Prewar transmission gears - R11

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dBDawg
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Prewar transmission gears - R11

Post by dBDawg »

Anyone ever have to make gears for their ride? They don't seem to follow conventional standards for metric MODULE sizes. My first gear is in rough shape. It's been MIG welded, has awful porosity, and wasn't re-hardened. Anyways, it will cost just as much to fix this mess as to make a new one so I figure I'd try and do that. I calculated it to be a MOD2.5. Problem is a 34 tooth with this profile has an OD of 90mm and my first gear falls with an OD of 88mm. The 33 tooth has an OD of 87.5mm.

I see random replacement gears here and there, so someone know what's up. Hopefully they're on this forum. Thanks....

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Darryl.Richman
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Do you have a three or a four

Post by Darryl.Richman »

Do you have a three or a four speed transmission? The three speed boxes are not a constant mesh design and 2nd gear has a very different tooth profile to stand up to the beating it takes.

I don't know anything about gear cutting, but I bought a replacement 2nd gear, input shaft and output shaft from Josef Heft for my R52. I got them as spares so I could use them in case I had a problem with my R52 on the Motorcycle Cannonball in 2014. When I first ordered these parts, Heft had them in stock, but the inner splined hole on the 2nd gear wasn't sized correctly and had to be opened up slightly to fit on the shaft. Now everything fits and it all seems to be hardened - though I've had problems with parts (from other sources) not being hardened correctly and thus wearing out quickly.
--Darryl Richman

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dBDawg
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I have the 3 speed. It is

Post by dBDawg »

I have the 3 speed. It is constant mesh in my opinion, 1st and 3rd gear sets are stationary and the second gear set slide together forward or back to engage either first or third gear. A small spline on the input shaft engages second.

Does Josef have a website or means of contact or does he even want to be contacted? ha ha. I'd love to see if he can help.

Thanks, Darryl
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Darryl.Richman
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That's very interesting!

Post by Darryl.Richman »

That's very interesting! Your transmission has been modified to be constant mesh! I've seen this adaptation before, it's a very clever idea, but I don't know how well it works in the real world. The photo attached shows what a stock 3 speed box looks like. Your box is not only modified to have a constant mesh 2nd gear, but a helical cut 3rd gear, which should cut down on the amount of whine that comes out of it. Mine's fairly loud, and Peter Nettesheim told me that of the several of these gearboxes he's worked on, all but one had a loud whine.

Heft seems to specialize in parts for the prewar tunnel cast motor bikes(R5 onwards), but he has a few parts for split case motors. The last catalog I saw from him, perhaps 2 years old now, didn't have a first gear, just the input shaft. But it is a stock item, like the one in my photo, so it probably won't help you.

You might contact Torsten Tausch in Berlin, he has a lot of specialty items for split case motor bikes. www.torsten-tausch.com. Actually, I was just verifying that link, and I see he has part of a constant mesh 3 speed box pictured on his home page. He's probably the person you need to talk to!
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--Darryl Richman

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Ian R11
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The parts book shows 1st gear

Post by Ian R11 »

The parts book shows 1st gear as the same part in both early and late versions of this gearbox. Maybe that increases your chance of finding a replacement, the rest of the gears being different.

My late model R11 has this type of gearbox, I believe it came in with series 4. I only have experience with one other early type gearbox (R62) and this later version changes easier and runs with very little whine, generally much nicer. The downside is I don't know of any suppliers doing the differing parts this version uses.

Please post any parts supply info you get.
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Darryl.Richman
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Crash box requires double clutching

Post by Darryl.Richman »

Ian, thanks for getting me to pull out my R11 parts book, it's very interesting to look at. Indeed, this constant mesh arrangement came with the Series 4 and 5 machines, and in fact, there were 3 different arrangements over the course of the R11's 5 year run. Not only were the shafts different, but even the shift levers and transmission cases came in 3 different forms.

A constant mesh box will certainly change easier. I have to double clutch every shift into 2nd, whether from 1st or 3rd, to get it smooth.
--Darryl Richman

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dBDawg
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protogear

Post by dBDawg »

Started reverse engineering 1st gear. I'm 3D printing them out of a rigid Nylon in order to test. It's very cheap, the tolerances are really good and the nylon is durable enough for testing it. This is the 2nd prototype gear I made before getting it right. Next step I'll have one made of steel and let ya'll know how it goes....
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schrader7032
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Location: San Antonio, TX

Wow! Everyone should have a

Post by schrader7032 »

Wow! Everyone should have a 3-D printer!!
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

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Darryl.Richman
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That is a wonderful idea! I

Post by Darryl.Richman »

That is a wonderful idea! I hope it works out for you.

I have had the thought in the back of my head that developing prototypes with 3D printing could overcome problems in making reproduction parts. In particular, if you need a floorboard for an R12, which is cast aluminum, you find that the reproductions don't fit. This is because they seem to have been made by using an original floorboard as a mold to do sand casting. But liquid aluminum shrinks by about 10% when it cools, so the resulting floorboard isn't right. If someone scanned an original floorboard, then printed it at 110%, it would make a better mold for reproduction floorboards.
--Darryl Richman

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dBDawg
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more printing

Post by dBDawg »

the Printing works well. I did this kickstart flange as well. It's printed 420 stainless and bronze. Needs post machining because there is shrinkage in the process and the shaft for the kickstart is worn in more ways than one (and needs machining).
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