800GS shock bolt design flaw? - Page 2

johngil · 08-04-2009, 03:58 PM

Quote:

Originally Posted by Bayner

John, I'll try to check mine in the next couple of days. I have ridden hard enough to bend the front rim in several spots, and even one in the rear rim. I have bottomed it on several occasions. I'll be a good candidate to see if this is due to riding style or a particular problem with your machine....

You noticed this bolt was bent when first removing your stock shock, correct?

I'll keep you posted.

Yes.

JRWooden · 08-04-2009, 04:14 PM

John... I forgot the part about your bent bolt in chapter #1 of this story ...

Perhaps that is the explanation ....

structural member has "buckled" it only retains a fraction of it's former strength.

The simple example is that a person of modest weight can successfully stand on a "perfect" aluminum beer can, yet if there is a small dent in the side of the can .. .you are SOL the can simply collapses. That's not a perfect example, but "whatever"...

Perhaps the explanation is that improper assembly at the factory (woefully inadequate torque) allowed your system to take a slight initial "buckle" and as time goes by ... all hell breaks loose with no real way for you to keep it from happening ....

Jim

Boon Booni · 08-04-2009, 04:21 PM

Quote:

Originally Posted by johngil

The design seems poor considering the intended use of the bike. The bushing that the top shock bolt threads into just floats.

So the shock isn't actually bolted to the bike? Looks like the bolt hole on the right is not threaded, bolt goes through some bushing, through the shock and threads into the bushing on the left. Everything is tightened against the tab on the right and the bushing on the left is just fit into the hole on the left tab but not tightened into it.

Would seem like a better design would be a nut behind the tab on the left so everything got clamped together.

I'm wondering if there is a design/meterial difference between the bushing in BMW shock and your aftermarket shock which would allow the bolt to flex more.

johngil · 08-04-2009, 04:22 PM

"John... I forgot the part about your bent bolt in chapter #1 of this story ...

Perhaps that is the explanation ....

structural member has "buckled" it only retains a fraction of it's former strength.

The simple example is that a person of modest weight can successfully stand on a "perfect" aluminum beer can, yet if there is a small dent in the side of the can .. .you are SOL the can simply collapses. That's not a perfect example, but "whatever"...

Perhaps the explanation is that improper assembly at the factory (woefully inadequate torque) allowed your system to take a slight initial "buckle" and as time goes by ... all hell breaks loose with no real way for you to keep it from happening .... "

Jim

I won't be able to prove any of that. I know I need to stay positive, but I'm only positive that I am fucked like a tuna.

My dealer just reamed me a new one for replacing the original bent bolt.
"That's just what you dirt bikers do." She didn't seem too concerned when she ordered it for me. She also mentioned there was only 4 hours allocated to replace the frame based on I don't know what. No profit in getting 4 hours to replace a frame for sure.

Worst case, I will call my insurance provider.
There will be a lot of 800 goodies for sale in the flea market soon enough.

johngil · 08-04-2009, 04:23 PM

Quote:

Originally Posted by Gramps

So the shock isn't actually bolted to the bike? Looks like the bolt hole on the right is not threaded, bolt goes through some bushing, through the shock and threads into the bushing on the left. Everything is tightened against the tab on the right and the bushing on the left is just fit into the hole on the left tab but not tightened into it.

Would seem like a better design would be a nut behind the tab on the left so everything got clamped together.

Like any regular bike that I have worked on for the last 30+ years?

Boon Booni · 08-04-2009, 04:28 PM

Does the rest of the bushing serve any purpose? From the flats left it looks like it's just hanging there.

In this photo you've got a hose on it?

johngil · 08-04-2009, 04:29 PM

Quote:

Originally Posted by Gramps

I'm wondering if there is a design/meterial difference between the bushing in BMW shock and your aftermarket shock which would allow the bolt to flex more.

The trouble started w/ the stock shock.

johngil · 08-04-2009, 04:32 PM

Quote:

Originally Posted by Gramps

Does the rest of the bushing serve any purpose? From the flats left it looks like it's just hanging there.

In this photo you've got a hose on it?

The "hose" is from BMW.
The whole setup is meant to mount the seat lock mechanism. Notice the opposite side. They could have lost a couple of inches of fastener if they simply just mounted the shock.

johngil · 08-04-2009, 05:57 PM

Quote:

Originally Posted by PackMule

I checked mine, all straight. About 4500 miles of mixed use including a dualsport event loaded with camping gear and luggage. Bent front rim, but the shock bolt and frame are fine.

What kind of replacement shock do you have?

Ohlins. It will be getting measured compared to stock tomorrow.

johngil · 08-04-2009, 07:50 PM

This is the problem w/ the design in my opinion. The span is just too large.

tmex · 08-05-2009, 05:42 AM

John, it "appears" to me that the upper mounting flange on the Ohlins is much smaller than the flange on the stock shock. The shorter flange would certainly aggravate if not actually induce the problem since it would be much easier to bend the mounting bolt with a smaller flange. The force would be much more concentrated with the Ohlins.

As it stands, the frame looks severely bent at this point and will probably need to be replaced even if you go back to the stock shock. After looking at your photos I would be reluctant to use the Ohlins as designed, although I am not sure I would have been smart enough to come to that conclusion apriori. I might be inclined to pick a fight with Ohlins if I were you (assuming they designed that shock for the F8). I'll take a look at my F8 this weekend since it is not at my current location.

johngil · 08-05-2009, 06:17 AM

Dennis, when comparing the stock shock to the Ohlins there is more surface area w/ the Ohlins shock. The stock shock looks larger, but is mostly just a rubber bushing w/ a smaller steel sleeve.
I will have both shocks compressed to make sure they are of equal length today.
The bolt bending started while running the stock shock. The Ohlins was to be a fix for the frequent bottoming.

