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Triumph Bonneville T140v, 1977
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Discussion Starter · #1 ·
Hi All
Im trying to piece together the tank fixing arrangement on my 77 T140v.
The rear bolt is a bit of a mystery.
Is this diagram as shown correct, or should the rubber cushion sit under the tank and in the opposite way to that shown? I'm also not entirely sure what the purpose of the flat metal front bridge at the front of the tank is there for. It bolts to the tank on both sides, and straddles under the frame but doesn't physically seem to do anything except act as a deterrent to someone trying to nick the tank.
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Part #2 is attached to the frame cupped side out and stays on the frame when the tank is removed. Two U shaped rubber pads support the tank underneath. They fit snugly over the tube of the frame and often stay tucked into the tank. The strap underneath the tank is for preventing vibration from shaking the tank and causing welds to break. At least that’s my understanding. Hope this helps.
 

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The sequence for parts 7, 8 and 9 as shown in your drawing is correct. Not shown are parts 4, 5 and 6 which are the mounting bolt, washer and distance tube. The head of the bolt (4) fits into an "eye" welded to the frame, followed by the washer (5), the distance tube (6), the tank itself, the mounting rubber (7), washer (8) and nut (9).
 

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Hi,
not entirely sure what the purpose of the flat metal front bridge at the front of the tank is there for. It bolts to the tank on both sides, and straddles under the frame but doesn't physically seem to do anything
Stops the two sides of the tank being pushed apart. BSA/Triumph were a bit stingy with the tank metal thickness, '71 OIF didn't have the "bridge" and, between the weight of a full tank, possibly with a tank bag on it, tanks could crack at the front in the middle. :(

Btw, if the "bridge" scratching the tank paint would bother you, consider using the studs, nuts and rubber spacers used '70-'74 on everything except the OIF, rather than the bolts listed for the OIF? Not only will the listed parts space the "bridge" away from the tank, the studs specifically replaced pre-'70 bolts to stop owners accidentally screwing the bolts through tank bottoms. :rolleyes: The holes in the "bridge" only need to be enlarged to 3/8" ID. (y)

Hth.

Regards,
 

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Hi Bonnie Lad, The tank center mount is all original from new how it came from factory.
The bolt is special. Grease it very well with water proof grease. Factory didn’t grease. It can/will rust & be very hard to remove. The cup washer over rubber was cup down from factory.
The weld bead can be quite thick. Recently I needed 3 spacer washers one side, 2 on the other. This cars I needed longer bolts.
On gas tank strap mine & the other few I’ve worked on the strap was hitting on weld bead, putting strap in a bind.
I put split lock washer on bolt, flat washer. Then strap, another flat washer (thicker or stack 2 as needed) for a spacer to keep strap from contacting weld. Covered 36k miles like this so far.
Depending on your bolt length, how many washers you need you may need different bolt.

Be very careful on bolt!! It must never bottom in threads. It must have at least enough threads into tank as thick as a regular nut is. Trial fit all this finger tight & figure best length. Take your time.
5/16-24 thread should you need new bolt. Mine I was able to use original bolt. Again grease the threads! Bolt will rust in!
Here’s some photos. Sorry I don’t have photo of spacer tube on phone.
Don
 

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Hi,
gas tank strap
Be very careful on bolt!! It must never bottom in threads.
consider using the studs, nuts and rubber spacers used '70-'74 on everything except the OIF,
For clarity, these parts are: 21-1883 Stud (2 off):-


... 82-5228 Rubber spacer (4 off):-


... 82-3814 Cup washer (2 off):-


... 14-1302 Nut (2 off 5/16"UNF self-locking):-


Be very careful on bolt!! It must never bottom in threads. It must have at least enough threads into tank as thick as a regular nut is. Trial fit all this finger tight & figure best length.
Risking stating the obvious, note the 21-1883 Stud has different lengths of thread at each end and the unthreaded middle is a larger diameter than the thread; specifically the short threaded end is for screwing into the tank; by definition, the stud's larger central diameter prevents the thread being screwed through the bottom of the tank. (y)

strap mine & the other few I’ve worked on the strap was hitting on weld bead, putting strap in a bind.
I put split lock washer on bolt, flat washer. Then strap, another flat washer (thicker or stack 2 as needed) for a spacer to keep strap from contacting weld.
Depending on your bolt length, how many washers you need you may need different bolt.
As "used '70-'74 on everything except the OIF", studs screwed into tank, the Rubber spacers are 1/4" thick so one fitted over each stud before the strap's fitted will space the strap clear of any weld bead on the tank. (y)

