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Author Topic: Mechanical preload Ohlins BM888  (Read 448 times)

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seasnake

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Mechanical preload Ohlins BM888
« on: March 29, 2019, 05:37:20 PM »

I bought a used BM 888 rear shock for my BMW.  The mechanical preload is set at the high end of right range for my weight with no hydraulic preload added.  Does anyone know how to adjust the mechanical preload on this?  It's know longer made and I can't find the owners manual.  It doesn't quite match ohlins shock I can see now.


I just want to set it in the middle so I can use the hydraulic preload to optimize it either way.
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Dave Miller
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seasnake

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Re: Mechanical preload Ohlins BM888
« Reply #1 on: March 29, 2019, 05:51:22 PM »

Doing my Rainman imitation in writing...

It's no longer made and I can't find the owners manual.  It doesn't quite match any ohlins shock made now.  I don't see any place to use a spanner wrench.
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Dave Miller
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seasnake

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Re: Mechanical preload Ohlins BM888
« Reply #2 on: March 29, 2019, 06:54:29 PM »

Never mind.  I finally found a video of a similar shock from Graves.  I wish I had found it before I removed it from the bike.  I would have to have a spring compression tool to break the shock down to reach the collar under the hydraulic adjust.
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Dave Miller
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andrew230

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Re: Mechanical preload Ohlins BM888
« Reply #3 on: March 29, 2019, 06:54:39 PM »

Loosen jam Allen nut to the right and loosen nut on the left turn counter clockwise to take preload off spring.

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Andrew Gold ccs#230 expert

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seasnake

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Re: Mechanical preload Ohlins BM888
« Reply #4 on: March 29, 2019, 08:00:06 PM »

Rotate the gold cylinder for the hydraulic adjust or the whole collar?
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Dave Miller
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andrew230

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Re: Mechanical preload Ohlins BM888
« Reply #5 on: March 29, 2019, 08:12:35 PM »

Just the nut that's just a fancy spanner nut for the preload. As you turn the nut it mechanically backs off the spring just like if you were turning a spanner nut

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Andrew Gold ccs#230 expert

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seasnake

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Re: Mechanical preload Ohlins BM888
« Reply #6 on: March 29, 2019, 08:22:10 PM »

Ahh.  That’s already all the way CCW.  Hence wanting the mechanical setting.  I can only make add preload at the moment.  If it was in the middle of the setting I would be golden.
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Dave Miller
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andrew230

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Re: Mechanical preload Ohlins BM888
« Reply #7 on: March 29, 2019, 08:28:29 PM »

If you dont have any preload in that spring and your sag is in range that spring is way to heavy for your weight.

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Andrew Gold ccs#230 expert

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seasnake

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Re: Mechanical preload Ohlins BM888
« Reply #8 on: March 29, 2019, 11:02:36 PM »

The spring has 13mm of preload and is the correct spring according to the charts I’ve found.  13mm of preload is the recommended preload for the shock.  If I had set it up It would have been 5mm less preload so that I could use the hydraulic adjust to put it at 13 and had room to adjust either way from there.
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Dave Miller
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52 Ruhe

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Mechanical preload Ohlins BM888
« Reply #9 on: March 30, 2019, 12:14:31 PM »

Remove preload from spring.
Load shock into spring compressor.
Compress to expose retaining clip. Remove clip remove lower spring seat.
Decompress spring press.
Remove spring remove adjuster.

There is a threaded split ring that the adjuster sits on.
Adjust Accordingly.

Not a bad idea to on proper spring start at 10mm of fixed preload. See where that gets you. Point is you want proper setting but to be in the middle of your preload adjuster. That way you can soften up on say rainy day. Or firm up when you start pushing a bit harder. Once you get that fixed preload set you should have a pretty good range on the adjustable preload for a number of conditions and tracks.


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« Last Edit: March 30, 2019, 12:18:04 PM by 52 Ruhe »
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Mike Ruhe #52

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52 Ruhe

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Re: Mechanical preload Ohlins BM888
« Reply #10 on: March 30, 2019, 12:17:28 PM »






Sent from Spinak’s samsuck phone
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Mike Ruhe #52

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seasnake

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Re: Mechanical preload Ohlins BM888
« Reply #11 on: March 30, 2019, 05:31:25 PM »

Yeah, I don’t understand what the person who last set this shock up was doing.  Compression was full open and rebound fully closed.  Doesn’t seem like it would have rode well.
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Dave Miller
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52 Ruhe

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Re: Mechanical preload Ohlins BM888
« Reply #12 on: April 03, 2019, 01:13:58 PM »

Was it serviced just before buying. I have had them comeback that way.
What spring rate? If you want to try some different settings I may have some springs that fit. Can bring my stuff and you could try one lighter or stiffer to get a feel. Road Atlanta?


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Mike Ruhe #52

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www.ridepre.com

Canton, GA

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mike.ruhe@ridepre.com

seasnake

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Re: Mechanical preload Ohlins BM888
« Reply #13 on: April 05, 2019, 07:13:21 AM »

I did not have it serviced when I bought it.  It was a last minute splurge for this year  :)  I'm planning on getting it serviced sometime this year.  Probably after the July event.


I'll definitely take you up on your spring offer at RA.  The current one is a 21040-31/95.  I'm 200#, so from what I read I'm on the upper end of the recommended weight for the spring, but still in range.


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Dave Miller
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52 Ruhe

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Re: Mechanical preload Ohlins BM888
« Reply #14 on: April 05, 2019, 12:00:01 PM »

Let me see if I have a 100 for that shock


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Mike Ruhe #52

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www.ridepre.com

Canton, GA

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