BMW K bikes (Bricks)

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1Back to top Go down   Fork seal leaking Empty Fork seal leaking on Fri Apr 19, 2019 4:08 am

audibob

audibob
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I recently changed a fork seal only to find the new one leaked, as did the second .

Everything was clean prior to fitting, I used cling film top of the leg to protect the new seal .

A seal driver tool was used to fit them.

Seal lube applied  but both leaked .

I then ordered a set from a different, well known uk  supplier, and this time all is good.

The seal from  the second set did feel more resistant when sliding it down the fork leg, 

 both sets were marked 41.4mm , perhaps my bike prefers blue seals rather than black ones.

Bob


__________________________________________________
Yamaha 90
Honda CD 175
Honda CB 360 
Triumph T 140V Bonneville
Triumph T150 Trident
Honda CB750 F1
Cz 175
Yamaha XS 750
R 100/7
R 80
K100 LT
K100 LT current bike
    

2Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Fri Apr 19, 2019 5:30 am

MartinW

MartinW
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There was a certain brand of seal that was renown for leaking, I can't remember the brand. I've had my current seals for nearly twenty years. I fill under the dust cap with heavy silicone grease which seems to have worked and lengthened their life. I change the grease every couple of years or more often in dusty conditions. Other Brickers have had success with a tool called Seal Mate which can clean out any crud under the lip. you can save money and make one out of the side of a plastic soft drink bottle.
Regards Martin.


__________________________________________________
K75s Hybrid
    

3Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Fri Apr 19, 2019 11:55 am

Laitch

Laitch
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@audibob wrote:I recently changed a fork seal only to find the new one leaked, as did the second . . . .  both sets were marked 41.4mm
Was it an OEM seal?



Last edited by Laitch on Fri Apr 19, 2019 5:47 pm; edited 1 time in total


__________________________________________________
1995 K75 81,000 miles
Fork seal leaking Usa-lo10
    

4Back to top Go down   Fork seal leaking Empty Fork seal leaking on Fri Apr 19, 2019 2:58 pm

audibob

audibob
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My tubes measure 41.4mm  

My leaky black seals came from Motorworks,  the blue seals are from Motobins.

Bob


__________________________________________________
Yamaha 90
Honda CD 175
Honda CB 360 
Triumph T 140V Bonneville
Triumph T150 Trident
Honda CB750 F1
Cz 175
Yamaha XS 750
R 100/7
R 80
K100 LT
K100 LT current bike
    

5Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Fri Apr 19, 2019 5:53 pm

Laitch

Laitch
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@audibob wrote:My tubes measure 41.4mm  
That seems to be measurement alright.


__________________________________________________
1995 K75 81,000 miles
Fork seal leaking Usa-lo10
    

6Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Mon Nov 16, 2020 8:01 am

Timos

Timos
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I've recently recommissioned an old K100.
I replaced the fork seals (from Motorworks), and cleaned out the forks as a matter of course.
They leaked straight away. So I got another pair of seals from Motorworks, this time they were ok for a hundred miles or so, and now they are both leaking again.
I've not had a BM before, and it seems a bit strange that the seals aren't held in with a circlip or anything!
Are you saying seals from a different supplier may solve the problem.
I will add, that the fork legs are in good condition.

    

7Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Mon Nov 16, 2020 8:08 am

RicK G

RicK G
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Measure the diameter of the forks they could be K75 which are 0.4mm smaller. As far as I know all the K100s had circlips.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

8Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Mon Nov 16, 2020 8:22 am

Timos

Timos
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@RicK G wrote:Measure the diameter of the forks they could be K75 which are 0.4mm smaller. As far as I know all the K100s had circlips.

My fork legs measure 41.4mm

    

9Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Mon Nov 16, 2020 8:34 am

mike d

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I believe the that the Fichtel & Sachs (K75C and K100 (not 4 valve) forks were 41.3mm diameter, and the later Showa forks K75 08/91 - 1996 were 41mm diameter.

Update: Looking at the MAXBMW parts list site, the snap ring to retain the seal was fitted from 09/87.

Mike



Last edited by mike d on Mon Nov 16, 2020 8:44 am; edited 1 time in total (Reason for editing : Added date when snap ring fitted.)

