Rear shock mount bending

[kcjaz]

Moving this topic from the LCDC9 thread to its own thread to get better visibility. @elkeye posted his damage (shown below) and then last night I was taking my shocks off and noticed similar damage.

Not sure of the cause or how best to fix it but some speculation below:

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elkeye​

JoinedAug 10, 2015Messages143LocationSteamboat Springs, CO

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• #318

It is. And i.didnt notice till I did the mud removal and battle damage assessment today. The trail in which it happened is unknown but Miller is my guess. I went full send a couple times on that trail.

I've sent BB the pics and we spoke. New one will be on soon.

My rear shock guards are not BudBuilt (BB).

After LCDC IX, when my OME BP-51 rear shocks were being removed so they could be sent to ARB to rebuilt, damage to a rear shock mount was discovered.

Could a damaged rear shock mount be heated and straightened? Maybe...but the heat would weaken the rear shock mount. Would the straightened mount fail when on a trail like Fins & Things in Moab, UT? on Poughkeepsie Gulch in the San Juans, CO? on Black Bear Pass?

I do not run trails like 'Metal Masher' or 'Poison Spider' in Moab, but I am not willing to accept the risk that a straightened shock mount will fail on any off-road trail.

Unfortunately the shock mount is part of the rear axel housing assembly (42110-60A52).

2015 LC200 - OME BP-51, SPC-UCA, ARB Winch Bar & Recovery Points, SLEE sliders, skid plate system, AL rear bumper, 2nd battery tray and ARB LED Light Brackets (with RIGID D2 Pro Driving Lights), STEDI Type-X Pro Driving Lights, IBS-DBR Battery System
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linuxgod​

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• #319

My rear shock guards are not BudBuilt (BB).

After LCDC IX, when my OME BP-51 rear shocks were being removed so they could be sent to ARB to rebuilt, damage to a rear shock mount was discovered.

Could a damaged rear shock mount be heated and straightened? Maybe...but the heat would weaken the rear shock mount. Would the straightened mount fail when on a trail like Fins & Things in Moab, UT? on Poughkeepsie Gulch in the San Juans, CO? on Black Bear Pass?

I do not run trails like 'Metal Masher' or 'Poison Spider' in Moab, but I am not willing to accept the risk that a straightened shock mount will fail on any off-road trail.

Unfortunately the shock mount is part of the rear axel housing assembly (42110-60A52).


View attachment 3385948
Click to expand...

I’d heat and straighten but I think worst case a decent shop could grind off the old mount and weld a coupling nut inside there as a replacement.

I’ve also seen a few people weld a bolt higher up to get more shock travel, so you could cut out the old one and do that and then your shock would mount up with a washer and a nut instead of a bolt.

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kcjaz​

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• #320

I’d heat and straighten but I think worst case a decent shop could grind off the old mount and weld a coupling nut inside there as a replacement.

I’ve also seen a few people weld a bolt higher up to get more shock travel, so you could cut out the old one and do that and then your shock would mount up with a washer and a nut instead of a bolt.

Hey @elkeye, just pulled my driver rear BP51 shock off and found this:

A slight bend. I was able to temporarily put my OEM shock back on. Not sure what I’ll do to fix it. Probably heat and bend it back. Tempted to just ignore and keep rolling but I do think the bend doesn’t make the bushing very happy.

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Markuson​

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Hey @elkeye, just pulled my driver rear BP51 shock off and found this:

View attachment 3388958

A slight bend. I was able to temporarily put my OEM shock back on. Not sure what I’ll do to fix it. Probably heat and bend it back. Tempted to just ignore and keep rolling but I do think the bend doesn’t make the bushing very happy.

Amazing you managed to bend it.
Personally, I think bending it back sounds reasonable. -Not a life and death failure point. Just a bummer.

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kcjaz​

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• #322

Amazing you managed to bend it.
Personally, I think bending it back sounds reasonable. -Not a life and death failure point. Just a bummer.

