Author Topic: V7 Stone - upper rear shock screw broken (Read 7506 times)

fossil · « **on:** May 02, 2015, 08:34:24 AM »

By looking-over the bike prior to a tour I made a discovery that really disturbs me: the upper fastening screw of the right rear shock is broken. I have mounted the original luggage rack that was never used with a real severe load. The mounting was done prior to delivery by my dealer two years ago. The screw broke exactly where the rack and the frame meet. The original screw is a M6 x 35, that has to be fastened with a torque of 10 Nm. I beliefe there was a longer screw in the package of the luggage rack but I don´t know for sure.

Is this something that happened before? How can I prevent sich an incident? And - should I limp with a snail´s speed to the dealer (about 5 km way) or should he come with his van and pickup the bike?

sib · « **Reply #1 on:** May 02, 2015, 03:08:24 PM »

Well, your posting motivated me to double check the upper shock bolts on my V7 Stone before starting off today. No issues, fortunately.

rodekyll · « **Reply #2 on:** May 02, 2015, 03:10:58 PM »

Isn't the top shock mount a post? Why don't you just drill out the broken one and replace it?

I had a broken one once. Someone loaded more buick on it than it was designed for.

Without pics of the damage it's hard to tell how or why the screw broke -- stretched, sheared, bent, etc. My guess is that it was cheap stainless and worked loose over time. I'd prevent it by using a good grade of fastener and going over the bike periodically to be sure all the fasteners are tight.

Bisbonian · « **Reply #3 on:** May 02, 2015, 03:56:36 PM »

6mm for an upper shock mount? That seems awfully light!

Guzzistajohn · « **Reply #4 on:** May 02, 2015, 03:59:22 PM »

It doesn't support the shock does it? just keeps it on the post.

father guzzi obrian · « **Reply #5 on:** May 02, 2015, 04:45:58 PM »

Just keeps it on the post, same as the big block cali's looks pretty wimpy, but never had a problem

pauldaytona · « **Reply #6 on:** May 02, 2015, 05:39:38 PM »

no force on it until you mount a lugage rack with it. as long as it's tight, no problem, but when a bit loose, there the problem starts

fotoguzzi · « **Reply #7 on:** May 02, 2015, 05:41:31 PM »

if like the big twins it won't go anywhere, the bottom bolt is still in the shock right? all the load is vertical so for it to slip all the way off the post horizontal would be near impossible if the lower bolt is tight. get it fixed but I'd ride to the shop with no worries.

rodekyll · « **Reply #8 on:** May 02, 2015, 05:50:55 PM »

I wouldn't bother the dealer since it's not a warranty item and a super easy fix. If it was a 35mm bolt it's not bottomed out in the hole. You should be able to turn it out with standard broken screw techniques.

fossil · « **Reply #9 on:** May 03, 2015, 01:02:47 AM »

Well, thank you all for those thoughtfull replies. Some answers from me:
First of all: Why should it not be a warranty item? These luggage racks are genuine Moto Guzzi, the bike was ordered with it, it was mounted by an official Moto Guzzi dealer. Then: of course: drilling it out is the way to go. But as the dealer is minutes away and i am more in electronics than in mechanics I leave that to the dealer.
I think it was the screw itself that was bad. In my company we mount heavy module cabinets with exactly such screw (also torqued with 10 Nm) to ship's walls and nothing ever happened.
You have convinced me that it is possible to drive carefully to the dealer.

rodekyll · « **Reply #10 on:** May 03, 2015, 01:55:05 AM »

Maybe it is covered under warranty. My assumption was that two years after installation, a bolt on an accessory item wouldn't be. I'm not a dealer. I could be wrong. Is your warranty still in effect? Does it cover bolts on accessories?

Personally I'd be embarrassed to take something this simple to a shop and raise a fuss about warranty. $0.02

fossil · « **Reply #11 on:** May 03, 2015, 02:54:01 AM »

Of course you are right there. My intention is not to make any fuss with the dealer but to get it done properly. I have not the proper tools to drill it and unscrew the stump of the bolt. The more as if it has been made properly according shop manual the bolt was secured with Loctite.