    

10Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Mon Nov 16, 2020 9:05 am

Timos

Timos
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@mike d wrote:I believe the that the Fichtel & Sachs (K75C and K100 (not 4 valve) forks were 41.3mm diameter, and the later Showa forks K75 08/91 - 1996 were 41mm diameter.

Update: Looking at the MAXBMW parts list site, the snap ring to retain the seal was fitted from 09/87.

Mike

Thanks Mike.

Mine is an 84 K100RS, so it appears to be correct.

I just need to know if there is a 'better' make of seals for it. In the UK.

Tim

    

11Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Mon Nov 16, 2020 9:25 am

Point-Seven-five

Point-Seven-five
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I use ATF in my forks. Cheaper than fork oil, and it has stuff that softens the seals a bit so they work better.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

12Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Mon Nov 16, 2020 10:12 am

mike d

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Were the seals from Motorworks OEM or pattern.

If pattern, I would look to buy genuine OEM seals.

Mike

    

13Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Mon Nov 16, 2020 2:20 pm

MartinW

MartinW
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If you pack heavy silicone grease between the seal and the dust cover it will prolong the life of the seals. Clean and change the grease every couple of years. It stops road crap from getting down to the lips of the seals and keeps them lubed. I last changed my seals over 20 years ago. Silicone grease packed under the boot of your rear master cylinder will also extend it's life. It'll stop the ingress of water and road scum.
Regards Martin.


__________________________________________________
K75s Hybrid
    

14Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Mon Nov 16, 2020 7:47 pm

RicK G

RicK G
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I have had very limited success with any of the aftermarket seals but genuine OEM have always been good. Check the fit of the two parts as 35 years can show some wear. If there is wear the only option is replacement. Also check for tiny rust pits on the moving surface as that will cut a seal to bits in no time flat.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

15Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Mon Nov 16, 2020 7:51 pm

Arlina

Arlina
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Forks used in K's ;


Fork seal leaking 91601482_648657772619577_5910241471675498496_n.jpg?_nc_cat=108&ccb=2&_nc_sid=730e14&_nc_ohc=vd2hhkgrvGgAX86-RcU&_nc_ht=scontent-ams4-1


__________________________________________________
Fork seal leaking Eu-log10  K1100RS/LT - R1200RT - R1100RS (RIP) - Cagiva SST 350 Ala Verde - K75LT project
    

16Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Tue Nov 17, 2020 4:53 am

Timos

Timos
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@RicK G wrote:I have had very limited success with any of the aftermarket seals but genuine OEM have always been good.
Check the fit of the two parts as 35 years can show some wear. If there is wear the only option is replacement. Also check for tiny rust pits on the moving surface as that will cut a seal to bits in no time flat.
I’ve ordered some OEM seals from Motobins.
The chrome on the legs is good, but I will check the slider to leg fit.
Thanks for the help.

    

17Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Tue Nov 17, 2020 10:34 am

Corkboy

Corkboy
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And gaiters always  fit gaiters (as you will have the forks apart anyway.

Otherwise, even with the OEM seals, they will eventually leak again. 

Since fitting gaiters, problem went away.


__________________________________________________
Regards,

Corkboy '87 K100RS SE (The black one - one of the two bikes I'm sorry I sold)
             '87 K100RS 0140995 (Gone)
             '97 K1100LT 0188024 (Gone)
             '08 K1200GT Wedge - but still a K
             '08 Transalp 700
    

18Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Tue Nov 17, 2020 10:38 am

Point-Seven-five

Point-Seven-five
Life time member
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@Corkboy wrote:And gaiters always  fit gaiters (as you will have the forks apart anyway.

Otherwise, even with the OEM seals, they will eventually leak again. 

Since fitting gaiters, problem went away.

+5 (the number of bricks I've put them on)  No leaks so far(knock on wood).

They also help in the BMW "look" of the bike by hiding those shiny fork stanchions.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

19Back to top Go down   Fork seal leaking Empty Re: Fork seal leaking on Wed Nov 18, 2020 4:23 am

Dai

Dai
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And do NOT use aftermarket ones. They won't last. Yes, they're half the price (or less) than OEM, but last less than a tenth of the time.


__________________________________________________
1983 K100 upgraded to K100RS spec, 1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

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