BMW K bikes (Bricks)

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1Back to top Go down   Fork diameter Empty Fork diameter on Sat Oct 05, 2019 9:09 am

K100uk

K100uk
active member
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Just wondering if someone could help me find a new set of fork pre adjusters and what the actual internal thread diameter is? Having trouble locating a nice set....
Does anyone have some links handy? 1984 k100 standard
Many thanks

    

2Back to top Go down   Fork diameter Empty Re: Fork diameter on Sun Oct 06, 2019 10:14 am

Snod Blatter

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Do you mean preload adjusters to go in the top of the stanchion? Because if so I've got some bad news for you, there isn't any thread - the tops are held in place by a really stupid circular clip thing instead.


__________________________________________________
1989 K100RS SE ABS 8v  VIN: 0149214
Others: 1.5 x Honda CBX250RS-E, '94 CB250, '95 TRX850, '16 Z250SL
http://justbikethings.blogspot.co.uk/
    

3Back to top Go down   Fork diameter Empty Re: Fork diameter on Sun Oct 06, 2019 10:56 am

K100uk

K100uk
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Thanks for that,bit of bumber but glad I asked.i assume bmw still stock this part? is it likely to try and take my eye out or stuburn to remove?

    

4Back to top Go down   Fork diameter Empty Re: Fork diameter on Sun Oct 06, 2019 11:34 am

Laitch

Laitch
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@K100uk wrote:i assume bmw still stock this part? is it likely to try and take my eye out or stuburn to remove?
If you have one and the filler screw in the center of it isn't permanently seized, then you shouldn't need to buy a new one. Replacing the circlip that holds it down might be a good move.

It takes leverage to remove it. The cap assembly must be pushed down far enough and held while the clip in the groove above it is removed using a screwdriver or pick. The cap is unlikely to be launched to the ceiling but if it's being pushed down by hand with a socket on an extension and things go sideways, parts or tools can jump at you. Some convenient leverage is all that's needed but brute force will do it, too, especially if you're blessed with a third hand. It's a wise precaution to wear safety glasses anytime around parts under pressure, and keep your mouth closed. Laughing

Here's a photo demonstrating the effective use of a gear puller for the task.

Fork diameter Fork_c10


__________________________________________________
1995 K75 81,000 miles
Fork diameter Usa-lo10
    

5Back to top Go down   Fork diameter Empty Re: Fork diameter on Sun Oct 06, 2019 12:33 pm

Snod Blatter

Snod Blatter
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I found it only somewhat difficult by using a hex bit in the bolt and a screwdriver to lever it down, using the top yoke:
Fork diameter CVwhVHB
Quite what BMW had against the usual threaded setup I can't imagine. Too easy perhaps?


__________________________________________________
1989 K100RS SE ABS 8v  VIN: 0149214
Others: 1.5 x Honda CBX250RS-E, '94 CB250, '95 TRX850, '16 Z250SL
http://justbikethings.blogspot.co.uk/
    

6Back to top Go down   Fork diameter Empty Re: Fork diameter on Sun Oct 06, 2019 12:52 pm

K100uk

K100uk
active member
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Thanks for the great info and pics very helpful, my bike looks like it might have a slightly different setup, maybe it was changed by previous owner I'm not sure.
Fork diameter Img_2010

    

7Back to top Go down   Fork diameter Empty Re: Fork diameter on Sun Oct 06, 2019 1:00 pm

Laitch

Laitch
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@K100uk wrote:Thanks for the great info and pics very helpful, my bike looks like it might have a slightly different setup, . . .
Only slightly. You'll still be using leverage to remove the snap ring. There's no escape. Smile


__________________________________________________
1995 K75 81,000 miles
Fork diameter Usa-lo10
    

8Back to top Go down   Fork diameter Empty Re: Fork diameter on Sun Oct 06, 2019 1:05 pm

K100uk

K100uk
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Ok thanks alot think I will have a look at a parts diagram just to understand the assembly better Smile

    

9Back to top Go down   Fork diameter Empty Re: Fork diameter on Sun Oct 06, 2019 3:46 pm

Laitch

Laitch
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@K100uk wrote:Ok thanks alot think I will have a look at a parts diagram just to understand the assembly better Smile
There are three types of fork assemblies used on the classic 2V Bricks. Although the plug with the hex bolt in its center (called the spring retainer in BMW parts fiches) might differ in appearance slightly from model to model, all of them are held in place by spring pressure pushing them against a snap ring that is installed into a groove along the inside perimeter of the fork tube. Fork assemblies have sometimes been swapped among models so do your best to identify what you have by comparing parts to fiche diagrams.

