1993 K75S - REPLACMENT FORK SPRINGS

[GasStation]

I recently purchased a pair of Wilbers Promoto front fork springs. I want to install these but there is very little information in either the BMW shop manual, Haynes or Clymer.

Does anyone have any experience with this type job? Would you be willing to share some pointers? With reference to the microfiche picture below, if I replace the old OEM compression spring (part #8, I presume), am I looking at what amounts to the equivalent job of changing the fork oil with a swapping of compression fork springs? What about the spacer tubes, will that remain or will I end discarding?

[frankenduck]

I'd contact Wilbers' tech support to ask them if you need spacers and, if so, how long they should be.

[GasStation]

Frankenduck,

You've taken you K75 apart, what is involved with this job?

[frankenduck]

Frankenduck,

You've taken you K75 apart, what is involved with this job?

Some people do it on the bike but I think it's easier to just drop the forks and do it on the bench.  I always take clean apart and give them a good cleaning.  It's best to do them one at a time.

I don't know if I've ever done the later K75 forks but they're all fairly similar in terms of dis-assembly/re-assembly.

Some of the forks have a shallow headed bolt at the bottom holding the cartridge in there that is easy to strip the head of if you're not careful.

Off the top of my head:

Remove plastic cap.

Use a large crescent wrench to hold the metal fork cap and undo the filler plug.

Undo the drain plug and drain the fork.

Push the fork cap down and pick out the circlip that holds it in.

Slide the springs and whatever out of it - being careful to note that the order the parts come out.

Invert the fork, put one of the caliper mounts in a bench vise and carefully remove the bottom bolt to get the rest of it apart.

Clean everything and put it back together.

It's not rocket surgery.

[GasStation]

Thanks for the input Frankenduck, it is very much appreciated.

It is not my intention to drop the forks for a thorough cleaning at this point in time. The riding season in Canada just started and it is already too short.

I am a novice with the legacy K-bike and not familiar with the nose diving with brake application. I thought I might be getting excessive nose dive and thought the OEM compression springs may have outlived their useful life (20 years old).

I also read that there appears to be some confusion as to the correct amount of fork oil for the K75S with Showa fork tubes. I will be attentive to note how much oil comes out of each fork tube; mine should be 410ml or .41 litre. I purchase some synthetic 10W weight fork oil.

Once that is done, I wanted to swap compression springs for the progressive, that's it!  :2thumbup: