Rear shock top mount choice

[ac427]

Are the reinforced Z3 items better then the standard E46 M3 part?

Are Powerflex, Rogue engineering or Turner any better?

[Tbonem3]

Reinforcement plates are a great idea, and cheap. Most aftermarket RSMs have them built in or supplied. The main question regarding RSMs is, do you want rubber isolation, poly, or a spherical bearing?

Assuming, like most, you want rubber or poly, there are a gajillion options, and I don't see how you can really go wrong. Even stock, with z3 plates, is a great solution for a typical car. Cheap, great comfort, decent durability, plates added as insurance.

If you're lowering your car quite a bit, but using normal length shocks like Sachs, Bilstein, or Koni, I personally like Ground control's "tall" RSMs that raise the droop up 2 inches. At $150, not too expensive, and the orientation of the bushings gives you a choice between comfort and more solid.

RSMs are one of those things where every vendor has their own version. That pretty much only happens when the part is simple. So you really can't go wrong.

[ac427]

It was suggested on another forum that the extra spent on Powerflex and the like was not worth it over the standard part.

Are the spherical bearings too harsh for road use?

[Tbonem3]

Yes & Yes (I have spherical on one car, poly on the other)

The only I'd say is, a poly based bushing will be stiffer, so theoretically, I think you'd preserve your alignment better (less deflection). But if you have rubber RTABS anyway, I can't see you caring about also having rubber in the RSM. I would guess a stock RTAB will allow for more (toe) deflection than stock RSM. Furthermore, I think a stiff bushing that doesn't articulate like a ball joint, will lead to a blown shock. I believe that our shocks' angle changes through the stroke, and only a spherical bearing will allow for that movement. OE Rubber is nice, because it will flex well, to accommodate that movement (preserving the shock seal), and provide a comfortable ride, and cheap enough to replace if it degrades sooner than later. Then there are RSMs that use rubber, but a stiffer compound, and are an aftermarket design - I was eyeing TCK's version. I ended up sticking with my GC's (poly) because I wanted the shorter droop. I should ask GC if they can supply rubber bushes, or make/find my own. It's a little harsh, though most of the harshness showed up when I added a rear shock brace. Neither of my rear springs are so stiff (550lb & 600lb) that'd I blame any harshness on them.

[jet_dogg]

A very long time ago I was running moton remote two ways with monoball camber plates/monoball rsms and it was not intolerable or very noisy at all. My new setup is going to likely be 5x worse so I don't have any data on that.

If you are sensitive or new to modding just stick to rubber. Personally I would never do poly for any situation.