wvaneck

Hi,

I need to replace the bearings on my OS 1.40 RX, I have the proper O.S. bearings on order and hopefully they will be here in time.

What I like to know is, is the following; what would the proper procedure be to replace these bearings? Is there a document or something somewhere that I could get?

It would be greatly appreciated if you could let me know as quick as possible.

Thanks,

Wouter

Bax

My Feedback: (11)

There really isn't a document for bearing replacement. After you have disassembled the engine to the point that you only have the case with bearings, heat the case to about 250 degrees F. You should be able to rap the case against a block of wood and have the bearings just fall out. You can heat the case with an oven, a heat gun, or even a small torch (if you move it around and heat the case evenly).

Clean the case, re-heat it, and install the new bearings. While the case is still hot, install the crankshaft, drive washer, propeller, prop washer and prop nut. Tighten the propeller and make sure the crankshaft spins freely. If the bearings are in straight, it will.

Make sure the bearings are fully-seated in their respective cutouts. If you need to add pressure to push them onto place, it can only be put on the outer race. Pressure anywhere else can damage the bearings.

Do not use the crankshaft as a puller to seat the bearings. This will load them. Youll find this out because they will not turn freely, even when seated fully and in alignment. You can sometimes fix this if you remove the propeller and drive washer and tap the end of the crankshaft with a padded hammer to jar the bearings a bit.

wvaneck

Hi,

Thanks for the prompt reply, I just need to know how I can get the piston pin out as it is blocked by cylinder liner.

Do I need to heat up the case until the cylinder liner moves a bit and then take it out so I can get to the piston pin?

I hope there is an easier way....

Thanks

Wouter

Bax

My Feedback: (11)

You slide the cylinder liner up, out of the case. You now have enough room to move the piston/rod assembly enough to get the lower-end of the connecting rod off of the crankshaft. If the liner is stuck, you can heat the case to free it. A lot of times, they are "glued" into the gase by congealed fuel residue.

bearing_man

One more source of info

RC ENGINE BEARING REPLACEMENT

Is your RC engine running unusually hot or noisy? Do the bearings feel gritty to the touch? Well get out your tools, because its time to replace your engine bearings. Most engines have a front and rear bearing. If you are unsure of the exact size replacement bearings that you need please check out our RC Engine Cross Reference Guide.

Place your engine housing in an oven at 325°-350° for 5 to 10 minutes. When you remove it from the oven your old bearings should fall right out, if not heat the engine a little longer. For some excellent step by step instructions on rebuilding your engine please see: NitroMonkey.com. We also suggest you place your replacement bearings inside a ziploc bag and keep them in the freezer overnight. Then slip the bearings into the engine while it is still slightly warm and when the temperature equalizes the bearings will have a press fit.

BillB

I have an OS 1.40 RX with Boca bearings. I've been flying (and rebuilding rc engines) for over 30 years. This is the first time I haven't been able to remove a bearing using the above advice. I wonder if the Boca bearings are slightly bigger than the stock OS bearings for the 1.40RX? I never had any problems with Boca bearings and other O.S. engines. Tomorrow it's time for an extended session with my Dremel tool and a cutting wheel or two.