Preload - BMW Luxury Touring Community
 
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post #1 of 7 Old Aug 17th, 2008, 12:42 am Thread Starter
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Preload

I finally made it to Sturgis. Rode there with three friends and took four days to get there from Western Washington. Took back roads and camped out everynight. It was a real nice ride experience, sort of. By the time we arrived my body was aching in places that I had almost forgotten about, neck, butt, shoulders, back, you name it. It wasn't till a day later that it occured to me that some of the aches and pains I had suffered before when experimenting with the preload on another motorcycle. So I checked and sure enough the preload had bled down. So I screwed it down as far as I could and waited to see what the ride home would be like. I had serviced the preload a couple of years ago and it needed fluid then. I don't know where that stuff goes but apparently it evaporates somehow cause I've never noted a leak. I didn't refill at Sturgis just screwed it down till I had some resistance on the knob/screw. Anyway I had to get back home for a wedding so I left early and made it home in one day, 1251 miles. No aches. No pain and only the slightest butt burn. So if your ride is getting uncomfortable, before you blame a heavy helmet or an old injury or old age, check the preload.

2002 R1150GS Adventure (current)
2000 K1200RS
1999 K1200LT (current)
1998 R1100RT
1985 Suzuki GS1150E
1985 Kawasaki Ninja 900
1983 Honda V65
1979 Yamaha XS1100
1977 Honda CB750
1963 Harley Duo Glide
1965 Honda 305
1962 Honda Cub 50
1960 Cushman scooter

Was I being naughty...officer?
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post #2 of 7 Old Aug 17th, 2008, 9:09 am
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Re: Preload

Thanks for the reminder Jim.

What people don't realise is that preload is very critical for suspension performance. When properly adjusted it places the shock damping in it's optimal position to do its job. If it is off one way or another the compression or rebound valving will not be able to do its job. Glad you found the sweet spot.

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 110 K and counting...
2006 Bushtec Turbo+2 Spell
2004 330 Ci Convertable
K4AN

Have ridden a Motorcycle in all 48
But lack DE, MA, RI and CT with the 2005 LT

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post #3 of 7 Old Aug 17th, 2008, 4:29 pm
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Re: Preload

Can anyone expand on the proper check and fill of the preload?
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post #4 of 7 Old Aug 18th, 2008, 1:05 am Thread Starter
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Re: Preload

Quote:
Originally Posted by STYLNLT
Can anyone expand on the proper check and fill of the preload?
Disconnect the cylinder from the hydraulic line and unbolt the cylinder from the mount. Turn it upside down and back out the adjustment knob all the way. Make sure the plunger inside is all the way down (in the upside down position) by using an awl or skinny screwdriver to push it down. Then fill it to the brim with jack oil. Reattach the hydraulic line. Bolt the unit back onto the hinged mount and your good to go after turning the adjustment down to the desired setting. You may want to replace the crush washers.

2002 R1150GS Adventure (current)
2000 K1200RS
1999 K1200LT (current)
1998 R1100RT
1985 Suzuki GS1150E
1985 Kawasaki Ninja 900
1983 Honda V65
1979 Yamaha XS1100
1977 Honda CB750
1963 Harley Duo Glide
1965 Honda 305
1962 Honda Cub 50
1960 Cushman scooter

Was I being naughty...officer?
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post #5 of 7 Old Aug 18th, 2008, 1:46 am
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Re: Preload

Thank you.

Jack Oil you say. Is there a specific density or brand recomendation?
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post #6 of 7 Old Aug 18th, 2008, 5:40 am
 
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Re: Preload Oil

Quote:
Originally Posted by STYLNLT
Thank you.

Jack Oil you say. Is there a specific density or brand recomendation?
http://members.cox.net/slartidbartfa.../shock-oil.htm

Top Up Shock Remote-Preload Oil
(Simple shock rejuvenation)

I read about this on the BMW Sport Touring Website. Aparrently quite a few BMW riders realized that their remote rear shock preload adjustment did not have the range it once had. The hydraulic preload adjustment circuit (which is independednt of the damping oil in the shock) seems to lose oil over time. Nobody can explain where the oil goes but someone figured out how to fix it.
The adjuster on my 95 GS had a lot of slack in it when the suspension was unloaded and I had wished for more adjustment range when I carried a heavy passenger. However, I had never compared the adjustment range to that of a new bike, so I was blissfully ignorant of what was missing.

Once enlightened, the repair is almost trivially simple. Here's what to do:

Back off the adjuster all the way.
If you can reach it, it is much easier to break the banjo bolt (arrow) loose before you unbolt the preload adjuster (circled allen bolt)

Once the adjuster is removed, turn it upsidown and remove the banjo bolt and hose. Be careful not to lose the copper sealing washers. Hold the hose up while you work on the adjuster so the oil in the hose won't drain.


Push the piston down and top up the oil. Some people have used hydraulic jack oil. I used whatever was handy.

<<<< BEFORE
AFTER >>>>

This is how much adjustment range was recovered. In these photos the adjuster is turned until resistance just begins, indicating that preload pressure is being applied to the spring. Before this repair, it appears that I should have had it set on HIGH just to get STD preload. HIGH preload was unobtainable even with the adjuster bottomed out.

This was an extremely simple, easy way to rejuvenate the shock preload adjustment. The whole operation took less than twenty minutes, including taking the photos. (I still have no idea where the original oil went.)

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post #7 of 7 Old Aug 18th, 2008, 7:36 am
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Re: Preload

Excellent. Thanks for that helpful info and pics. I'm in the process of getting some last minute service work done on the bike before CCR, and this is definatley going on the list.

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