R75/5 not smoothly shifting 2nd to 3rd

If you will listen to folks who have actually been there and done that, walked the walk and not just talked the talk.........It's a common thing, if maintenance is performed as it is supposed to be done, for the /2 and above to go 100's of thousands of miles. It is just maintenance and riding with a style of trying to make the machine last rather than seeing how quickly one can wear it out...........Just thinking about how learning to shift a particular type of machine the way it asks the rider to shift goes a lot further than the type of oil......just thoughts......Good luck........Dennis

It is my understanding that an 80w or 90w gear oil has about the same viscosity as say 40w engine oil. They must measure them on a viscosity scale or something.

I'll probably jinx myself, but I have 110K on my /7 using 80w90 gear oil since I got the bike. I'm experiencing no issues with the transmission or drive line. From what I've read from people like Tom Cutter and Oak, I'm likely nearing a point of considering a transmission overhaul, but for now, I'll just keep riding.

Viscosity

Part of one of my jobs was to measure viscosity of liquids. A viscosity meter is used, viscosity is viscosity, a fluid that pours like molasses has a high viscosity whereas water has low viscosity. The numbers are the numbers.

I have been running regular gear oil in my R80RT for 240K miles, and have never had the transmission apart even for inspection. It works, it works perfectly fine. I expect it to out last me.

Same goes for the engine, I have been using standard 20w50 oil, best quality approved for air cooled engines for the same length of time. Crank bearings, cam bearings, cam lifters, connecting rods, all main bearings are original at 240K miles.

I follow the recommended fluid change intervals.

I would have to ride an exact same model bike set up exactly the same way with the exception of synthetic gear oil in one bike and regular gear oil in the other to see if I could tell any difference in gear box operation. I have no desire to go out and experiment. Mind you, I have had my RT since new so I know its transmission's history well.

Could it be the change over to synthetic oil by second owners isn't really any better than just changing the gear oil in a new to them bike? I mean, who knows what a previous owner ran in the gear box, or when they changed it. Unless of course a person knows the PO very well or has maintenance logs. It is a gamble the old gear box oil was sludge.

Just my two cents, I know what has worked and still works in my two airheads, now in my cars, of course they are new enough synthetic oil is called for. Different fish. St.

High Mileage

It is encouraging to hear of Airhead transmissions lasting 100,000 miles or more. It seems some last longer than others, and those who predict early failure are also in the repair business. A few GL1800 GoldWing transmissions fail at 4000 miles, but millions last over 200,000; I suspect it's similar with Airheads. If I look back since my first (of six) Airhead(s) in 1981, I have ridden them collectively over 200,000 miles, and closer to 250,000. I only replaced two transmissions, and pretty sure both were in the first Airhead, a 1978 R100/7, which I rode about 140,000 miles. Back then, good used transmissions were plentiful, for $50 to $100. So I simply swapped in a 'good one' each time. I didn't even save the old ones, just tossed them in the scrap metal. None of the other five Airheads had over 100,000 miles when I bought or sold them, and none needed a transmission while I owned them.
I have only owned 5-speed Airheads, 1976 through 1995, and don't recall any special operating procedures required. Any transmission that must be 'babied' in any way is not for me. If it must be double clutched, throttle blipped, or 'played with' in any way, it's a safety hazard and must be fixed.

For gear oil, I recall the 1980s when a molybdenum additive was recommended by BMW gurus, and I used it faithfully; later, oil became available with molybdenum already added, which was more convenient. The molybdenum was said to improve shifting and extend service life. So folks have been trying to 'improve' Airhead transmissions with oil additives for decades. As for modern synthetic oils with additive 'packages' included, using it for about 20 years now (in other applications) I have found it to be one of the easiest, cheapest, best things to improve any transmission, even if already perfect. It simply makes a good transmission better. I have never experienced leaks or premature failure with it either. Don't knock it if you ain't tried it. LOL

STEVEN you said 'viscosity is viscosity', and I agree. But multi viscosity oils continue to evolve, and make the conversation more interesting!

jhall -

A bit off track, but what year is your Airhead? Is it outside the window of the missing circlip in the transmission? Snowbum has it covered as does Anton. Seems it began with the '85 models and ended with the '94 models, maybe slipped into the '95 model year.

