Broken driver rear shock mount

[EZ-GT]

After putting on some divorced rear coil overs, I must have adjusted the Shocks too high when compared to the height of the Springs because after a few hours of driving I hit a dip in the road at about 110 mph and heard a big bang. After driving around every little bump I hit, I get a knock sound in the driver side rear.

I took a look to see if it the Shock Bracket was loose and it was far worse, completely broken, and the inner bushing shot right through the top.

The passenger side looks ok, so will only have to replace one of them, but here is the question. There are two part numbers from Motorcraft AD-1123 and AD-1118, and both are listed to fit my 2019 GT Convertible.

AD-1123

AD-1118

Comparing the two, one has a metal cover over the top and other just the rubber bushing, Looking at my passenger
side, I have the AD-1123 model.

Passenger side rear:

Just curious as to why there would be two different ones and is the AD-1118 stronger with the metal portion?

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[Dana Pants]

Looks like you bottomed out the shock and the mount failed as intended. What happened to your bump stops and is the shock compressed length different than stock?

Sorry I don’t have an answer to your main question.

 

[EZ-GT]

Looks like you bottomed out the shock and the mount failed as intended. What happened to your bump stops and is the shock compressed length different than stock?

Sorry I don’t have an answer to your main question.

There appears to be some type of bushing under the dust sleeve, as I don’t see how regular bump stops like the kit from Steeda could be added because of the shock damper adjustment wheel on the top.

-stock pics, not my car-

Also there was no mention of needing anything else on the AM installation video either.




The Steeda and Ford Performance bump stops are relatively inexpensive so I wouldn’t mind adding them in if I knew they would help?

 

[EZ-GT]

I probably should just invest in the Steeda brackets instead.

https://www.steeda.com/steeda-555-8...oCJAoQAvD_BwE#/filter:ss_ymm:Mustang$253E2019

 

[Dana Pants]

You could, but first look at the threads where the aftermarket mounts rip off the unibody. I think either raise the ride height or put in a stiffer spring are your best bets.

 

[fatbillybob]

OP,

The conclusion it that this is a poorly designed area. The sheetmetal is too thin. The shock mounts too weak. mount break so that the thin sheet does not rip. The solution is making sure the shocks have the right stroke for the ride height. Do not bottom out your shocks. Running big coilover springs also puts stress on the metal. If going big coilovers consider better steel shock mounts like J&M or others, make sure you have proper shock travel, consider plating the thin sheetmetal, consider adding to the mount to distribute the loads like the one shock company who adds 2 more anchors per side and has a big plate to distribute loads over the thin sheet. I for get their name. I like the J&M mounts because it is easy to weld a plate to them and copy the load distribution mounts.

 

[EZ-GT]

Yes it was definitely too low, as it dropped significantly after the suspension set in.

Plan on adding back about 1/2 to 3/4 of an inch in height.

 

[tj@steeda]

I probably should just invest in the Steeda brackets instead.

https://www.steeda.com/steeda-555-8...oCJAoQAvD_BwE#/filter:ss_ymm:Mustang$253E2019

Shoot me a note if I can help assist - we have forum discounts to soften the blow. You can email me at [email protected]

TJ

 

[EZ-GT]

OP,

The conclusion it that this is a poorly designed area. The sheetmetal is too thin. The shock mounts too weak. mount break so that the thin sheet does not rip. The solution is making sure the shocks have the right stroke for the ride height. Do not bottom out your shocks. Running big coilover springs also puts stress on the metal. If going big coilovers consider better steel shock mounts like J&M or others, make sure you have proper shock travel, consider plating the thin sheetmetal, consider adding to the mount to distribute the loads like the one shock company who adds 2 more anchors per side and has a big plate to distribute loads over the thin sheet. I for get their name. I like the J&M mounts because it is easy to weld a plate to them and copy the load distribution mounts.

After I raise it up I will check the shock height to ensure it’s closer spec to the spring height, but for sure will order the Steeda brackets to be safe.

At 110 MPH it was a little scary, I can’t even imagine something like that happening at 150 mph.

 

[EZ-GT]

Shoot me a note if I can help assist - we have forum discounts to soften the blow. You can email me at [email protected]

TJ

Thank you, as I have used it before

 

[Hotpart.com]

There's a problems with the design of that rear shock from ISC. The stock/factory bumpstop is about 3 inches long very soft progressive bumper that gets compressed on the bottom of the aluminum shock mount which helps reduce the loads going into the body/sheet metal. The ISC bumpstop is 1/2 inch long hard bumpstop that when it gets loaded it puts all the force through the rubber part of the mount not the designed bottom of the mount. Basically what's happening is every time you hit the bumpstop you are spiking the force causing overloading the rubber mount area along with the swaged area that holds the rubber in place. My concern is that you will tear the sheet metal over time if you switch to a mount like ours or the Steeda based on the design of that shock setup.

 

[WildHorse]

I probably should just invest in the Steeda brackets instead.

And if you don't properly adjust it again, the same thing will happen, or depending on the strength of those steeda pieces, something else could fail. Also as mention earlier, proper bump stops depending on how much drop you want.

 

[EZ-GT]

Well noted on all of your comments, as this all makes sense.

I already lowered the shock down to what ISC recommends it to be as relative to the height of the spring.

It looked like I had the shock at nearly its highest setting (set to about 1/2 inch drop) while the spring was set at nearly its lowest (set to 2 1/2 inch drop). This must of contributed to the whole ordeal.

Am still concerned about the overall design as it doesn’t seem the best, sand will consider going with a different setup all together.

Thanks again for everyone’s contributions.

 

[K4fxd]

The AD-1123 is for mono tube shocks. I don't know if it stiffer or softer, but that mount comes on the GT350 and R

This is the Ford part number for the mono tube version. An "A" suffix makes it the twin tube model.

FR3Z-18A161-B

 

[EZ-GT]

The AD-1123 is for mono tube shocks. I don't know if it stiffer or softer, but that mount comes on the GT350 and R

This is the Ford part number for the mono tube version. An "A" suffix makes it the twin tube model.

FR3Z-18A161-B

Great to know, as the AD-1123 came on my 2019 GT Convertible too, maybe Ford changed from the AD-1118 in the later years of the S550.

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