And perhaps (as in the last cases my bike was there) he lends me another bike for the time. He is dealer also for Aprilia, Ducati and Suzuki...

fossil · « **Reply #12 on:** April 10, 2018, 02:19:15 AM »

Well, it has happened again. Yesterday in the morning all was well, in the afternoon the shafted part of the screw was lost again, the screw was broken. It seems to be that the OEM luggage rack is warped in a way that the mounting holes do not fall in line at the right side. When mounted this adds stress concentration on the screw, combined with vibration this leeds to fatigue. Annoying!

tris · « **Reply #13 on:** April 10, 2018, 05:53:22 AM »

Are they stainless or carbon steel cap screws?

If stainless, I'd sacrifice the shiny stainless ones and stick a couple of high tensile 12.9 grade steel ones in and then challenge them to break again!

Zoom Zoom · « **Reply #14 on:** April 10, 2018, 09:13:52 AM »

Since you have pretty much solved the immediate trouble, aren't there two different racks for the V7 line? One being rated for a heavier load than the other, perhaps mounting to either an additional hard point or mounting differently all together? Which rack are you using? If the lighter duty one, maybe consider the other one?

John Henry

ken farr · « **Reply #15 on:** April 10, 2018, 10:20:27 AM »

Quote from: fossil on May 03, 2015, 01:02:47 AM

Well, thank you all for those thoughtfull replies. Some answers from me:
First of all: Why should it not be a warranty item? These luggage racks are genuine Moto Guzzi, the bike was ordered with it, it was mounted by an official Moto Guzzi dealer. Then: of course: drilling it out is the way to go. But as the dealer is minutes away and i am more in electronics than in mechanics I leave that to the dealer.
I think it was the screw itself that was bad. In my company we mount heavy module cabinets with exactly such screw (also torqued with 10 Nm) to ship's walls and nothing ever happened.
You have convinced me that it is possible to drive carefully to the dealer.

Lucky bahstad.......

kjf

Wayne Orwig · « **Reply #16 on:** April 10, 2018, 04:40:00 PM »

Does it need some large washers or something like that, to trap it so it is not moving. Even with a side load from the rack, it should be trapped so it does not move. If it is moving and hammering on the screw, that may always fail.

fossil · « **Reply #17 on:** April 11, 2018, 12:40:30 AM »

Perhaps the mounting hole needs a chamfer. I will take a look on that.

malik · « **Reply #18 on:** April 11, 2018, 04:01:36 PM »

FWIW, the OEM rack (the original heavy one) came with the V7C from new. I don't think that top mount has moved since mounting the Gazi shocks some 120,000 km back. But the Gazi's have a brass bush over the post, and a hefty spacer between the rack and the top of the shock. In the past, the nut holding the LHS lower mount has disappeared en route, but that's the one that comes off every time the wheel comes off. Also neither of the top bolts on the Special (also the original heavy rack) have moved in the last 100,000 km. both racks have regularly carried significant weights - I'd guess 10-12kg. It does sound as if your rack may be slightly distorted. Is there any way you can check that? Has the thread now been compromised?

Here's a photo from the V7C.

Do note that recently I discovered one the two bolts securing the pillion footpeg hanger has disappeared itself. Don't know how long it had been missing. I merely replaced the missing bolt.

fossil · « **Reply #19 on:** April 12, 2018, 12:11:23 AM »

Well, the rack is distorted. The alignment of the mounting hole of the rack is out by about 3 - 5 mm. So it has to be aligned by force when it is mounted. I think this creates the stress on the mounting bolt.

On my Stone the rack is mounted without the washers. I do not see how they could clear this trouble as the shear loading would only occur on a slightly different point of the bolt.

malik · « **Reply #20 on:** April 12, 2018, 11:19:26 AM »

So you are going to have to straighten it - probably best to get advice/assistance of someone who works with metal & to whom steel is another plastic substance. That w ay you are more likely to get the angles (of the applied force) right. Good luck. Let us know how it works out.

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Author Topic: V7 Stone - upper rear shock screw broken (Read 7506 times)

father guzzi obrian