Turbiner...awesome thread my friend..we gotta keep this sort of thing up you know...lets make a movie of it ..Quist..Interesting point about the cost of the bearing compared to what the manufactuers charge...the true answer is that we only think they replace the bearings every 25 hours...if you call Boca Bearings or any of the bearing manufactuers they will tell you that the bearings last longer than that..way longer...I challenge you all to request the old bearings to be sent back to you on engine service...I bet we wont get em back..

the thing is that after 25 hours most brgs don't need replacement (some do, some even as short as a few hours need it depending on flight environment) but most need new bearings before 50 hours so if they didn't replace the bearings at each 25 hr service when you had a brg fail before the next 25 hrs you'd be ticked at the repair cost then compared to brgs every 25 hr service.

I've always asked JetCat USA to return all parts with my turbines and they always have, it's never been a problem........YMMV.

Just loving these thread lately .

Just to echo Nunu these bearing don't go bad easily unless there is lack of oil supply reaching the bearing. So before reassembling the engine remove the connector from the (T) that lube the bearing. Use your plane fueler (WITH A GOOD FILTER) to pump fuel into the supply line to front bearing and check for fuel lubing the front bearing. Good luck

I could be wrong but i think missing your first start & continuing to have Fail starts shorting bearing life.

I was also told when I had my turbine serviced after a crash that the cast compressors expand over time due to centrifugal forces and part of the 25hr service is machining the compressor wheel to within tolerances again. Not sure if this is accurate as it's WAY out of my expertise, but I have NO reason to doubt them. My turbine is better than new now. They also re-glued several parts inside (oiler and such) that needed attention. Overall, a very good experience.

Like I said. I have no idea if this is true, but I'm not going to argue something of which I have no knowledge.
Better to stay silent and be thought a fool than to open my mouth and remove all doubt!

That is so true [&o]

I'm stipping down an older P-120 due to bearing noise and I have a small problem...The rear bearing didn't come out as an entire unit...When I removed the shaft with the turbine wheel the outer bearing race remained in the bearing tunnel and, of course, the inner race remained on the shaft...

How do I remove the outer race from the shaft tunnel???...It is in there pretty tight...

Kevin

There is ussally an o-ring recessed in a groove in the tunnel to keep the race from spinning. If it got warm the o-ring may have melted to the race. It should slide easy if you get a straight pull. You could make an easy tool with a lathe. make a plug to fit the inside of the race leave a lip to catch the edge . drill an tap the center for a small bolt. tap from cmpressor side or pull from back. you can put a small wiight to make a slide hammer if need be . Heat gun can be used if real;ly stuck.

Hi Kevin
I had asked the same question earlier.
The rear bearing has no o-ring it’s just too hot in the back.
You will have to heat up the rear tunnel to remove the race.
But this is where us DIY guys get messed up, by the time the turbine wheel bearing is removed and replaced balance is out just enough to mess with compressor bearing preload system.
In a KJ/ wren 54 systems the preload is in the rear bearing, which I have found a little more forgiving.
Let u know how it goes
Johnny

I was really hoping for this thread to stay alive, I have a p70 that has a bunch of dust and dirt inside from a gear up landing 'turbine was shut down but still spinning' i was about to send it to jetcat to be taken apart and inspected, I have pulled the front case, the electronic board and the rear and outer cover and cleaned what I could, will I damage the turbine if there is sand in the combustion chamber? also are the bearings sealed or do they need to be cleaned and oiled? if a few more pictures show up I will take it apart myself, great thread guys add a few more pics

I am experienced in wren 54 repair but not jetcat. I have recently bought a second hand jetcat P70 ( I suspect there has been someone in here before me) and have had to replace the rear bearing. I noticed that the front comressor bearing has three wavey washers behind it and the rear bearing only one. This seems strange! The compressor is also rubbing on the front intake. Can anyone confirm that there should be two wavy washes behind each bearing as this would move the compressor to the back of the engine away from the front intake.

Hi Tony

From my understanding the wavy washers are there to alter the forward & aft position of the rotor to take up machining tolerances and I doubt there is a position for these washers which is the same for all P70 engines. Personally I would clean off any rub on the intake and put little strips of insulation tape in the compressor blades and place the inlet back on tight, If it tape makes the rotor tight to turn then I would take one of the three washers from the front and put on the rear.

Jason

I normally put engineers blue ( or you can use felt tip marker) on the surface of the intake, run the engine and take off the intake to find the 'rub'. As you say the wavey washers may well be used to adjust for machining differences as well as providing the preload for the bearings, I had not thought of that. Thanks for your advice. Tony

Hi Tony

I might use blue after the initial build if there is a problem but the tape shows any tight clearances before you run it so before the compressor stretches that tiny bit.

Jason

Thanks for the input Jason

Just about to strip my P60 for a service & bearing change, will start a new thread with some details.

Other interesting stuff on [link=http://www.rcuniverse.com/forum/fb.asp?m=9049882]this thread[/link] I started some time back regarding this kind of work, come on guys we need more of it.

Heat the comp. wheel with hot air gun,hair drier,monakote gun,,paint stripper...Set it on the shaft,apply heat,it will drop on ..[X(]

Hi Guys!I bought bearings from boca bearings and I saw that exist a mark (V) in the bearing maybe indicate the correct position um the shaft. How do I know the correct position of the bearings?best regards

the arrows point at the wheels (away from each other)

Thank you very much!!

Handel them like eggs, do not let the balls fall out of the racers.