bearings

[coxy]

g day all
I was talking to a former bs owner restorer mate of mine and we got talking about the odd size of the crank bearings and that trying to find a source in the automotive industry is impossible.
he suggested that maybe the bearings are not automotive at all and maybe aviation bearings as to there odd size seeing Bridgestone was so high tech and maybe from Mitsubishi air craft ?  any thoughts cheers

[dcr]

Anything would make more sense than Bridgestone having bearings made a special size with no other possible application.

[hardy]

If someone was kind enough to measure the bearings up and post the results, it would mean we would have more chances of trying to source a replacement...

[SR-175]

Hi All,

Some years back we investigated the 350 bearings. Had all the sizes but can not locate them now. These bearing sizes were discontinued, along with a range of other sizes by the bearing manufacturers in the early 70's.

Between Richard, Kotaro & myself, we went as far as contacting various bearing manufacturers for any old stock they may have had.

The small end bearing was also an odd ball size. However, I was able to have these remanufactured when we made the 350 con rod kits.

I wish anyone else the best of luck locating these, as maybe you get lucky.

later ... ray

[davis]

The crank bearing sizes are: 30x64x16 for the inner and 25x64x17 for the outer bearings. The "64" makes them special since the standard O.D. is 62mm. I found a bearing with the inner bearing dimensions, Yamaha 93306-20648. I machined a blind hole on the O.D. to match the pin in the crank case. These bearings have a relief machined from one end of the O.D. which should not make a difference if the hole is machined opposite. The Yamaha bearings have 8 ball bearings to the Bridgestone's 9, but the outer Bridgestone bearings have the same 8. These are Koyo and readily available for about $35 ea.

They are also available with ceramic ball bearings at $155 a pop. I am consider building a competition crank using them. With some modifications the inner bearings could adapt to the outer positions.

[slawsonb]

Pretty! Nice work, Bob!
...bert

[SR-175]

Hi Bob,

Is the plan to make up a 1.0 mm shim to wrap around the bearing, to take up the difference in diameter ?

[hardy]

I read the 17 was thickness, and you would need a 1mm shim between the flywheel and bearing to space it out???

[davis]

Just thinking this through, maybe the "gurus" could help. Yes, 1.3mm of shim would be required on both ends and a standard snap ring groove would have to be machined opposite the machined O.D. relief notch in one bearing. So special machining would require two bearings with blind holes and one with a snap ring groove and one as is. A concern is that now the sling space for oil coming from the oil pump is too wide and oil will not reach the outer bearings and rod big end bearings as designed. Perhaps the crank seal could handle that? If not then perhaps premix only? Slotting the big end rod on the sides would help lubricate the bearing there okay (performance Bridgestone builders have recommended this plus it is standard practice on YZ350 cranks).

The other option is to just use the standard bearings on the outside. I have taken apart a number of cranks and have salvaged nine very good outer bearings and only one very good inner one. So I plan to use the Yamaha bearings only for the inner position. My ambition to build a performance crank (pinned and balanced) would include using all Yamaha bearings of a ceramic variety if I'm crazy enough to spend the money for them. Hobbies aren't always cheap!

[SR-175]

Sorry, I am asking about the diameter differences. The standard ones are 64.0 mm, the Yamaha, or any other standard bearings made today are 62.0 mm. This requires a sleeve of 1.0 mm to take up the difference.

As for machining bearings, you will need to get your hands on an EDM machine (electrical discharge machine). Will need make electrodes to make holes / etc ...

later .. ray

[slawsonb]

Apparently Bob is unable to post at this point, but he mentioned that the blind bearing alignment holes were done using a carbide end mill...
...bert

[OldSwartout]

That's good to know.  I always figured it would take EDM to do that job.

[slawsonb]

I would think that the preferred process would put the hole in the outer race BEFORE the bearing is assembled, so in either the EDM or end mill case how do you mask the inner part of the bearing to keep coolant and chips/slag out?
...bert

[OldSwartout]

I'm certain the manufacturers do it that way.  In the case of buying bearings and modifying them, roller bearings such as the center bearing for a 175 crank, you could take the race off.  However, with ball bearings,  you don't have that option.  If I was doing it, EDM would just get a thorough cleaning afterward, for end milling, I'd pack it with grease before machining.

[bsracer]

I've seen some video's on YouTube where someone is adding a hole for a locating pin to a bearing race. I had someone add a hole to a set of early 175 cases that didn't have a locating pin (center groove type bearing lubrication). I found some Honda bearings that would be perfect for a four bearing conversion on a 175/200 but still don't know what kind of rating the bearings have. They are a CRF250 transmission bearing. I was planning on having locating pins added so both the bearings and cases would have to be modified. Still on the to do list one of these days.

paul

[craig641]

Paul - Is that a labrynth seal?  Where did you get that?  Make it yourself?

Craig

[dcr]

Paul - is that a 175 case in your picture with a double inner bearing setup? If so, I'd really like to hear about the configuration and what that setup consists of.

Dan

[proudhon]

Am I out to lunch here
but
  Yamaha WR 250 R 2008-2015 ProX Crankshaft Bearing 830046-1 30x64x16
It sounds right or am I missing something
jd

[vinny g]

Those are the bearings..I'm guessing they'll be upto the job if they're designed for crank usage.To simplify things...you can just machine a dowel hole to take a 3mm pin on the edge of the un-machined side of the bearing..and then grind a locating slot in the lower crankcase just deep enough to take the pin.Sandwiched between the two halves it wont(the bearing) spin.Make sure you centralise the crank,making sure the centers of the rods are exactly in the centers of the bores,before grinding the slots for the pins.

[bsracer]

Hey Craig,

Yes, I had some made a few years ago. I have one SR crank with one but never tried it because the crank wasn't pressed together properly and it binds in the case. The one in the picture is just for mock up. I wasn't completely happy with them and I will probably have something made when I'm ready.

Dan, the case is actually a 200. Mostly the same as the 175 as far as the crank goes. It's been all cut up for different uses like making the rotary valve covers and shimming transmissions. These bearings fit with a narrow seal. I think they are 11mm wide and 55mm OD. ID is 20mm. I've found a similar bearing out of a Suzuki (SUV) transmission that has a 25mm but I want to use the 20mm. I think the lab seals I had made are 9mm wide. These bearings are for a Honda CRF250 transmission. I don't have a rating on them so that's why I haven't done anything further with them.

Vince, that was what I was planning to do. The lab seals I had made also don't allow enough room for lubricating the bearings on the inner side(they were just a copy of some existing lab seal). The cases can be modified by adding another hole to allow lubrication.

JD. Sorry didn't mean to hijack your thread. This is for a 175/200 crank. The 350 crank has different size bearings and already has four bearings. As far as the rod dimensions for a 350 go I don't have any 350 stuff. I'm sure once you get the dimensions you can find something that can be made to work.

This project is still pretty far on the back burner. I need to just get some new crank center pins made. I'll start a new thread that just pertains to the 175/200 cranks to avoid any confusion.

paul