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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Enfield on January 25, 2018, 01:46:00 PM

Title: Worn out fork springs??
Post by: Enfield on January 25, 2018, 01:46:00 PM
Hi. Just to be sure before I order new springs for my Brembo forks I want to ask if anything else can cause my front forks to bottom out ( like not going further down _ says clunk) than worn out springs - happens when I brake hard? It also feels quite terrible in corners. I changed seals and oil this summer - but they are still way too soft. They go halfway down when I sit on the bike - and I am only around 107 kgs… :lets-eat: .  There is no leaking or anything. And did fill the right amount of oil.
 If the springs are dead I plan to order progressive springs from Motoworks.
Regards
Christian
Title: Re: Worn out fork springs??
Post by: Enfield on January 25, 2018, 02:15:59 PM
I guess it is the springs.... but read somewhere something about adding more Oil???
Title: Re: Worn out fork springs??
Post by: Laitch on January 25, 2018, 02:21:36 PM
Quote from: Enfield on January 25, 2018, 01:46:00 PM
. . . And did fill the right amount of oil.
How much oil was the "right amount" and what was the weight of the oil—5W,7W, 10W, ATF or something else?
Title: Re: Worn out fork springs??
Post by: Enfield on January 25, 2018, 02:41:19 PM
Ahhh can’t remember - have to look in the haynes manual - took it from there. And it wa 10w for forks.
Chr


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Title: Re: Worn out fork springs??
Post by: Enfield on January 25, 2018, 03:02:53 PM
It was 360 ml . I followed the manual on Fichtel and Sachs - as I couldnt find any info regarding Brembo forks. Mine is an early 1984.


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Title: Re: Worn out fork springs??
Post by: Laitch on January 25, 2018, 03:09:11 PM
Quote from: Enfield on January 25, 2018, 02:41:19 PM
It was 360 ml . I followed the manual on Fichtel and Sachs - as I couldnt find any info regarding Brembo forks. Mine is an early 1984.
360ml for the K100RS. Sounds about right.

Did you disassemble the fork legs, clean the components then reassemble them and add the oil? You shouldn't add more than is specified for your bike in an attempt to cure the bottoming of the fork. You might be asking more from the 34 year old springs than they can bear. Riders were smaller way back in olden times.
 :giggles
Title: Re: Worn out fork springs??
Post by: Enfield on January 25, 2018, 03:14:00 PM
Yeah - did clean everything before assembling. Thanks for removing doubt about springs. I will order new progressive springs at Motoworks :2thumbup:
Title: Re: Worn out fork springs??
Post by: Enfield on February 26, 2018, 02:09:32 PM
Does this look right? New progressive spring from Motobin vs old spring..
(https://uploads.tapatalk-cdn.com/20180226/265ea711a3d34fe3ed0c6644e670b39d.jpg)
Regards
Christian


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Title: Re: Worn out fork springs??
Post by: Enfield on February 26, 2018, 02:20:52 PM
To me it looks Like I should drop both the plastic tube and the plastic “seats” as the new spring is perfect “ flat” in both ends?
(https://uploads.tapatalk-cdn.com/20180226/e476738f5670b7eedb599cdaddc474f6.jpg)


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Title: Re: Worn out fork springs??
Post by: Enfield on February 26, 2018, 02:31:15 PM
Found it[emoji56]
(https://uploads.tapatalk-cdn.com/20180226/90ca11aab396b8bf003fd70c5565785c.jpg)


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Title: Re: Worn out fork springs??
Post by: K1300S on February 26, 2018, 09:50:17 PM
the spacer is needed...but...its length will vary.  it is used to set suspension sag.  longer spacer equals less sag.  you need to assemble whole thing, measure sag, then take back apart to make spacer longer or shorter to get the sag you want.
Title: Re: Worn out fork springs??
Post by: Enfield on February 26, 2018, 11:34:11 PM
Quote from: mlytle on February 26, 2018, 09:50:17 PM
the spacer is needed...but...its length will vary.  it is used to set suspension sag.  longer spacer equals less sag.  you need to assemble whole thing, measure sag, then take back apart to make spacer longer or shorter to get the sag you want.
Thank you [emoji1303]
 As I am not exactly featherweight I Like the front forks without too much sag. But in order to assemble the whole thing without getting hurt I need to shorten it a bit 🤪
Regards
Christian


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Title: Re: Worn out fork springs??
Post by: Enfield on February 26, 2018, 11:44:51 PM
Had to google “sag” - am I correct in that it refers to how much the fork lower when I just sit on the K?
Regards
Christian


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Title: Re: Worn out fork springs??
Post by: K1300S on February 27, 2018, 08:10:30 PM
yes. it is the difference between the max extension of the forks and the extension with you on the bike in riding position.  there is a correct number for the bike...regardless of rider weight.  it places the suspension in right range to minimize bottoming out in either direction.
Title: Re: Worn out fork springs??
Post by: Enfield on February 27, 2018, 11:59:36 PM
Quote from: mlytle on February 27, 2018, 08:10:30 PM
yes. it is the difference between the max extension of the forks and the extension with you on the bike in riding position.  there is a correct number for the bike...regardless of rider weight.  it places the suspension in right range to minimize bottoming out in either direction.
Ok thank you [emoji1303].
 Will give it a go without the plastic tube.
Regards
Christian


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Title: Re: Worn out fork springs??
Post by: Enfield on March 03, 2018, 03:33:43 AM
Am I correct in that it it is possible to change the plastic tube - with the forks in place and Oil filled? Just by removing the top plug? Also possible to use the handlebar if leveragevis needed?
Regards
Christian
Title: Re: Worn out fork springs??
Post by: Inge K. on March 03, 2018, 05:32:51 AM
That's posibble.....it would be easier and more controllable if you get the handlebar out of the way and
using a small two legged bearing puller.
Title: Re: Worn out fork springs??
Post by: Enfield on March 03, 2018, 08:12:39 AM
Good point! My handlebar is also easy to remove - with no fairings etc.
Thanks
Christian