The BSA A7-A10 Forum

Technical => Frame => Topic started by: SteveM on 30.06. 2011 15:10

Title: Tank wih central bolt
Post by: SteveM on 30.06. 2011 15:10
Hi guys,
My Goldstar tank has the central bolt fitting and has the 2 bolts at the front for what I think is called a transverse strap which is supposed to act as a steady at the front of the tank. I understand that the later A10 tank was the same.
I do not have that strap.
I was hoping someone could show me a photo and description of this strap and how it fits, in what I have seen, it does not seem to be attached to the frame so not sure how it steadies the tank.
Also, if the correct straps are not available, has anyone made one? Also the nut size of the bolt?
Thanks for any info.

Cheers
Steve
RGS Replica


 
Title: Re: Tank wih central bolt
Post by: MG on 30.06. 2011 16:15
Hi Steve!

The intention of the strap is to hold the two tank halves together. I have however made a slightly different one that will also pull the tank down on the frame tube and thus take a bit of strain off the central bolt.
I've posted a pic of it here some time ago (on page 2):
http://www.a7a10.net/forum/index.php/topic,2628.20.html (http://www.a7a10.net/forum/index.php/topic,2628.20.html)

The nuts are 5/16 x26 TPI.

Here's the original strap:
http://cgi.ebay.co.uk/GOLDSTAR-B31-33-A7-10-petrol-tank-support-strap-76-8085-/310327798734?pt=UK_Motorcycle_Parts&hash=item4840fa6bce (http://cgi.ebay.co.uk/GOLDSTAR-B31-33-A7-10-petrol-tank-support-strap-76-8085-/310327798734?pt=UK_Motorcycle_Parts&hash=item4840fa6bce)

Cheers, Markus
Title: Re: Tank wih central bolt
Post by: alanp on 30.06. 2011 16:28
Steve, as Markus has shown, the strap is a simple shape just to hold the two halves of the tank from oscillating to and fro due to vibration and causing fatigue spilts in the tank.
Don't be surprised if a plain straight strap contacts the frame since this will depend a lot on how thick the rubber is that you have mounted the tank onto the top tube. Don't worry about having to notch the strap to clear the frame if you are happy with the location of the tank.
Title: Re: Tank wih central bolt
Post by: RichardL on 30.06. 2011 16:55
For my 2-1/2 gal. tank, the landings for the strap occur in the exact line of the the lower hole in the tank-bumper holder below the horizontal member. Therefore, the strap passes through that hole. I don't know if that is normal, but it worked for me. I fabricated the stap from leftover tubing I used to make front fender stays. Having the round tubing through the round hole in the bumper holder improved the clearance between the two and looks like an intended fit. I don't have a picture right now, but I can take one tonight.

Markus, is your strap isolated by rubber grommeting? I think the idea of the rubber isolator in the center hole must be to reduce the amount of small-excursion vibration that is transferred to the tank, which could stress the seams. Though, you've probabaly put thousands of miles on your bike(s) without such problem.

Richard L.  

P.S. If you were quick, you caught me leaving the "p" off of "passes" in the second sentence. One of those typos that could go down in lore.    
Title: Re: Tank wih central bolt
Post by: Topdad on 30.06. 2011 17:09
Hi Steve , as per the other guys comments but i also use a couple of rubber bushes just to soften everything up vibes wise. I found that the tops cut off car tyre valves are perfect and I just pick up an handful everytime I go in right diameter for the bolts as well. I use the same on my seat bracket where it attaches to the frame at the rear and i've not lost a nut from there since . hope that is of help regards bob.
Title: Re: Tank wih central bolt
Post by: MG on 30.06. 2011 17:10
Hi Richard!

No, the strap is not that sophisticated, you are over-estimating my inventive talent.  *lol*
It is just made a bit wider to reach back below the anti-roll bracket on the frame. There is a small bit of rubber between the bracket and the strap, and when the latter is tightened, it will pull the tank down slightly, compressing the rubber wrapped around the frame tube and fixing the tank to the frame in the front, thus taking the strain off the centre bolt. The stainless bracket is acting like some sort of leaf spring,
Using grommets is a nice idea though, but so far I have had no problems and no noticeable vibration in the tank.
Title: Re: Tank wih central bolt
Post by: RichardL on 30.06. 2011 20:11
Just remembered: Everything old is new again. Here are my photos from a previous thread. A bit embarrassed for the dust and knicks.

http://www.a7a10.net/forum/index.php/topic,2628.msg17177.html#msg17177

Richard L.
Title: Re: Tank wih central bolt
Post by: SteveM on 30.06. 2011 20:51
Thanks everyone for this very useful info, very much appreciated. Will make and install a bracket. 

Cheers
Steve
Title: Re: Tank wih central bolt
Post by: trevinoz on 01.07. 2011 05:59
Funny things, these straps.
Some are straight and some have 2 double sets in them to clear that bracket.
I custom make them to suit each bike as the centres are all different due to the tanks having been pulled apart for repairs with slight dimensional differences when reassembled.

  Trev.
Title: Re: Tank wih central bolt
Post by: SteveM on 01.07. 2011 14:35
Hey Guys,
After all the feedback, I made and installed a bracket last evening, looks much better and safer. Again, thanks for the advice.

Cheers
Steve