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1Back to top Go down   K75S fork component arrangement Empty K75S fork component arrangement on Mon Dec 28, 2015 7:42 am

Gaz

Gaz
Life time member
Life time member
It's time to change the seals in my K75 with the S type forks and I thought I would ask if anyone has a definitive answer on the correct arrangement of the springs and spacers in these forks.

I have read a lot of the threads on the forum about forks and have identified my forks as having the same components as those in the photo in Inge's post number 2 in this thread.

There are two white spacers of different lengths, one short spring and another longer spring that appears to be progressively wound. The photo below is the arrangement that I found when I bought the bike and is how I re-installed them at the initial clean up of the forks.

K75S fork component arrangement Image36

Any information based on factory literature will be appreciated as there are lots of opinions out there and also lots of conflicting info in various after market publications.

Also would it actually make any difference to the performance of the forks if the order of assembly was not as per the factory set up?

Thanks


__________________________________________________
Gaz
1990 K75 6427509; 1987 R80G/S PD 6292136; 2010 G650GS ZW13381; 95 K1100LT 0232224
    

2Back to top Go down   K75S fork component arrangement Empty Re: K75S fork component arrangement on Mon Dec 28, 2015 8:48 am

Inge K.

Inge K.
VIP
VIP
Normally progressive springs should be mounted with the thight coils up to reduce unsprung weight.

But the mounting instructions for the S fork says:
First the progressive spring with the thight coils down, then the short spring followed by the long spacer and the short spacer on the top.


__________________________________________________
Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

3Back to top Go down   K75S fork component arrangement Empty Re: K75S fork component arrangement on Mon Dec 28, 2015 11:37 am

robmack

robmack
Life time member
Life time member
The S fork spring arrangement appears to be combining a progressive spring with a straight wound spring in a stacked spring design. Stacked springs usually utilise straight wound springs and the normal arrangement for a stacked spring design is longer spring, shorter spring, preload spacers (arranged from the bottom of the fork towards the top). First, it's unusual to mix progressive wound with a straight wound spring in a stacked arrangement; it's further unusual to have two preload spacers (why BMW?). A stacked spring arrangement will lower the overall spring rate of both springs.  

Follow Inge's advice in arranging the parts of the fork.  When you assemble the fork, you might want to introduce a washer between the springs to minimise them breaking at their meeting point and scraping against the stanchion in use, which increases stiction and causes oil contamination.

When you assemble the fork, measure the dynamic sag of the bike and adjust the length of the preload spacer to give 35mm of sag.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

4Back to top Go down   K75S fork component arrangement Empty Re: K75S fork component arrangement on Mon Dec 28, 2015 4:30 pm

Gaz

Gaz
Life time member
Life time member
Thanks for the prompt responses guys, much appreciated.


__________________________________________________
Gaz
1990 K75 6427509; 1987 R80G/S PD 6292136; 2010 G650GS ZW13381; 95 K1100LT 0232224
    

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