OHLINS HEIGHT ADJUSTMENT

[stivesvelo]

Hi,

Not sure where to post this as it's a follow on from my post on the newbies thread, so hope I've got it right.

Now that I have the bike in the garage having brought it down from Newcastle over Easter I thought I'd look at the suspension after scraping one of the head protectors on the way back. I'd like everyone to think that I'm a demon like Randy Mamola, but the truth is that there is still a 1" chicken strip on the back tyre!

Undid the swinging arm fitting on the shock (bit of a pain as the bolt stopped on the y piece so needed to remove the exhaust & various other bits to allow it to pull back, bike is now stripped to remove battery which was almost dry & I wonder at the wisdom in fitting a conventional battery which needs topping up every couple of months as it's so easy to get to!

Checked the measurements & the shock seemed short (312 max).

After various phone calls to Ohlins & head scratching I unscrewed the bottom fitting from the shock & discovered that it had been chopped down at some time...... so another call to Ohlins & in 10 days time the next shipment from Sweden arrives with a replacement.

If anyone needs to shorten an Ohlins back end I will have a spare part....

Front shock very easy to remove, seems to be the right length, does anyone know if the measurement is from the bottom of the flanged top fitting (screwed fully down) to the centre of the bottom eye?

Also finding that quite a few of the fastenings are corroding, I see quite few different suppliers of stainless fittings & wonder if there are any to avoid as there is a fair difference in prices, there's this lot but wonder if it's just an assorted selection

http://www.ebay.co.uk/itm/BMW-R1100S-R- ... vi-content

Any pointers gladly received
Rob

[Nookiebear]

This is in response to the corrode bolts issue I would try this technique recommended by a forum member:

"Hi,

Had my bike in bits last week and was going to replace the standard rusty bolts with stainless, however, as stainless torx fasteners weren't available locally and I was in a hurry I bought a spray paint called ZG90. I soaked the old bolts in Phosphoric acid (Wonder Wheels is the same stuff) which removed the rust (and any remaining (zinc?) plating). Then I stuck them upright by pushing them into a cardboard box, gave them a good spray the balanced them on end and finished off spraying them.

All the bolts look like new now!

Jon"

I am going to try this as all it costs is the can of ZG90 and time. I found the can of silver colour for £5.99.

[r550s]

Ohlins front shock:

The 'length' is the dimension from the centre of the bottom eye, to the load bearing platten (the top of the hexagon that the OE rubber doohickey sits on).

Out of the box, brand new, mine measured 321mm. The Ohlins spec sheet that came with it stated the length as 318mm...?

If it helps, Ohlins recommend front static sag (bike stood on its wheels, no rider - sag measured at the fork legs) at 15 to 30 mm. I got my static sag to 20 - 23mm by reducing the 'out of the box' preload by 6mm. For reference, this left 15mm of exposed thread on the shock body.

My rear Ohlins measured 313mm out of the box (eye to eye centre). Ohlins recommend rear static sag 15mm (measured at the wheel spindle arc).

I messed with the rear shock and ended up with it 319mm long. This increased rear ride height (approx x 3) by about 18 -20mm. I did it in stages, fearing tankslappers, but they just don't happen on this bike.

My first settings that I was happy with (brand new units) were:

Front rebound 10 clicks out.
Rear rebound 10 clicks out / Rear compression 20 clicks out

God says that, when messing with suspension, take notes.

regards
chris

[r550s]

oops

[stivesvelo]

mmmmm, just measured the shock & it looks a bit short to me, measurements as follows:

length from centre of eye to top of hexagon on platten above spring = 300mm approx

length from centre of eye to bottom of platten which sits above the top of the rubber mounting in the frame = 330mm approx

I'm beginning to think that both shocks were made up shorter than normal, more calls to Ohlins tomorrow![/img]

[r550s]

Your front shock looks around 20mm short then... that would make the front ride height ( x 1.5) about 30mm shorter than standard. Definite head-grinding territory.

I think there's scope to shim the top mounting - by putting spacer discs on top of the platten. This is how I adjust my front ride height (I lowered the shock bottom mounting 10mm by altering the wishbone). I have a set of 3 spacers at 3.3mm (don't laugh - I'm not to decimal places here!) which allow me to incrementally replace the 10mm I 'lost' by altering the wishbone.

So you could certainly add 10mm to the length of your shock by the same method, possibly a bit more.

But...I suspect your shock is not just the 'normal' ohlins lowered. This is because that would allow your mudguard to hit the fairing on a big bump. I know this because my lowered front (equivalent to a 311mm shock length) was bad news in this area.

I now run with one spacer in, this gives me an effective shock length of 314mm - which just prevents the mudguard hitting the fairing.

