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Old 07-25-2012, 06:11 PM   #31
pthomas
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Quote:
Originally Posted by Wirespokes View Post
The 74s have a bad rep, but from my personal experience they do just fine!
From my personal experience, they have 100% failure rate

Or it was just a bad week for my vehicle: the radiator failure on my car, the transmission went on the 74' R90, and then the trio was completed when the timing belt broke on the car.
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Old 07-25-2012, 07:17 PM   #32
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I'd like to have a 1974 5 speed for one purpose. To make a cut away model of. You know slice into it an expose the workings. I think they would be fine for this, I think.

The '74 transmission really is bad you know.
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Old 07-25-2012, 08:20 PM   #33
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Quote:
Originally Posted by Wirespokes View Post
I'm working on another friend's 74 R90 upgrading to dual discs - it's been his daily rider for many years now.

...

The 74s have a bad rep, but from my personal experience they do just fine!
*knock on wood* Of all the problems I've had with BMW's, none of them have been because they're a 1974 model year. Every problem was because of previous owner abuse.

It seems like there are a lot of '74s still out there..

Oh, and I've got two sets of dual-disc front ends sitting on my shelf. Maybe this winter, I'll slap one on my '74 R90.
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Old 02-06-2013, 03:59 PM   #34
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Originally Posted by crazydrummerdude View Post
This is an early 1974 R60/6. For those of you keeping up, I now own every BMW model from the "dreaded" 1974 production year.. and I ain't dead yet! I think..
Quote:
Originally Posted by Wirespokes View Post
The 74s have a bad rep, but from my personal experience they do just fine!
I am completely airhead illiterate, so please excuse my ignorance; but why exactly does the 1974 have a negative reputation?

I'm considering having a look at a rough 1974 R60/6 for a Cafe project. It's my understanding that '74 was the final year of kickstart, which is appealing to me.

TIA.

Tipsy

This is a 1973 R60/5, that is my inspiration:

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Old 02-06-2013, 05:03 PM   #35
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Originally Posted by TipsyMcStagger View Post
I am completely airhead illiterate, so please excuse my ignorance; but why exactly does the 1974 have a negative reputation?

I'm considering having a look at a rough 1974 R60/6 for a Cafe project. It's my understanding that '74 was the final year of kickstart, which is appealing to me.
1974 is the first year of the 5 speed transmission. The /5 four speed was the final refinement of the older /2 trans, they are very similar, some of the parts interchange. But the industry was moving toward 5 gears instead of 4 so the Getrag 5 speed.

I think there were two problems basically.

One was the grooves that the shifter forks ride in had edges that were too thin and these gears could break. I think we had one on Adventure Rider that was broken just with in the last couple of months. I'm not sure it was all of the grooves, it might have been two of the three I think or it might have been all three but they do break and the trans can lock up too I think when this happens. In order to make the edges of these grooves strong enough in 1975 the shifter forks were made thinner for thinner grooves and the edges then grew thicker. So different gears, at least three gears, and different forks.

The kick starter never had enough throw to it. It was difficult to start the bike with the kick starter unless it was in top notch tune. One of the parts used on the kick starter was not hardened properly or somehow made not properly. I think it was a hardness problem. The part that is at fault is apparently the gear on the input shaft that the segment gear turns (I forget what it's called). The electric starter had been proving very dependable and had increased in size so that this was determined to be all that was really needed to start the bike. A substitute hardened gear was made available for awhile but it is NLA anymore I think. If you wore the part out by using the kick starter the lever hung down half way when not in use and you hit your leg on it.

I don't know if there are any other items we call "problems" but I think there were some other changes.

I wasn't into Airhead bikes when all this was going on but I have tried to piece the story together from small snippets of information that pop up now and again. I don't know if I have all of the story right yet so I'll keep my ears open for more info.

The bottom line is that I don't recommend you try to even save a 1974 transmission. If you get one that works count your lucky stars. If you really have to have this particular trannie get one of the Gurus to rebuild it and be prepared to spend accordingly. The later GS and G/S bike had a kick starter that could be special ordered. I think this is the same design with better parts. These trannies bring a lot more when auctioned than most 1974 trannies.

If you have a '74 bike that you want a kick starter on for show purposes then consider a dummy starter that has the lever but is not complete. If you do have a working kick starter I suggest you don't use it because it may break.

I once had a 1974 R90/6. It was hand painted with a brush and had a tractor battery that died on me. The kick starter never worked and I had to push start that bike. But I was younger then.
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Old 02-06-2013, 06:30 PM   #36
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I found the thread that was the last broken gear in a 1974 transmission we had here. It was around Xmas and includes a bunch of pictures;

http://advrider.com/forums/showthread.php?t=851143
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Old 02-07-2013, 12:44 AM   #37
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I rode my 1974 75/6 all the way home from Australia to the UK in 77/78. , lots of crappy fuel and bad roads, the only serious problem was that a rear wheel bearing went, easily replaced because we were in Greece at the time.

