned can be done quicker and the plane flown straight away and doesn't require messing around with flock. Both work but niether will eliminate the shudder you describe.

 

Both are factory rectifications so it is your choice how to go about it.

 

Safe Flying

 

JabSP6

JabSP6

Cheers for that, I was speaking with a mate who owns a tyre shop the other day and we discussed the balancing of the Jab wheels, will surely notice the difference when done. As the parts have already been ordered I will continue with that option, thanks for your input.

 

 

[nong]

[ATTACH=full]19701[/ATTACH]This is what I use if it is any help. It is a copy of what they use at the factory.

 

FrankM

Wondering if you should reduce wing bending loads by placing wing stand closer to lift strut pick up. Would be a shame to overstress your aircraft without leaving the hangar. :-)

 

 

[jetjr]

Wondering if you should reduce wing bending loads by placing wing stand closer to lift strut pick up. Would be a shame to overstress your aircraft without leaving the hangar. :-)

Thats what I thought too, but apparantly thats the recommended method from Jabiru

I lift mine just outboard of the strut

 

The shudder Im talking about is more like shopping trolley, very hard and violent just before takeoff and just on landing. Basically when the weight of not fully on legs. Can be strong enough to break spat.

 

 

[biggles]

Thats what I thought too, but apparantly thats the recommended method from JabiruI lift mine just outboard of the strut

The shudder Im talking about is more like shopping trolley, very hard and violent just before takeoff and just on landing. Basically when the weight of not fully on legs. Can be strong enough to break spat.

Regarding wheel alignment ,I used a few long pieces of wood and ,with the aircraft empty , set the toe-in at 20 mm (each wheel) , level with the nose wheel by shaping the wedge to align both camber and toe-in . I changed the tyres and tubes at 200 hours even though they still had plenty of tread left . I have not heard about that violent shudder you describe , but would be advising anybody with those symptoms , to have a real good look a the undercarriage also , before next flight . Jabiru also recommend to lift the a/c at the strut which makes good sense , would hate to doing it with near full tanks .

 

Bob