BMW K bikes (Bricks)

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1Back to top Go down   Fork stabilizer? Empty Fork stabilizer? Sat Nov 06, 2010 12:19 am

wikur

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Do I need this?
http://flatracer.com/#/stabilizers-european/4543509008
When riding my RS at fairly high speed in sweeping bends I do sometimes feel the front end flexing a bit.
The rubbermounted handlebars may have something to do with this.
Would a fork stabilizer improve handling?
What do you think?
Cheers,Wikur!

    

2Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Sat Nov 06, 2010 7:03 pm

Comberjohn

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Hi Wikur. I picked up a fork brace for my LT last winter on ebay for £1!
Did not think it would make any difference but put it on anyway. I found that the bike was more stable, especially on bumpy bends.
BMW must have thought it needed a fork brace as the later two piece front guards have one built in.
Make sure you get the right version. The post '86 forks are different. Thats how I got mine cheap. It didn't fit the '85 model belonging to the seller.

http://www.johnsdrivingschool.co
    

3Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Sat Nov 06, 2010 7:08 pm

Guest

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Your bike, if a 1988 RS model, might already have a stabiliser built in. It's the large, black metal bit that the two-piece mudguard attaches to. The picture of your bike in your avatar isn't clear enough to show it...but I have seen some later models delivered with the old style one-piece mudguard. In that case it would fit. German brand Telefix also make one. They are a bit fiddly to set up properly, can pinch the fork slider tops if overtightened, leading to chronic fork seal leakage, and alignment is critical, but they work a charm in reducing flex at an eager pace. I use them on my two Airheads with excellent results.

BTW, eliminating the rubber mounts does a hell of a lot in allowing you to 'feel' the road better. I ditched the rubber mounts on both of my Oilhead RS models and high speed turns could be made with such ease after the mod: they go where you point them from then on! What a concept. I have plans to swap a non-rubber mounted upper triple clamp from a K75 to my RS. Note that some increased engine vibration could be felt, the reason they rubber mounted them in the first place.

Check this catalogue image of my 11/86 RS...it shows the brace.
http://www.realoem.com/bmw/showparts.do?model=0503&mospid=51751&btnr=31_0368&hg=31&fg=10

(Redundant information alert! Just spotted a larger image of your bike in a previous post and you have the one-piece mudguard, so yes, the fork braces available would fit your model.)



Last edited by Two Wheels Better on Sat Nov 06, 2010 7:18 pm; edited 5 times in total (Reason for editing : Updated info.)

    

4Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Sun Nov 07, 2010 6:03 am

wikur

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Thanks for your thoughts!
I now remember that later K100`s have the brace integrated in the fender design.
I Have a slight wobbel when accelerating and slowing down,at around 50-60kph.I`ve heard of other K100 owners having the same experience.
It`s only notabel if you have a really loose grip of the handlebars.
I`ve tried different tires without improvment.
Maybe a brace would help?
Cheers,Wikur!

    

5Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Sun Nov 07, 2010 7:49 am

blaKey

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I also have the wobble, but I haven't done anything to fix it yet; I suspect it's my steering head bearings (being too old, lack of grease as well as needing adjusting).

I'm thinking that installing a brace would not help the wobble, but it would improve the handling through the corners by tightening-up the front end.


__________________________________________________
Neil
K100RS 1986 RED!

Dress for the ride and the potential slide.
    

6Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Mon Nov 08, 2010 2:32 am

wikur

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My "To do" list is getting longer!
It will include steeringhead bering check.
Thanks for the tip!
Cheers,Wikur!

    

7Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Mon Nov 08, 2010 7:17 am

sgmayhew

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[quote="Two Wheels Better"] I have seen some later models delivered with the old style one-piece mudguard. In that case it would fit. German brand Telefix also make one. They are a bit fiddly to set up properly, can pinch the fork slider tops if overtightened, leading to chronic fork seal leakage, and alignment is critical, but they work a charm in reducing flex at an eager pace.

Many thanks for that comment TWB. It explains why both of my recently replaced fork seals leak. I have evidently over-tightened the fork brace fitted by a PO!

