/5 frame versus /6 frame

dan-o · 01-08-2013, 04:27 PM

Does anyone know the changes between a /5 main frame and a /6 main frame? Other than the battery mount bottom piece and ears, and the tab for the steering friction plate. Can I swap everything from a /5 to a /6 frame without major modifications? It appears the horizontal crossmembers at the rear are a larger diameter.
thanks,
dan

Big Bamboo · 01-08-2013, 04:57 PM

I believe the fork locks have different diameter cylinders.

Wirespokes · 01-08-2013, 09:33 PM

I believe everything will swap right over. I think (sort of a dim recall on this) the only real difference between the /5 and /6 was rake angle, but that's nothing to worry about.

pommie john · 01-08-2013, 09:42 PM

I believe that at some point they fitted a second tube up the middle of the main spine presumably in an attempt to strengthen it. Mine has this double wall tube.

Wirespokes · 01-08-2013, 09:49 PM

I think they did that in 76. But that doesn't complicate the swap from /5 to /6.

dan-o · 01-09-2013, 04:04 AM

thanks so much for the information. I appreciate it!

supershaft · 01-09-2013, 01:43 PM

Quote:

Originally Posted by Wirespokes

I believe everything will swap right over. I think (sort of a dim recall on this) the only real difference between the /5 and /6 was rake angle, but that's nothing to worry about.

I have read that in glossy magazines but BMW's frame jig test all airhead frames. They all have the same rake. /6? ?6's were constantly changing. It probably depends on what year /6. You at some point got the doubled tubed backbone, the extra cross brace under the steering head and a lot more and bigger gussets. By '81 the frames were a lot stiffer and heavier.

dan-o · 01-10-2013, 03:02 PM

this frame is dated 6/74. Sounds like a good strong frame to hold all the torque from my R50/5 power plant

bmwhacker · 01-10-2013, 04:14 PM

As you surely know the rear sub frames changed from the short wheel base to the long wheel base. The late 1973 long wheel base sub frames are a double tube cross brace arrangement and stronger than the 1974 stamped steel cross brace arrangement. When I cobbled together my 1974 framed sidecar rig I sought out a 1973 1/2 rear subframe for that additional strength, plus my old QSL solo seat needed the arrangement for the mounting system.

dan-o · 01-10-2013, 04:30 PM

yes, I am keeping the short wheel base subframe and swingarm. Did you weld on the tab for the old front end friction type steering dampner?

bmwhacker · 01-11-2013, 12:19 PM

Quote:

Originally Posted by dan-o

yes, I am keeping the short wheel base subframe and swingarm. Did you weld on the tab for the old front end friction type steering dampner?

I ended up with a modified dual disc BMW 60's Earls front end... lengthened a /5 damper rod to fit the Earls, then had to get "creative" for the lower damper pieces to mount.

bmweuro · 01-11-2013, 10:49 PM

The battery box is the only major difference. Everything else will bolt on

01-08-2013, 04:27 PM	#1
dan-o ^OP Adventurer Joined: Apr 2007 Location: Bowling Green, Ohio Oddometer: 75	/5 frame versus /6 frame Does anyone know the changes between a /5 main frame and a /6 main frame? Other than the battery mount bottom piece and ears, and the tab for the steering friction plate. Can I swap everything from a /5 to a /6 frame without major modifications? It appears the horizontal crossmembers at the rear are a larger diameter. thanks, dan

01-08-2013, 04:57 PM	#2
Big Bamboo Studly Adventurer Joined: Sep 2010 Location: Big Island of Hawaii Oddometer: 806	I believe the fork locks have different diameter cylinders. __________________ "No hour of life is wasted that is spent in the saddle." =Winston Churchill=

01-08-2013, 09:33 PM	#3
Wirespokes Beemerholics Anonymous Joined: Jul 2002 Location: Jackson's Bottom Oregon Oddometer: 7,354	I believe everything will swap right over. I think (sort of a dim recall on this) the only real difference between the /5 and /6 was rake angle, but that's nothing to worry about. __________________ Wanted: Dead, smashed, crashed or trashed gauges BMW GAUGE REPAIRS - TACHSPEEDOCLOCKVOLT METER PODs & LIGHT BOARD*

01-08-2013, 09:42 PM	#4
pommie john Beastly Adventurer Joined: Apr 2008 Location: Brisvegas, Australia Oddometer: 1,113	I believe that at some point they fitted a second tube up the middle of the main spine presumably in an attempt to strengthen it. Mine has this double wall tube. __________________ The trouble with the world is that the stupid are cocksure and the intelligent are full of doubt. Bertrand Russell

01-08-2013, 09:49 PM	#5
Wirespokes Beemerholics Anonymous Joined: Jul 2002 Location: Jackson's Bottom Oregon Oddometer: 7,354	I think they did that in 76. But that doesn't complicate the swap from /5 to /6. __________________ Wanted: Dead, smashed, crashed or trashed gauges BMW GAUGE REPAIRS - TACHSPEEDOCLOCKVOLT METER PODs & LIGHT BOARD*

01-09-2013, 04:04 AM	#6
dan-o ^OP Adventurer Joined: Apr 2007 Location: Bowling Green, Ohio Oddometer: 75	thanks so much for the information. I appreciate it!

01-10-2013, 03:02 PM	#8
dan-o ^OP Adventurer Joined: Apr 2007 Location: Bowling Green, Ohio Oddometer: 75	this frame is dated 6/74. Sounds like a good strong frame to hold all the torque from my R50/5 power plant

01-10-2013, 04:14 PM	#9
bmwhacker Still on 3 wheels Joined: May 2009 Location: MONTANA NATIVE from NATIVE MONTANA Oddometer: 3,372	As you surely know the rear sub frames changed from the short wheel base to the long wheel base. The late 1973 long wheel base sub frames are a double tube cross brace arrangement and stronger than the 1974 stamped steel cross brace arrangement. When I cobbled together my 1974 framed sidecar rig I sought out a 1973 1/2 rear subframe for that additional strength, plus my old QSL solo seat needed the arrangement for the mounting system. __________________ http://jupiterhack.blogspot.com Living proof you shouldn't play with matches bmwhacker screwed with this post 01-10-2013 at 04:22 PM

01-10-2013, 04:30 PM	#10
dan-o ^OP Adventurer Joined: Apr 2007 Location: Bowling Green, Ohio Oddometer: 75	yes, I am keeping the short wheel base subframe and swingarm. Did you weld on the tab for the old front end friction type steering dampner?

01-11-2013, 10:49 PM	#12
bmweuro Mad Scientist Joined: Nov 2003 Location: Chico, California Oddometer: 2,943	The battery box is the only major difference. Everything else will bolt on __________________ BOXER Metal BMW Biker Scum BMW Mad Scientist! VBMWMO #7770, BMW MOA #48694 & Airhead BMW Club #600

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