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Ohlins shock settings?

 
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hindsight



Joined: 13 Feb 2010
Posts: 27

PostPosted: Mon May 21, 2018 9:25 pm    Post subject: Ohlins shock settings? Reply with quote

After doing a bit of maintenance on my DB2, I've just spotted a problem. it's clear that on the last ride, the rear hugger must have impacted the exhaust
. Something clearly ain't right (possibly involving too many pies on my part...).

Suspension tuning really isn't my forte, but I think what I need to do is to increase the shock length to raise the back end slightly (I've not yet checked to see how much, if any adjustment is available here), and to increase the preload to add a bit more stiffness (then stop eating pies).

Does anyone happen to have a note of their rear shock settings to compare with my own?
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2bims



Joined: 03 Apr 2010
Posts: 5104

PostPosted: Mon May 21, 2018 10:40 pm    Post subject: Reply with quote

Whereabouts has it "hit"...? Is the hugger still intact?....I've seen the curved rear part of the swinging arm where the bottom of the shock is attached hit the large Single vertical collecter exhaust pipe before it branches off into 2 heading towards the end cans...(on my bike)....

The Db2 has effectively 2 No. ride height adjusters.....only one of which will move the hugger part away though...and that is on the bottom of the Ohlins shock...there should be an anodised blue locking nut above the spigot fixing that goes onto the swinging arm...undo that...you may need to put a spanner on the other silver alloy nut also at the same time as often they spin together...so slacken the blue one...and then clockwise wind up the other silver one...you should see thread becoming exposed if its been wound down...and then lock off with the blue one

Another ride height adjuster are the concentrics...as the spindle is offset from the centre...but this wouldn't make any difference to the position of the hugger...I am assuming your hugger is hitting the exhaust end cans and not the branches or collectors???

You should also though be setting the correct preload and "sag" of the bike by winding up or down the spring top collars...2 no...one of which is a locking ring...both are silver....it helps if you have the correct Ohlins spring spanner for this....

Changing the twurly black knob at the bottom of the shock or the twirly knob on the remote body is for compression and rebound....and if like me youre partial to the odd van load of pies...that aint gonna make no difference until you've set the correct sag of the preload....bike should sink an inch or two when you get on it and feet of ground...if its sinking more than this...you need to wind the top 2 shiney alloy rings down on top of the shock.....Compression and rebound is for speed of compression and speed of rebound....not for loaded mass....

If you'd like to provide some kind of Height and "mass" figures...by pm if you wish to keep private...please do so....and I'll compare with my stats also and tell you how many rings of thread my preload is set at...

Only other checks...are is the spring intact and not snapped? (rare occurrence).....is the shock still fully gassed or have the seals gone and its lost all its gas? Which would result in just a pure springey back end.....where it sinks easy and rebounds rapid....pushing the back end down of a properly working set-up Db2 should squish easily the back end an inch or two...that's the sag...then the gassed up body of the shock takes over and resists more down pressure....but allows up pressure from road bumps if you get my drift?...pictures would help of top of shock (remove tank/seat cover)...and bottom of shock for height adjustment....try that one first....
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hindsight



Joined: 13 Feb 2010
Posts: 27

PostPosted: Tue May 22, 2018 7:50 am    Post subject: Reply with quote

Super helpful reply - thanks.
2bims wrote:
Whereabouts has it "hit"...? Is the hugger still intact?....

Right on the crown of the hugger, impacting at the branch of the exhaust pipe. I tried to capture it here..





2bims wrote:
The Db2 has effectively 2 No. ride height adjusters.....only one of which will move the hugger part away though...and that is on the bottom of the Ohlins shock...


Yep - that's the adjustment I had in mind, though looking closer this morning - I don't think there is too much adjustment left on it - it looks like it is already at full extension.



2bims wrote:
Another ride height adjuster are the concentrics...as the spindle is offset from the centre...but this wouldn't make any difference to the position of the hugger...I am assuming your hugger is hitting the exhaust end cans and not the branches or collectors???

Best leave this solely for chain adjustment then, yes?


2bims wrote:
You should also though be setting the correct preload and "sag" of the bike by winding up or down the spring top collars...2 no...one of which is a locking ring...both are silver....it helps if you have the correct Ohlins spring spanner for this....

In a weird coincidence, a friend was round at my place last weekend with his BMW HP2, asking if I had that very C-spanner. After an extended rake through various bike toolkits, I decided that I didn't, but I think it's about time I got one.


2bims wrote:
Changing the twurly black knob at the bottom of the shock or the twirly knob on the remote body is for compression and rebound....and if like me youre partial to the odd van load of pies...that aint gonna make no difference until you've set the correct sag of the preload....bike should sink an inch or two when you get on it and feet of ground...if its sinking more than this...you need to wind the top 2 shiney alloy rings down on top of the shock.....

