Boing

Been a while since I've come close to taking my eye out, so...

....anyone got any reccommendations for a spring compressor?

The Ohlins I had earmarked for the ZX-9R has turned out to have a
soft-as-all-buggery spring in it (static sag of ~20mm and just resting
my weight on the grabrails comes to within 10mm of bottoming out), so I
need a stiffer one, and I might as well replace it myself.

 

Let us know when you get one - I might need to borrow it, the 748 shock
I got from eBay just showed up, now its time to see whether all the
poeple who said it _will_ fit the Monster are right, or whether all the
people who said it _won't_ fit are correct - the entire world seemed to
be a pretty even 50/50 split when I started asking around before
bidding...

big

 

Anything will fit, it just come down to how determined you are, and how
good a machining shop you have access to....

JL
(I'm guessing that didn't help ?)

 

Just lose some weight you fat bastard.

Glad I could help.

Jules

 

From the Ohlins website

monster 750




Öhlins shock absorber

Part No. DU 440

Type 46HRC

Length 330 mm

Stroke 65 mm



. Type 46HRC with hose mounted reservoir, easy to fit where it
is easy to reach.
. Fully adjustable, compression and rebound adjustments.
. Fits bikes where there is no room for a "piggy back"
reservoir.

Learn more about 46HRC

The pictures are only representative for the shock absorber type
and may differ in apperance from the shock absorbers specified for your
vehicle.


748

Öhlins shock absorber

Part No. DU 143

Type 46PRXB

Length 305 mm

Stroke 71 mm



. Super effective adjustable high and low speed compression
damping.
. Unique hydraulic spring adjuster, with integrated adjuster,
makes adjustments quick and easy.
. Easy adjustable rebound.
. Internal temperature compensation for the damping.
. "Piggyback" type gives improved cooling with more consistent
damping and longer damper life.

Learn more about 46PRXB

The pictures are only representative for the shock absorber type
and may differ in apperance from the shock absorbers specified for your
vehicle.

 

25mm is a fairly significant decrease in ride height on a bike that's
already on the slower side of the sports bike world - would be looking
at longer dog legs or mount points to stretch it up again

JL
(it's not like you need a lower seat height)

 

Thanks Glen, I didn't think of looking there...

Heh - so I'll have a Monster Chopper!

The old Monsters (like mine) have a fair bit of ride height adjustment
where the rear suspension "hoop" attaches to the swingarm via screw
threaded rose joints. The problem is more likely to be that the linkage
geometry means a 25mm shorter shock actually translates to somewhat more
that 25mm less ride height... The specs for my Monster say 65mm of shock
travel and 144mm of wheel travel, so that implies I'm looking at 55mm
less ride height (which is probably within the limits of adjustment
available), but with 6 mm more travel, I may actually end up wanting
closer to 69mm of extra ride height to make sure the wheel doesn't top
out against the bottom of the seat - thats definitely going to be right
at the far end of the adjustment if it works at all...

The other problem is that the 748 shock had an integrated reservoir
hanging off the side which the Monster shock doesn't have - it might not
fit around the shock linkage compnents and exhaust...

Still, I got the shock cheap off eBay, if it doesn't fit easily, I'm
pretty sure I can offload it again without losing much on the deal...

big (so if I show up on Sunday morning on the Spada...)

 

on the VFR400 the shock length to ride height ratio is 3:1

every 1mm of shock length equates to 3 mm ride height due to the linkage
ratios

but in the end depending on the fittings you might be able to rig up a
spacer
to take up the extra and of course add a little bit more ide height for a
quicker turn in

 

Agreed, as per J5's post, there's a ratio which can be anywhere from
less than 1:1 to 3 or 4:1. However...

No it doesn't... does it ? Shock *travel* isn't a function of ride
height (ie you cant assume a one to one relationship). Shock travel and
wheel travel are obviously related, but the correlation with ride height
is with shock length, no ?

Ie your ride height change will be some multiple of 25mm (depending on
what the linkage ratio is), the change in wheel travel will be the
linkage ratio times the change in shock travel, no ?

So worst/best case scenario I doubt your wheel travel increase will be
more than 4x6mm = 24mm (i've not heard of ratios much above 1:4 but I've
obviously only a limited range of experience)

The logic here is sound - the additional travel is going to require
additional ride height, however a doubt you'll need to go plus 69mm ride
height plus 50mm should be enough.

But note, this is all theory - I've never played with a Monster's
suspension and I'm open to someone pointing out a logic fault.

Sounds like a plan

I'll be quite understanding

JL
(and don't think I'll even try to keep up with you on the Raptor if
you're on the Spada, I care way too much about not crashing at the
moment to try and stay in sight of you on that thing)

 

Glen wrote:

Number 5 isn't alive ?

JL
No more J5 ?

 

Or, just to complicate things, a variable "rising-rate" (yeah, its an
odd looking linkage setup)...

Ummm - I probably didn't explain that well enough, I guestimated the
linkage ratio from the specced shocktravel/wheeltravel numbers (about
2.2:1), then used that ratio on the 25mm shock length difference. The
comes out at about 55mm less ride height, with 14mm more travel (not
allowing for the rising rate linkage).

worst case, the 748 shock will be 31mm shorter overall when fully
compressed than the monster shock, which (ignoring the rising rate)
could mean the wheel would end up 69mm closer to the seat/subframe.
Having thought it through further, I expect the rising rate thing will
actually allow the 748 shock to work with the available ride height
adjustment... Which is cool

Yeah, I haven't either - yet

Actually, I've just noticed the MotoGP telecast starts at 1:30pm (on
Fox) - looks like I won't be joining you...

big

 

Hmmmph ! didn't anyone tell you about video recorders ? Piker !

JL