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Discussion Starter #1
I've looked through a lot of the threads about the 'Tubular Nut' or 'Castle Nut' - that nut attached to the rear of the Clutch Basket that loosens off over time.

As it loosens, it can either give you the impression under hard acceleration that you've been 'kicked out of gear' (but in fact, if you quickly back off on the throttle, you find that you're in still in gear) or, as it worsens, you encounter the same symptoms of a 'slipping clutch'.

The Tubular Nut has 6 - lugs. So a tool with 6 -lugs would give you the greatest amount of torque while re-tightening the nut. (Besides, 4 - lug tools don't line up).

I found a 6-lug tool online which has an outside diameter of 2-5/8" inches.

So my question is this:

Has anyone actually measured the Tubular Nut? What are the Inside and Outside Diameters?
 

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When i did this last year I bought a 2-3/8" 4wd Lock Nut Socket from the local auto parts store. After about an hour with a grinder and file to get 2 tabs cleaned off and file down the other 2 it was ready to use. Worked perfectly.

Check this out.
starts at post 46 or so.
https://www.m109riders.com/forums/showthread.php?t=347636&page=2
 

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I've looked through a lot of the threads about the 'Tubular Nut' or 'Castle Nut' - that nut attached to the rear of the Clutch Basket that loosens off over time.

As it loosens, it can either give you the impression under hard acceleration that you've been 'kicked out of gear' (but in fact, if you quickly back off on the throttle, you find that you're in still in gear) or, as it worsens, you encounter the same symptoms of a 'slipping clutch'.

The Tubular Nut has 6 - lugs. So a tool with 6 -lugs would give you the greatest amount of torque while re-tightening the nut. (Besides, 4 - lug tools don't line up).

I found a 6-lug tool online which has an outside diameter of 2-5/8" inches.

So my question is this:

Has anyone actually measured the Tubular Nut? What are the Inside and Outside Diameters?
Neither of the symptoms you describe above apply to a tube nut problem in my experience.

Normally when you pull the clutch lever the end result is the push pin moving the pressure plate off the clutch stack, disengaging the clutch.

But when the tube nut becomes loose the basket and entire clutch stack are allowed to move outward with the pressure plate as well.

This results in you not being able to disengage the clutch, your clutch lever may feel totally normal but your clutch will not disengage.

Cannot see how the tube nut coming loose could cause the clutch to slip or kick the bike out of gear as you say above, the pressure plate will keep the stack tight so the symptom will be exactly opposite of that.

As Andy33 pointed out a 4x4 hub nut socket with 2 prongs ground off is a quick solution for a tool if you need one fast or cannot find the correct socket to fit the nut. Its not perfect but it will work.
 

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I've looked through a lot of the threads about the 'Tubular Nut' or 'Castle Nut' - that nut attached to the rear of the Clutch Basket that loosens off over time.

As it loosens, it can either give you the impression under hard acceleration that you've been 'kicked out of gear' (but in fact, if you quickly back off on the throttle, you find that you're in still in gear) or, as it worsens, you encounter the same symptoms of a 'slipping clutch'.

The Tubular Nut has 6 - lugs. So a tool with 6 -lugs would give you the greatest amount of torque while re-tightening the nut. (Besides, 4 - lug tools don't line up).

I found a 6-lug tool online which has an outside diameter of 2-5/8" inches.

So my question is this:

Has anyone actually measured the Tubular Nut? What are the Inside and Outside Diameters?
Brandon Bicasso just went over this in one his videos like a week ago jump to 4:33


As Andy33 pointed out a 4x4 hub nut socket with 2 prongs ground off is a quick solution for a tool if you need one fast or cannot find the correct socket to fit the nut. Its not perfect but it will work.
Yep and Brandon learned it from Joe jump to 7:02

 

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Discussion Starter #5
I really appreciate the link to the second video. I hadn't seen it before, and it's a great instructional video.

Thanks!

I am curious how people are securing the clutch basket in order to tighten the tubular nut, and what torque is required (Ft-lbs)?
 

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Discussion Starter #6 (Edited)
Neither of the symptoms you describe above apply to a tube nut problem in my experience.