Serial Number & Cir-clip Fiasco

20774 said:

jhall -

A bit off track, but what year is your Airhead? Is it outside the window of the missing circlip in the transmission? Snowbum has it covered as does Anton. Seems it began with the '85 models and ended with the '94 models, maybe slipped into the '95 model year.

Click to expand...

Researching this transmission serial number was early on my list, and it falls in SnowBum's category of most likely to be already installed. If repair is ever needed, will do the job myself, and check for a cir-clip then. Till now no symptoms, as described by Snowbum and others, have been noted. Thanks to RedLine, spline lube, a new cable, and cleaning & greasing all pivot points, the transmission is working better than ever!

I have repaired several gearboxes over the years, including some that others describe as complicated. Don't see anything particular about Airhead transmissions, other than the Germans like to use tight fitting boxes, which call for heat to disassemble and reassemble properly.

View attachment ShockProof_Tech_6.20_.pdf

This is the Redline I used the last time I changed the transmission oil in my R100S. Bike had about 140K on it, changed clutch and serviced rear engine seals etc. Noticed seepage at seal at trans shift rod and had read about someone using Redline in their Airhead trans as well, did a little research and talked to some one at Redline through email, which I no longer have. I've been very pleased ever since.

Response from Red Line...

In case anyone is interested, here's part of the (quick!) response I received from Red Line:

"Thank you for contacting Red Line Oil, in your BMW transmission and final drive the V-Twin Transmission Oil/ShockProof Heavy would be recommended, these are the same products. This helps reduce the inherent clunk and noise, plus helps to find neutral."

I'm going to try it out in one of my airheads (a 1979 R80/7), and will report back after I've run it a bit....

ECJ

ecjjce said:

In case anyone is interested, here's part of the (quick!) response I received from Red Line:

"Thank you for contacting Red Line Oil, in your BMW transmission and final drive the V-Twin Transmission Oil/ShockProof Heavy would be recommended, these are the same products. This helps reduce the inherent clunk and noise, plus helps to find neutral."

I'm going to try it out in one of my airheads (a 1979 R80/7), and will report back after I've run it a bit....

ECJ

Click to expand...

ShockProof Looks Great

ecjjce said:

In case anyone is interested, here's part of the (quick!) response I received from Red Line:

"Thank you for contacting Red Line Oil, in your BMW transmission and final drive the V-Twin Transmission Oil/ShockProof Heavy would be recommended, these are the same products. This helps reduce the inherent clunk and noise, plus helps to find neutral."

I'm going to try it out in one of my airheads (a 1979 R80/7), and will report back after I've run it a bit....

ECJ

Click to expand...

Considering your response from RedLine, and Kinterridge's experience with the same oil RedLine recommends (Heavy ShockProof 75W250), looks like the 75W140 I am running is comparable to their LightWeight, and is without the ShockProof additive (which, I am sure, is proprietary). Their Heavy version 'can be rated as a 75W250 gear oil' but flows like 75W90, impressive. Think I will jump on eBay and order a quart of Heavy. I see no problem with the 75W140 currently in the RT, but might as well go with Kinterridge's longer term experience and RedLine's official recommendation.

Thanks!

RedLine ShockProof Now

Well as of this morning I am a member of the RedLine Heavy ShockProof club. I drained the RedLine 75/140 NS overnight, and this morning filled the gearbox with Heavy ShockProof 75W90W250 (or whatever weight it technically is). It seems RedLine uses same base stock in both of those oils, as they both pour with about same consistency.

The ShockProof's cling is impressive; it is tinted pink, and thoroughly colored the clear plastic funnel. I used the same clear funnel, un-wiped, to pour the old 75W140 into a container. The 75W140 did not wash away ANY of the pink tint. I am not a chemist, but that is interesting. Planning 100 miles or so today, so will see how the gearbox shifts with the ShockProof. If it shifts as smoothly as the 75W140 NS, I will be happy.

Nice! Mine arrived as well, and goes in today...

ECJ