Help! Identify this Rear Shock

[TommyT]

Okay I have a new to me 1990 K75s with 45,000+ miles and there was no documentation about the bike. I been working on various things on the bike with a lot of help from the members here on Motobrick. Now I am working on the handling of the bike. I am trying to determine what rear shock is on the bike. I think it must be a older IKON shock, there is a marking of IKON 606 on the spring (glad there was a 0 and not another 6 there!). There is also an adjustment at the top, thumb dial with markings of 1 - 4 on it as you turn it.


Questions: Is this a IKON shock? What model? Is the 1-4 adjustment for damping? Is 1 the softest, 4 firm? Does anyone know the spring rate for the 606 spring (it is not on the IKON website). Is the IKON shock rebuildable?




Thanks ng

[TommyT]

Thanks Johnny, I fired off an email to IKON this AM, I could not see a shock that looked like the one I have in their product info. I will post what I find for the benefit of the knowledge base here on Motorbrick.


It seems to work well, especially now since I took a fair amount of preload off the spring. I am a lightweight guy and the bike seemed a bit twitchy on the crap roads we have here in upstate NY. Once I get a helper I will do the "sag" measuring I have seen here in Motorbrick posts to fine tune the spring preload.

[TommyT]

I got a nice reply from Roger from IKON, here is what he said:


The shock fitted is an early Ikon unit, sold at the time that the transition of[/size] [/size]Koni[/size] [/size]to[/size] [/size]Ikon[/size] [/size]was taking place. FYI, Koni (Holland)decided to get out of the motorcycle shock absorber business in the late 1990s (but still keep producing automotive shocks) and essentially sold the global motorcycle shock manufacturing rights and tooling to their long time Australian importers.[/i]

As the name 'Koni' was still being used, the Australian importers (now manufacturers) adopted the name Ikon - all of which is totally irrelevant to your question, but as an enthusiast, I thought you might be interested to know.

So, you have a '7614' series Ikon shock which is oil and nitrogen filled - the nitrogen gas helping to reduce oil foaming during hard use. The '606' spring fitted is a stiff spring whose spring rate is 41-62 N/mm or 229-345 Lbs/inch if you prefer. it measures 235mm long and was standard (Ikon) fitment for the BMW K75.

It's worth noting, although by now I'm sure you're well aware, that the single shock BMWs were very hard on their rear suspension due to their frame / swing arm design. The single shock chassis of that period wears out shocks far quicker than the twin shock chassis. Ikon addressed this with an overall larger shock for 1989-1995 models, the 3610-1009 priced at $600.00 (plus $25 shipping).

While all Ikon shocks are re-buildable, when it comes to the single shock K75s, excessive wear necessitating a replacement piston rod is commonplace (regardless of brand) which along with the usual seals, bushes etc. make rebuilding financially unviable. Better to go for a new shock in other words.

The 4 position dial, commonly referred to in both Ikon and Koni terminology as dial-a-ride, is an adjustable rebound damping system. Position 1 gives a fast rebound; position 4 a stiffer rebound action. Used in conjunction with the adjustable pre-load for the main spring, it enables the rider to tune the shock."

I later asked them to estimate the age of the shock, he estimated around 2000. He also said I could consider a light spring, [/size]part# 235-32/41/52 code 515, which is the same length but lighter wire (9mm instead of 9.5mm which you have now) and a spring rate of 32-52 N/mm or 180-292 Lbs/inch. For now I am going to continue to play with spring height before I would consider buying another spring.

[Laitch]

I got a nice reply from Roger from IKON, here is what he said:

Good followup, TommyT. The response to your query provides useful information.

[TommyT]

Johnny I guess you are saying time for a new shock?

[Elipten]

That is just a terrible way to have an accident.  Gives one something to think about.  I'll never look at a shock again the same way.


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[TommyT]

Well I too now worry about the momo rear shock design. Johnny you say "go with what works", who/what shocks would that be?


Any other know shock failures?

[Laitch]

That is just a terrible way to have an accident.

List the good ways and we'll pick from those, Elipten. :giggles

[Filmcamera]

I wonder what on earth could have happened to have the shock fall apart like that on a stretch of what looks like flat straight road.  I hope the rider as ok.  I just put in a used progressive shock on my K-bike but now I am thinking of upgrading to a brand new one at some point.