UK Monster Owners Club Forum .: Technical :. Cans, Tyres, Brakes, etc. » 1100 Evo front spindle pinch bolts torque

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Old 28-02-2020, 04:53 PM   #1
bigredduke
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1100 Evo front spindle pinch bolts torque

Just re-fitting the front wheel after new tyre fitment.

The official Ducati workshop manual states a torque setting for the spindle clamp pinch bolts as 18NM +/-5%

I usually set the torque wrench a bit lower to begin with & after the click then increase it.

However, they have tightened up past my comfort zone (you know that sickening feeling when you give it a little more & it suddenly goes slack)? with no sign of a click.
I have tried another torque wrench with the same result.

I also checked the torque setting for the Sport Classic & they are actually higher at 20NM so it would appear there isn't an error in the manual.

I'm rather nervous of a) shearing a bolt or stripping the thread in the fork leg & b) having a pinch bolt come loose whilst riding.
Any suggestions?
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Old 28-02-2020, 05:20 PM   #2
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On my 750, I usually tighten by hand and only use the torque wrench to check the final tightness once the job is essentially finished.
And I very much do it in stages .. often four or five until the final torque is reached (which isn't very much anyway).
During the process it is very noticeable that the clamp area distorts as each bolt is tightened a little more.
If you've gone in with the torque wrench at full spec from the start it will be very likely to give an inaccurate result and can even sometimes lead to cracking of the casting due to overtightening on one side (even if the spec torque has not been exceeded).
My method is as follows.
Using a std allen key with no extension, I first snug both bolts down.
I then tighten one bolt a fraction further.
Then applying the allen key to the other bolt, I usually find that it has gone slack as the clamp area has distorted .. so I snug it back down and then tighten just a fraction more.
Then applying the allen key back to the first bolt, I often find that it too has gone slack due to further distortion of the clamp area .. so I repeat the snugging down and slightly tightening process again.
After that the bolts will probably remain snug on both sides but might still lose a little of their former torque as the opposite bolt is tightened.
I proceed from there, alternating from one bolt to another until the distortion ceases and the residual torque is maintained and ultimately gradually increased up to the estimated spec figure.
Finally I get the torque wrench out and check the final torque.
The whole process is very much about feel in my experience and a torque wrench can, if used insensitively, do more harm than good.
Essentially, its all about tightening evenly.

Hope that makes some kind of sense .. and that your fork bottoms remain crack free.
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Old 28-02-2020, 05:47 PM   #3
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This is probably another one of those famous Ducati misprints.

The text in the manual says 18Nm...



But the torque table in the same manual says only 14Nm...



I've always used the lower figure and I've not had any problems with them backing out. (Always apply moly grease too.)

I'll echo utopia's sentiments and hope that your fork bottoms are ok.
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Old 28-02-2020, 05:52 PM   #4
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I'd agree with Utopia, it's about getting them on evenly with a final tightening which I'd've done by feel. I only ever used a torque wrench for cylinder heads tbh. Most of the forces on the spindle are upwards into the fork legs. I knew someone many moons ago who rode a bike for a distance with the front spindle clamps missing. He'd got distracted and forgot to put them on. Luckily it was studs in the fork legs with nuts to hold the clamps on. I think it was a wee bit clunky.
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Old 28-02-2020, 06:40 PM   #5
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Quote:
Originally Posted by Luddite View Post
This is probably another one of those famous Ducati misprints.

The text in the manual says 18Nm...



But the torque table in the same manual says only 14Nm...



I've always used the lower figure and I've not had any problems with them backing out. (Always apply moly grease too.)

I'll echo utopia's sentiments and hope that your fork bottoms are ok.
Yes, I did notice that, which is why I set the torque wrench initially at 10NM
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Old 28-02-2020, 06:45 PM   #6
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Jeff, your advice is sound as ever. I will try a simple allen key to start with & use 'feel' rather than a specified setting.

Thanks Guru!
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Old 28-02-2020, 07:27 PM   #7
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Thanks everyone for the great advice as always. Odd isn't it that tightening up a bolt or nut can 'feel' wrong even though a torque setting has not apparently yet been reached.

Just loosened the pinch bolts back off, used a conventional allen key as tight as I can manage, then a short 3/8" drive ratchet and allen key socket. Feels about as tight as I am comfortable with, will check tomorrow.
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Old 29-02-2020, 02:53 PM   #8
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So, having tightened with a 3/8" drive short ratchet I popped round to see a neighbour. He is a retired senior engineer at Perkins diesel & has recently built a Caterham 7.

He lent me a lovely vintage Britool torque wrench, which was calibrated for his build. I set it to 15NM & it clicked immediately. So I loosened the pinch bolts a little & started again.

Much happier with how tight they felt when the wrench clicked!

The lesson seems to be, beware cheap torque wrenches, especially at relatively low settings!

Now on the lookout for a decent quality TW!
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Old 29-02-2020, 02:59 PM   #9
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Quote:
Originally Posted by bigredduke View Post
Much happier with how tight they felt when the wrench clicked!
Good news! Panic over.
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Old 29-02-2020, 03:40 PM   #10
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I've never had to use a torque wrench for small bolts like that as you can do more damage than good with even a small torque wrench. I use one for big stuff like suspension bolts and wheel nuts, head bolts etc. But usually i just hand tighten with an allen key and once you feel it bending, that's usually tight enough. Even disk bolts, fork clamp bolts and brake lines. If you're dead set on using one then it needs calibration and the bolt threads need to be clean and greased and under the bolt head too.
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Old 29-02-2020, 07:23 PM   #11
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I must admit to a certain degree of paranoia when tightening bolts. I once had a brake calliper mounting bolt come out mid-journey & the front rim had to be skimmed & the wheel rebuilt (spoked). I had only used a long allen key & clearly hadn't tightened the bolt sufficiently. Having looked at a few articles online, it would appear that if a torque wrench is used infrequently (guilty as charged) they can give seriously inaccurate readings.
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Old 29-02-2020, 08:07 PM   #12
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Read the manual that almost certainly came with a torque wrench!
Usually: Always back them off to their minimum reading after use, this prevents the spring developing a ‘set’, leading to bad readings. Do NOT however back them right off the scale (less than zero) as this can also damage them.
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Old 29-02-2020, 09:47 PM   #13
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Knew about backing them off after use but didn't realise they should not be left below zero.

Thanks Rob!
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