Normally when you pull the clutch lever the end result is the push pin moving the pressure plate off the clutch stack, disengaging the clutch.

But when the tube nut becomes loose the basket and entire clutch stack are allowed to move outward with the pressure plate as well.

This results in you not being able to disengage the clutch, your clutch lever may feel totally normal but your clutch will not disengage.

Cannot see how the tube nut coming loose could cause the clutch to slip or kick the bike out of gear as you say above, the pressure plate will keep the stack tight so the symptom will be exactly opposite of that.

As Andy33 pointed out a 4x4 hub nut socket with 2 prongs ground off is a quick solution for a tool if you need one fast or cannot find the correct socket to fit the nut. Its not perfect but it will work.
Hi Stalker:

Thanks for your reply.

I disagree with you however. The bike does NOT jump out of gear. It gives you the impression that it has jumped out of gear.

Here's a description again of what happens:

Hard acceleration thru first gear, then shift to second gear and keep accelerating. Suddenly, there's a strong jolt or kick, and the power is briefly lost for a moment. It feels like the transmission has been kicked out of gear. To an observer driving alongside, they'd think that you missed a shift or something. But rolling the throttle back you discover that you're still in gear. Then you go, 'what the heck was that'?

I first started experiencing it about a year ago, and it was shortly after I did a clutch rebuild.

I ignored the problem at first because it only occurred during really hard acceleration. But the problem grew to where it began to feel as if the clutch was slipping. Tach RPMs weren't matching the power to the rear wheel. So I thought, 'how could the be clutch slipping if I just recently replaced all of the plates and springs'?

As it grew worse, I had no choice but to open the clutch again. I re-checked everything, and it all looked fine. Reassembled, adjusted the push pin, and clutch cable.

Same thing.

Now I was stumped. Then I did some reading on this site about the Tubular Nut.

I stripped it all down again and removed the clutch basket. I tried unsuccessfully at the time to find a socket tool to tighten it, and the Suzuki Dealer told me that there is no tool available. And they had nothing themselves in the shop. There was apparently a socket on the market for Honda VTX that people were using, but it was selling online for 200 bucks. I didn't want to fart around with it for too long, so I ended up buying a whole new OEM clutch basket with the Primary Drive gear attached to the back side of it. Cost: $300 CDN.

When I reinstalled, the problem disappeared.

My thought about this is that there's higher torque in the second gear power band, and that is when the Tubular nut is more likely to loosen.

Once it loosens - even slightly - the gear 'skips'. Meaning that the clutch basket and the attached Primary Drive gear are briefly out of 'sync'. Torque is not fully transferred from the engine to the rear wheel.

When the gear skips, you momentarily loose some power to the rear wheel. And if the Tubular nut continues to loosen, it has the same symptoms of a slipping clutch. That's because the clutch basket and the Primary Drive gear are spinning independently of each other, rather than as an integrated unit.

As others have pointed out, this is a weakness in the design. That Tubular nut should not be able to loosen at all. Or, Suzuki should have a proper socket for it.

I could certainly be wrong about this. But it's just my thought.
 

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I really appreciate the link to the second video. I hadn't seen it before, and it's a great instructional video.

Thanks!

I am curious how people are securing the clutch basket in order to tighten the tubular nut, and what torque is required (Ft-lbs)?
The service manual should tell you the torque I thought Joe said what it was in the video as well...

The page listed above from Andy listed has it too! Check out this THREAD! Tube Nut is torqued to 105 ftlbs.
 

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Hi Stalker:

Thanks for your reply.

I disagree with you however. The bike does NOT jump out of gear. It gives you the impression that it has jumped out of gear.

Here's a description again of what happens:

Hard acceleration thru first gear, then shift to second gear and keep accelerating. Suddenly, there's a strong jolt or kick, and the power is briefly lost for a moment. It feels like the transmission has been kicked out of gear. To an observer driving alongside, they'd think that you missed a shift or something. But rolling the throttle back you discover that you're still in gear. Then you go, 'what the heck was that'?

I first started experiencing it about a year ago, and it was shortly after I did a clutch rebuild.