My guess is that I bent it before I put the BB guards on. Not quite sure how to bend it back. Sure I can heat it but I don’t really want to hammer on it and bang it all up. I’m thinking maybe bore a hole on a bar and use the bar as a lever? Or maybe make a metal bushing to slide over the pin and hammer on it?

2013 200, T13 (Deer Slayer), BP-51, Slee sliders, ICON 17” Six Speed
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elkeye​

JoinedAug 10, 2015Messages143LocationSteamboat Springs, CO

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• #323

My guess is that I bent it before I put the BB guards on. Not quite sure how to bend it back. Sure I can heat it but I don’t really want to hammer on it and bang it all up. I’m thinking maybe bore a hole on a bar and use the bar as a lever? Or maybe make a metal bushing to slide over the pin and hammer on it?

The rear shock mount, like a coupling nut, has inside threads that may get damaged when trying to bend the mount back.

One idea to bend it back was to heat the mount and bend it back using a section of pipe (with a slightly larger inside diameter than the mount) as a lever. Keep our fingers crossed and hope for the best.

The question is how does the shock mount get bent downward?

Could the rear shocks have too soft of compression setting and bottom out … thereby allowing the shock mount to be pushed downward?

2015 LC200 - OME BP-51, SPC-UCA, ARB Winch Bar & Recovery Points, SLEE sliders, skid plate system, AL rear bumper, 2nd battery tray and ARB LED Light Brackets (with RIGID D2 Pro Driving Lights), STEDI Type-X Pro Driving Lights, IBS-DBR Battery System
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kcjaz​

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The rear shock mount, like a coupling nut, has inside threads that may get damaged when trying to bend the mount back.

One idea to bend it back was to heat the mount and bend it back using a section of pipe (with a slightly larger inside diameter than the mount) as a lever. Keep our fingers crossed and hope for the best.

The question is how does the shock mount get bent downward?

Could the rear shocks have too soft of compression setting and bottom out … thereby allowing the shock mount to be pushed downward?
Click to expand...

The pipe idea is what I meant by boring a hole in a bar. If the fit was snug enough, maybe it would keep the threaded hole round. Or maybe you could just thread a long bolt into the hole and use it as a lever to bend the mount back up.

As for how it got bent downward, I think I (we?) probably dragged the mount over a rock. If the shock bottomed out hard enough to bend the mount, I’d think that would have blown up the shock or bent the upper shock tower/mount.

2013 200, T13 (Deer Slayer), BP-51, Slee sliders, ICON 17” Six Speed
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[kcjaz]

For the OEM lower rear shock mount, is there supposed to be a large, thick washer that covers the bushing here:

The BB shock guards have a large mounting tab that functions as a washer against the bushing. I just don't recall if there originally was a big washer there and can't tell from the FSM picture. Seems like there should be. I'm pulling my BP51s off for rebuild and temporarily putting the old OEM shocks on.

 

[tbisaacs]

I am trying to imagine what would cause this. Maybe needs more bumpstop? Shock hit its compression limit and way over levered on that shock mount?

 

[bloc]

For the OEM lower rear shock mount, is there supposed to be a large, thick washer that covers the bushing here:

View attachment 3389138

The BB shock guards have a large mounting tab that functions as a washer against the bushing. I just don't recall if there originally was a big washer there and can't tell from the FSM picture. Seems like there should be. I'm pulling my BP51s off for rebuild and temporarily putting the old OEM shocks on.

The washer is captive on the shock bolt.

And your ideas of boring a hole into a bar to bend it or a mandrel to hammer on.. exactly what we’d do in the steel shop to resolve that issue.

My big question is why? Shocks bottoming? I don’t see dragging a shock doing this. If anything it would bend up. But a mostly-hollow post at a right angle to the shock travel not mounted in double shear.. in my head that would give long before the upper mount would.

