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 09-16-2011, 04:21 AM   #1
xavier296 OP
Alaska Planner
 
xavier296's Avatar
 
Joined: Nov 2010
Location: Augusta, GA
Oddometer: 284
R100 Big Tube swingarm questions

I bought a good looking "big tube" swingarm, from the 81-84 model year, to install on my 79. You can immediately see why this would make a difference in handling on the rear. Max bmw microfiche makes it look like the pivot pins are a different length, does anyone know if I need the shorter pivots to run this swingarm?

Or maybe I can put earlier style bearings and seals and use the original pins? I was expecting to change the bearings anyway, and would prefer to avoid buying 70 dollars worth of pivot pins.

I know I have to mod the rear brake switch also, but unfortunately, the instructions on this forum have lost all the pics that used to be there.
__________________
2011 R1200GSA 30th Anniversary, 2008 WR250R
Recently Completed: 79 R100RS
Build Thread: http://advrider.com/forums/showthread.php?t=732078
I welcome any and all couch surfers if you are traveling through Augusta. I even have a well stocked garage for emergent repairs.
xavier296 is offline   Reply With Quote
Old 09-16-2011, 06:16 AM   #2
DoktorT
BigBrowedNeandereer
 
DoktorT's Avatar
 
Joined: Apr 2009
Location: Chewelah, WA
Oddometer: 1,139
[QUOTE=xavier296;16867404]I bought a good looking "big tube" swingarm, from the 81-84 model year, to install on my 79. You can immediately see why this would make a difference in handling on the rear. Max bmw microfiche makes it look like the pivot pins are a different length, does anyone know if I need the shorter pivots to run this swingarm?

I cannot be specific as I have not done this. Check the fiche and see if the part no.s are different for the 79 and 81 piviot pins. I was under the impression this was a straight forward swap.

I know I have to mod the rear brake switch also,

News to me. I would think any 81+ RS/RT would have the disk brake and others would have drum, so there may be some difference if you use a disk swingarm with a drum setup or vice versa. Switch is same but mounting varies?? Again, you can compare part no.s, but the parts blowups are marginally usefull for assembly, and some are just flat wrong. That is why many of us try to confirm these things before throwing time/money at swaps and such.

Anyway, hold the phone because expect someone with direct experience will be along to confirm. Or you could spend a few days at the Snobum site where likely this type of info is available.

Do submit this to the Airheads list for quick response and likely from the Bum himself. Cutter is there daily as well and he would know.
DoktorT is offline   Reply With Quote
Old 09-16-2011, 09:03 AM   #3
bmweuro
Mad Scientist
 
bmweuro's Avatar
 
Joined: Nov 2003
Location: Chico, California
Oddometer: 3,313
Screw the original ones in and see if they bottom out and you can still get the jamb nut on. If you can then use them
__________________
BOXER Metal
BMW Biker Scum
BMW Mad Scientist!
VBMWMO #7770, BMW MOA #48694 & Airhead BMW Club #600
bmweuro is offline   Reply With Quote
Old 09-16-2011, 09:18 AM   #4
wirewrkr
the thread-killer
 
wirewrkr's Avatar
 
Joined: May 2008
Location: HIGH desert
Oddometer: 4,297
You can use the bearing and seal and spacer setup from the earlier style if you want.
Especially since those late model bearings will set you back around $130.00!!
Don't forget the grease retainer on the one side.
For the brake light setup, you'll have to get creative.
__________________

www.wirewerkes.com
KILL YOUR TELEVISION !!!!
wirewrkr is offline   Reply With Quote
Old 09-16-2011, 11:51 AM   #5
Max Headroom
lost in the '70s
 
Max Headroom's Avatar
 
Joined: Feb 2008
Location: New Zealand
Oddometer: 502
As it happens, I've just about finished installing a big-tube swingarm on my R90S, and it appears to me that the earlier pins will work with the later bearings. I haven't adjusted and tightened them yet, but they seem to fit OK at this stage.

The brake light switch is a bit more of a fiddle. I trimmed about 10mm (or 3/8" in the old currency) off the mounting bracket with a Dremel to clear the new swingarm, and then re-mounted the switch as close to the muffler bracket as it would go. I was fortunate to have a matching foot brake pedal, as It has a deliberate kink at the "switch end" where it strikes the switch when compared to the earlier style which is straight. If you're stuck with the earlier brake pedal, you'll probably need to fit a little tab to meet up with the switch. There's probably several ways of dealing with this issue, hence the advice to "get creative" from Wirewrkr!

I didn't take any photos. sorry. I could take some later today if it helps, but everything is assembled and I'm not sure if the photos would reveal anything meaningful.
__________________
'76 R90S silver smoke
'75 R90/6 hybrid

"Don't worry, it's not loaded."
last words of Chicago's Terry Kath before shooting himself in 1978
Max Headroom is offline   Reply With Quote
Old 09-16-2011, 12:01 PM   #6
bmweuro
Mad Scientist
 
bmweuro's Avatar
 
Joined: Nov 2003
Location: Chico, California
Oddometer: 3,313
I too am installing a big tube swing arm on an R90S. I have it loosely fitted. I'll take pictures as I go.



