R42 gearbox oil level

[Darryl.Richman]

Peter, BMW rates the R42 for 95 kph top speed, with 12 hp at 3400 rpm. My R52 is quite similar: 100 kph. However, at least according to the speedo, mine won't quite get to 100, though that might be because I'm not the typical German rider from the 20s, at 16 stones or so.

It's also not a ripsnorting bike, and as soon as there's nearly any up grade, a downshift to 2nd is called for. As I live at the top of a steep road, with grades in the 16-22% range, I have to shift to low and keep the throttle open to get to the top.

I did find that my mag had been pretty badly mistimed to the retarded side (15-20 degrees!), and retiming it did give the bike some extra punch, but don't expect it to change things dramatically.

[bmwmyplace]

Hi Darryl....thanks for that.... perhaps you might help me with the oil level, I see the R52 has a filler plug and it appears to be below the bottomj of the out put saft.

Could I impose on you to estimate the bottom of the thread of your filler plug and sight across the output shat and give your best guess as to how far down below the shaft it is ....Or you could get a tape measure eatimate the oil level and measure up to the middle joint in the gear box cases... that would give me a pretty good reference.. Regards Peter

[bmwmyplace]

Hey Darryl , yes well im a bit slower than most just realized that all I need is for you to tell me the oil capacity for the gear box from one of your books , Ill suck out all the old stuff and the measure the new stuff in ....Derrr REgards peter

[Darryl.Richman]

Unfortunately, my multi-generational photocopy of the owner's manual doesn't list a gearbox fill volume. However, it looks like the bottom of the threads of the fill hole are about 30-32mm below the centerline of the output flange. I hope this helps you, Peter!

[bmwmyplace]

Darryl that does indeed help thank you for all your trouble

REgards Peter

[Peter D. Nettesheim]

OK, tell me again, Why are you putting oil in an R42 gearbox????? and then trying to figure out the proper level??
This is like saying "I'm putting diesel in the fuel tank but can't figure out how much to put in"
Peter D. Nettesheim
bmwmuseum@hotmail.com

[bmwmyplace]

Hi Peter thanks for responding to my question, from the info that I had to hand I couldnt find out what grade of grease was recomended for these bikes. I know that too thick a grease will cause voids in the gearbox and fail to lubricate.

1 The bike was filled with oil by the previous owner, not a valid reason I know.
2. I had trouble finding semi fluid grease ,( have since found that MobiluxEP023 is available.
3 I thought that grease would probably eat a little hp and we dont have much

4. BMW went to oil the following year. also it is generaly considered that oil lubrication is probably more eficient if you can keep it in..

5 if I did put grease back in how full do I fill it , sort of the same question really

If you have any first hand knowledge at all that you would like to share with us I'm sure we will be richer for the experience, and eternaly greatful

Kind regards Peter

[Peter D. Nettesheim]

Peter G,
Here's what I think
1) I have no info on the greese you mentioned, but if it is a semi fluid lubrication, it ,might be OK.
2)I can't remember what I am using but I seem to be having success with it. I will have to look at home for the viscosity. I remember something like "O" or "OO".
3) The sealing of the transmission is not designed for oil.
4) Forget about the horsepower thing here. Buy a GSXR1000.
5)The process by which you service the transmission is simple. I hate the way everybody tries to take shortcuts when dealing with antique BMW's. It is as follows. Dismount transmission, remove from bike. Split case, wash out with a solvent, reassemble, add lubrication in the proper amount and reinstall. Simple
For your information on these prescribed services, I will give you a paragraph directly from the owners handbook for the 1923 R32.
"When climbing steep grades it is necessary for the rider to richen the mixture of combustion to aid in the cooling of the cylinders. This richer mixture has the negative affect of creating soot inside the cylinders of the M2B33 (the R32's engine designation). It is therefore advisable for the rider, once hill climbing is completed, to remove the cylinders and clean out the soot with a stiff brush. Thereafter the cylinders can be reinstalled and riding can proceed as normal."
Of course all of you know that I do this on a regular basis whenever I climb hills with the R32.
And you are complaining about how to service a R42 trans...........
There are no short cuts.
Peter D. Nettesheim
bmwmuseum@hotmail.com

[bmwmyplace]

HI Peter thanks for you response, if you think to check on the viscosity of the greese that would be useful thanks

I for one am not really looking for short cuts, but by the same token if it improves the beast i will consider it.

I enjoy old machinery and particularly the Idiosyncrasies that go with them. For example I have a hot air engine that drives my 14 " cooling fan so instead of plugging in the electricity I prefer to fill the burner with kerosene light it place it under the expansion chamber wait for it to heat up then turn the blades by hand to start it. It is about 25% as efficient as the electric one also smells a bit of burning kero, but it is wonderful to see the pistons going up and down

When I rebuilt the R12 engine I even resisted putting new lip seals in and prefered to try the original laberinth system using felt I made a couple of tools and cut the felt rings from A grade engineers felt... seems to be working

I also disasembled and refubished my own cranshafts which for me being totally untrained in mechanial engineering was no small feat.

when I rebuilt the rear drive I couldnt get the correct bearings at the time ( this was some years ago now) so I got wider ones took out the lip seals and bought a surface grinder and ground them down, as there were no shims available, i ground them to the correct size to get the perfect pattern, do you have any idea how long that took, each check requiered the bearings to be cleaned assembled it the pre heated rear drive blued dissassemble and regrind. recheck and so on and so on.

But i digress So back to my original question do you happen to know how much grease to put in

Kind regards peter

[Peter D. Nettesheim]

Peter,
I will look for this spec. If you have been involved in rebuilding these old bikes (it sounds like) and have the full complement of service manuals, one underlying issue begins to surface. Unlike the manuals of today that give step to step instructions on disassembly and assembly these early manuals only have very limited specific information.
What becomes clear is that the people who wrote them made certain assumptions. One of these is that the person working on the bike will have the necessary basic mechanical skills to do relatively involved mechanical repairs. To explain this further, its like a manual of today starting out explaining what a wrench is and that you need to turn the nut counterclockwise to loosen. These things are taken for granted by the writer of the manual. Much more was taken for granted earlier on.
What is my point? Well, if you read these manuals, and I have read almost all of them, it becomes clear that they are only going to give you the information that you couldn't possibly know. The timing point of the ignition, the wiring of electrical components, the exploded views and order of assembled components and so on.
I suspect that how much grease to use might also be within the realm of normal mechanical skills.
My answer would then be an adequate amount to assure all gears are constantly exposed to the lubrication.
If you want to have a quantitive amount, I will try to see if its in a book or come up with what I would use.
I will look.
Now to the problem I think you have with your ignition that you think is the carburetor.............. well not everything at once......