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Replacement nuts and bolts?

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Rocknrider View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rocknrider Quote  Post ReplyReply Direct Link To This Post Topic: Replacement nuts and bolts?
    Posted: 21 Jun 2018 at 00:05
Hi All, 

Thinking of buying an old Moto Guzzi Griso, Stelvio or Bellagio. 

The 10 year old ones I've seen look like they have wear - the chrome plated indicator lights looks pretty bad, as does the screws and bolts.  Mirrors too.  But all these parts are replaceable. 

Are there better OEM sized hex bolt and screw kits (like the speedometer ones which have rusted to bits) or would I have to assemble the whole lot from scratch? 

I like the Bellagio cafe racer style most but I see its been discontinued.  Any issues? Feedback from users?  

How is maintenance/service? 

The Griso is more common than the Stelvio (that I could find) - same issues with the screws/bolts etc.  If you could recommend any dealers who sell parts.  Last time I was in Corsa Italiana admiring their MGs - now I discover it's closed :(

Cheers

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Post Options Post Options   Thanks (1) Thanks(1)   Quote Petros GR Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jun 2018 at 17:28
To answer your question, I think probolt had complete set for Griso. 

There are 2 things to consider when replasing a bolt: Strength and corrosion.

Generaly steel bolts are stronger that stainless. You'll have to do some research about bolt grades, but you'll be able to find what fits you.

The other thing you have to consider is corosion, especialy galvanic seizing. For example, if you change the galvanized steell bolt that holds the engine to the frame, with a stainless or titanium, the bolt will probalbly last forever, but will probably seize, and when you try to undo it, it will take out with it the aluminium thread of the engine. The calipers are also aluminum, the frame is steel... 

Look at the anodic index table at the bottom of this page (link bellow), the biger the difference the more the corrosion - the more negative number looses matterial to the less negative number.
A galvanized steel bolt (-1.20) will loose matterial to the btrake caliper thats aluminium alloy (-0.90~-0.95) because of the difference of 0.20 to 0.25. If a titanium (-0.30) bolt is used, the aluminium will loose material to the titanium, because of the difference of 0.60~0.65.
So, usining a titanium bolt, not only will be more prone to seizing, but undoing it if seized, will not damage the bolt but its housing (caliper, motor, frame, whatever)


What I do, is using anti-seize for all bolts. Most common are the anti-seize compounds that contain copper, can also be found with aluminium, nickel, zinc, molybdenum... Each being best for some metal combination while being worst for some other. I use loctite 8009, its mettal-free (so ok for all metals) and has some graphite to allow electric flow (engine ground connects to frame through engine bolts)
As antiseize is a lubricant, the bolts need about 20% less force to be tightened corectly.

Not what you asked about, it felt right to warn you, I had some bolts seized, some threads repaired, some helicoil used, a caliper changed (felt usafe to repair the thread)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PeterB Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jun 2018 at 17:49
Petros that was a very informative post - thank you. I'm not the original poster but I learned from it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jun 2018 at 18:17
Correct lubrication pays dividends in the long term.
Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote BobV7 Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jun 2018 at 23:06
V7 Classic Black and gold was the best. But green & black was nice too. Now blue is in!
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Rocknrider View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rocknrider Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jun 2018 at 23:17
Thanks All - especially Petros.   That has put me off for good :D

I didn't know about the Loctite 8009.   Some thinking to do then.  This is more work than I thought!

Cheers


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Mike H View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2018 at 11:01
I've used a dab of copper grease on many fasteners for year's, including stainless, in steel and alloy, including on bikes left standing outdoors under covers for years, never had a seized one or any other problems. So a case of try it and see I think. Just FYI. 

"Chicken nuggets don't dance on a Tuesday."
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cyclobutch Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2018 at 12:55
A specific model stainless N&B set is going to sell at a premium. Spend some time measuring up what you want and then make up an order. I use these folks - http://www.groveco.co.uk/

There are issues with tensile strength when replacing 8.8 with stainless and I have read recommendations that you shouldn't use stainless for mounting brake calipers for instance. I do and have had no problems - but that's just me.

On most fixings I use copper slip. For areas where there may be some galvanic/electrolytic issues I use a marine grease. The main issue where I suffer from this is the steel studs that mount the drive box onto the s/arm on my V50. I'm on my third s/arm on that bike due to having to cut two off at those mountings (and the studs are steel, not stainless).  

And never put a Guzzi through a salty British winter.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Android Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2018 at 20:46
I ride all winter and have changed out as many as possible of the external screws and bolts for stainless, there are 2 grades 304 (A4) and 316 (A2)
316 has a higher tensile strength.

Never known any galvanic corrosion and just to add to the mix any helicoil you have put in will be stainless.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2018 at 20:59
https://www.westfieldfasteners.co.uk/ScrewBolt_M.html
Have a look here. Westfield Fasteners are very helpful and this link will lead you to a chart showing the strengths and corrosion resistance of stainless bolts etc. For example,a bolt of A4 80 grade has the same tensile strength as an 8.8 high tensile bolt. Materials key on the top R/H side of the page.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote iansoady Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jun 2018 at 10:27
That's a handy site - thanks.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BobV7 Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jun 2018 at 10:40
Originally posted by Dave P. Dave P. wrote:

https://www.westfieldfasteners.co.uk/ScrewBolt_M.html
Have a look here. Westfield Fasteners are very helpful and this link will lead you to a chart showing the strengths and corrosion resistance of stainless bolts etc. For example,a bolt of A4 80 grade has the same tensile strength as an 8.8 high tensile bolt. Materials key on the top R/H side of the page.

Always useful to have someone independently corroberate ones opinions. Wink
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jun 2018 at 10:51
Originally posted by Dave P. Dave P. wrote:

https://www.westfieldfasteners.co.uk/ScrewBolt_M.html
Have a look here. Westfield Fasteners are very helpful and this link will lead you to a chart showing the strengths and corrosion resistance of stainless bolts etc. For example,a bolt of A4 80 grade has the same tensile strength as an 8.8 high tensile bolt. Materials key on the top R/H side of the page.

The main difference between A2 and A4 is the corrosion resistance for marine use. In fact I saw a table published on this recently which showed the tensile strength of A4 was slightly lower than A2 because of the composition of the stainless.

You have to look further into the bolt description, A2-70, or A2-80, the last figure refers to the tensile strength.
A2-70 has a tensile strength of 700N/mm2     2% yield strength = 450N/mm2
A4-80 has a tensile strength of 800N/mm2                                  = 600N/mm2

An 8-8 alloy steel bolt has a tensile strength of 828N/mm2.         = 635N/mm2

A4-70 would be no stronger than the A2-70.


Edited by Brian UK - 23 Jun 2018 at 11:08
Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jun 2018 at 11:20
Thanks for this excellent find. Thumbs Up


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Edited by Mike H - 23 Jun 2018 at 11:24
"Chicken nuggets don't dance on a Tuesday."
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