The tank strap holes will need to be enlarged to fit over the unthreaded part of each stud, which is 3/8" OD. Again risking stating the obvious, the tank halves will spread apart 'til both bolts or studs contact the outer edges of both strap holes. If you know a machinist or have access to more machining facilities than an electric DIY drill and bits, if the studs' actual OD can be measured and the strap holes enlarged to give only 2~3 thou. clearance, this will prevent the tank halves spreading much before the studs contact the holes' outer edges. (y)

Fit tank strap over studs, a second Rubber washer, a Cup washer and a nut on each stud; the hole in a Cup washer is 5/16" ID so the nut can only be tightened on the stud 'til it's tight. Then done. :)

Other nice things about the "used '70-'74 on everything except the OIF" bits:-

. Studs and nuts can be tightened as you fit. (y) No "Trial fit", "finger tight", "figure best", etc.

. Riding, worst-case a bolt drops out, all the spacer and other washers are gone too, nothing stopping the tank halves being pushed further apart. (n) Otoh, a nut comes off a stud, worst-case the Cup washer goes missing - the Rubber spacers are a tight fit on the studs. Certainly the stud doesn't go missing, the tank halves can't be pushed any further apart.

. If you need to remove the tank any time, the studs remain in the tank. Note the very end of the stud's longer thread is a reduced diameter? Means, if the end of the stud is paced on a hard surface, the thread won't be damaged, the studs prevent damage to the tank paint over most of the underside of the tank. (y)

:confused: No idea why bolts were used to secure the strap to OIF tanks, when Meriden had already specifically moved away from using them because owners screwing bolts through tank bottoms had been a problem for years. All I can think is: the OIF were designed at Umberslade Hall; when the tank cracking problem appeared, Umberslade were tasked with finding the fix, whoever specified the bits wasn't aware Meriden had better parts. By this time, there wasn't any love lost between Meriden, Small Heath (BSA) and Umberslade - I believe it was Meriden staff who referred to Umberslade as "Mecca" because (said with a Midlands accent), "They always mekka a balls-up of everything." :sneaky:

Hth.

Regards,
 

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Hi
The 85 on Harris bikes were fitted with a special plastic spacer (97-1931), I believe the main reason for this was because the Harris tank was not de-seamed. These spacers I have also used to hold the strap away from the paint on MeridenT140 tanks.
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Triumph Bonneville T140v, 1977
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Discussion Starter · #8 ·
Part #2 is attached to the frame cupped side out and stays on the frame when the tank is removed. Two U shaped rubber pads support the tank underneath. They fit snugly over the tube of the frame and often stay tucked into the tank. The strap underneath the tank is for preventing vibration from shaking the tank and causing welds to break. At least that’s my understanding. Hope this helps.
Hi Bonnie Lad, The tank center mount is all original from new how it came from factory.
The bolt is special. Grease it very well with water proof grease. Factory didn’t grease. It can/will rust & be very hard to remove. The cup washer over rubber was cup down from factory.
The weld bead can be quite thick. Recently I needed 3 spacer washers one side, 2 on the other. This cars I needed longer bolts.
On gas tank strap mine & the other few I’ve worked on the strap was hitting on weld bead, putting strap in a bind.
I put split lock washer on bolt, flat washer. Then strap, another flat washer (thicker or stack 2 as needed) for a spacer to keep strap from contacting weld. Covered 36k miles like this so far.
Depending on your bolt length, how many washers you need you may need different bolt.

Be very careful on bolt!! It must never bottom in threads. It must have at least enough threads into tank as thick as a regular nut is. Trial fit all this finger tight & figure best length. Take your time.
5/16-24 thread should you need new bolt. Mine I was able to use original bolt. Again grease the threads! Bolt will rust in!
Here’s some photos. Sorry I don’t have photo of spacer tube on phone.
Don
Thankfully the nut on mine came off easily and the bolt wasn't rusted. I can see what you mean if it is rusted. There is very little to stop the bolt from turning. And if it did, I have no idea how the nut could be removed....!
 

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There is very little to stop the bolt from turning. And if it did, I have no idea how the nut could be removed....!
Remove the anti vibration bar at the front, disconnect the fuel hoses Lift the seat, place thin protection at the front of the tank to save the paint, wiggle the tank a little forward then take a long thin drift and feed it under the tank from the back until it touches the bots, hit the drift with a hammer forcing thebolt along its retaining slot. Wiggle the tank further forward and knock the bolt further forward. Keep repeating this sequence and if you are lucky there is enough slack for the bolt to pop out of its retaining slot. If you don’t make it, you might get a little extra wiggle room by removing the to yoke.
Regards
Peg
 
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