Do we need reinforcement plates?

[dre99gsx]

Trying to get feedback on those who track their Z4's hard:

- Rear shock upper reinforcement plate: Anyone actually have this go bad requiring that plate on top of the shock mount?
- Rear lower spring perch reinforcement plate: I saw just one photo of a upper control arm where the cast aluminum perch cracked through. I don't know how it happened, but any Z4's experience this issue? The plate would sit on the bottom of the rear spring to spread the load. I actually run lower and upper rubber spacers (OEM units) and haven't really had an issue. Yes, 700lb/in rear springs... trying to avoid unnecessary plates
- Front upper shock reinforcement plate - are these failures consistent necessitating the plates? I don't have a strut bar, but trying to also avoid if not needed.
- Front ARB plates: I've seen many failures, so I do have thicker units welded in place. Good here

Anything else I need to reinforce suspension-wise?

[B328iC]

A while back I asked about the front plates. A lot of people suggested using them. Nobody came back and said they had issues that required them. Always referred to as cheep insurance.
If you look around the only reinforcement plates out there are for E46 BMW's. You will need to remove the alignment pin to get them to fit but they will in fact fit.

[No_Dominion_2]

Originally Posted by B328iC

A while back I asked about the front plates. A lot of people suggested using them. Nobody came back and said they had issues that required them. Always referred to as cheep insurance.
If you look around the only reinforcement plates out there are for E46 BMW's. You will need to remove the alignment pin to get them to fit but they will in fact fit.

I installed a set for the same line of reasoning. These cars might not currently show susceptibility to strut tower deformity, but strut towers are always a potential weak point for any vehicle. $75 a pair to significantly reduce the chances of problems down the literal and figurative road was a no-brainer for me. I also installed ECS rear shock mount reinforcement plates at the same time when I installed my coilovers for the same reason.

[Vanne]

the only rear spring pertch seat that ive seen cracked was in a major acco, those rear upper control arms are strong as hell, zero issues..

The rear subframe mounts are a different cattle of fish. ill be looking to re-enforce that when i start pulling my stuff apart, or not, i havent decided on that yet.. depending on how it looks when it comes out. Obviously that would depend on what youve been running. Solid mounts? there might be some issues.. just have a good look and see what you think. I have solid mounts , so thats why ill need to assess that area when it comes to it, if youve got polly, id say there will be zero issues..
Unless your running rear coil overs, no need to re-inforce the rear shock towers.

[dre99gsx]

I run KW Clubsport, but all poly bushings in rear subframe.

[dre99gsx]

Safe to say then the rear upper control arm spring perch reinforcement plate is unnecessary? I am running the spring on top of the OEM rubber mat, unlike some kits I've seen where the lower spring mount is directly bolted to the upper arm.

The rear upper shock mount reinforcement is easy to add, low weight.

The front shock upper reinforcement I suspect needs to be added. I looked at my perches from the top and can see the indent starting appear. I'm hoping the added thickness of the plate doesn't impact ride height - I'm at the end of spring adjustment on my KWs (yeah I have long springs I guess).

Assumption is mounting anything on the TOP of the front spring perch won't aid in reinforcement anyway?

[No_Dominion_2]

Originally Posted by dre99gsx

Safe to say then the rear upper control arm spring perch reinforcement plate is unnecessary? I am running the spring on top of the OEM rubber mat, unlike some kits I've seen where the lower spring mount is directly bolted to the upper arm.

The rear upper shock mount reinforcement is easy to add, low weight.

The front shock upper reinforcement I suspect needs to be added. I looked at my perches from the top and can see the indent starting appear. I'm hoping the added thickness of the plate doesn't impact ride height - I'm at the end of spring adjustment on my KWs (yeah I have long springs I guess).

Assumption is mounting anything on the TOP of the front spring perch won't aid in reinforcement anyway?

The strut tower reinforcement plates are surprisingly thin, around 1mm or so. It surprised me how thin they were when I put mine on, but they seemed extremely sturdy.

