Upper Rear Shock Mounts - Broke 'em both

[BackinBlackS550]

The AD-1118 mount is the same as the GTs. I know because I bought a few pairs after mine broke

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[DickR]

The AD-1118 mount is the same as the GTs. I know because I bought a few pairs after mine broke

I'll clarify my post. The mount pic is the GT mount. The GT350 mount is only shown in the MagneRide pic. It looks like the only difference between it and the GT mount is the bracket for the cable.

 

[Project Whitemare]

Wicked bummer :(


Were you using Viking shocks or OEM?

AirLift shocks.

I attribute the failure of the part to the lack of bump stops, more aggressive stance I was driving in, and my speed all played a factor here.

My fault, not the OEM part. However, I'd really like the idea of a HD version!

I dont get how frpp gets away with their upgrade shocks and springs not breaking it...

There haven't been too many reports of these breaking IIRC. The Viking shocks and now my AirLift. Mine was an actual failure that was a direct result of bottoming out. I'm sure these mounts would have broke with the same hit on OEM shocks as well. Just a really jarring hit I took. No fault of anyone but my own.

 

[theman]

Looks like and extra upper shock mount washer may be an easy initial upgrade to spread the load around circle of the mount face at least... something similar to these bmw 318 upper washers with the heavier thickness towards shaft center may help.
part # 33 52 1 092 363 for $2 each is worth a look...

or number 4 is this for a better idea of the thickness change towards center I am referencing...

 

[DickR]

theman - Are you suggesting that the large od washer be used to bypass the rubber mount that currently is supposed to carry the shock compression and rebound forces?

 

[theman]

heck no! I am suggesting augmentation of the rubber mount with the specific load-baring washer, to spread what looks like a small area of stress at the center of the shaft hole and the center of the rubber mount across the whole circular area of the mount.

So take the shock, slide the washer onto the shaft until it seats on that shaft shoulder, then slide the rubber mount on the shaft next, then the mount over that...
rear shocks are on the right side here for example...notice the shouldered seat area on the shaft. As folks have stated it is only about 17-19mm across. Set onto that the specified washer with thickened structure towards the shaft and you now spread that same load across a 40-50mm area contacting the entire rubber mount and in turn the entire circular area of the cast aluminum mount.

 

[DickR]

I think I see what you are saying but I could be all wet.:doh:

Unless the additional washer is smaller OD than the hole in the casting but larger than the nut that current takes the load it will bear on the casting instead of the oem rubber encased metal plate. In the oem design the shock shaft bears on the rubber encased metal plate which popped out of the overall mount in the original poster's pictures.

He didn't actually punch the shock rod through the oem rubber encased metal plate. He pushed that plate out the top of the mount. Essentially the relatively weak top of the mount (compared to the casting and the metal plate) served as a shear pin rather than other parts bending or breaking.

I suspect the real issue is the lack of bump stops in both failures that we know about.

The oem bump stop shown below bears on the casting when heavily loaded IF the shock rod doesn't bottom first. The oem bump stop is progressive but will rapidly compress to essentially solid given enough shock rod travel.

You can see from the first pic below that the bump stop (which is hidden by the dust cover) fits into the recess in the casting so that when the shock body compresses the bump stop the load is directed to the casting.

 

[theman]

Aaaah, now I'm seeing clear-er DickR... the whole top half mount circle popped right off, leaving only the bottom circle half and ears attached to car. So the rubber mount comes encased in the mount, with the top thin section bearing all that load? That is insane, as the bottom circular section of the mount is 4x as thick and yet bears no force until the shock bottoms out and bump stop would actually contact it.

These mounts would work waaaay better flipped upside down with the thicker section up top!

 

[BMR Tech]

For those reading who have the Viking Shocks, I recommend installing bump-stops.

They are somewhat tricky to get over the top of the Viking Shafts. You can simply unthread the upper portion of the Viking, put the stop on, and re-attach the upper portion - or you can slide the stop over the shaft (this is a tight fit)

As for the bump stop itself, it is easiest to use the following bump-stop part # when using the Viking Shocks.

FR3C-5K570-A (The A part # has a larger top ID)

If you are also lowered, I recommend trimming the lower portion of the rear stop approximately 3/4".

I am working with Viking on a shaft design that makes the Bump Stop install easier, as well as some different shock bodies to help prevent bottoming out based on various ride heights. It is looking like it will be about 5-6 weeks before these are available.

 

[Jmeo]

Great work Kelly! I will be patiently waiting for the revised shocks

Jaime

 

[DickR]

As for the bump stop itself, it is easiest to use the following bump-stop part # when using the Viking Shocks.

FR3C-5K570-A (The A part # has a larger top ID)

If you are also lowered, I recommend trimming the lower portion of the rear stop approximately 3/4".

For reference so that you you what it looks like that is the GT PP bump stop shown on the shock picture that I posted. I know because I bought a pair. The part itself has a "B" even though the part number has the "A".

 

[dwaleke]

I am working with Viking on a shaft design that makes the Bump Stop install easier, as well as some different shock bodies to help prevent bottoming out based on various ride heights. It is looking like it will be about 5-6 weeks before these are available.

Great work Kelly! I will be patiently waiting for the revised shocks

Now this is excellent customer service. Replacing everyone's shocks with new parts that work correctly for the S550. Very happy to see this.

Way to go BMR and Viking!

 

[Nanashii]

For those reading who have the Viking Shocks, I recommend installing bump-stops.

They are somewhat tricky to get over the top of the Viking Shafts. You can simply unthread the upper portion of the Viking, put the stop on, and re-attach the upper portion - or you can slide the stop over the shaft (this is a tight fit)

As for the bump stop itself, it is easiest to use the following bump-stop part # when using the Viking Shocks.

FR3C-5K570-A (The A part # has a larger top ID)

If you are also lowered, I recommend trimming the lower portion of the rear stop approximately 3/4".

I am working with Viking on a shaft design that makes the Bump Stop install easier, as well as some different shock bodies to help prevent bottoming out based on various ride heights. It is looking like it will be about 5-6 weeks before these are available.

Great news, thanks for the update! Are the revised upper mounts still in the works?

 

[BMR Tech]

For reference so that you you what it looks like that is the GT PP bump stop shown on the shock picture that I posted. I know because I bought a pair. As I recall the part itself has a "C" even though the part number has the "A".

I've got so many bump stops laying around and on my desk, I can't see straight.

All the stock ones, and some aftermarket ones.

I still don't know why there are discrepancies. For example, when we order "PP" stops, we get the larger ID versions for the rear....but the PP comes with smaller OD shafts (the monotube PP shaft is smaller than the TT base shock) - and of course, my base model stops which I am holding right now, with a "B" part # - have a smaller ID....yet the base shock is a larger TT shaft.

lol

 

[DickR]

Kelly - My "as I recall" was wrong. The PP part is marked with a "B" suffix. Original post corrected.

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