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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Vespa no more on July 24, 2016, 12:45:29 AM
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Am in the process of installing progressive springs and fork seals to K100RT 1984
Do I remove the white spacer above the spring? Pic shows that both the original spacer and spring are the same length at progressive spring. I assume this is the case but wanted to check before proceeding.
Fork damper piston ring: groove - should this face towards the ground or the top of the piston. I know the manual says down but I am just checking (in case)
Am intending to swap RT forks with RS (stanchions not pitted) - all parts look the same.
Removing the seal: have not muscled it out for fear of damaging fork. Anyone got some advice? Manual says lever it out but it's pretty firmly installed.
Gators will be installed before reinstallation.
Any help greatly appreciated
Regards
Guy
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Do I remove the white spacer above the spring? Pic shows that both the original spacer and spring are the same length at progressive spring. I assume this is the case but wanted to check before proceeding.
Removing the seal: have not muscled it out for fear of damaging fork. Anyone got some advice? Manual says lever it out but it's pretty firmly installed.
I'd want the spacer in there. Was your fork top cap—the part with the filler screw plug—under a lot of tension when you removed retaining clip? If it wasn't, your spring may be severely fatigued. What's the Progressive part number?
Regarding the seal: this video—starting at 9:40—tells the story.
https://www.youtube.com/watch?v=vrmYJgcGX30#t=395
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i think you have posted this in the wrong section--maybe move it to the workshop to get more response.
i think the white spacer is not used--you wouldn't be able to install the top cap without a huge preload and possibly strip some threads.
The so-called progressive spring has 42 spring coils vs 34 of the oem, but 14 coils are wound very tight such that they will bind at the slightest load and thereby function as the solid spacer block. The wire and coil diameters appear identical, and the remaining 28 active coils are wound with a wider spacing to take up the same travel as the stock spring's 32 active coils--so theoretically it is 0.5% stiffer than stock, but only before and after sag measurements might show it...
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The so-called progressive spring has 42 spring coils vs 34 of the oem, but 14 coils are wound very tight such that they will bind at the slightest load and thereby function as the solid spacer block.
Thanks for your observation on that, kennybobby. Some riders have written of altering the spacer length to change the fork dynamics but with this setup as you've described it, that option isn't possible—even if it were practical in the first place.
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Thanks gentlemen.
Forks shown in the video are very similar to those on a Suzuki SV650 I did the seals on (bushes etc)
The rubber seal clip was not visible but on closer inspection it is buried in the middle of the top face of the rubber seal. It is not one that is pried out while in situ as shown the video.
Found out how to do it (see pics) without any damage to fork. The seal is in there tight but as it is not being reused damage to the rubber is not relevant.
Note the crap in the bottom of the fork (sorry about pic). This is from a fork that had recently had the oil replaced. Not critical but shows how much more effective compressed air is (as well as regular flushing).
http://www.k100-forum.com/t2064-progressive-springs
This links deals with fitting progressive springs... top spacer and plastic ends caps are removed - progressive springs are flat on the ends while the original ones are not (hence the end cap to create a flat surface). Have sent an email to Motobins to confirm this. If no update by me then this info is correct.
Probably need to replace fork damper piston plastic ring.
When trying to adjust hardness (ie air space) in the fork, can I suggest a large syringe - am constantly thinking of the inaccuracy of large measuring jugs because of fluid left on the walls of the container.
Pics:
the grot that builds up on the inside of the seal over time - see elsewhere for the DIY plastic bottle cleaning tool
How to lever the seal up - using putty knife and slot headed screw driver (might do well to grind the end nice and fine). A start is created by twisting the screwdriver. Eye protection recommended.
No damage to fork body
the putty knife (better than a paint scraper due to curved shape that will better match the curve of the fork)
Grot in the end of fork AFTER flushing with forks on bike.
Hope this helps
Regards
Guy
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Great pictures of your rebuild, thanks for sharing.
i had noticed the shiny spot on your fork tube in the original post, and now you have shown the top of the slider with the little worn spot where it was rubbing on the tube. The rubbing polished the tube and it can be rotated to a fresh surface, but the slider is fixed and will wear in that same location--will probably need a new slider in another 30 years... :hehehe
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Received the reply from Motobins that may clarify this matter
When replacing original springs with progressive springs:
remove large white spacer above spring and both plastic end caps.
It is suggested that when ordering parts: springs, damper piston rings, o-rings, drainage bolt crush washer, maybe upper and lower pinch bolts. Copper paste on reassembly.
While in there, consider the condition of steering head bearings and wheel bearing. Local bearing supplier will need serial number located on the bearing.
Regards
Guy
PS - Motobins reply:
The caps are removed and the spacers too – usually. Although as I said, some people experiment with the spacer, without and cut down!
Regards from Ross