Good rule of thumb, thanks. I've definitely got more sag than this.

2bims wrote:
If you'd like to provide some kind of Height and "mass" figures...by pm if you wish to keep private...please do so....and I'll compare with my stats also and tell you how many rings of thread my preload is set at...

Genuinely I have no idea - I'll need to track down some scales. I'm 5'10", and I would neither describe myself as either oversize, or athlethic.. Very Happy


2bims wrote:
Only other checks...are is the spring intact and not snapped? (rare occurrence).....is the shock still fully gassed or have the seals gone and its lost all its gas? Which would result in just a pure springey back end.....

Definitely not on both counts, though I'll need to go back to Ralphs build thread or drop him an email, I don't recall him mentioning whether the shock was ever rebuilt. Might be something for the to-do list.
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2bims



Joined: 03 Apr 2010
Posts: 5104

PostPosted: Tue May 22, 2018 8:19 am    Post subject: Reply with quote

Scales would help.....I'm the same height....but most...as in "all but the blind" would say I'm very overweight

My bottom "thread" height adjuster has 5 threads showing before you get to the blue anodised locking nut....so no....you have quite a bit of height adjustment upwards still to extract from that part of the shock.

Your spring preload seems to be set way too soft.....as you only seem to have around 4 threads showing above the top locking ring.....I'll count mine and add later

at 5ft 10...you are maybe finding the bike quite tall....certainly to throw a leg over....this is where the concentrics can help....where is your spindle set at the moment? top or bottom...more later son just phoned...missed his school bus
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hindsight



Joined: 13 Feb 2010
Posts: 27

PostPosted: Tue May 22, 2018 8:52 am    Post subject: Reply with quote

2bims wrote:
My bottom "thread" height adjuster has 5 threads showing before you get to the blue anodised locking nut....so no....you have quite a bit of height adjustment upwards still to extract from that part of the shock.

Ah - yes, of course, my head was operating upside down, so to speak. Raising that will be straightforward.


Quote:
at 5ft 10...you are maybe finding the bike quite tall....certainly to throw a leg over....this is where the concentrics can help....where is your spindle set at the moment? top or bottom...


I'm not finding it noticeably tall - similar to both my 916 and 888.

Just so I'm sure that we're speaking about the same thing (sorry, I'm still relatively new around here, and my terminology may not be correct) - when you're talking about concentric - you mean the eccentric chain tension adjusters, right?:



Quote:
more later son just phoned...missed his school bus

Oops! Emergency school run?

Preload spanners now ordered from Harris performance Smile

Thanks,
Mike
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2bims



Joined: 03 Apr 2010
Posts: 5104

PostPosted: Tue May 22, 2018 10:46 am    Post subject: Reply with quote

Back again......once you've extended the height adjuster at the bottom of the shock to show at least 4 or 5 threads....measure the gap between the crown of the hugger and the underside of the branch of the end cans.....vertical height...mine is 11 cms with the bike on its sidestand...to just where the branch splits...but then I do have a different set of end cans and branch on my bike...not the standard Bim set-up....I'm staggered that the hugger has hit the branch where it has WITHOUT the swingarm itself hitting the upswept collecter pipe.......as the tolerance is close there...and perhaps closer on yours as it still has a cat in your system at that point

I'd be looking at winding down your 2 No. top rings on the shock at least 3 or 4 lines of thread......hard to say without being there or knowing your weight....and again...mine aint standard spring either it was uprated for a harder dual progressive spring...yours is dual progressive also (coils tigher wound at top than bottom).....

And if the bike is getting too tall at the back....swing the rear spindle concentrics so that the spindle is top most and not bottom most....although your chain length/slack/tightness may dictate where it has to be....Chain tension correctness SHOULD be checked with you on the bike not off it....as the swingarm motion tightens the chain when a riders weight is added....Can you post a picture of the rear end can outlets and also the bracket thats holding and bolted to the rear subframe...to check if they are right/correctly fitted...

If you get scales....weigh your bike F & R...set up scales and blocks of wood at same height so that you can roll bike front wheel onto scales and weigh the front end...with the rear tyre underside at the same level...and then repeat process for back wheel....Bims and the DB2 are usually set up 50:50....scales are up to the job as the bike only weighs some 160kgs....and you'll only be weighing half of it each time..thus 80Kgs
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2bims



Joined: 03 Apr 2010
Posts: 5104

PostPosted: Tue May 22, 2018 10:54 am    Post subject: Reply with quote

Eccentrics...Concentrics...I'm getting old....yeh those fixed round things stamped Bimota on the face either side of the wheel spindle....you can quite happily prop up the rear on a pop up stand and just loosen the C clamps top bolts on each side to swing the eccentrics around...as the whole unit is locked together as one...to ensure constant perfect wheel alignment with the front...your DB2 is currently set up with the spindle at the bottom...and thus "high"...although its only the wheel that is high...not the hugger...I have mine set the same as yours....but once you've fiddled with the bits you may find its not squishing down as far...and maybe too tall...so dont worry...it can be flipped to reduce the back end down and still keep the same chain tension...