In the meantime, look at this extract from an instruction manual found in the Tech Section of this site.


__________________________________________________
1995 K75 81,000 miles
Fork diameter Usa-lo10
    

10Back to top Go down   Fork diameter Empty Re: Fork diameter on Sun Oct 06, 2019 4:32 pm

volador

volador
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@Laitch wrote:There are three types of fork assemblies used on the classic 2V Bricks...

Showa or Fichtel or Sachs


__________________________________________________
1984 K100RS  1991 K100RS  Reap The Wild Wind... Ever Commute Is An Adventure
    

11Back to top Go down   Fork diameter Empty Re: Fork diameter on Sun Oct 06, 2019 5:20 pm

Laitch

Laitch
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@volador wrote:
@Laitch wrote:There are three types of fork assemblies used on the classic 2V Bricks...
Showa or Fichtel or Sachs
Showa, Brembo, Fichtel&Sachs.
Fork diameter Screen85


__________________________________________________
1995 K75 81,000 miles
Fork diameter Usa-lo10
    

12Back to top Go down   Fork diameter Empty Re: Fork diameter on Sun Oct 06, 2019 5:44 pm

Laitch

Laitch
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@volador wrote:Showa or Fichtel or Sachs
Your webinar ticket has been given to a recent immigrant moto mechanic from Honduras who indicated mashed peas sounded good to her. The squid ink has been sold off to recoup costs. Your refund will be in gift cards to be sent to you by one of five Seattle area motorcycle dealerships as soon as they reopen.


__________________________________________________
1995 K75 81,000 miles
Fork diameter Usa-lo10
    

13Back to top Go down   Fork diameter Empty Re: Fork diameter on Mon Oct 14, 2019 5:24 pm

jbt

jbt
Silver member
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@Laitch wrote:

Showa, Brembo, Fichtel&Sachs.
Fork diameter Screen85
There's a slight difference in the early K100 forks.
The top of the slider, where sits the gasket ring,  is wider before 09/1985 than after.
One should not notice but...it makes impossible to mount Tarozzi or Telefix fork braces on it. Yet they mention K100 from 83 on the box , they only fit post-09/85 models.
Don't ask how I know that...

    

14Back to top Go down   Fork diameter Empty Re: Fork diameter on Thu Nov 19, 2020 10:48 am

cycleman

cycleman
Silver member
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I have an early 86 K100RT that has Brembo front forks, with the single piece fiberlgass front fender. From a chart somewhere I see these where meant to be on a K75, but seeing as I bought the bike used and previous ownership is deceased, no way to try and track back the reason why.

In installing a Tarozzi Fork Brace I noticed that the clamps that fit on the lower portion of the fork tube fit fine, but that as noticed in the previous post the piece that goes between the the two clamps is too wide. As a result you can only put the center piece in with force and then the holes for the 4 top screws don't all line up. It also throws out the location of the front axle in the lower clamps. It is not much too wide, just a very small amount, less than a 1/4 of a mm. I haven't measured the distance between the clamps but will do so before I fix it.

My solution is going to be to tighten everything up, bolts on tree, and front axle. Just as they are without the fork brace. Install the brace clamps on the forks, tighten them up, set the top piece down between the clamps to see how much needs to be filed off the ends of the cross piece so that it will slide into its spot. Then I will have to file, test fit and file some more the bolt holes until I can get just a bit of slack so they can move a bit before the bolts are tightened up.

Good looking fork brace and with all the possible front ends on the early K series, be they 75/100's, pretty hard to get an exact fit out of the box. The fork brace is marked for a 86 and earlier K100.

    

15Back to top Go down   Fork diameter Empty Re: Fork diameter on Thu Nov 26, 2020 2:37 pm

Matthew-Brisbane

Matthew-Brisbane
Life time member
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@Laitch wrote:
@K100uk wrote:i assume bmw still stock this part? is it likely to try and take my eye out or stuburn to remove?
If you have one and the filler screw in the center of it isn't permanently seized, then you shouldn't need to buy a new one. Replacing the circlip that holds it down might be a good move.