 

[kcjaz]

The washer is captive on the shock bolt.

And your ideas of boring a hole into a bar to bend it or a mandrel to hammer on.. exactly what we’d do in the steel shop to resolve that issue.

My big question is why? Shocks bottoming? I don’t see dragging a shock doing this. If anything it would bend up. But a mostly-hollow post at a right angle to the shock travel not mounted in double shear.. in my head that would give long before the upper mount would.

would you use heat or just beat on it cold? If heat, how much (i.e. grey, orange, red)? I wouldn't worry too much about weakening it from a strength perspective but I would worry about making it brittle or too hard though and making it susceptible to cracking.

As for how, IDK. The way the BB guards are mounted creates a pivot point above and in back of the lower mount. Bashing rocks would tend to put a bending moment on the hollow post. A shock bottoming out would be potentially worse as the load would be perpendicular to the hollow post. I just would have though that would damage the shock but perhaps the hollow post is the weak link in that situation.

 

[bloc]

would you use heat or just beat on it cold? If heat, how much (i.e. grey, orange, red)? I wouldn't worry too much about weakening it from a strength perspective but I would worry about making it brittle or too hard though and making it susceptible to cracking.

As for how, IDK. The way the BB guards are mounted creates a pivot point above and in back of the lower mount. Bashing rocks would tend to put a bending moment on the hollow post. A shock bottoming out would be potentially worse as the load would be perpendicular to the hollow post. I just would have though that would damage the shock but perhaps the hollow post is the weak link in that situation.

I’d see how much trouble I had with it cold then move to some heat. My concern with making it too soft would be bending the threaded end. Perhaps a bolt threaded in while fixing to preserve things. Also IMO there is a large distinction between yours and the other heavily bent post. That one likely isn’t going back happily without making the steel soft.

And shocks can deal with tremendous forces.. at least with my kings when they do bottom it’s not internal. It is the flat bottom of the shock hitting the flat top of the rod end adapter. Certainly not good for the shock mounting system, but from my understanding unlikely to cause leaks or internal damage or anything. But, you’d definitely feel something like that through the chassis. It would be a sudden, sharp, bang.. at full compression. And unlikely with our jounce and bump stop configuration. But possible if the shock body is just too long.

 

[TeCKis300]

Answering the question first, I wouldn't hesitate to bend it back. The shock mount isn't really safety critical in an LC. Maybe more in an LX where AHC uses it to also carry load.

Heat is okay, but not too much to keep this mount from becoming brittle. Take my comments with a grain of salt as metallurgy is not an area I practice, but don't heat it beyond probably gray or ~750*F, using reference from a basic non-contact thermometers. Then allow it to slowly cool after fixing.

I would use a close fitting metal sleeve over it. Put a bolt in to avoid deforming with a grinded down bolt head. Then a large lever like the steel handle of a jack.

For the metal sleeve, best would be the inner sleeve from the OEM bushing. Then maybe sockets if additional spacers are needed to the lever tube size.

As for how this is happening, I'm scratching my head. It shouldn't be that the shock is the compression limiter and able to exert that type of force without blowing out the shock too? The way these are bending is weird too. The stock shock bushing has a robust metal inner sleeve that reinforces the mounting stud such that when bolted down, most of the forces would be concentrated at the stud base. Yet these things are bending mid-way within the sleeve??

I wonder if it's due to badly designed aftermarket spherical mounts that are not using a proper supporting sleeve with the ball swivel? And simply placing a floating ball swivel on the mounting stud. That would be my guess, which puts forces on the single sheer mount in ways it was never designed for.

 

[bloc]

I can’t speak for other shocks but my kings have a very solid misalignment spacer over the post, which working with the bolt being tight effectively increases its diameter/strength substantially.

And I went and looked closely at my shocks.. they could absolutely bottom without harming the shock itself. The problems would be at the mounting at the ends.