Does your front spring have the rate printed on it - maybe it's a harder spring to compensate for the chopped length?

Do you know your static sag at the front - or maybe the unladen ride height measured by the length of exposed stanchion (bars below the yoke!) - do you have a cable tie on the stanchion to see how low you are going?

[r550s]

Thinking on - is your shock assembled properly? - I don't know how much thread there is on the damper rod - maybe the platten has been screwed too far on. If this were possible, then you'd have a shorter shock, but the rest of the operation of the shock would be unaltered if the preload adjustment (the screwed collars on the shock body) had been backed off to compensate.

You'd definitely wreck the front mudguard though with a shock that short and a standard spring.

[r550s]

...then again, if someone's ignored the need for static sag, and wound the preload right up to somewhere back towards the setting for a normal length shock, your mudguard would get away with it. Just avoid anything but mirror-smooth corners!

[r550s]

Happiest when I'm talking to myself!

[stivesvelo]

Thanks for the answer to the rusty bolt issue, I've given them as waxy sort of covering for the time being but will need to do something better in the fullness of time, most likely next winter when I can do it at my leisure.

This is in response to the corrode bolts issue I would try this technique recommended by a forum member:

"Hi,

Had my bike in bits last week and was going to replace the standard rusty bolts with stainless, however, as stainless torx fasteners weren't available locally and I was in a hurry I bought a spray paint called ZG90. I soaked the old bolts in Phosphoric acid (Wonder Wheels is the same stuff) which removed the rust (and any remaining (zinc?) plating). Then I stuck them upright by pushing them into a cardboard box, gave them a good spray the balanced them on end and finished off spraying them.

All the bolts look like new now!

Jon"

I am going to try this as all it costs is the can of ZG90 and time. I found the can of silver colour for £5.99.

[stivesvelo]

Thanks Chris,

All food for thought, so keep talking to yourself ... coz we're listening.

I'm initially trying to find out what was done to the shock in the first place to work out what to do. They have Kais stickers on them so I've emailed them to see if they have a record of what they did & will look at what to do next. I may just put the originals back on for the time being.

Following on from your height adjustment idea for the front, what's to stop me from fabricating a fitting to go between the lower eye of the shock and the fitting on top of the wishbone to raise the height by a specified amount rather than spacing it at the top? Is that what you did as I've not quite grasped what you mean?

Rob

[r550s]

Nothing to stop you making a fitting as you describe. I was just wondering whether your shock wasn't just a 'normal' ohlins, shortened - because (according to me at least) that'd let your mudguard collide with the fairing.

It would be useful if you could measure the length of exposed stanchion with the bike stood on its wheels - that would tell you if it's riding low at the front. A cable tie, a bumpy road and a bit of speed would settle the issue.

I 'altered' my front wishbone by replacing it with one from a rockster. That has a 10mm lower shock mounting than the standard item. It's the same as having a 10mm shorter shock.

I found that 10mm was too low (for the mudguard thing) so I put a spacer on the top of the shock, this leaves me effectively running a 314mm ohlins. Length for length comparisons between the ohlins and the standard shock have limited meaning unless the spring rates are the same.

Don't forget, all this 'shock length' thing is left meaningless if the preload is all over the place. You can alter the ride height by the collars on the shock body, which preload the spring before it's even fitted to the bike. The spring will, for a given load (i.e you and the bike) compress to a corresponding length that cannot be altered, by anything short of a blowlamp. This means that screwing the collars up and down the shock body (altering the preload) doesn't alter the length of the compressed spring with you on the bike; it just lifts the bike up and down. This sounds like a great and simple way to adjust the ride height - and it is up to a point - but you have to watch the sag.

[r550s]

Wittering on...
I have the spec sheets for both Ohlins here in front of me - they state the preload, length etc.
I can scan them and email them to you if you haven't got any.

[stivesvelo]

I think you're right re: a shortened standard front shock, just trying to get an answer from the original suppliers.

Difficult to measure anything as the shocks are both off & I'm waiting for the part for the rear one before putting everything back together (it was a devil to lift it onto the higher boxer cup Abba stand with the lowered suspension, it's about 10" off the ground, nearly gave myself a hernia).

Yes please ref the data sheet, could you send it to: rob@orientalexpression.co.uk

I'm sure that email is working & will make sure tomorrow morning.

Thanks
Rob

[r550s]

Rob
Found some info about Ohlins part numbers

the L084 suffix on your front spring part number is just a batch number - the rest of your number is the same as mine - so you've got the standard R1100s Ohlins spring.

Seems like the rest of the number is just code:

http://www.ducati-upnorth.com/tech/suspensionspring.php