The New And Improved Unofficial R65 Forum V2

Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Ben_Carufel on January 20, 2011, 08:12:27 PM

Title: Fuel Tank Mounting
Post by: Ben_Carufel on January 20, 2011, 08:12:27 PM
At some point one of the previous owners of my 1979 R65 buggered with the fuel tank and didn't get it mounted on tightly...that, or the rubber pads it rests on have "compressed" and the u-bolt that holds the back of the tank has loosened as a result.

In looking at the ETK, it seems like there's 3 "isolators" for the tank. One is the long, somewhat cylindrical rubber piece at the front (#4 in the below diagram). It also appears that there are two near the back of the tank, close to the u-bolt. Are these #2 and #3 in the diagram?

I'm planning to order the parts (and a petcock rebuild kit or new petcock), pull the tank, polish and clearcoat it using two part clearcoat, install new emblems and the new/rebuilt petcock, install a new overflow drain hose, and reinstall the tank using the new mounting rubbers.

Thanks for your help in nailing the parts down!

(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fwww.chartersventures.com%2Fcar%2Fbencoupe%2Fr65%2Fr65tankdiagram.jpg&hash=f60c80f4375f1f4dfc31d4adfee5219b0a2021c7)
Title: Re: Fuel Tank Mounting
Post by: Rob Valdez 79 R65 on January 20, 2011, 08:26:45 PM
Yes - you have identified all three cushions.

The front one is no problem, but I've found the glue can fail on one or both of the rear pads.  I lost one when I didn't realize it had fallen off when I removed the tank, once, a long time ago.

I doubt compression will be a problem with these OEM pieces.
Also, make sure the rubber on the u-strap (bail) is in good shape.  Being rubber, it can only deteriorate, although mine is doing just fine.
Title: Re: Fuel Tank Mounting
Post by: Ben_Carufel on January 20, 2011, 08:28:05 PM
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Yes - you have identified all three cushions.

The front one is no problem, but I've found the glue can fail on one or both of the rear pads.  I lost one when I didn't realize it had fallen off when I removed the tank, once, a long time ago.

I doubt compression will be a problem with these OEM pieces.
Also, make sure the rubber on the u-strap (bail) is in good shape.  Being rubber, it can only deteriorate, although mine is doing just fine.

Damn, I didn't realize that bail was supposed to be covered with a piece of rubber. I didn't find the bail or the rubber piece in ETK. Any idea if they're in there, Rob? Is the rubber piece just fuel hose slid over the bail?
Title: Re: Fuel Tank Mounting
Post by: Rob Valdez 79 R65 on January 20, 2011, 08:29:33 PM
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Damn, I didn't realize that bail was supposed to be rubber coated. I didn't find the bail or the rubber piece in ETK. Any idea if they're in there, Rob?  
#13.  They call it a "bracket".   ::)

It is not "rubber coated", it is a thick piece of rubber with a hole in the center, which the bail goes through.
When you do the final install of the tank, that rubber just rolls underneath the main frame tube.

It looks like the bail & rubber come as once piece.

Find a really trashed tank, and you can probably pick it up for a song.
Title: Re: Fuel Tank Mounting
Post by: Rob Valdez 79 R65 on January 20, 2011, 08:35:06 PM
If the rubber on the bail is missing, the whole thing will feel wrong.
Title: Re: Fuel Tank Mounting
Post by: Bill Conquest on January 20, 2011, 10:07:05 PM
I'm having the same problem on my '79..i'll order the two back parts, same as Ben, but the rubber is also missing on the bail & there's nothing available locally..any other solutions?
thanks, bill conquest
Title: Re: Fuel Tank Mounting
Post by: Rob Valdez 79 R65 on January 20, 2011, 10:43:52 PM
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the rubber is also missing on the bail & there's nothing available locally..any other solutions?
Take the bail to the hardware store to see what they have.  When I get home I can measure the outside diameter for you, if you want.
Title: Re: Fuel Tank Mounting
Post by: Ben_Carufel on January 20, 2011, 11:02:35 PM
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I'm having the same problem on my '79..i'll order the two back parts, same as Ben, but the rubber is also missing on the bail & there's nothing available locally..any other solutions?
thanks, bill conquest