Yup...emergency school run...and he has his GCSE proper exam this morning...but as he says "Its only English Literature Dad........."..........
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vort28



Joined: 22 Mar 2010
Posts: 1813
Location: Northwest , UK

PostPosted: Tue May 22, 2018 12:56 pm    Post subject: Reply with quote

Adjusting the lower of the shock will raise ride height . Generally there is about 15mm of adjustment on the is lower shock and as standard setting will be in the middle of the range, so this been seriously lowered . There should be a length setting in the handbook , mount to mount



Spring preload is by rider weight , again there will be a starting position in the handbook but have the bike at rest , upright, measure seat height, sit on bike(riding position) seat should drop by 15-20mm ( probably need a friend to measure) adjust spring to get correct preload/drop.

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hindsight



Joined: 13 Feb 2010
Posts: 27

PostPosted: Tue May 22, 2018 4:56 pm    Post subject: Reply with quote

Lesson learned - for something so easy to check, I've not had to do so in the past. Where a bike has been foul handling enough to deserve, I've taken it to a suspension shop for tuning.

I'll try and get onto setting the shock length this evening - the preload will likely wait until the weekend, once I've got the C-Spanners.

Quote:
There should be a length setting in the handbook , mount to mount


In a weird coincidence, I just downloaded a copy of the owners manual yesterday (thanks again Par), and indeed, I can see that it specifies:

"NOTE. The damper is delivered with a spring pre-loading of 166mm and with fitting points of 315mm-length."
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2bims



Joined: 03 Apr 2010
Posts: 5104

PostPosted: Tue May 22, 2018 5:39 pm    Post subject: Reply with quote

I hope you didn't "chip" Ralph too hard on the purchase price of his DB2SR....as I find it strange he didn't pass on the Owners Manual, Workshop Manual or Spare Parts Manuals that I know he has at least electronic copies of....more than likely because I send them out to anyone that needs them....

Did he keep hold of the Tool kit and rear stand also?

Always a dilemma when selling a motorbike.....if I felt I had been "dealered" on a sale price less than I would have liked...I'd probably hold back all the trinkets that usually come with Bimotas....pieces that owners cherish in collecting to "complete" their beloved Bimota....Owners Bimota leather key fob...rear stand...eccentric adjustment tool...eccentric adjustment spanners....Special "pins" that fit into the rear eccentrics in the Bimota paddock/crating stand.....Red velour cover and container bag etc etc....although I'm not saying that Ralph that any or all of these pieces....Even the Ohlins rear shock adjustment C spanner is a labelled tool within the tool kit (I know Ralph didn't have one of those though...)
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hindsight



Joined: 13 Feb 2010
Posts: 27

PostPosted: Tue May 22, 2018 6:10 pm    Post subject: Reply with quote

To be clear - Ralph was a true gent, and it was a pleasure being able to deal with him.

Transactions such as these can be somewhat fraught by distance, and I was glad to have flown down from Scotland to meet him and to have got a feel for his manner and seal the deal, safe in the knowledge that the subsequent shipping of the bike would be carried out as agreed.

He did indeed pass on those things, and a nicely bound hard copy of the electronic docs - but with the exception of the stand pins, they are largely still sitting in the cardboard box that he neatly packed them in Smile
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2bims



Joined: 03 Apr 2010
Posts: 5104

PostPosted: Tue May 22, 2018 6:16 pm    Post subject: Reply with quote

Yeh...>Ralphs a nice guy...he brought his DB2SR to our Annual Mcr Show last year for the first time....after previously having visited on other occasions....and sat on my Db2 to see if it fitted...hence became his search for his own DB2....and stayed over at mine for the weekend...Just never take him to an Indian restaurant and feed him beers....he's like a Furbie.....shouldn't be fed after dark or gotten wet....Boy that bloke can eat......
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hindsight



Joined: 13 Feb 2010
Posts: 27

PostPosted: Fri Jun 15, 2018 6:15 pm    Post subject: Reply with quote

To close the story on this - it took a while, because when I got the C-spanner to adjust the shock, I couldn't get a good purchase on it, and decided to remove the shock itself so that I could get good access without damaging it.

That meant finishing the service of my 888, and getting it off the abba stand and workbench. Once the shock was off, adjusting it was easy enough, and I now have it set with about 24mm of sag, and the recommended length that the manual said.

Feels a good bit different, and will take a few miles to get used to it again.

Next job is to get the 888 MOT'd. First time in four years, so definitely looking forward to that.. Very Happy
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