ADVrider

Go Back   ADVrider > Bikes > Old's Cool > Airheads
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 07-14-2012, 11:39 AM   #16
JonnyCash
turd polisher
 
Joined: Jan 2011
Location: Midcoast, Maine
Oddometer: 1,393
I've got a good one, I listed it in the airhead flea market. Check it out!
__________________
I wouldn't bring her home to Mama, but Mama ain't home tonight.
JonnyCash is offline   Reply With Quote
Old 07-15-2012, 05:43 AM   #17
pthomas OP
Gnarly Adventurer
 
Joined: Jan 2011
Location: St. Petersburg, FL
Oddometer: 179
I not yet ready to pull the trigger on a used transmission; mine only had 30k from the factory. I'd like to open it up and survey the damage, even if it's just to learn before I shop for one.

The transmission is ready to come out, when the swing arm gets out of the way... I don't have a 27mm thin wall socket and didn't want to a good one to the grinder, if I had a lathe it would have been in a different story. Sears doesn't carry thin wall sockets so I'm not sure where to grab one that will fit locally. I might have to order the BMW Airhead Swingarm Tool from Northwood.
__________________
Paul

1974 R90/6
pthomas is offline   Reply With Quote
Old 07-15-2012, 08:12 AM   #18
disston
ShadeTreeExpert
 
disston's Avatar
 
Joined: Mar 2011
Location: Silver Spring, Md
Oddometer: 8,181
There is a wrench in the tool kit that will work on the swing arm lock nuts. It is the tool intended for this work. The BMW part # for this tool is;

71 11 1 237 857

The thin wall socket is a regular 12 point socket turned down to meet the size limit of this application. The tool kit tool will work if you have that tool in your tool kit. It should be in your tool kit but then individual tools are often missing. The problem with the tool kit tool and the reason why there has appeared the after market socket is that people over tighten the lock nut and the tool kit tool gets broken. It also has a short handle and people have a hard time using it.

I have the socket but almost always do this job with the tool kit tool. I'm explain how I do this. I use a small hammer to hit the wrench so that I can make it work. I don't hit it hard but hard enough to loosen the nut after several whacks. This is the Red Neck impact wrench. I haven't broken a tool kit 27 mm wrench yet.

Here is a page from Max BMW that shows the tool kit tool. It is #19 on this page. You may already have this tool.


http://www.maxbmwmotorcycles.com/fic...9&rnd=05012012
__________________
.
Never memorize something you can look up.
---Albert Einstein

Pay your debt, piratejohn.http://www.advrider.com/forums/showthread.php?t=949341
disston is online now   Reply With Quote
Old 07-15-2012, 11:56 AM   #19
pthomas OP
Gnarly Adventurer
 
Joined: Jan 2011
Location: St. Petersburg, FL
Oddometer: 179
I don't have a BMW tool kit but I'm familiar with the Red Neck impact wrench; I didn't have much when I grew up and had to improvise regularly. Ordering a socket is cheaper than the official tool and will take less space when on the road so that's what I will do.

The delay in getting the transmission out will give me a chance to read up on what broken or damage things I'm looking for on the clutch side of things.
__________________
Paul

1974 R90/6
pthomas is offline   Reply With Quote
Old 07-15-2012, 12:44 PM   #20
disston
ShadeTreeExpert
 
disston's Avatar
 
Joined: Mar 2011
Location: Silver Spring, Md
Oddometer: 8,181
That is an expensive tool, I agree. The after market socket is cheaper.

To recap; You have a running BMW motorcycle that does not transmit power to the rear wheel? You are going to remove the transmission and check the clutch?

Have you looked at the transmission output flange yet? This is under the boot at the junction of the trans to the drive shaft, at the swing arm.

Part of removing the trans is to disconnect the drive shaft and remove the swing arm with the drive shaft. The flange that the drive shaft bolts to is a taper fit to the output of the trans. This taper is held onto the trans by a large nut. If this large nut is loose the taper has spun and is loose. It will be easier to see when the trans is out. It is still a possible source of your problem, if I have correctly summarized what is going on.
__________________
.
Never memorize something you can look up.
---Albert Einstein

Pay your debt, piratejohn.http://www.advrider.com/forums/showthread.php?t=949341
disston is online now   Reply With Quote
Old 07-15-2012, 01:57 PM   #21
pthomas OP
Gnarly Adventurer
 
Joined: Jan 2011
Location: St. Petersburg, FL
Oddometer: 179
Quote:
Originally Posted by disston View Post
That is an expensive tool, I agree. The after market socket is cheaper.

