I am still new to bikes so maybe this is a simple question. I recently bought a 1984 K 100 as a project (I also have an '83 K100 as my regular bike)

The "new" bike had leaking fork seals. Replacement was easy, but when I put back in the yokes found that the two sides are different lengths. To easily slide the axle through I would need to lift one fork tube about 10mm higher in the upper yoke.

Should I simply compress one side to insert the axle with the two uppers level with top of upper yoke?

PS, the fork tubes are certainly in the same plane, just length difference.

Someone on here with BMW teles will tell you the likely cause and resolution. But in the meantime do not attempt to ride with one leg compressed as you suggest.

To be clear, that is not normal!

Are you sure they're the same type of fork? Are the markings on the inside near the mudguard the same on both?

Michael, you didn't miss a spacer when you were reassembling one leg?

I think you need to strip the forks. It's possible (but not the only explanation) that one is incorrectly assembled - if the damper rod isn't seated correctly in the bottom of the slider then the assembled fork will seem 'longer'.

The damper rods are retained by a single bolt which is accessed through the bottom end of the slider. Undo that bolt before you remove the spring - that'll stop the damper rod from turning.

chris846 wrote:I think you need to strip the forks.

Indubitably.

Michael's posts on this forum about his moto don't seem to indicate that the fork assembly has been thoroughly inspected, maintained with oil replacement, or checked after damage that might have occurred in accidents since he has owned it. It's conceivable that extension and compression are being effected by lack of fluid viscosity, sludge, broken or fatigued springs, and maybe bad bushings.

Disassembling of the fork legs, confirming correct assemblies, cleaning their tubes, inspecting the bushings, springs and other parts, then replacing what might be worn or damaged should be undertaken. After that, they could be measured.

A few more details!

I dismantled the forks, one at a time, and reassembled as I found them. The axle was tight on removal and required some force to remove but this was probably due to a little corrosion but I have since cleaned and oiled it.

No spacers that I found. The damper rods fastened easily to the single bolt at the bottom. Springs went back in with end pieces in place and correct amount of oil into each thoroughly cleaned assembly.

I will disassemble them again and compare the damper rod lengths.

Well, it was simple, but not what I expected.

Earlier I just replaced fork seals so had not touched the damper rods. Today I removed the forks again and found a definite mismatch in rod length so removed both dampers from the stanchions.

The damper assembly is held together by screwing the piston down the rod to achieve a length of 258 mm according to Haynes. One piston was loose, the other nearly falling off! Clearly the thread locking compound had failed.

So, no lost parts, nothing broken, but a 24 hour wait for the Locktite to set, then the fun of getting the damper with piston ring back in place

Good news then Michael.  

Meanwhile as the Loctite is setting you could do a run up to Sofala on one of the other bikes?  

TacKler wrote:Good news then Michael.  

Meanwhile as the Loctite is setting you could do a run up to Sofala on one of the other bikes?  

Ah yes, there are some members there this weekend? Never quite understood the post, started in 2017, and nothing in the calendar. Perhaps organised rides could be made a sticky to get attention?

Anyway, a long solo ride and no booked accommodation. Maybe next time.