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 05-14-2012, 11:03 AM   #1
sigpe57 OP
Gnarly Adventurer
 
Joined: Oct 2005
Oddometer: 335
Airhead Transmission inspection

Hi,

Can you inspect the condition of a airhead 5-speed transmission when it's out of the bike? or it needs to be in running condition?

What are the symptoms of a transmission when it needs a rebuild?

Are the parts and gears available from BMW?

Thank you for the reply,

TT

sigpe57 screwed with this post 05-14-2012 at 11:53 AM
sigpe57 is offline   Reply With Quote
Old 05-14-2012, 12:35 PM   #2
benthic
glutton 4 punishment
 
benthic's Avatar
 
Joined: Dec 2011
Location: sunny san diego
Oddometer: 398
you can't really inspect anything without opening up the gear box, and that has to happen with it out of the bike.

I just had mine rebuilt and it was $550 labor, and i needed $450 worth of parts. If I had only had it "inspected" - stopping after the case was opened to see how bad it was, I still would have had to pay a couple hundred $'s. I believe all the parts are available new. or at the very least, used.

some symptoms would be lots of metal on the magnetic plug, lots of bearing noise, difficulty shifting...

Hopefully some actual knowledgeable people will chime in:)
__________________
1978 BMW R80/7
"all we need is time and courage." - Renner
"A lightened flywheel on your bike is like me getting into Spandex and putting on track shoes to walk the dog." - M
www.blindfishz.com
benthic is offline   Reply With Quote
Old 05-14-2012, 03:37 PM   #3
sigpe57 OP
Gnarly Adventurer
 
Joined: Oct 2005
Oddometer: 335
Bob's bmw- $385 labor- Parts $220-$360. Total $740. Has anyone done the rebuild with good result and cheaper price?
sigpe57 is offline   Reply With Quote
Old 05-14-2012, 03:54 PM   #4
benthic
glutton 4 punishment
 
benthic's Avatar
 
Joined: Dec 2011
Location: sunny san diego
Oddometer: 398
Quote:
Originally Posted by sigpe57 View Post
Parts $220-$360
just be warned - I was initially quoted the same estimate for parts. It doesn't always work out that way;)
__________________
1978 BMW R80/7
"all we need is time and courage." - Renner
"A lightened flywheel on your bike is like me getting into Spandex and putting on track shoes to walk the dog." - M
www.blindfishz.com
benthic is offline   Reply With Quote
Old 05-14-2012, 09:34 PM   #5
DiabloADV
Semi-Occasional
 
Joined: Oct 2010
Location: Nor Cal, USA
Oddometer: 2,176
Quote:
Originally Posted by sigpe57 View Post
Bob's bmw- $385 labor- Parts $220-$360. Total $740. Has anyone done the rebuild with good result and cheaper price?
I'll find out in two weeks. Gearbox tech day in NorCal!

I have a box full of ~$300 of parts. Some from Hucky; some from dealer. I have all six bearings; all seals and gasket; all the springs and miscellaneous little bits like felts and rubber ring on clutch push piston. If anything is bad besides what I have, I might be returning the parts and binning the gearbox.

Labor? FREE! Expert guidance and all tools will be on site.
__________________
1974 R90/6 w/1050 kit. Motor only. Seeking a frame.
1970 R60/5

'91 Bill Holland Steel w/Dura Ace[/SIZE]
'01 Z3 3.0 Coupe. The Clownshoe.
DiabloADV is offline   Reply With Quote
Old 05-15-2012, 05:20 PM   #6
robsmoto
Motorcycleton
 
robsmoto's Avatar
 
Joined: Jul 2001
Location: Columbus, Ohio
Oddometer: 326
Quote:
Originally Posted by sigpe57 View Post
Bob's bmw- $385 labor- Parts $220-$360. Total $740. Has anyone done the rebuild with good result and cheaper price?
I rebuilt my 77RS transmission for slightly less (although I spent more when including the tools purchased.) I needed a replacement intermediate shaft ($200 for used one from Re-Psycle BMW), around $400 (guessing a bit) for bearings, seals, gasket, shim kit, shift upgrade "kit" (included new pawl spring) from Re-Psycle, local bearing distributor, and Cycle Works.