To recap; You have a running BMW motorcycle that does not transmit power to the rear wheel? You are going to remove the transmission and check the clutch?

Have you looked at the transmission output flange yet? This is under the boot at the junction of the trans to the drive shaft, at the swing arm.

Part of removing the trans is to disconnect the drive shaft and remove the swing arm with the drive shaft. The flange that the drive shaft bolts to is a taper fit to the output of the trans. This taper is held onto the trans by a large nut. If this large nut is loose the taper has spun and is loose. It will be easier to see when the trans is out. It is still a possible source of your problem, if I have correctly summarized what is going on.
Your understanding is correct. I've disconnected the driveshaft and everything looked good while I disconnected it but I couldn't really see in there because there is not much room. Once I'm able to take the swing arm out, I'll know more and could have found the source of my problem.

Either way, I want to read up on the clutch because it's been pointed as the likely source of my issue so I want to understand it better.

Since the transmission magnetic drain plug had a lot of metal shavings stuck to it, I think that it needs to be opened up and looked at.

I appreciate the help I'm getting; thanks!
__________________
Paul

1974 R90/6
pthomas is offline   Reply With Quote
Old 07-25-2012, 07:54 AM   #22
pthomas OP
Gnarly Adventurer
 
Joined: Jan 2011
Location: St. Petersburg, FL
Oddometer: 179
Update:

The output flange is fine and the transmission is out. The transmission is shot; when I turn the output flange, the input shaft turns. If I hold the input shaft and continue to turn the output flange, I can feel it slipping in any gear.

I'll be opening up the transmission and update the thread with pictures.

The question now becomes what do I look for in a used transmission?
__________________
Paul

1974 R90/6
pthomas is offline   Reply With Quote
Old 07-25-2012, 08:22 AM   #23
boxerkuh
Gnarly Adventurer
 
Joined: Oct 2008
Location: Carolina's
Oddometer: 231
I would rebuild your exsiting tranny instead of buying someone elses problem. With slippage it can be the gears, the dog ears or the bearings or a combination thereof. I have had both of my transmissions rebuild and only replaced what was broken. It saves in $$$$. Is this something that you can't tackle then there are plenty of folks that can and do it reasonable.
boxerkuh is offline   Reply With Quote
Old 07-25-2012, 09:37 AM   #24
pthomas OP
Gnarly Adventurer
 
Joined: Jan 2011
Location: St. Petersburg, FL
Oddometer: 179
Quote:
Originally Posted by boxerkuh View Post
I would rebuild your exsiting tranny instead of buying someone elses problem. With slippage it can be the gears, the dog ears or the bearings or a combination thereof. I have had both of my transmissions rebuild and only replaced what was broken. It saves in $$$$. Is this something that you can't tackle then there are plenty of folks that can and do it reasonable.
Sending it out is most likely the route I'm going to be taking but I expect something to be broken inside which is going to raise the cost of an overhaul. I'll open it up first to see the damage.

I looked in the airmail an only saw one place that advertises overhauls and charges $625 for the basics. What are the recommendations if I send it out?
__________________
Paul

1974 R90/6
pthomas is offline   Reply With Quote
Old 07-25-2012, 11:26 AM   #25
disston
ShadeTreeExpert
 
disston's Avatar
 
Joined: Mar 2011
Location: Silver Spring, Md
Oddometer: 8,181
Please post what you find in the broken 1974 5 speed transmission. The 1974 5 speeds are unique. And I do mean that to say they are one of a kind.

!974 was the first year of the 5 speed transmission. It is the only year that ordinarily has the kick starter. That is found later on some GS or G/S bikes I think but for most the kick starter was dropped after 1974. It is recomended if you have a working kick starter on a 1974 trans that you not use it because it can break. There is a gear that wears and can break leaving the trans unworkable or the kick lever hanging down lower than it should be where it hits your left leg. Riders want their kick starter because they think a motorcycle should have a kick starter but this one is a poor prospect because of it's faults. The electric starter is much more reliable. But this is maybe not really the problem of this trans. I can't say I visualize something like what you describe.