 

[Fisher23]

We would bend them back on the MDR and SCORE race vehicles all the time without issues.

 

[TeCKis300]

Correct me if I'm wrong as I haven't seen these shocks first hand. Adding some pictures to help but it would be helpful to have pics of the actual lower mounting hardware.

I can't find specific pics of real BP51s but the instructions already have me concerned with the washer on the inside of the mount. Does the OME lower bushing have an inner metal sleeve? Or are they just putting the rubber bushing over the stock stud? Hopefully I'm wrong, but I suspect that is what it is based on the failure pictures above. This configuration is really suspect as it puts the lower shock mount in a much weaker cantilever configuration rather than single sheer. That'll give up enough strength that with heavy loads and extreme use, might be what we're seeing above.

I can’t speak for other shocks but my kings have a very solid misalignment spacer over the post, which working with the bolt being tight effectively increases its diameter/strength substantially.

And I went and looked closely at my shocks.. they could absolutely bottom without harming the shock itself. The problems would be at the mounting at the ends.

The Kings sounds like they would be configured right for the single sheer mount. The spacer in really critical as it significantly contributes to handling side loads when it is compressed by the OEM shock mount that works more as a tensioning component when bolting down on the spacer. I imagine the Kings setup looks somewhat like this?

 

[kcjaz]

Correct me if I'm wrong as I haven't seen these shocks first hand. Adding some pictures to help but it would be helpful to have pics of the actual lower mounting hardware.

I can't find specific pics of real BP51s but the instructions already have me concerned with the washer on the inside of the mount. Does the OME lower bushing have an inner metal sleeve? Or are they just putting the rubber bushing over the stock stud? Hopefully I'm wrong, but I suspect that is what it is based on the failure pictures above. This configuration is really suspect as it puts the lower shock mount in a much weaker cantilever configuration rather than single sheer. That'll give up enough strength that with heavy loads and extreme use, might be what we're seeing above.

View attachment 3389859



The Kings sounds like they would be configured right for the single sheer mount. The spacer in really critical as it significantly contributes to handling side loads when it is compressed by the OEM shock mount that works more as a tensioning component when bolting down on the spacer. I imagine the Kings setup looks somewhat like this?

View attachment 3389867

I think you are on to something here. The BP51 lower bushing is just rubber with no inner sleeve.

Currently I can’t get the OEM back on because the mount is bent. I think I could hammer it on but I’m worried it won’t come off.

As for bending it back a 19mm socket fits over it pretty well just need to find a piece of pipe to go over that.

Or maybe thread in a long bolt and pry up on it? Or as a third option, thread in the bolt and cut the head off and use both.

 

[TeCKis300]

I think you are on to something here. The BP51 lower bushing is just rubber with no inner sleeve.

View attachment 3389969View attachment 3389970

Currently I can’t get the OEM back on because the mount is bent. I think I could hammer it on but I’m worried it won’t come off.

As for bending it back a 19mm socket fits over it pretty well just need to find a piece of pipe to go over that.

View attachment 3389973

Or maybe thread in a long bolt and pry up on it? Or as a third option, thread in the bolt and cut the head off and use both.

Bummer. Sorry to see this and I would really have expected better from a big name like Arb.

That socket could work with maybe a floor jack to put bending pressure on it? Want to make sure there is enough leverage to bend it back in a controlled fashion to not overshoot.

That's an awesome jack you have...been eyeing them.

 

[kcjaz]

Bummer. Sorry to see this and I would really have expected better from a big name like Arb.

That socket could work with maybe a floor jack to put bending pressure on it? Want to make sure there is enough leverage to bend it back in a controlled fashion to not overshoot.

That's an awesome jack you have...been eyeing them.

I e emailed the ARB guy who is working on my rebuild order and asked if the have seen this on other 200s. I’m now not sure I want to keep running them.

