The New And Improved Unofficial R65 Forum V2

Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: MikeFossl on February 20, 2015, 03:03:13 PM

Title: Forkseal
Post by: MikeFossl on February 20, 2015, 03:03:13 PM

I'm having trouble getting a replacement.  I ordered a new set from Canada Motorcycle and received a set of BikeMaster Seals PN: P40FORK455046 which are 38.5 x 48 x 7 mm.

The seal that I pulled off my bike is a 36 x 46 mm (QKWA 36 46 7.3 / 8.8 VGF 01).

Does anyone know any cross reference parts that will work?

Thanks,  Mike

Title: Re: Forkseal
Post by: nhmaf on February 20, 2015, 03:33:08 PM

I'd contact a BMW dealer - sounds like you got the fork seals that might fit the later model monolever airhead, but not the twinshock frame model - what year is your motorcycle?  If it is a twinshock (79-85) model, it should be BMW part # 31421232655.
http://www.maxbmwmotorcycles.com/fiche/DiagramsMain.aspx?vid=51897&rnd=04282014

Title: Re: Forkseal
Post by: Bob_Roller on February 20, 2015, 04:29:28 PM

You have the dimensions for the seal, any auto parts stores in your area, that aren't the chain type, a real auto parts store .
Or possibly a local seal supplier .

Title: Re: Forkseal
Post by: MikeFossl on February 20, 2015, 07:36:40 PM

Can someone tell me the R65 fork tube diameter?  Mine is 36 mm but now I'm wondering whether it's something non-standard.

Title: Re: Forkseal
Post by: Barry on February 21, 2015, 05:02:03 AM

Stanchion OD is definitely 36mm for the early models 78 -84.

I think 85 - on models are 38mm.

The question is what is the manufacturing date of your bike ?  36mm stanchions suggest maybe it's an 84 build model.

Any generic fork seal of the correct size should fit. They are usually widely available and listed by ID and OD dimensions.

Title: Re: Forkseal
Post by: MikeFossl on February 22, 2015, 09:33:16 AM

So it looks like the fitment guide for some aftermarket fork seals are off by a year for the r65.  When I specify 1984 I get 38.6 mm seals but when I specify 1983 the correct 36 mm seals are suggested.

This is consistent across a number of websites and at least two seal manufacturers.

Live and learn.

Title: Re: Forkseal
Post by: montmil on February 22, 2015, 11:50:54 AM

Mike, It would appear that you are a victim of the "One Size Fits All" school of parts suppliers.

I so often see Airhead parts offered on-line with the note saying, "Fits all R-model BMWs".  Balogna, Baloney!

As Grandpa learned me, Trust, but verify.

Title: Re: Forkseal
Post by: Tony Smith on February 22, 2015, 03:28:27 PM

Quote

Mike, It would appear that you are a victim of the "One Size Fits All" school of parts suppliers.

I so often see Airhead parts offered on-line with the note saying, "Fits all R-model BMWs".  Balogna, Baloney!

 

To which I might add that I have only ever found two brands of seal that correctly fit the BMWs I've owned - OEM and Ariette (sold by moto bins).
 
For the difference in price - buy genuine. The research I conducted (unwillingly and at my own expense) years ago tells me that .5mm difference can mean either so much stiction the forks don't work, or fork fluid blowing past the seal over large bumps.

Forgetting my own experience I bought some "Pyramid Parts" seals last year - the oil seal is fine, but the dust seal was so tight I eventually cut it away, not such a big deal as I run gaiters, but yet again proof that thhe only seals known to fit are OEM.