There is a cushion drive part of the input shaft. This may have something to do with this trans problem

It is most likely that you will have to replace the trans with something from another year because of the uniqueness of the 1974 trans very few of the internal parts are available. The gears are one year only. The shift forks are one year only. This stuff was redesigned for the 1975 transmission. Most of the time it is cheaper to use another trans and have that rebuilt if needed than try to rebuild the 1974 trans.

Long input shaft 5 speeds are 1974 thru 1980. If you eliminate the problem year of 1974 that leaves 6 years trans that you can use for replacement. The /5 4 speed will also work in your /6 bike but most riders don't want a 4 speed. It will work and others think this is fine. We've been over this numerous times. Maybe I can find the link to the discussion last week. It is pages and pages of argument over which year trans works in a /6 bike.

It is a long input shaft 5 speed.
__________________
.
Never memorize something you can look up.
---Albert Einstein

Pay your debt, piratejohn.http://www.advrider.com/forums/showthread.php?t=949341
disston is online now   Reply With Quote
Old 07-26-2012, 03:43 PM   #26
pthomas OP
Gnarly Adventurer
 
Joined: Jan 2011
Location: St. Petersburg, FL
Oddometer: 179
I'm definitely in the market for a new transmission; the gear on the input shaft is completely shredded; said gear is $100. I can get a trans that's already apart (so I know what I'm getting into) for that price; I'm thinking that probably going to be the best way out.

I'll post pictures later; I have not been able to get the output shaft and its companion. I did use heat but no it just didn't want to come out.
__________________
Paul

1974 R90/6
pthomas is offline   Reply With Quote
Old 07-26-2012, 04:21 PM   #27
disston
ShadeTreeExpert
 
disston's Avatar
 
Joined: Mar 2011
Location: Silver Spring, Md
Oddometer: 8,181
Replacing gears gets confusing. Most of the gears for a '74 trans are not available. If you buy the small gear on the input, new, it will most likely be the 17.5 degree gear. The 15 degree gears that all 5 speeds were built with up until March of '82 are hard to find. If they say it's the right gear ask them what angle it is.

If you need a lay shaft, the middle shaft has no individual parts it is sold as one unit, they are next to impossible to find.

If you are going to try and fix this '74 trans then the donor trans must have everything you need I think. Possible. But probably more work than it's worth.

Questionable high mileage trans are sold for $250 roughly. One with a better pedigree will run about $350. +
__________________
.
Never memorize something you can look up.
---Albert Einstein

Pay your debt, piratejohn.http://www.advrider.com/forums/showthread.php?t=949341
disston is online now   Reply With Quote
Old 07-26-2012, 04:28 PM   #28
SOLO LOBO
airhead or nothing
 
SOLO LOBO's Avatar
 
Joined: Mar 2004
Location: Shoreline, WA
Oddometer: 8,547
Motobins has some 15 degree gears (new) and some other shafts as well...

http://www.motobins.co.uk/bmw-parts.php?model=R Series 2 valve Twin
__________________
"punkrocks what it's all about" - J. Strummer



Quote:
Originally Posted by Stagehand
your bike is suitably dirty. Well done.
SOLO LOBO is offline   Reply With Quote
Old 07-26-2012, 06:07 PM   #29
AntonLargiader
Beastly Adventurer
 
AntonLargiader's Avatar
 
Joined: Aug 2003
Location: Charlottesville, VA
Oddometer: 4,126
It's really easy to spend good money on junk when it comes to these older gearboxes. If you're buying a used transmission that isn't known-good, at least make it a '77-on just to improve your odds.

If your '74 trans just needs an input gear, that isn't such an expensive repair. The problem is, it's likely to need more than that. I suspect that anyone advertising rebuilt exchange prices isn't figuring actual repairs into the price. If you send in a transmission with toasted helicals, that's $400 in gears right there. If you can find someone who will eat that in a $625 rebuild, go for it!!
__________________
Anton Largiader largiader.com BMWRA.org
AntonLargiader is offline   Reply With Quote
Old 07-26-2012, 07:28 PM   #30
Bill Harris
Confirmed Curmudgeon
 
Bill Harris's Avatar
 
Joined: Sep 2008
Location: backwoods Alabama
Oddometer: 6,326
Quote:
If you send in a transmission with toasted helicals, that's $400 in gears right there. If you can find someone who will eat that in a $625 rebuild, go for it!!
...or run away as fast as you can.
__________________
'73 R60/5 Toaster
Luddite. Not just a philosophy, a way of life...
Bill Harris is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 09:18 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014