[dre99gsx]

Wow...

I didn't take pictures, but the front strut towers were REALLY starting to bulge upward! I got the plates and began to install them. I test fitted the plate underneath the drive tower and it wouldn't sit flush on the inner diameter area. There was about 1/4" gap. Matter of fact, I could see the indent of the strut camber plate creasing bulging up from tower.

I saw someone had trimmed the outer edge of the reinforcement plate but It seemed to me something else was not right to have to do that trimming.

So, I started hammering away with a big hammer and wood block to flatten the shock tower back down, and finally got it flat again. This explains why my drive side shock height adjustment was almost 1/8" off from the left side just to maintain the same corner ride height as the passenger side.

Passenger side isn't as bad, but required just a small tap on top to get it flat.

I highly recommend you guys check your strut towers.

[No_Dominion_2]

Originally Posted by dre99gsx

I highly recommend you guys check your strut towers.

Yikes!!! Sounds like you caught it in time, but that’s definitely disturbing. Makes me thankful I reinforced when I did. I’m actually surprised mine didn’t have issues like that, considering the endless supply of potholes we have here in Indy.

[CJW2OO4]

How much you guys pay to get the rear subframe bushings swapped out?

[F360C]

Originally Posted by dre99gsx

Trying to get feedback on those who track their Z4's hard:

- Rear shock upper reinforcement plate: Anyone actually have this go bad requiring that plate on top of the shock mount?
- Rear lower spring perch reinforcement plate: I saw just one photo of a upper control arm where the cast aluminum perch cracked through. I don't know how it happened, but any Z4's experience this issue? The plate would sit on the bottom of the rear spring to spread the load. I actually run lower and upper rubber spacers (OEM units) and haven't really had an issue. Yes, 700lb/in rear springs... trying to avoid unnecessary plates
- Front upper shock reinforcement plate - are these failures consistent necessitating the plates? I don't have a strut bar, but trying to also avoid if not needed.
- Front ARB plates: I've seen many failures, so I do have thicker units welded in place. Good here

Anything else I need to reinforce suspension-wise?

I have the plates on the rear upper control arms and i would suggest them. I am running around the same rates as you and I think it is the only thing that has stopped the springs from ripping through arms. Even with the plates my control arms have deformed a little over the years. They are definitely not flat now.

I think I was around one of the first to ripped the front ARB mounts out but since reinforcement I have had no issues.

I did the front upper shock tower reinforcements early in my cars life and even though i have been running 700+ lbs front springs for half of my cars life the front shock towers are still perfectly flat.

The only one you don't have listed that I thought of was the rear trailing arm pocket reinforcement. I think this is more of an E36 thing but they do make them for the e46 which i think would fit our cars. I have seen some videos of these failing on track in e36s and it looks like a wild ride when they go. I inspect this area often to make sure no cracks are forming.

[Vanne]

Sourced a table today to function as a carrier for when i rip out the rear subframe

[FigureItOut]

I added the front and rear strut tower reinforcements and a strut tower brace when i swapped in my BC Coilovers. I didn't see any obvious indication that they were deforming but as mentioned above its was an extra $40 for "insurance" and minimal additional effort while I was in there. I get the sense it might be excessive for factory or factory-ish installs. I was switching to a stiffer spring rate and shorter travel so it seemed like it couldn't hurt to hedge my bets some.

[wdb]

Wasn't there something about front swaybar mount points? I'm working from foggy memory here, ignore as needed...

[thrak410]

Originally Posted by wdb

Wasn't there something about front swaybar mount points? I'm working from foggy memory here, ignore as needed...

thats what they mean when they're saying 'front arb' (anti-roll bar)

[filtercoffee]

Originally Posted by F360C

I have the plates on the rear upper control arms

Link or pic? Never seen this in the aftermarket. Was it custom?

update - found it -
https://www.rogueengineering.com/Rog...E46_p_124.html