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Old 02-15-2013, 06:43 PM   #320
DRONE OP
Dog Chauffeur
 
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Joined: Oct 2007
Location: Tacoma, WA-ish
Oddometer: 3,570
Rear Ohlins Shock - Rebuilt and Re-Sprung

Here's the next big thing -- I've upgraded my rear shock. It's an Ohlins BM 215-1.

Last September I upgraded my front shock--just a straight rebuild of the Ohlins BM 216-2 but with a new size 15 spring (354 lb) replacing the size 13 (331 lb) I had. Cost $300. I also increased my rebound damper to 10 clicks back from all the way. Went on two backcountry camping trips after that and was really happy with the result. My front end sag was reduced, and my travel was increased, no more bottoming the front shock in holes, wallowing almost completely eliminated, and the handling was just generally nicer. I posted a pic of it back on page 16 but here it is again--




Encouraged by the front shock improvement, I decided to bite the bullet and do the rear shock too. This one cost $500--basic rebuild service was $210, plus another $40 because the remote preload adjuster was totally blown, plus $100 for the new spring, PLUS--another $130 to add a Ride Height Adjuster! (for you math wizards--the rest is sales tax.) My new spring is a 1095-84-200 (1142 lb) replacing a 1095-64-160 (914 lb) so that's about a 25% increase in spring rate. Yes, I know - huge!

Lots of angst went into this. Here's some of the threads that helped with the decision--
2004 1150 GSA needs new shocks
New shocks for 04 GSA rig
GS aftermarket spring calculations?
Ohlins for GSA question
Ohlin spring rate markings on spring?
Ohlins spring rate?? for 1150 ADV
Goliath has come to play
Because it seems like several guys with 1150GS hacks have blown out the seals on the pre-load adjuster (including me) I'm convinced that the adjuster is not really robust enough to deal with the strain of a sidecar rig. I'm gonna run mine with the pre-load adjuster backed off all the way to "zero". Then, using the collar on the shock body, I put just a little bit of pre-load tension on the spring. The idea here is to give me as much travel as possible, and the softest ride as possible, given the stiffness of the spring. Like the front shock, I plan to start out with the rebound damping at 10 clicks from full.

Here's a pic of the OEM shock, my new Ohlins shock, and the old spring--




Now, about that Ride Height Adjuster. This is an option available straight from Ohlins. In the pic above, I have the adjuster all the way tight--in other words, the shock is as short as it will go. Even so, my shock is now 416mm eye-to-eye. Too long! The OEM shock is 390mm. My swingarm only has 404mm of total travel. After I took this pic, I brought the shock back to the shop and asked them to shorten it to 400mm with the RHA turned out about 10mm. This they did (no charge) by changing around the internal stops on the shock.

OK, so now my shock is 10mm longer than the stock shock which translates to about a 20mm change in ride height measured at the axle. I'm not sure how much my ride height and ground clearance have changed in total with the longer shock and the stiffer spring, but clearly it'll be more than it was. The only measurement I've made so far is the static sag (which means, as I'm using it here, the distance the suspension sags under the bike's weight alone, without a rider, from its fully extended position, as measured from the rear axle to the frame). With my old spring it was 2-1/2 inches (65mm). Now it's about 5/8" (16mm). That seems like a pretty decent improvement!

Not everything is going upwards, though, I'm also going to try a 175/65-15 tire which will lower my axle height about 10mm from the 155/80-15 Snow+ tire I used the last two seasons (link to tire calculator).

One thing that seems like almost too much of a coincidence is the ground clearance on the bike now as it sits in the garage. The lowest point on the bike is the subframe and right now (with no rider) the very front of the subframe and the very rear of the subframe are both exactly 9 inches from the garage floor. In other words, the bike looks totally level. How'd that happen? Dumb luck I guess. I'll have to load it up and get on board then have Queen Bee get down on the floor and re-measure to see what it looks like fully loaded.

How does it ride? Don't know yet. Still got a few more things on my winter punch list to do before I take it out on the road. I will post up more pics and my impressions later on this Spring.

Next up? I've got to get that new FD installed, and I'm adding a custom-made alu cage for an aux gas can.
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DRONE screwed with this post 02-15-2013 at 06:51 PM
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