It takes leverage to remove it. The cap assembly must be pushed down far enough and held while the clip in the groove above it is removed using a screwdriver or pick. The cap is unlikely to be launched to the ceiling but if it's being pushed down by hand with a socket on an extension and things go sideways, parts or tools can jump at you. Some convenient leverage is all that's needed but brute force will do it, too, especially if you're blessed with a third hand. It's a wise precaution to wear safety glasses anytime around parts under pressure, and keep your mouth closed. Laughing

Here's a photo demonstrating the effective use of a gear puller for the task.

Fork diameter Fork_c10

Hands up for thoes of us that have launched  part of the forks into the air once the clip is removed


__________________________________________________
1986 K100 RS Motorsport
#### K100 RS Project 
2011 R1200 GS
    

16Back to top Go down   Fork diameter Empty Re: Fork diameter on Thu Nov 26, 2020 3:17 pm

chris846

chris846
Life time member
Life time member
Just a tip with fitting a fork brace. Allow a bit more time and install it with the bike on a jack and with the fork tops removed. That'll allow you to keep moving the forks through their full travel as you add the wheel and spindle and progressively tighten eveything up. Just a little bit of stiction can ruin the front end handling and be a huge backwards step, despite fitting a brace.
Only common sense and you might have been doing that already  Fork diameter 112350


__________________________________________________
Sometimes I'm not really Suzi Quatro.
    

17Back to top Go down   Fork diameter Empty Re: Fork diameter on Thu Nov 26, 2020 4:03 pm

92KK 84WW Olaf

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@jbt wrote:
@Laitch wrote:

Showa, Brembo, Fichtel&Sachs.
Fork diameter Screen85
There's a slight difference in the early K100 forks.
The top of the slider, where sits the gasket ring,  is wider before 09/1985 than after.
One should not notice but...it makes impossible to mount Tarozzi or Telefix fork braces on it. Yet they mention K100 from 83 on the box , they only fit post-09/85 models.
Don't ask how I know that...

That's interesting.....my 83 K100RS, 84 K100RT and 92 K100LT should be the same...they ain't. Looking at my 83 RS and 84 RT they look quite similar but the LT definitely not the same and its original.


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 37,190 miles
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles.
    

18Back to top Go down   Fork diameter Empty Re: Fork diameter on Fri Nov 27, 2020 9:34 am

Snod Blatter

Snod Blatter
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@92KK 84WW Olaf wrote:That's interesting.....my 83 K100RS, 84 K100RT and 92 K100LT should be the same...they ain't. Looking at my 83 RS and 84 RT they look quite similar but the LT definitely not the same and its original.
Yeah it's not quite right, Brembo took to making the F&S forks under licence at some point in the late 80s. My '89 K100RS had Brembo forks, the "S" variant.


__________________________________________________
1989 K100RS SE ABS 8v  VIN: 0149214
Others: 1.5 x Honda CBX250RS-E, '94 CB250, '95 TRX850, '16 Z250SL
http://justbikethings.blogspot.co.uk/
    

19Back to top Go down   Fork diameter Empty Re: Fork diameter on Tue Dec 01, 2020 10:56 am

cycleman

cycleman
Silver member
Silver member
With the fork brace I ended up filing the side ( of the pieces that attach to the fork leg ) where the center piece of the brace fits against these pieces, as the center piece was too wide and wouldn't fit between the fork tubes with the trees and wheel torqued in place. I then had to slightly enlarge the holes in the brace center piece, so that the heads of the bolts wouldn't bind and the bolt could get a straight run at the threads. The area between the bolt holes on the center piece and its edge, where too narrow to file it, so had to file the pieces that fit on the fork tube.

What I did was just create a bit of sideways slack in the fitting of the center piece so that it could move slightly and allow it to be tightened down. You still have to be careful on how tight you get all the bolts.

Too cold to ride up here but with everything tightened down, fork action up and down is good with no binding. I will know more in the spring. Likely a waste of money, but looks good on the naked bike with fork rubbers.

    

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