Author Topic: Indian petrol tank  (Read 1874 times)

Online Roger (Doomtrainbarx)

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Re: Indian petrol tank
« Reply #30 on: 21.05. 2021 15:29 »
My Indian tank on my SR fits ok, but does anybody know what size/thread the two front tie bar studs are ?- I just can't find any nuts to fit !!
The studs are approx 8 mm dia. but neither metric or 5/16 bsf/unf nuts seem to fit - any thoughts please?
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Online Rex

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Re: Indian petrol tank
« Reply #31 on: 21.05. 2021 15:36 »
BSCy?

Online Roger (Doomtrainbarx)

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Re: Indian petrol tank
« Reply #32 on: 21.05. 2021 17:58 »
I'm afraid "BSCy" means nothing to me ?
1962 Super Rocket
2003 Kawasaki Z1000
1987 Kawasaki ZL1000 Eliminator
1989 Harley FXRS (Turbo)
1978 Triumph T140 Bonneville

Online Rex

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Re: Indian petrol tank
« Reply #33 on: 21.05. 2021 18:19 »
Cycle thread, as was. Google  "5/16 BSCy" and you should see a selection of suppliers. Nooky's Nuts are very good, I find.
Before you do that try and find another 5/16  nut (not Whit or BSF!) on your bike and see if it fits the studs.

Online Greybeard

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Re: Indian petrol tank
« Reply #34 on: 21.05. 2021 23:22 »
Google says:

BSC (British Standard Cycle) Thread.
This fine thread profile was formulated for, and is well suited to cycle and motorcycle applications. Its fine pitch, allows high torque settings, and resists the tendancy to loosen under vibration, the larger core diameter also gives greater shear strength. Most people think that all cycle threads are 26 tpi pitch. Whilst this is true of all the most popular sizes from 1/4" to 3/4" diameter, other pitches were also used

Offline Swarfcut

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Re: Indian petrol tank
« Reply #35 on: 22.05. 2021 08:18 »
     An original nut from a front engine mounting plate/crankcase through  stud is worth a try.  This will be cycle thread. However as the tank is an Indian repro,  no guarantee as it's unlikely that  the thread on the tank  stud is actually cycle thread.

   The other slim chance possible is that the  Indian thread is  simply a poor attempt at a cycle thread and careful fettling with a die (more unbudgeted expense) may resolve matters. This original nut should fit easily on an original OEM tank fixed stud.

   Literature Section of the Forum has a Nut and Bolt Chart (thanks to Musky) which cross references BSA  Part Nos with thread sizes, bolt and stud lengths and appropriate nut sizes.

 Swarfy.

Online Triton Thrasher

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Re: Indian petrol tank
« Reply #36 on: 22.05. 2021 09:48 »
BSCy?

I think you have a job for a mm and threads per inch thread gauge.


Offline RDfella

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Re: Indian petrol tank
« Reply #37 on: 22.05. 2021 11:59 »
Roger, when you say the threads 'are around M8' of course they could be 5/16" (as you are aware). But if an M8 nut doesn't fit, could it be you're trying the wrong pitch? Most metric threads in use are coarse pitch, but many motorcycles use a finer pitch. The standard M8 pitch is 1.25mm, but could well be 1.0mm on a motorcycle, or even .75mm. I find the range of pitches on metric annoying - as many as four on some diameters. I've always thought the best compromise was BSF/BSW.
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Online KiwiGF

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Re: Indian petrol tank
« Reply #38 on: 22.05. 2021 12:35 »
My Indian tank on my SR fits ok, but does anybody know what size/thread the two front tie bar studs are ?- I just can't find any nuts to fit !!
The studs are approx 8 mm dia. but neither metric or 5/16 bsf/unf nuts seem to fit - any thoughts please?

The two most used tools I have for working on old brit bikes are a thread guage (mm/tpi) and a vernier 😏, I think you need a thread guage.

I like to keep to the original bolts etc but it's not easy, my B44 has a mixture of bsc, bsf, ba, unc and unf on the various engine cases as oem, plus some metric bolts bodged in by previous owners  *problem*

The A10 is simpler, generally using bsc and whitworth with the occasional oddball thread like bsf (particularly on the lucas components).

I think it unlikely the indian tank has bsc, its more likely to be unf or unc.
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Offline Colsbeeza

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Re: Indian petrol tank
« Reply #39 on: 22.05. 2021 13:06 »
Roger,
I have an Indian tank, but don't know who made it. I bought it from a local motorcycle parts dealer.
The threads are definitely 5/16" BSCy. I had not fitted a strap, and the threads were rusty. I cleaned them up a few days ago and some new 5/16" BSCy nuts fitted perfectly. Hopefully yours is the same.
Col
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Online groily

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Re: Indian petrol tank
« Reply #40 on: 22.05. 2021 13:11 »

The threads are definitely 5/16" BSCy. I had not fitted a strap, and the threads were rusty. I cleaned them up a few days ago and some new 5/16" BSCy nuts fitted perfectly.


Same here. Straight on, no problems with the one I had on mine either.
Bill

Online Roger (Doomtrainbarx)

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Re: Indian petrol tank
« Reply #41 on: 22.05. 2021 15:42 »
Well, I've tried all the suggestions using nuts from other parts of the bike and all 5/16 nuts of any thread will not even start - nor 8mm - the stud diameter is 8.2 mm so it seems I need a m9 nut or the imperial equivalent which would be a very unusual size !!
So to recap : 5/16 or m8 - too small- won't even start
                    3/8 or m10 - too big.
Still scratching my head.
1962 Super Rocket
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Online Bsareg

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Re: Indian petrol tank
« Reply #42 on: 22.05. 2021 16:34 »
Is it a coarse thread like whit or UNC? The core of these threads are smaller dia because of the deeper thread, cycle or BSF might not start due to the thicker core dia.
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Online groily

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Re: Indian petrol tank
« Reply #43 on: 22.05. 2021 16:59 »
Is or was the tank chromed in part or whole? If so, are there traces on the threads? Might need a die (or a nut with a slot cut across one flat) running up the threads?
If the threads are fine / fine-ish, than it can only really be BSC at 26tpi (as it's meant to be), possibly BSF at 22tpi, or UNF at 24tpi, outside chance M8 x 1.25 or 1mm. They're too slim for 9mm. BSW or UNC would have been a bad choice for them, for being too coarse with too thin a minor diameter, so I doubt it is either of them  . . . but you never know!
I'll stick my **** on the block and say I think that, because  the design of these things has been pretty much standardised now among the various tin-bashers out there, it'll be BSC in need of a clean-up, but hey, could be wrong of course!
Bill

Online Roger (Doomtrainbarx)

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Re: Indian petrol tank
« Reply #44 on: 22.05. 2021 17:24 »
It looks to be a fine thread and I think Groily might be onto something.
The tank is chrome/red so if there is a chrome build up plus a bit of red overspray, that might explain the "oversize" diameter.
Thanks guys - I shall investigate further - if it ever stops raining !!
1962 Super Rocket
2003 Kawasaki Z1000
1987 Kawasaki ZL1000 Eliminator
1989 Harley FXRS (Turbo)
1978 Triumph T140 Bonneville