About $40 for Cycle Works Transmission Re-Build video. About $35 for Chinese depth micrometer (worked surprisingly well). Borrowed tool from local BMW dealership for holding shafts/bearings for shim measurements (subsequently purchased my own from Cycle Works). Got some free advice from Re-Psycle BMW's transmission guy.

I had already purchased a Harbor Freight 12-ton press (way less than $100 on sale).

I took my time and made multiple measurements to determine the shim sizes needed. I used Olympic scoring - after about a dozen measurements for each bearing I threw out the high and low values and averaged the remaining measurement values.

The experienced guys at Re-Psycle indicated that a dancing spit bubble on the transmission would be the indicator that it was hot enough to disassemble / assemble (upon heating with one or more torches). I decided to use several Tempil-Stiks (175, 200, 225, and 250 degF) to help me determine when the proper heat was obtained. Now I have an infrared temperature measuring device (from HF for around $30) that works quite well - the red laser dot shows where the temperature is being taken.

Bike shifts easily, no odd noises, and transmission is pretty much free of metal "fuzz" and other bits after a few oil changes. I run a dollop of Dow Gear-Guard M (also called MolyKote) with Valvolene 80W-90 transmission oil. The Gear-Guard M seems to help the shifting be a bit smoother (although maybe the shift kit helps somewhat also - the shift kit was from Re-Psycle BMW).
robsmoto is offline   Reply With Quote
Old 05-14-2012, 04:05 PM   #7
disston
ShadeTreeExpert
 
disston's Avatar
 
Joined: Mar 2011
Location: Silver Spring, Md
Oddometer: 8,600
That sounds like a good price for a rebuild at a dealer but I'm not surprised by which dealer that is, Bob's. Look's like the bare minimum parts tho, nothing wrong with that, probably all it needed. Bob's is one of the few dealers recommended regularly for Airhead repair and that includes transmissions.

There are maybe a dozen known mechanics around the country for Airhead 5 speed repair. It's recommended to use somebody with experience and a proven tract record. This does mean that sometimes you will have to ship the trans to somebody who can do the work.

In the bike the best indicator of problems is metal in the oil, on the magnetic plug, when the oil is changed. There will be a bit of soft black substance on the magnetic plug of a healthy transmission. This is soft when squished in the fingers. The danger signal is gritty, starts small like sand grains, particles. This harder metallic swarf is disintegrating bearing metal. If you find hard gritty metal on the magnetic plug the trans is ready for a rebuild. It can be postponed for a couple hundred or a couple thousand miles but it gets worse and the longer you wait the more expensive it is likely to get.

High mileage 5 speeds get several problems that indicate repair needed. False neutrals, whinning bearings, missed shifts. Some of these are expensive to fix and some of them you can learn to live with.

That's all for now. You don't mention what year 5 speed. Like most other parts on the Airheads the transmissions went thru a lot of changes. Repair options will depend on the vintage.
__________________
.
Never memorize something you can look up.
---Albert Einstein

Pay your debt, piratejohn.http://www.advrider.com/forums/showthread.php?t=949341
disston is offline   Reply With Quote
Old 05-15-2012, 02:22 PM   #8
hzbloke
n00b
 
Joined: Nov 2010
Location: Bottom right corner of Oz
Oddometer: 9
Circlip on output shaft

If your gearbox is from the period when BMW thought a circlip (actually a snap ring) was not necessary on the front bearing on the output shaft then I strongly suggest that you have a groove turned in the shaft and fit one.

I rebuilt my gearbox without installing one and so had to rebuild it again in about 15,000km. BMW seem to have relied on the bearing being a tight enough fit on the shaft for it not to move. Mine moved. The bike has now done about 30,000 with the re-rebuilt gearbox and it's excellent.
hzbloke 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 04:20 AM.


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