New rear shock headache
 

Hi All,

I've got the chance to get a very reasonably priced Ohlins rear shock, but am up in the air a bit about whether to go for the old SS length or the IE length version....

If I understand right then the Showa IE shock is about 10mm longer but with the same mounts as the Showa SS shock. I assume Ohlins make the standard ride height in the middle of the shock's adjustment range (about 15mm end-to-end?) meaning the Ohlins IE shock on lowest setting would be about 3mm higher than a fit, standard Showa.

I've always found the rear ride height to be too low on SSs, so I doubt I'll be wanting to go below standard, but I'd like to have the ability to go 3-18mm up from standard. The way I see it is that, as the shock is at 45 degrees not vertical like a 916, 15mm of adjustment is actually only equivalent to 8mm vertical adjustment.

I'm absolutely positive that I've got some of the above wrong, so feel free to laugh at my massive ineptitude in all things suspension related...:lol:

Cheers,


Ali

ps: I will be doing the front end soon, but once you get into changing the springs, you may as well change to 996 forks, so you'll need a 996 wheel (or a mag), so you'll need a cyclecat yoke, so you'll need goodridge hoses, to connect to your brembo billet master cylinders, so you don't mess up the look of your cyclecat clip-ons, etc......... About £2k if I've got me sums right:(:(:(

I'd go for the Ohlins SSie version were I to have any money left after my 748 forks, cyclecat yokes, MR bars etc etc....

I've got a Showa SSie shock on my SL at the moment and there's still no way the steering could be described as being quick.

Chris Kelley (Of http://www.ca-cycleworks.com and http://www.ducatitech.com/ ) sells a custon Penske shock for SS's that comes 1/2" longer than standard and has an additional 1/2" adjustment on top so...

While the OEM showas were a bit longer in length for the SSie, check the Ohlins website. The smae Ohlins shock Du235 (46PRCL) / Du245 (46PRCLS) are listed for both the carbed SS and the SSie.

Oh, and you can get about 1/2 to 3/4 inch increase in ride height with the Ohlins fully extended. Does sharpen the steering a bit. :)

Ali the Ohlins shock recommended for the 2001 900SS is part No. DU235, this is also the shock that they recommend for a Superlight, its range in length is from 328mm to 340mm. There is also a DU245 available but is indicated as Japanese special this goes from 324mm to 336mm

Öhlins shock absorber
Part No. DU 235
Type 46PRCL
Length 328 +12/-0 mm
Stroke 68 mm


Part No. DU 245
Type 46PRCLS
Length 328 +4/-8 mm
Stroke 67 mm
Comment Japan Special

Cheers guys. Had a chat with Harris about this, as I'm really looking for something with a range of 335mm - 347mm. They reckoned it'd only be another £40 to modify the DU 235 to suit.

Doesn't alter the fact that it still costs and arm and a bloody leg to start with...... :(

Don't want shot of that Penske by any chance Kev??? Thought not. :)

Cheers,

Ali

I would say you are a bit wrong there Ali, the chances are your shock ratio is about 2:1 but the not in the way you have discribed. Assume 50mm of Stroke on the shock this will give 100mm of rear wheel travel if the ratio is 2:1
To get a rough idea of the ratio measue from the swingarm pivot to the rear wheel spindle and then from the swingarm pivot to where the shock fixes on the A-frame of the swing arm, this will give you a basic ratio, a small degree of rising rate is added as the shock moves through a arc, this means things aren't totaly linear so you end up with a rising rate curve could be in the region of 1.9 to 1 through to 2.0 to 1.
Now if you increase the shock length by 5mm it will push the rear wheel futher from the seat by 5mm X the ratio..
try taking 5mm of preload off the rear spring, this will effectively make the damper rod sit futher into the shock body simulating a 5mm shorter shock, I bet a distance measured between the rear spindle and a point on the rear of the seat unit reduce by nearly 10mm, conversely increasing the shock length by 5mm will raise the bike by 5mm X the ratio so almost 10mm in the example.

A Harris Magnum 2 with the cantilever rear end has a ratio of 1.7 to 1

And no you cant have my Hi/Low speed damping Penske it cost more than a Ohlins and unlike a 916 Ohlins it also has a rideheight adjuster.

Kev

You are, of course, 100% correct. Can't quite believe how I missed that....

Many thanks for the lesson in simple trigonometry. :)

The question now is, how much of an increase is too much? And would the money be better spent on having some kind of bodged spacer made up to extend the shock, while spending the rest on a mag/carbon front wheel?

And I love the idea of hi/low speed damping on the penske shocks. Can't quite work out how it manages it, but I'm sure you'll be along with an answer shortly. :D

Cheers,

Ali

Ali put up a few wanted adds for a standard 900SSie shock and if you find one give it a go, failing that I have a 900SS alloy swingarm for £30 that it should be possible to get a different shock mount fabricated and fitted, but the shock is usually the cheaper way to go. Try Jim at Bike Enders on 01708 455530 he may have one.

As for high low speed damping
The slow speed forces oil through small holes that you can partially restrict with the damper control, the high speed is controlled by the shim stack on which you can vary the pressure with the adjuster. The holes will only pass oil through at a certain rate so as the shock moves slowly most of the oil will pass through the holes.
At higher speeds of shock movement the amount of oil being moved is more than the holes can cope with so the extra pressure that builds up forces the remainder of the oil through the shim stack.

The Ohlins on my R6 also has this system

Kev

blurdy hell, guys, this has just confused the ferg outa me (and I hear you all say...........thats not difficult)
I woz just talkin to Nelly yezzerday about gettin my rear worked over by K-Tech. Its been done once but guess it would need a good service after two - three years of no work on it.
What benefits, at my level of riding, am I likely to see with a different (better ?) shock
Woz also thinking about a front end respring and oil jobbie this winter going for something slightly better than the standard ssie stuff. Would progressive ohlins springs/oil help out and what benefits again would I see

I do have a standard SSie shock (at present lent to a club member up in Dundee) if anyone wants to get it reworked, let me know and I'll find out when its coming back. Dano??????

Rgds
Mort