I believe you can buy replacement OEM bushings and it would be cool if they would just fit the BP51 shock but I don’t think they would fit the BP51s.

 

[TomEf]

Then allow it to slowly cool after fixing.

Absolutely take this advice. This is your ticket to avoid any brittleness (not likely but might as well avoid) or cracking during cooling (also not all that likely but might as well avoid too). Throw a welding blanket or similar on top when you’re done and let it cool slowly. Don’t try to cool it quickly.

As for strength, I wouldn’t be too concerned. The worst thing you could do is leave it too hot for too long, but dollars to donuts you could heat it up, bang it straight, and be done before being anywhere near the ballpark of being concerned with grain growth, etc. For temperature, about as cold as it can be and about as hot as it needs to be to move. Don’t sweat it too much.

Don’t forget you’ll probably want to repaint it. Totally something I’d forget and then be pissed that it’d be on jackstands for extra time while the paint dried.

I’m a materials scientist and used to work in aerospace heat treat and welding. I left that specialty last year but luckily basic steels are still basic steels and are pretty forgiving.

 

[TeCKis300]

Absolutely take this advice. This is your ticket to avoid any brittleness (not likely but might as well avoid) or cracking during cooling (also not all that likely but might as well avoid too). Throw a welding blanket or similar on top when you’re done and let it cool slowly. Don’t try to cool it quickly.

As for strength, I wouldn’t be too concerned. The worst thing you could do is leave it too hot for too long, but dollars to donuts you could heat it up, bang it straight, and be done before being anywhere near the ballpark of being concerned with grain growth, etc. For temperature, about as cold as it can be and about as hot as it needs to be to move. Don’t sweat it too much.

Don’t forget you’ll probably want to repaint it. Totally something I’d forget and then be pissed that it’d be on jackstands for extra time while the paint dried.

I’m a materials scientist and used to work in aerospace heat treat and welding. I left that specialty last year but luckily basic steels are still basic steels and are pretty forgiving.

Just the guy we need. Thanks for the insight!

 

[bloc]

100% this is happening because ARB effectively weakened the shock mount post by eliminating the captive sleeve. I'm quite surprised they'd do this.

Will get pics of the king spacers tomorrow, just to add info to the thread.

 

[04UZJ100]

If this isn’t happening on @cruiseroutfit Monica than it is 100% related to the guards.

 

[kcjaz]

Absolutely take this advice. This is your ticket to avoid any brittleness (not likely but might as well avoid) or cracking during cooling (also not all that likely but might as well avoid too). Throw a welding blanket or similar on top when you’re done and let it cool slowly. Don’t try to cool it quickly.

As for strength, I wouldn’t be too concerned. The worst thing you could do is leave it too hot for too long, but dollars to donuts you could heat it up, bang it straight, and be done before being anywhere near the ballpark of being concerned with grain growth, etc. For temperature, about as cold as it can be and about as hot as it needs to be to move. Don’t sweat it too much.

Don’t forget you’ll probably want to repaint it. Totally something I’d forget and then be pissed that it’d be on jackstands for extra time while the paint dried.

I’m a materials scientist and used to work in aerospace heat treat and welding. I left that specialty last year but luckily basic steels are still basic steels and are pretty forgiving.

Thanks! I’m going to give it a shot without any heat mostly because I don’t have a torch where I am.

 

[bloc]

King 2.5 rear lower.

Edit: these sleeves fit very tight on the posts, so if you moved to something like this the post would need to be very, very straight.

 

[bloc]

If this isn’t happening on @cruiseroutfit Monica than it is 100% related to the guards.

Good point on Monica, but I disagree on the cause.

IMO what teckis is talking about with the lack of a sleeve is the cause. The stock shocks even have this sleeve that when the bolt is tightened against it this effectively increases the diameter of the post substantially, and changing the geometry of where the forces are applied along it. King and others accomplish this with misalignment spacers. The LX supports significant load on these posts, with the stock sleeve.