[Mountain]

Originally Posted by Ryephile

Ok just checked. 23136675 is the tag on my rear springs. Could we be missing a Chevrolet-to-Cadillac cross-reference somewhere? That part number is for the ATS-V sedan rear spring. Why would GM have those other Camaro FE4 spring numbers too?

Well, after I checked the first 1LE, I thought it was odd too. Almost like, “Did LGR put the wrong springs on this car?” But, I had to bring myself back to a DRE mindset when I worked at an OEM... It makes total sense to reuse parts, especially since it’s the same platform and nearly same exact suspension (dimensionally). All the engineering is essentially done and all the production costs are done. The major difference with the ATS suspension over the Camaro is in the front. Hence, needing special springs.

[RUQWIKR]

Originally Posted by Ryephile

Thanks. Do we have a way to verify this? Maybe a build-date break point? Hopefully sooner rather than later the online parts catalogs will be updated accordingly.

Working on it.

[Ryephile]

Originally Posted by Mountain

Well, after I checked the first 1LE, I thought it was odd too. Almost like, “Did LGR put the wrong springs on this car?” But, I had to bring myself back to a DRE mindset when I worked at an OEM... It makes total sense to reuse parts, especially since it’s the same platform and nearly same exact suspension (dimensionally). All the engineering is essentially done and all the production costs are done. The major difference with the ATS suspension over the Camaro is in the front. Hence, needing special springs.

Oh I definitely understand that. My question is more along the lines of, is there a way to get a Chevrolet to Cadillac Alpha platform part number cross-reference?

[Mountain]

Originally Posted by Ryephile

Oh I definitely understand that. My question is more along the lines of, is there a way to get a Chevrolet to Cadillac Alpha platform part number cross-reference?

Oh, man. Technically yes, but I feel like that's digging into some information only a good dealer parts person or GM engineer could dig up. That would be sweet though.

[ChildhoodMuscle]

Originally Posted by Ryephile

Front strut mounts. This is a little strange. All cars get # 840103429, except F55 [aka MRC] FE3 cars, those get 84013428.

Hi, does anybody know why this is?

I'm thinking about upgrading various suspension components on my 2SS to the 1LE components, and wondering under what combinations of components the strut mounts need to be changed.

For example, if I change to 1LE sway bars & handling links but not springs (go with aftermarket ones instead), do I need to change strut mounts?

[Ryephile]

Originally Posted by ChildhoodMuscle

Hi, does anybody know why this is?

I'm thinking about upgrading various suspension components on my 2SS to the 1LE components, and wondering under what combinations of components the strut mounts need to be changed.

For example, if I change to 1LE sway bars & handling links but not springs (go with aftermarket ones instead), do I need to change strut mounts?

I wish I had a solid answer. A key is to look at the GM Performance 1LE suspension kit that comes with springs, anti-roll bars, and front control links. It also includes new strut mounts. Strangely it's missing the FE4's rear trailing links, rear subframe bushings, and rear knuckle though.

Anyway, look at this link and scroll down to "mount"

https://www.gmpartsgiant.com/parts-l...ilter=(m=1AJ37)

You'll see 3 entires. The first is "84103428", for FE3, F55, or a normal SS with MRC. The 2nd and 3rd entires are actually the same thing, but the note on the 3rd one says it's for kit #84130608, which is that GMPP 1LE suspension kit, thus reinforcing that the FE4 suspension uses the #84103429 strut mount.

[ChildhoodMuscle]

Thank you for the answer! But I guess ultimately either someone from GM who knows have to answer, or someone with the physical parts in hand might be able to tell us what's the difference between the strut mounts.

[Ryephile]

I just found the FEA rear cradle part number, and woah doggie it's expensive!

84224918 and an SRP of $2.024.59! It does include all the bushings and the aluminum mounts though.


I also updated the springs & dampers post to include new FEA numbers. It appears the FEA front struts are sold in two parts; housings and inserts. The housing part numbers say "assembly" and are priced such that they seem like they should include everything, but I can't verify that. Nevertheless, the prices make buying the whole #84352121 DSSV retrofit kit a good deal!

[cooper1965]

@Ryephile - Thank you sir for this work!

[Ryephile]

Originally Posted by RUQWIKR

Working on it.

Quick data point. I was rotating my winter tires yesterday and had a close look at the rear knuckles, comparing them to the FEA knuckles that came with my #84352119 ZL1 1LE links & bushings kit. They appear to use identical bushings, complete with the booted LCA ball joint. My SS 1LE is an early November 2016 build, an early 2017 build. So the questions are; are all SS 1LE's using the FEA knuckle, is there a build-date break-point, and do the ZL1 FE4's use the FE4 or FEA part number? Quite strange.

[Mountain]

Originally Posted by Ryephile

Quick data point. I was rotating my winter tires yesterday and had a close look at the rear knuckles, comparing them to the FEA knuckles that came with my #84352119 ZL1 1LE links & bushings kit. They appear to use identical bushings, complete with the booted LCA ball joint. My SS 1LE is an early November 2016 build, an early 2017 build. So the questions are; are all SS 1LE's using the FEA knuckle, is there a build-date break-point, and do the ZL1 FE4's use the FE4 or FEA part number? Quite strange.

Are you talking about the the knuckle mounting area for the actual lower control arm (the arm supporting the spring) or the lower trailing arm? Because the actual lower control arm mount on my '16 SS's knuckle is a spherical...

https://www.mishimoto.com/engineerin...ar-suspension/

The picture shows it (a little hard to see), but the video shows it better and the BMR guy even comments on it.

I always thought the FEA knuckle was just different in that the actual bushings were just stiffer. That's it.

[Ryephile]

Hmm, you bring up an interesting point.

Both the knuckles I've seen (on my car, and in the FEA kit box), have solid [non-spoked] rubber bushings on both trailing links and upper lateral link, but I have no good way to test to durometers.

Oh, another point. In GMPartsGiant's listing, 84089877 & 84089878 are now replaced by 84258571 & 84258572, meaning we're down to 3 sets of part numbers. There are still separate numbers for FE2 and FE3.

[RUQWIKR]

Originally Posted by Ryephile

Hmm, you bring up an interesting point.

Both the knuckles I've seen (on my car, and in the FEA kit box), have solid [non-spoked] rubber bushings on both trailing links and upper lateral link, but I have no good way to test to durometers.

Oh, another point. In GMPartsGiant's listing, 84089877 & 84089878 are now replaced by 84258571 & 84258572, meaning we're down to 3 sets of part numbers. There are still separate numbers for FE2 and FE3.

There are two PN's on the knuckles, whether the old version or new version. There is a spot drill next to the PN the final assembly number is. On car, take a lighted mirror between the e-brake backing plate and the lower section of the knuckle to see this.

[Ryephile]

Originally Posted by RUQWIKR

There are two PN's on the knuckles, whether the old version or new version. There is a spot drill next to the PN the final assembly number is. On car, take a lighted mirror between the e-brake backing plate and the lower section of the knuckle to see this.

I'll put that on the to-do list. Thanks.

*edit* was able to use my phone to take a picture of the casting numbers. On the right I have 84089878, the "ZL1 series". Any idea what the difference is between that and the new 84258572? They look identical in terms of bushings and ball-joints.