After the shocks are compared and everything checks out, I'll start by calling BMW and go from there. I was told that the local rep. is out for injuries right now. That isn't going to help me.

v8toilet · 08-05-2009, 06:28 AM

Quote:

Originally Posted by johngil

I was told that the local rep. is out for injuries right now. That isn't going to help me.

Unless he.she was injured when his rear shock bolt on his F800 let go.... Keep us posted.

TwilightZone · 08-05-2009, 06:54 AM

Wonder if replacing the stocker with a high strength titanium bolt would do the trick. Gotta be available out there somewhere on the internets.

Kawidad · 08-05-2009, 08:02 AM

Quote:

Originally Posted by TwilightZone

Wonder if replacing the stocker with a high strength titanium bolt would do the trick. Gotta be available out there somewhere on the internets.

Ti is cool and all, but it is really brittle. I don't think I would want that, bending is better than snapping for this application.

I have to agree this looks like a silly design. But, if you are frequently bottoming out your shock like you said, that may have been the original source of the problem.

08-04-2009, 04:22 PM	#19
johngil ^OP Reseda, CA Joined: Jun 2007 Oddometer: 3,489	"John... I forgot the part about your bent bolt in chapter #1 of this story ... Perhaps that is the explanation .... structural member has "buckled" it only retains a fraction of it's former strength. The simple example is that a person of modest weight can successfully stand on a "perfect" aluminum beer can, yet if there is a small dent in the side of the can .. .you are SOL the can simply collapses. That's not a perfect example, but "whatever"... Perhaps the explanation is that improper assembly at the factory (woefully inadequate torque) allowed your system to take a slight initial "buckle" and as time goes by ... all hell breaks loose with no real way for you to keep it from happening .... " Jim I won't be able to prove any of that. I know I need to stay positive, but I'm only positive that I am fucked like a tuna. My dealer just reamed me a new one for replacing the original bent bolt. "That's just what you dirt bikers do." She didn't seem too concerned when she ordered it for me. She also mentioned there was only 4 hours allocated to replace the frame based on I don't know what. No profit in getting 4 hours to replace a frame for sure. Worst case, I will call my insurance provider. There will be a lot of 800 goodies for sale in the flea market soon enough. johngil screwed with this post 08-04-2009 at 08:18 PM

08-04-2009, 04:28 PM	#21
Boon Booni Red Clay Halo Joined: Aug 2003 Location: Richmond, Va Oddometer: 11,162	Does the rest of the bushing serve any purpose? From the flats left it looks like it's just hanging there. In this photo you've got a hose on it? __________________ Maybe Old's Cool is a bunch of dirty old men who swear because , let's face it, old bikes run on blasphemy as much as they do gasoline and oil. --Jinx You can be Han Solo, and I can be another Han Solo...

08-05-2009, 05:42 AM	#26
tmex Beastly Adventurer Joined: Apr 2006 Location: NorCal Oddometer: 2,039	John, it "appears" to me that the upper mounting flange on the Ohlins is much smaller than the flange on the stock shock. The shorter flange would certainly aggravate if not actually induce the problem since it would be much easier to bend the mounting bolt with a smaller flange. The force would be much more concentrated with the Ohlins. As it stands, the frame looks severely bent at this point and will probably need to be replaced even if you go back to the stock shock. After looking at your photos I would be reluctant to use the Ohlins as designed, although I am not sure I would have been smart enough to come to that conclusion apriori. I might be inclined to pick a fight with Ohlins if I were you (assuming they designed that shock for the F8). I'll take a look at my F8 this weekend since it is not at my current location. __________________ my favorite bike - R1200GS tmex screwed with this post 08-05-2009 at 06:11 AM

08-05-2009, 06:17 AM	#27
johngil ^OP Reseda, CA Joined: Jun 2007 Oddometer: 3,489	Dennis, when comparing the stock shock to the Ohlins there is more surface area w/ the Ohlins shock. The stock shock looks larger, but is mostly just a rubber bushing w/ a smaller steel sleeve. I will have both shocks compressed to make sure they are of equal length today. The bolt bending started while running the stock shock. The Ohlins was to be a fix for the frequent bottoming. After the shocks are compared and everything checks out, I'll start by calling BMW and go from there. I was told that the local rep. is out for injuries right now. That isn't going to help me. johngil screwed with this post 09-16-2009 at 09:53 PM

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08-04-2009, 04:14 PM	#17
JRWooden Beastly Adventurer Joined: Jul 2008 Location: The great state of confusion Oddometer: 3,436	John... I forgot the part about your bent bolt in chapter #1 of this story ... Perhaps that is the explanation .... structural member has "buckled" it only retains a fraction of it's former strength. The simple example is that a person of modest weight can successfully stand on a "perfect" aluminum beer can, yet if there is a small dent in the side of the can .. .you are SOL the can simply collapses. That's not a perfect example, but "whatever"... Perhaps the explanation is that improper assembly at the factory (woefully inadequate torque) allowed your system to take a slight initial "buckle" and as time goes by ... all hell breaks loose with no real way for you to keep it from happening .... Jim

08-04-2009, 07:50 PM	#25
johngil ^OP Reseda, CA Joined: Jun 2007 Oddometer: 3,489	This is the problem w/ the design in my opinion. The span is just too large.

08-05-2009, 06:54 AM	#29
TwilightZone Beastly Adventurer Joined: Dec 2008 Location: Behind the Redwood Curtain Oddometer: 1,949	Wonder if replacing the stocker with a high strength titanium bolt would do the trick. Gotta be available out there somewhere on the internets.