SWB vs. LWB

[Cam3512]

What's the difference between the R75/5 SWB an LWB? How can I tell the difference without the two to visually compare?

[dlearl476]

About an inch.

[dlearl476]

Seriously, I can't think of a better method than VIN. Check the part numbers on the MAX BMW parts fiche for the rear subframe. You'll get a <up to number and a >from number.
I'm sure someone will post soon with a real easy way to differentiate the two.

Strike that, the fiche doesn't have the vin info. If someone has an ETK, maybe they can post the info.


Lifted from Snowbum's website (http://pweb.jps.net/~snowbum/models.htm):


"There were improvements made over the years that were not so radical. Many small changes added up. One such modest change was the incorporation of a longer wheelbase in mid-1973 and the addition of a cushioned driveshaft. The earliest /5 models had a shorter wheelbase (easily seen by a glance at the rear area of the black colored driveshaft housing, it has NO welded section a few inches from the flange end). The early /5 SWB (Short Wheel Base) and the early R65 (also short wheel base) could, not will, have some potential for instability under SOME SPECIFIC types of riding....and IN PARTICULAR if a STEERING mounted windscreen was installed. Thus, BMW elected to go to the LWB (Long Wheel Base). Frankly, my personal preference is the SWB. It feels quicker-handling*."

*I concur. Also, some but not all, early SWBs don't have battery covers, but that's not very conclusive if you're looking at a potential purchase.

[DarrylRi]

I'm not sure if I understand, but it's easy to look at any given bike and tell if it has the LWB or SWB frame. All you have to do is look at where the swingarm bolts to the final drive. If there's an obvious welded cylinder, approximately 2" long, just ahead of the flange on the swingarm, then it's a long wheelbase bike. On the SWB bikes, the swingarm tube broadens out directly to the flange, but there's no straight, cylindrical part. Also, the SWB bikes take a smaller battery.

[barryg]

Look at the driveshaft housing. The lwb has welded bead all the way around,where the extention was added, I think about 1 1/2 inches. My 74 R90/6 has the welded in extention. I don't know when the driveshafts were made longer from the get go, and not modified

[Cam3512]

Thanks for the quick replies. Mine's a 1970 with no visible weld extension on the swingarm driveshaft. Must be a SWB.

[flash412]

Thanks for the quick replies. Mine's a 1970 with no visible weld extension on the swingarm driveshaft. Must be a SWB.1970 is DEFINITELY SWB. The difference is about an inch and a half. It is simple to see. If the flange that bolts to the rear end is welded to the swingarm at a short (inch and a half) cylindrical section, then it is LWB. If the flange is welded directly to where the swingarm flares out, then it is SWB.

Later model LWB swingarms did not have the cylindrical section welded in as an extension. The right arm of the swingarm was made in one piece.

[lkchris]

1970 is DEFINITELY SWB.


LWB happened 1973-1/2.

VERY necessary.
http://w6rec.com/duane/bmw/whbase/index.htm

[RevWillie]

Another way to tell a LWB from a SWB is by the color of the air intake pipe from the air cleaner assembly to the carb. The SWB bikes had GREY pipe and the LWB had BLACK intake. Of course, the added length of the swingarm is the ultimate decider, but the intake pipe was a good quick-look way of knowing.

You know, /5's bring back a flood of memories. One of the "hot spots" was the memory of how I found out that /5's did not have main fuses in their electrical system. You never knew how important that dub little plastic door over the ignition socket really was! Drip, drip,WHOOM! :violin

Don't get me going on the factory rubber bands that held our toaster sidecover onto our /5......for a short while! :mad

[dlearl476]

>The SWB bikes had GREY pipe and the LWB had BLACK intake.

My '73 LWB R60/5 originally came with silver intake tubes. When I replaced them in '98, they told me all silver ones were NLA and the replacements were black.

[barryg]

My 71 R50/5 has silver intake tubes and a grey bunghole rubber plug for the timing hole. Not alot of power, but still a great bike.

[dlearl476]

My 71 R50/5 has silver intake tubes and a grey bunghole rubber plug for the timing hole. Not alot of power, but still a great bike.

Alas, the grey bunghole is NLA as well. The one I bought for my R75 earlier this year is black. Mine was so old, it was white. And the top surface was cracking all off, looked like a mushroom! It now sits in a place of honor alongside the safetywire-drilled wing-nut for the OEM police bags on one of my shelves.