    

8Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Mon Nov 08, 2010 8:19 am

Guest

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There's a procedure for being sure the fork brace, sliders and fork tubes, etc., are in alignment. It'd take a fair piece of writing to properly describe it. Suffice to say that you'll want all mounting screws loose (and coated with anti-seize) and then you'll bounce the front suspension whilst holding the front brake lever firmly. This will, in theory, put all of the bits into proper alignment and then you'll tighten all of the fasteners gradually and check the job again before torquing them all to final specification. There should be no binding of the suspension movement and the, what, 5 or 6mm screws only need a few ft/lbs of torque to be tight enough.

Experience often comes from mistakes made innocently.

    

9Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Fri Mar 11, 2011 12:08 pm

Oldgoat

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@Two Wheels Better wrote:
Experience often comes from mistakes made innocently.
Soo true! I usually had a much better understanding of something once I've screwed it up at least once, lol! Do you remember the name of the tool TWB, and while we're talking forks what is the difference between the standard k75 fork and the S model and are all the 75 forks the same diameter Showa units?
Thanks!

OG



Last edited by Oldgoat on Fri Mar 11, 2011 12:10 pm; edited 1 time in total (Reason for editing : update)

    

10Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Fri Mar 11, 2011 9:03 pm

Guest

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OG, I'm not clear on what you mean by 'the name of the tool'. I have looked at this post but don't what that refers to.

The basic difference is that on the 'S' forks the damping is done by one side and the rebound by the other. There will be a small 's' stamped into the top cap of the fork legs at the upper triple clamp where the oil filler hole is. Showas are used on early 90's and beyond, I think it was 8/91. These ('S' forks) I have retrofitted to my K100RS. I like them due to their firmness. They are much harder and have significantly shorter travel than the longer travel standard K100/RS/LT/RT forks. I use a lightweight 5W oil in them for some return to suppleness over road irregularities. There are actually several manufacturers of forks for the early K's. Marzocchi had a hand in it, as did Fichtel & Sachs, and another whose name escapes me at the mo'. 41mm is the standard diametre of the forks, but seal designs vary.

    

11Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Fri Mar 11, 2011 11:01 pm

Oldgoat

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My bad TWB. I thought there was mention of a fork alignment tool. I did find an article which talked about using a pane of glass to assist with fork alignment and I'm looking for more articles as well. Thanks for the info on the forks. The firmer/less travel with a lightweight oil sounds like the ticket though. Also looking into possible spring swaps and/or cartridge emulators. Any clue how difficult it would be to get a clean set of K75 forks?

    

12Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Sat Mar 12, 2011 1:03 am

Guest

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This bloke is up in Seattle and has a few secondhand bits for K bikes.

http://www.kbikeparts.com/#Front%20End

Send him an email and enquire. Another is

http://www.beemerboneyard.com/1sections.html

and then of course there's always good old eBay.

Progressive Suspension make a firmer spring for an '85 model, available through any local motorbike shop.

I use lightweight oil because I don't queue up at the buffet table much and the front end suits my riding style which is more sport than touring, although I've been known to cover a few kilometres at a time. It might not suit a bigger, heavier bloke, this light oil. The factory recommend 10W and some use 15W.

    

13Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Sat Mar 12, 2011 1:09 am

Oldgoat

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Thanks TWB! I'm only 150# myself and definitely come down on the sport side of the equation. That's why I thought your described setup might hit the sweet spot nicely.

    

14Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Sat Mar 12, 2011 1:14 am

Oldgoat

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These are suppose to be off a 95. Would they be the Showa?

Fork stabilizer? Screen11

    

15Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Sat Mar 12, 2011 1:31 am

Guest

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Yeah, those are likely Showa, and any decent suspension outfit could sweeten 'em up for you. There's an aftermarket cartridge available for them since that design was used on many Japanese sportsbikes from the era. You'd get the built-in fork brace too, which does wonders for the mighty K's stability, but with yours you'd have to buy and paint a matching two-piece mudguard, which I reckon looks heaps better anyway. Your brakes'll bolt right up, same axle diametre, and the bearings and handlebar clamps are the same, though you'd have to forego the rubber mounted clamps - no big deal on a sweetly tuned K100. Oh, and a good flat piece of glass laid across the fork tubes bolted into their triple clamps is an excellent way to determine if anything is out of alignment.

    

16Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Sat Mar 12, 2011 1:36 am

Oldgoat

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You read my mind TWB. Race Tech makes cartridge emulators for the Showa fork and I didn't know about having to loose the rubber clamps, but that would just be frosting on the cake! Cool

    

17Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Sat Mar 12, 2011 1:39 am

Oldgoat

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Do you know buddy if there would be a stamp or serial number on these somewhere so the guy could confirm they are Showa?
Thanks again for the help!



