Ohlins spring

[<ABSDoug2@xxxxxxxxxxx>]

	Seen this on the net ...

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- -- Posted by MikeH on 2:06 am on Mar. 23, 2003

I fitted the Ohlins last weekend - quite simple and
straightforward. But I had a problem setting the sag on the rear
unit. Even with the hydraulic adjuster fully wound in to maximum,
it was sitting too low at the rear. A short ride of a few miles
confirmed there was a problem. The backend was too low and too
soft resulting in the RS understeering into bends and dropping
the rear end under acceleration. The bike felt unbalanced. It's
nothing to do with the rebound damping as increasing it firmed
the shock but doesn't alter the ride height.

I spoke to the Ohlins technician at Harris Performance, the UK
importers, and he agreed that it may need a stiffer spring (it
could also be a faulty shock). Very puzzling as I expected the
Ohlins to be firmer than the OEM BMW shocks ? Anyway, it's on its
way to Harris to be sorted.

I refitted the BMW shock to the rear with the Ohlins on the
front. Immediately sitting on the bike it felt right - a fair bit
firmer on the rear. I rode into the hills and the RS felt
perfect - it corners better than it's ever done. The front Ohlins
has made a significant improvement to the front end, and dialling
the rebound in was simple. It's very clear when you've got the
correct setting.

I just hope that the rear Ohlins will make further improvement
when they sought it out. I'll let you know the outcome when I get
it back.

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- -- Posted by MikeH on 2:25 pm on April 18, 2003

I've just got the rear Ohlins back from Harris and fitted it to
the bike. What an improvement ! - the bike feels totally balanced
now. Much better than the standard unit. Harris have fitted a
stiffer spring and reset the preload. The new spring rate is now
170 N/mm. compared to the standard spring for a BM-704, which is
160 N/mm, making the unit 6% stiffer. It doesn't sound a lot, but
it has made all the difference in the way that the bike handles.
It turns into bends really quick and tracks like it's on rails. I
was a little worried that rough surfaces might be a problem, but
the bike just glides over them - almost like being on smooth
tarmac! A sure sign that the suspension is now working well.

One curious point is that the sag measurements (with and without
rider) are now identical to the OEM BMW unit that I just taken
off, which means that the spring rates are indentical. It also
confirms that the standard Ohlins BM-704 is 6% softer than the
OEM shock, which begs the question as to why Ohlins would reduce
the spring rate from the standard setup ? Whatever the reason,
I'm glad that I had them alter the shock - it just didn't feel
right before. Now it's perfect !

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