I ignored the problem at first because it only occurred during really hard acceleration. But the problem grew to where it began to feel as if the clutch was slipping. Tach RPMs weren't matching the power to the rear wheel. So I thought, 'how could the be clutch slipping if I just recently replaced all of the plates and springs'?

As it grew worse, I had no choice but to open the clutch again. I re-checked everything, and it all looked fine. Reassembled, adjusted the push pin, and clutch cable.

Same thing.

Now I was stumped. Then I did some reading on this site about the Tubular Nut.

I stripped it all down again and removed the clutch basket. I tried unsuccessfully at the time to find a socket tool to tighten it, and the Suzuki Dealer told me that there is no tool available. And they had nothing themselves in the shop. There was apparently a socket on the market for Honda VTX that people were using, but it was selling online for 200 bucks. I didn't want to fart around with it for too long, so I ended up buying a whole new OEM clutch basket with the Primary Drive gear attached to the back side of it. Cost: $300 CDN.

When I reinstalled, the problem disappeared.

My thought about this is that there's higher torque in the second gear power band, and that is when the Tubular nut is more likely to loosen.

Once it loosens - even slightly - the gear 'skips'. Meaning that the clutch basket and the attached Primary Drive gear are briefly out of 'sync'. Torque is not fully transferred from the engine to the rear wheel.

When the gear skips, you momentarily loose some power to the rear wheel. And if the Tubular nut continues to loosen, it has the same symptoms of a slipping clutch. That's because the clutch basket and the Primary Drive gear are spinning independently of each other, rather than as an integrated unit.

As others have pointed out, this is a weakness in the design. That Tubular nut should not be able to loosen at all. Or, Suzuki should have a proper socket for it.

I could certainly be wrong about this. But it's just my thought.
Nope,
The primary gear has splines so there is no way it can slip on the clutch basket, so your theory does not work in a real world application.
If the tube nut comes loose it will keep the clutch from disengaging, not cause it to slip.

BCS
 

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The service manual should tell you the torque I thought Joe said what it was in the video as well...

The page listed above from Andy listed has it too! Check out this THREAD! Tube Nut is torqued to 105 ftlbs.
Can one of you screen shot the page in the service manual that shows the torque spec for the tube nut?
I only ask this because I have never seen this torque spec in the manual. The tube nut is not listed as a serviceable part by Suzuki and does not have a part number where it can be purchased separately, it is only sold as a complete assembly with the basket and gear.
(I don't need the torque spec personally, just curious if anyone actually found this in the manual or if its just another urban legend) :p

BCS
 

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Can one of you screen shot the page in the service manual that shows the torque spec for the tube nut?
I only ask this because I have never seen this torque spec in the manual. The tube nut is not listed as a serviceable part by Suzuki and does not have a part number where it can be purchased separately, it is only sold as a complete assembly with the basket and gear.
(I don't need the torque spec personally, just curious if anyone actually found this in the manual or if its just another urban legend) :p

BCS
Hey BCS,
From what I have read, I haven't seen a TQ Spec for the Tube Nut. Most that I have read and I did as well was just apply the Red Loctite and then just use an impact on it and call it the day. I'll see if I ca find it in the manual
 

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Can one of you screen shot the page in the service manual that shows the torque spec for the tube nut?
I only ask this because I have never seen this torque spec in the manual. The tube nut is not listed as a serviceable part by Suzuki and does not have a part number where it can be purchased separately, it is only sold as a complete assembly with the basket and gear.
(I don't need the torque spec personally, just curious if anyone actually found this in the manual or if its just another urban legend) :p

BCS
LOL I do try to READ... So where did the 105ftlbs come from?
Was given this torque spec by Harris via Facebook. He said that after repairing dozens of tub nuts on M109s he's found that anything over 100ftlbs is good. I did 105 just to make sure it wouldn't come off again.
To my knowledge this spec is not found in the manual.
 

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LOL.....:p :bigthumbsup:

I already knew for sure there was no spec in the service manual, but have seen a lot of guys say it is, which is why I asked for the screen shot. :doorag:

Harris is a good source for real world, hands on information though and will not steer you wrong.

BCS
 
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