Last edited by Oldgoat on Sat Mar 12, 2011 1:41 am; edited 2 times in total (Reason for editing : update)

    

18Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Sat Mar 12, 2011 4:12 am

Guest

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Fork stabilizer? Showa10 is on the inside of the lower fork leg, either side, along with the usual circular BMW date stamp with the month of the year represented as a dot around the year of manufacture. If it's truly from a '95 it should be a Showa. It is showing the later-type of fork seal in the picture.

    

19Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Sat Mar 12, 2011 6:28 am

RicK G

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Yeah my 75 is 8/93 and has the showa forks they are much more stable that the usual K100 forks.

Around my place there are a couple of places that have high speed sweepers and when I ride the 100 with no brace the front brake usually slacks of a bit in the corners, the warp with the sideways force forces the pads of the disc, but on the 75 nothing at all is effected and when I apply the brake first time all is ok and I dont need to grab another handfull of front brake like on the 100.
Even the K1100 is better than the 100 but it has only a thin metal plate and not the more rigid cast alloy brace as on the 75.
It can be very disconcerting the first few times it happens untill you remember to check the front brake as you exit the sweepers.

    

20Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Sat Mar 12, 2011 11:35 am

Oldgoat

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Thanks for the great input guys! Very Happy I'm definitely going to owe you that bear TWB, and Freak thanks for the road report. Gotta luv this board!

OG



Last edited by Oldgoat on Sat Mar 12, 2011 2:23 pm; edited 2 times in total (Reason for editing : update)

    

21Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Tue Mar 22, 2011 6:46 pm

Oldgoat

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Forks should be here by the end of the week. Anyone have exprience with the RaceTech cartridge emulators and/or other after market springs?
Thanks for input guys!

OG

    

22Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Sat Nov 26, 2011 5:10 pm

robmack

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So, how does one tell the difference between a Fichtel Sachs / Showa / Marzocchi fork used by BMW on different K-bkes at different times? by looking for part numbers or manufacturer's marks?

The challenge I'm facing right now is the bike handles poorly; it is very twitchy in corners when leaned over. My goal is to understand what preload and sag adjustments I have available to me based on the type of fork currently installed on my bike. To achieve this goal, I feel that knowing what manufacturer of forks will lead me down the path to understanding which adjustments I have available and what after-market parts can be fitted to improve the situation.

My bike was originally a modified '88 K100RS with parts added from different K-bikes types and vintages over it's lifetime. I think the forks are from either a late model 16V K100 or K1100 (I know this because I have two-piece front fender with integrated fork brace, hydraulic splitter mounted on the brace, 3-spoke front and rear rims and 4-piston Brembo calipers on the front). According to the BMW K-bike mechanical history page at Anton Largiader's site , Marzocchi forks were used on the 4V K100RS, K1, and K1100RS/LT without changes. So, chances are I have Marzocchi forks.

Here is some additional information: At first blush, I appear have the following identifying fork parts on my bike: 31422310799 INNER TUBE, BLACK, LEFT - ABS and 31422310876 BRACKET. These are part numbers for the following models: K100RS (89V1) 03/89-06/92, K1 (89V1) 08/88-09/93, K1100RS (89V2) 04/92-12/96. What I don’t have on my bike (although these numbers are for the fiche for my model year) is: 31421454324 INNER TUBE, BLACK, RIGHT - D=41,4MM and 31421457900 STABILIZER, POLISHED. Would this confirm Marzocchi forks?

TIA.



Last edited by robmack on Sat Nov 26, 2011 8:51 pm; edited 2 times in total (Reason for editing : Added part number references for narrowing down fork type)


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

23Back to top Go down   Fork stabilizer? Empty Re: Fork stabilizer? Sun Nov 27, 2011 5:59 am

K75cster

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Nobody seems to have mentioned that removing the fork caps and loosening off the axle clamp allowing the bike to sink to the bottom then tighten the axle clamp and reinstall the fork caps. do we not do this when playing with the forks?? I've done it ever since I learnt to ride, my 650 Yammie and tr7rv triumph required it to avoid sticksion? so surely the unbraced forks would need it?? Guest has mentioned the bounce method, is there something damaging about bottoming out these forks??? Keith


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The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

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