Author Topic: Will K100 fork fit a K75?  (Read 975 times)

Offline ed3541

  • Motobrick Curious
  • Posts: 37
Will K100 fork fit a K75?
« on: December 10, 2018, 09:01:20 AM »
Hi,

The forks on my K75 are leaking and dinged - so probably will leak forever. I want to replace them. A guy on eBay says his forks from his 1986 K100 will fit my K75. The part numbers are different (from MaxBmw parts fiche). Does anybody know if these forks are compatible?

Thanx in advance to all knowledgeable Brick Bikers.
Ed
  • Boca Raton, Florida
  • '92 K75s '95 K75 '85 FYK100

Offline Laitch

  • Redline 7000
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Re: Will K100 fork fit a K75?
« Reply #1 on: December 10, 2018, 09:28:25 AM »
Measure a fork stanchion on each moto. In the 2V motos, 41.0mm is the Showa fork tube diameter on late model K75. 41.3mm is the Fichtel and Sachs/Brembo diameter on K100 and earlier K75. If the measurements don't match, you won't be able to swap stanchions and sliders.
  • Along the Ridley in Vermont.
  • 1995 K75 72,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline The Mighty Gryphon

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  • Posts: 4823
Re: Will K100 fork fit a K75?
« Reply #2 on: December 10, 2018, 09:34:28 AM »
I would check the specs to see if they're the same diameter so they will clamp up in the triple clamps.  Also would check the travel and overall length of the legs to make sure they don't mess up the suspension geometry.  Will your brake calipers work on the new forks? 

I would suspect that the damping and spring rates might be a bit different, but close enough to be usable.

Of course, you can always cut off the rear loop and replace your old forks with an upside down Suzuki front end.  Not only will you fix your leak problem, but you'll have a yuneek project bike.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue, '89 K100RS Special edition White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too
'89 K100RS SE

Offline ed3541

  • Motobrick Curious
  • Posts: 37
Re: Will K100 fork fit a K75?
« Reply #3 on: December 10, 2018, 09:41:05 AM »
Thanx Laitch.
 I can't measure the fork tube on the K100 forks because it's on eBay. But you gave me a clue when you called it a Fitchell and Sachs/Brembo fork. The eBay ad said it's a Brembo fork. So it doesn't look good - too bad 'cause it's rebuilt and only $75.00.

thanx,
Ed
  • Boca Raton, Florida
  • '92 K75s '95 K75 '85 FYK100

Offline Laitch

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Re: Will K100 fork fit a K75?
« Reply #4 on: December 10, 2018, 10:47:56 AM »
So it doesn't look good - too bad 'cause it's rebuilt and only $75.00.
Your '95 is the one with the damaged tubes? You can pretend the one on eBay isn't as good as it's made out to be, which is likely the case anyway.  Disappointment and resentment avoided.  :2thumbup:
  • Along the Ridley in Vermont.
  • 1995 K75 72,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline Martin

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  • Posts: 4002
Re: Will K100 fork fit a K75?
« Reply #5 on: December 10, 2018, 03:26:18 PM »
Pitted forks and rams can be restored either by a professional (expensive) or there are a couple of cheap methods. A work mate repaired his Honda forks which were badly pitted with a US sourced  solder designed for ram repairs. It was still working when I lost contact with him after five years. I will try and find out what it was and post it. There is also sites on pit repairs using various other methods including super glue. I would also invest in a pair f fork gaiters.
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline Martin

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  • Posts: 4002
Re: Will K100 fork fit a K75?
« Reply #6 on: December 10, 2018, 03:50:01 PM »
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Tags: k100 fork k75 fork