schatztf

I recently replaced the gearbox on my Spitfire because it seems a bushing seized and stuck to the propeller shaft and than proceeded to chew its way through the gear box.

So I bought another gearbox and went flying this weekend and I heard some weird noises coming from the plane in-flight, landed it and the gear on the propeller shaft ate through the side of the gear box.

I am thinking that I might not have setup the gearboxes properly, can someone help explain to me the proper way to setup this gear box and how to maintain it?

I posted this question in another thread and someone posted that these gearboxes may be prone to failure, is anyone out there having similar problems?

Thanks!!

gunracer

are you using the stock power setup?...possibly a gear mesh or bearing issue...

schatztf

Yes, everything is stock.

gunracer

have you already disassembled the gearbox?...if not, a photo showing its current condition may explain what happened...

schatztf

I'll try to post some pictures tonight. Thanks!!

schatztf

Wasn't able to get the photos up last night, I'll try to post some tonight.

29904

A friend and I have also had trouble with the PZ Spitfire gearboxes. They have been redesigned and ours have hair line cracks that causes the airframe to vibrate when flying. We have determined that the redesigned gearboxes have a cut out for the motor that the old box doesn't have and that is where our gearboxes have failed. I hope Horizon will do away with the redesigned gearboxes and go back to the old gearboxes.

Larry

mezd

Hi guys, according to Model FLight - the gearbox for the FW-190 and the Spit are the same. Same motor, prop shaft etc aswell.
I have the FW and have had no gearbox problems..... other than the ones caused by crash landings. i am on my 3rd gearbox and all have been ok!

The prop shaft isnt being done up too tight is it? i always make sure there is a little freeplay between the nylon bushes and the bearings.

Mez.

29904

Mez,

The shaft and bearings are not the problem but a result of the problem. What happens is the cut out for the motor on the redesigned gearbox cracks from the twisting action of the prop. Remember for every action there is an equal reaction. Therefore the oscillation of the then loose motor causes alignment problems for the gears, shaft and bearings. If you look at the old design gearbox, it didn't have the cut outs in the motor mount area so it was stronger. The new gearbox has a designed weakness that should be corrected by Park Zone since they now know of the problem.

Larry

schatztf

It seems I must have gotten a batch of bad bushings. My latest gearbox has been working fine for several 10+ minute flights.

29904

Bad bushings? There are no bushing in the gearbox, it has sealed bearings. They are not the problem. The housing that supports the motor cracks and lets the motor move causing problems with the gear mesh and alignment with the shaft that the prop is mounted too. That's only with the newer design gearboxes, the older ones I have don't crack and cause vibration problems.

Larry

mezd

Whats the part number of this new design gearbox? i am using PKZ1628, have had no problems with them..... maybe we are still getting old stock her is OZ, but i havent had any problems at all!
Maybe try the PKZ1528 off the mustang, i beleive its pretty much identical.

On mine the motor is held into position by the 2 screws - if these are tight i dont see how the whole gearbox can twist enough to crack...... photos would help.

The bushes i was taling about are 2 nylon bushes that o on the prob shaft on the outer side of each bearing. If you dont have the bushes where does you prop shaft gear and motor gear mesh? must be very close to the actual gearbox housing.

gunracer

here's the new gb...notice the relieved areas around the motor mount...i have both and the motor casing also looks thicker on the first generation...

schatztf

I meant bearings, I always say bushings when I mean bearings.

schatztf

I have had the bearings seize or come apart, they than heated up and melted the plastic.

29904

I haven't had the bearings problem yet but when we started having the vibration problem I thought it was from dry bearings and we lubed the bearings but that did not help. That is when I noticed the hairline cracks on both sides of the cut outs for the redesigned gearbox and figured out what was going on.

Seized bearing can also be a challenge.

Keep them flying,

Larry