One thing that was better on the 74 were the handlebar electrical switches, easy to use and intuitive.
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Old 02-07-2013, 01:30 AM   #38
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Yes Charles. I loved my '74 R90/6 for that reason. The switches were the older design. When you think about it, "Why do switches on motorcycles need to have labels on them?"
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Old 02-07-2013, 01:52 AM   #39
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I have a feeling that redesign was prompted by the US authorities who required both labelling and a kill switch.
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Old 02-07-2013, 07:34 AM   #40
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74 r90/6

I've had my 74 R90 for 7 years. Only put about 12k mi. on it. No real problems to speak of. Yes, the kickstarter did break when using it. Recently had total front brake failure. Other than that, no big issues.
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Old 02-07-2013, 12:30 PM   #41
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Thanks for the comprehensive explanation, Disston. So, it seems it's really just the tranny that gets the bad rap? And if I'm understanding correctly, just about any 1975 to early 1980 box can be swapped to the 1974 and alleviate the problems associated with the '74 gearbox?

I'm not sure how difficult it is to source a '75-'80 box, or how expensive they tend to be, but if I'm understanding correctly, the '74 R60/R90 are decent bikes, the weak gearbox notwithstanding.

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Old 02-07-2013, 01:00 PM   #42
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You can get untold of miles out of a 1974 Airhead. When it breaks then you can say you have been there. Nobody can say when that will happen or for that matter that it absolutely has to happen. It's just a matter of it has happened to many of us. BMW changed a lot of stuff in many of the years of Airhead production. The first edition 5 speed trans lasted one year, 1974. I guess it's the one really really bad thing we like to harp about.

When it comes to Airhead boxes there is one thing to know so you can swap them around. All boxes made from model years 1970 up till and including 1980 are long input shafts. This is the same shaft with the splines that we talk endlessly about lubing. Model years 1970 trough 1973 of course are 4 speeds but you should maybe know that you can use a four speed /5 trans on a bike that originally had a five speed. As long as it's a long input application. Long input boxes use the flywheel and then in 1981 we get the short input transmissions that use the clutch carrier.

So you have a 1974 bike and are maybe worried about this box being a problem some day? If a 4 speed drops in your lap grab it but I recommend you try to get a 5 speed. The 4 speeds are good trannies but I think the 5 speeds are better that's all. I will get no end of gruff from riders that want me to tell you that a 4 speed is OK. Alright, it's OK. But a 5 speed is what you want.

You are therefor looking for a 5 speed for models 1975 thru 1980. Any Airhead box will do including the early R65es or an R60.

If you are feeling really adventurous and wanted a better clutch with faster acceleration then you could find the parts for a clutch carrier and use a short input shaft trans. But if you are thinking of going to all that trouble it might be better to just get a later model bike to start with. Don't worry it has been done numerous times. And since you are starting with a 1974 bike the swap to a clutch carrier is the most involved, it is easier after 1976.

So you want a newer trans. that's all. If the one you have is working don't worry about it. A good deal can still be had on these boxes if you are patient.

I advise you to follow any and all threads here about transmissions. There are some finer points we cover and the subject of riders rebuilding their boxes is never ending.

I've rebuilt one box myself but I'm using a used box right now. I need to rebuild another.

BTW, your assessment in the last post was right on. The 1974 box is a weak point. But there are certainly other things that can give you heck while you're worrying about the trans.

BTW, if you can come with a suitable replacement and the '74 box still works it can bring decent money because so many riders think there's some advantage to owning a kick starter trans. Or it makes a good spare maybe.
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Old 02-07-2013, 02:16 PM   #43
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Original gear box went out on my '74 R90/6 about 3 years ago. At the time, the bike had a little over 100K miles on it. Luckily I was only about 2 miles from home, and made it there in 1st gear.

At first, I looked into repairing it myself. It sounded like it could possibly be a broken pawl spring, which is an inexpensive part. But after much thought, and knowledge gleaned from ADVRider, I decided not to. Mainly due to lack of mechanical skills/tools/experience in that area. I got quotes to ship it out to get fixed, and they were all $600+.

Found a '75 Transmission with 60K miles on ebay. Got it for around $275 shipped to me. I installed it, and have had no problems since. Now it was not exactly an easy task to replace the transmission, but if you go slow, and stay patient, you can do it no problem.

I still have the 74 Transmission sitting in my garage waiting for me to repair. Maybe...someday...
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Old 02-07-2013, 04:08 PM   #44
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Sorry for a potentially saucy response, but I find it funny when people on internet forums tell me how bad my bikes are.

I have probably 50-60k miles on my 1974 transmissions with no problems. I did have two of them rebuilt just as a matter of refreshing them from a two-decade-slumber.

You all forgot about the smaller front axle, solid rotor (for R75 and R90), flywheel bolts, oil-pump cover screws, under-tank master cylinder, etc of the 1974s! Surely each thing alone would kill anyone who dared to ride one!

But guess what.. They're all fine bikes and there is no reason to avoid them. Yeah, someone who owned one three decades ago might have some horror story that's been endlessly perpetuated on the internet since then, but.. I currently own three almost-bone-stock 1974 BMW airheads and none of them have stranded me, let alone given me any 1974-year-based problems.

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Now it was not exactly an easy task to replace the transmission, but if you go slow, and stay patient, you can do it no problem.
I'll bet I could have one swapped out in 30 minutes.
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Old 05-01-2013, 07:15 AM   #45
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Rebuilding my gearbox...

In my 1974 after GASP! only 30k miles due to severe abuse on my part and most importantly excess use of the kickstarter by the former owner which got little metal bits into the bearings. Actually the bearings weren't to bad I figured since I was in there to replace all the leaking seals I might as well freshen it up. Well lets add that to the 74's bad rep,the transmission seals dry out and leak after only 38 years! But seriously nothing wrong with these bikes, maybe the trans has a higher re-build rate than other airheads but that doesn't make it unreliable by any means.
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