Author Topic: ST G.15 rear bearing.. (Read 1718 times)

Joe Yau · « **on:** March 15, 2014, 03:25:59 PM »

Looking for a bearing upgrade for the Super Tigre G.15.. I have the Boca Econo grade ones at this point. and wants to upgrade to something better incase they pick up the ol' habit (retainer comes apart when pushed) like the stock ones. Just wondering if there is a bearing with the nylon retainer available for this engine? or something even better.

Paul Smith · « **Reply #1 on:** March 15, 2014, 11:57:08 PM »

I ran G15's in the bad old days. The rear bearing always went bad and took the rest of the engine with it. You can buy better bearing from several sources including Cox, OS, Nelson, and Fora. The bearings come with the rest of the parts you need at no extra cost.

Joe Yau · « **Reply #2 on:** March 16, 2014, 10:23:25 AM »

Quote from: Paul Smith on March 15, 2014, 11:57:08 PM

I ran G15's in the bad old days. The rear bearing always went bad and took the rest of the engine with it. You can buy better bearing from several sources including Cox, OS, Nelson, and Fora. The bearings come with the rest of the parts you need at no extra cost.

I had two that let go back in the days.. usually just when they starts to go fast (which is great!) then the bearing goes.

Would you know which is the better source? didn't know Cox has bearings.

phil c · « **Reply #3 on:** March 17, 2014, 08:55:20 PM »

I'm sure Boca has the same size bearing with a plastic retainer. Is a a 10mm or 12mm i.d.?

Paul Smith · « **Reply #4 on:** March 17, 2014, 09:55:38 PM »

I forgot a few more sources of bearings: Rossi, Fox, and MVVS.

In the middle 1970's it was found that the way to make a G15 run like a champ was to over rev it on a smaller prop, which also caused the bearings to come apart.

C.T. Schaefer · « **Reply #5 on:** March 18, 2014, 06:40:11 AM »

Many years ago I had a friend make an adapter sleeve so I could use a rear bearing from an X-15. Worked good but by then the G-15 was obsolete for our use. Just recently I put together a fresh one with the bearing conversion. I looks good on the bench. just not sure yet what I want to put it in!

Paul Smith · « **Reply #6 on:** March 18, 2014, 07:54:28 AM »

One fix that guys used was to make a FULL compliment bearing with no retainer and all the balls that fit. They ground a tiny groove in the inner and outer races to squeeze in the last few balls. Or you could just cut a larger grove in the outer race only. As I recall, the groove was placed in the upper front position, out of the load area.

I ran bearings like this in Fox Mark combat 36's with no problem. There is one opinion that the balls create friction against one-another, but the friction against the cage is eliminated. The downward force of combustion spreads the balls (slightly) apart in the load area at the bottom, thereby relieving the theoretical friction.

RandySmith · « **Reply #7 on:** March 18, 2014, 03:54:22 PM »

Quote from: Joe Yau on March 15, 2014, 03:25:59 PM

Looking for a bearing upgrade for the Super Tigre G.15.. I have the Boca Econo grade ones at this point. and wants to upgrade to something better incase they pick up the ol' habit (retainer comes apart when pushed) like the stock ones. Just wondering if there is a bearing with the nylon retainer available for this engine? or something even better.

I have a lot of new parts for them, but not the rear bearings, I do have more new piston and sleeve sets.

Randy

Joe Yau · « **Reply #8 on:** March 19, 2014, 12:32:41 PM »

Quote from: phil c on March 17, 2014, 08:55:20 PM

I'm sure Boca has the same size bearing with a plastic retainer. Is a a 10mm or 12mm i.d.?

I've checked numerous times on that, they just have the one. The i.d. is 10mm.

Joe Yau · « **Reply #9 on:** March 19, 2014, 12:55:48 PM »

Quote from: Paul Smith on March 17, 2014, 09:55:38 PM

In the middle 1970's it was found that the way to make a G15 run like a champ was to over rev it on a smaller prop, which also caused the bearings to come apart.

yup, that how I ran them with those semi soft yellow Tornado props cut down to around 6.6"-6-4" or so, on 25% Missile Mist or higher.

Quote from: Paul Smith on March 18, 2014, 07:54:28 AM

One fix that guys used was to make a FULL compliment bearing with no retainer and all the balls that fit. They ground a tiny groove in the inner and outer races to squeeze in the last few balls. Or you could just cut a larger grove in the outer race only. As I recall, the groove was placed in the upper front position, out of the load area.

That might be a good way to go if there're no other bearings are available.. will have to see.

Quote from: RandySmith on March 18, 2014, 03:54:22 PM

I have a lot of new parts for them, but not the rear bearings, I do have more new piston and sleeve sets.

Randy

That's good to know..

I've broke some crankshaft as well. Thx.

Author Topic: ST G.15 rear bearing.. (Read 1718 times)

Joe Yau

ST G.15 rear bearing..

Paul Smith

Re: ST G.15 rear bearing..

Joe Yau

Re: ST G.15 rear bearing..

phil c

Re: ST G.15 rear bearing..

Paul Smith

Re: ST G.15 rear bearing..

C.T. Schaefer

Re: ST G.15 rear bearing..

Paul Smith

Re: ST G.15 rear bearing..

RandySmith

Re: ST G.15 rear bearing..

Joe Yau

Re: ST G.15 rear bearing..

Joe Yau

Re: ST G.15 rear bearing..