BTW- Use the early drive shaft. The spring breaks in the later ones.
__________________
BOXER Metal
BMW Biker Scum
BMW Mad Scientist!
VBMWMO #7770, BMW MOA #48694 & Airhead BMW Club #600
bmweuro is offline   Reply With Quote
Old 09-16-2011, 01:22 PM   #7
xavier296 OP
Alaska Planner
 
xavier296's Avatar
 
Joined: Nov 2010
Location: Augusta, GA
Oddometer: 284
Thanks for the timely input gentlemen! I am trying to be a good little builder and install everything now before I have everything painted and powdercoated, so I think I have enough info to just try to install the new swingarm with the parts I have. I took a good look at the brake light switch earlier, and can see that cutting the mount and reinstalling the switch closer to the ear would be the answer. I have an earlier pedal, so I will have to make up something to push the switch closed.

I am hesitant to install my solid driveshaft into the new swingarm as I hear it is quite a pain to install. Don't you need a special press?
__________________
2011 R1200GSA 30th Anniversary, 2008 WR250R
Recently Completed: 79 R100RS
Build Thread: http://advrider.com/forums/showthread.php?t=732078
I welcome any and all couch surfers if you are traveling through Augusta. I even have a well stocked garage for emergent repairs.
xavier296 is offline   Reply With Quote
Old 09-16-2011, 01:51 PM   #8
bmweuro
Mad Scientist
 
bmweuro's Avatar
 
Joined: Nov 2003
Location: Chico, California
Oddometer: 3,313
I had someone with the proper tools swap it out.
__________________
BOXER Metal
BMW Biker Scum
BMW Mad Scientist!
VBMWMO #7770, BMW MOA #48694 & Airhead BMW Club #600
bmweuro is offline   Reply With Quote
Old 09-16-2011, 04:52 PM   #9
SOLO LOBO
airhead or nothing
 
SOLO LOBO's Avatar
 
Joined: Mar 2004
Location: Shoreline, WA
Oddometer: 8,520
Quote:
Originally Posted by bmweuro View Post
I had someone with the proper tools swap it out.

"Proper tools" Pffft...... (not that I would advise anyone else to use the method below

__________________
"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 09-17-2011, 07:58 PM   #10
bmweuro
Mad Scientist
 
bmweuro's Avatar
 
Joined: Nov 2003
Location: Chico, California
Oddometer: 3,313
Got the rear brake switch figured out today using a BMW brake switch. I'll do a full tutorial soon.



__________________
BOXER Metal
BMW Biker Scum
BMW Mad Scientist!
VBMWMO #7770, BMW MOA #48694 & Airhead BMW Club #600
bmweuro is offline   Reply With Quote
Old 09-17-2011, 11:32 PM   #11
bmweuro
Mad Scientist
 
bmweuro's Avatar
 
Joined: Nov 2003
Location: Chico, California
Oddometer: 3,313
Here is the how to deal with the rear brake switch tech article http://boxermetal.com/?p=248
__________________
BOXER Metal
BMW Biker Scum
BMW Mad Scientist!
VBMWMO #7770, BMW MOA #48694 & Airhead BMW Club #600
bmweuro is offline   Reply With Quote
Old 09-18-2011, 01:39 AM   #12
xavier296 OP
Alaska Planner
 
xavier296's Avatar
 
Joined: Nov 2010
Location: Augusta, GA
Oddometer: 284
Thanks for the great article euro. What type pivot pins did you end up using?

My new swingarm is waiting patiently:

__________________
2011 R1200GSA 30th Anniversary, 2008 WR250R
Recently Completed: 79 R100RS
Build Thread: http://advrider.com/forums/showthread.php?t=732078
I welcome any and all couch surfers if you are traveling through Augusta. I even have a well stocked garage for emergent repairs.
xavier296 is offline   Reply With Quote
Old 09-18-2011, 10:25 AM   #13
bmweuro
Mad Scientist
 
bmweuro's Avatar
 
Joined: Nov 2003
Location: Chico, California
Oddometer: 3,313
You're welcome. The early pivots appear to work fine.
__________________
BOXER Metal
BMW Biker Scum
BMW Mad Scientist!
VBMWMO #7770, BMW MOA #48694 & Airhead BMW Club #600
bmweuro is offline   Reply With Quote
Old 09-18-2011, 07:08 PM   #14
Jon-Lars
Jon-Lars
 
Jon-Lars's Avatar
 
Joined: Apr 2006
Location: Beverly
Oddometer: 537
This setup works best with the use of the later, wider-race bearings that are specified for the later swingarm.
The wider race puts the load closer to the frame, reducing flex.
__________________
Cheers, Jon-Lars Sorenson
Beverly, WA
http://www.facebook.com/BMWR90S
Jon-Lars is offline   Reply With Quote
Old 09-18-2011, 08:18 PM   #15
bmweuro
Mad Scientist
 
bmweuro's Avatar
 
Joined: Nov 2003
Location: Chico, California
Oddometer: 3,313
Quote:
Originally Posted by Jon-Lars View Post
This setup works best with the use of the later, wider-race bearings that are specified for the later swingarm.
The wider race puts the load closer to the frame, reducing flex.
Do you know what the width difference is between the 2 bearing? Since either bearing race bottoms out in the swing arm I am curious.
__________________
BOXER Metal
BMW Biker Scum
BMW Mad Scientist!
VBMWMO #7770, BMW MOA #48694 & Airhead BMW Club #600
bmweuro 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 10:52 AM.


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