Help with bolt size please

[Split_Pin]

I am in the middle of trying to replace the fuel tank strap on the 75.

 

Having finally got it into position, the bolts are now too short.

 

I saved an old bolt from the original strap. It has a 13mm head but I need to find out how big the thread is. All it says on the head is '10.9'.

 

Can anyone help? This job has been a total piss-ant and I am at my wit's end.

[DodgeRover]

13mm head on a modern is usually M8 size, not sure what the thread pitch will be though.

[Split_Pin]

Here is the thread if that helps?

[Guest Hooli]

10.9 is the strength, proves it's metric as they didn't do that on imperial bolts.

Pop down a fasteners/nut n bolt shop with it. It'll take seconds to find the thread by winding a nut on to it. Unless you've got a tap n die set to check it with.

[cobblers]

That's not a fine pitch thread, so if that's a 13mm head then it'll be m8x1 m8x1.25 thread. Just your standard m8 bolt.

[sierraman]

Pop down tool station, looks a M8 coarse thread to me. You could always rig something up from some threaded bar and some nuts and washers.

[twosmoke300]

If you lack a vernier to check thread sizes just use an open end spanner . Obviously not that accurate but you are usually only looking for 6,8,10, 12 mm anyway

[twosmoke300]

On the actually threaded bit obviously

[twosmoke300]

That's not a fine pitch thread, so if that's a 13mm head then it'll be m8x1 thread. Just your standard m8 bolt.

Isn’t m8 std 1.25 pitch ?

[cobblers]

You're right. I was thinking m6 for some reason.

[twosmoke300]

Unless it’s an early jap bike with m6x0.9 jic threads ! Bastards

[castros_bro]

Would you put a photo of ye bolt next to a metric ruler, or even a 2p,  bit then the borg that is Autoshite will tell you the size + thread + the middle name of the designer.

[cobblers]

Unless it’s an early jap bike with m6x0.9 jic threads ! Bastards

Jesus, so when replacing a JIC screw cos you rounded the head off trying to get it off with a PZ/PH screwdriver, the replacement fastener goes about three turns before stripping. 

[Eddie Honda]

Here's a fresh looking thread to eyeball.

 

Guess M8 X 1.25 x 50/60mm long?

 

https://rimmerbros.com/Item--i-wyp100220

 

72p a pop!

[Split_Pin]

Cheers guys, I have the bolts that came with it but the strap is about 100mm too short on the leading edge. It fits round the tank fine though.

 

It was a TOTAL BASTARD to get in, even with the exhaust lowered (hacksawed off the rubbers) so I would rather just get a mega long bolt, some nuts to take up the gap and just fuck it all back together.

[Eddie Honda]

What's trapped above it stopping it being closer?

[Split_Pin]

Nothing, the strap doesnt reach up round far enough. Just about to set fire to it tbh.

[Mally]

That would be easy where you are working.

 

Longer bolts or threaded bar, will be fine, save the matches for the next problem.

[Split_Pin]

I can get 80 mm m8 bolts from Screwfix, thread looks about the same pitch. Should be long enough I think.

[Mally]

Thread will be the same, could get threaded bar and nuts as well just in case. Not expensive.

[colnerov]

 Hi, If it's a standard fuel tank, standard strap, standard bolts and it doesn't fit without longer bolts then something is wrong somewhere causing it to not sit correctly. You need to investigate otherwise it could move on the road and make a noise or end up rupturing the tank.  I'm not adverse to modifying things but this sounds like something is wrong.

 

 Colin

[steveo3002]

I can get 80 mm m8 bolts from Screwfix, thread looks about the same pitch. Should be long enough I think.

 

doubt its a 10.9 from them

 

check its seated properly the old bolt should still fit

[Split_Pin]

Hi, If it's a standard fuel tank, standard strap, standard bolts and it doesn't fit without longer bolts then something is wrong somewhere causing it to not sit correctly. You need to investigate otherwise it could move on the road and make a noise or end up rupturing the tank. I'm not adverse to modifying things but this sounds like something is wrong.

 

Colin

There are recesses on the base of the tank for the strap to sit in and everything there is positioned correctly. I can measure against the old one as it literally crumbled to pieces when I removed it.

 

The 2 forward fastenings dont reach the hole on the chassis by about 20 cm.

[Mally]

doubt its a 10.9 from them

 

 

 

Screwfix bolts 8.8.

Threaded Bar maybe not.

[twosmoke300]

Thread bar is usually 4.8 low tensile . There is black bar which can be high tensile but not always .

8.8 will be fine for a tank strap

[Split_Pin]

Thanks for the help guys, nowehere else on the internetwas in any way useful!

[sierraman]

Wouldn't have thought it would need to be 8.8 or 10.9 hardened. Regular threaded bar with some loctite on it should suffice. So long as its tight it should be fine. A nyloc nut on the base should hold it nicely.

[Squire_Dawson]

M8, m8.

[Des]

Is there a longer bolt you could borrow from elsewhere on the car, you could wind it in to bed in the strap and then quickly swap over the short one.

[Split_Pin]

I had thought of that but I dont get know the car well enough to know where to find one.

 

The other reason I want to use longer bokts is so that the strap is not excessively tight. The tank is only plastic and I dont want to crack it.