Hey, Bill, I'll be in Kauai next week. There's a new resort near poipu beach that I'm photographing.
Title: Re: Fuel Tank Mounting
Post by: Rob Valdez 79 R65 on January 21, 2011, 12:30:00 AM
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There's a new resort near poipu beach that I'm photographing.  
Wow - you get paid to go to Hawaii and take pictures?  I'm jealous!  :)
Title: Re: Fuel Tank Mounting
Post by: Ben_Carufel on January 21, 2011, 03:43:26 PM
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Quote
There's a new resort near poipu beach that I'm photographing.  
Wow - you get paid to go to Hawaii and take pictures?  I'm jealous!  :)

Yep, that's the "glamorous" description of the job!
Title: Re: Fuel Tank Mounting
Post by: Rob Valdez 79 R65 on January 21, 2011, 04:39:22 PM
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the rubber is also missing on the bail & there's nothing available locally..any other solutions?
Take the bail to the hardware store to see what they have.  When I get home I can measure the outside diameter for you, if you want.
Well - I am back at work, again, and I forgot to go out to the garage last night or this morning.  Perhaps it was the very very cold temps that made me forget.
But it will be the weekend soon!  I promise not to disappoint! :)
Title: Re: Fuel Tank Mounting
Post by: Bill Conquest on January 21, 2011, 09:25:52 PM
Thanks alot, Rob..i'm hoping to improvise something. Hey Ben - give me a call if you get time.. maybe we can get together for a beer!
bill conquest 808-635 - 2975
Title: Re: Fuel Tank Mounting
Post by: chewy4x4 on January 21, 2011, 09:39:38 PM
Hey would 3/4 of a tube of pipe insulation replace the #2 and #3 supports? I was thinking just zip tie it to the tube.
Title: Re: Fuel Tank Mounting
Post by: Rob Valdez 79 R65 on January 21, 2011, 10:15:12 PM
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Hey would 3/4 of a tube of pipe insulation replace the #2 and #3 supports? I was thinking just zip tie it to the tube.
Yeah - I've seen all kinds of cheesy improvisation supporting the tank.  Nothing beats OEM, as far as I am concerned - especially as they are still easily available.  Did you know you can special order ANY BMW part at your local BMW auto dealer?

I'll shut up, now.  :-X
Title: Re: Fuel Tank Mounting
Post by: Julio A. on January 22, 2011, 04:52:51 AM
I don't have those side mounted rubber thingys on my tank.
I did not even know they were supposed to have those.  ;D

No wonder they are wobbly.
Title: Re: Fuel Tank Mounting
Post by: Rob Valdez 79 R65 on January 22, 2011, 04:56:52 PM
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I don't have those side mounted rubber thingys on my tank.
I did not even know they were supposed to have those.  ;D

No wonder they are wobbly.
Without some kind of padding, it is possible for the frame, or something else to rub against the tank, and possibly wear a hole through it!
Title: Re: Fuel Tank Mounting
Post by: Julio A. on January 22, 2011, 07:41:37 PM
Where do these mounts fit? on the frame or on the tank itself?
Title: Re: Fuel Tank Mounting
Post by: Bob_Roller on January 22, 2011, 07:44:19 PM
They are glued to the tank itself .

If you take the tank off, you can probably still see the glue where they were originally installed .

I think they were installed at the aft end of the tank, they sit on the frame tubes .
Title: Re: Fuel Tank Mounting
Post by: Rob Valdez 79 R65 on January 22, 2011, 10:49:04 PM
20mm wide, 15mm thick.

I wonder why so many bikes have them missing?
Title: Re: Fuel Tank Mounting
Post by: Teo on January 23, 2011, 01:08:06 PM
I put a 2"-3" piced fuel line on the bale.  Works fine.
Title: Re: Fuel Tank Mounting
Post by: chewy4x4 on January 24, 2011, 01:37:55 PM
Yeah Yeah Rob. I agree. What kind of adhesive would you use to put them back on?
Title: Re: Fuel Tank Mounting
Post by: Rob Valdez 79 R65 on January 24, 2011, 02:14:43 PM
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Yeah Yeah Rob. I agree. What kind of adhesive would you use to put them back on?
I haven't found it, yet.  My left one is still in place from the factory.  The right one I have to keep track of whenever I remove the tank.
Title: Re: Fuel Tank Mounting
Post by: Barry on January 24, 2011, 02:35:58 PM
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What kind of adhesive would you use to put them back on?

Stuck mine back on with ordinary impact adhesive .. did the job.
Title: Re: Fuel Tank Mounting
Post by: Bob_Roller on January 25, 2011, 09:48:25 AM
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Yeah Yeah Rob. I agree. What kind of adhesive would you use to put them back on?

An automotive exterior trim adhesive should work, usually found at the chain type auto parts store .