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Old 06-18-2015, 10:06 AM   #1
fronton OP
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R80/7 suitable for a hack?

I recently bought a 76 R90S with a Spirit Eagle sidecar. The bike was not modified in any way, the hack was attached by custom brackets that bolted to the bike with existing bolt points. Since the hack has no electrical, the bike's wiring harness was not 'hacked' and when the sidecar brackets detach, the bike is still 100% original (except for the white paint job ).

I have removed it from the R90 and will probably swap it over to a R80/7 for the occasional joyride but have a couple questions first.

1. The rig with assembly weighs ~170 lb. Despite being attached for less than 100 miles, would there be any wear on the bike that I should be concerned about or look into? Or is 100 miles nothing with a properly mounted sidecar and I wouldn't need to worry about it regardless of how long it was used?

2. Is a R80/7 a suitable bike for occasional sidecar duty? With a single disc brake being barely adequate two up, am I asking for trouble with a hack or is it about the same as riding two up braking-wise? I know there are plenty of R75/6 and much less powerful engine and braking setups around but I'm also concerned about potentially hurting the engine, frame or drivetrain. I am only 140 lb. and the most weight the sidecar would get would be 160 lb. payload. I'll only be cruising around town and under 45 mph.

Thanks!

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Old 06-18-2015, 11:22 AM   #2
LexLeroy
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I had a 1977 R100/7 w/ a California Sidecar Co. Friendship attached - about 50 lbs heavier than your chair. Observations:

1) Single disc was inadequate so I found a fork leg, disc & caliper from a wrecked R90S and went to twin discs up front.

2) The R100's 3.20 rear gears were still too tall.

3) The steering effort was pretty high so I bought a Unit leading-link frontend.
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Old 06-18-2015, 04:30 PM   #3
Ivan Rider
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I have a 1978 BMW R80/7 that I've owned since 1992. I put a Ural sidecar on it in 2000. In 2001 I rode it Coast to Coast and back without any major problems. I broke a throttle cable and wore out the pusher tire. My wife and I combined weigh over 500 lbs and it handles it just fine. A few years ago I did upgrade it to a 1000 cc by changing the jugs and pistons which has increased my top speed to around 95 mph. So if I was you I would not worry about putting a sidecar on your R80. The stock final drive on an R80 is perfect for a sidecar tug.

The attached photo was taken in Missouri in 2001. More photo can be seen in my Flickr link below my signature.
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Old 06-18-2015, 05:46 PM   #4
MotoJ
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http://www.advrider.com/forums/showthread.php?t=713860

My '78 R80/7 is still going strong 3 odd years after I hung a Dnepr sidecar on it. It's way more fun than it was as a solo bike.
I compensated for no leading link with wider bars and jacking up the rear a bit. I have the 3:20 final and it does take a bit to get going but it also cruises highway speeds nicely. I have a 3:36 in reserve but I haven't been bothered enough to swap. I installed a second disc and caliper up front and I'm glad I did that. Power is adequate with my 70 lb dog in the chair. A heavy adult slows things down a bit but it will still cruise at 70-75, indicated. That's probably more like 65.
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Old 06-19-2015, 05:07 AM   #5
LexLeroy
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If I had my old outfit back I'd:

1) dump the California Sidecar chair & go w/ a Dnepr or Ural (or a chair from CSM)

2) lace the front & sidecar wheels w/ 18" rims so that I could use the same tires all around - and install 3.36 rear gears, OR

3) lace all 3 wheels w/ 15" auto rims and use old school high-profile radials while retaining the 3.20 gears.

It sounds like you've got the basis for a wonderful outfit. Have fun.
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Old 06-19-2015, 08:11 AM   #6
fronton OP
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Quote:
Originally Posted by LexLeroy View Post
Single disc was inadequate so I found a fork leg, disc & caliper from a wrecked R90S and went to twin discs up front.
I'm in the market for dual disc conversion! My options for a straight fork swap are only from '75-80 correct?

Quote:
Originally Posted by Ivan Rider View Post
I have a 1978 BMW R80/7 that I've owned since 1992. I put a Ural sidecar on it in 2000. In 2001 I rode it Coast to Coast and back without any major problems. I broke a throttle cable and wore out the pusher tire. My wife and I combined weigh over 500 lbs and it handles it just fine. A few years ago I did upgrade it to a 1000 cc by changing the jugs and pistons which has increased my top speed to around 95 mph. So if I was you I would not worry about putting a sidecar on your R80. The stock final drive on an R80 is perfect for a sidecar tug.
This is encouraging, thanks

Quote:
Originally Posted by MotoJ View Post
http://www.advrider.com/forums/showthread.php?t=713860

My '78 R80/7 is still going strong 3 odd years after I hung a Dnepr sidecar on it. It's way more fun than it was as a solo bike.
I compensated for no leading link with wider bars and jacking up the rear a bit. I have the 3:20 final and it does take a bit to get going but it also cruises highway speeds nicely. I have a 3:36 in reserve but I haven't been bothered enough to swap. I installed a second disc and caliper up front and I'm glad I did that. Power is adequate with my 70 lb dog in the chair. A heavy adult slows things down a bit but it will still cruise at 70-75, indicated. That's probably more like 65.
Your build was a great read.
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Old 06-19-2015, 12:37 PM   #7
LexLeroy
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Quote:
Originally Posted by fronton View Post
I'm in the market for dual disc conversion! My options for a straight fork swap are only from '75-80 correct?
My 1977 R100/7 had the swinging ATE calipers - not what you want. I'd look for a way to use 4 piston Brembos w/ floating discs & HH pads. Someone familiar w/ older airhead enhancements can probably chime in and make a recommendation.
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Old Yesterday, 08:02 PM   #8
Someguytexas
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Quote:
Originally Posted by LexLeroy View Post
My 1977 R100/7 had the swinging ATE calipers - not what you want. I'd look for a way to use 4 piston Brembos w/ floating discs & HH pads. Someone familiar w/ older airhead enhancements can probably chime in and make a recommendation.
I have the early 80's forks with dual disk brembos on a 77 frame easier than you think
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