Motion Motorsport Undertray - Questions

[Driver407]

Anyone own one of the Motion Motorsport undertrays?
Debating picking a used one up and have a few questions if anyone can chime in with your experience. On the fence if it is even worth it.

1) Kinda seems like it may be a pain to remove and do maintenance on car once it is installed? Is that true or is it still about as easy as the plastic oem panels?
2) How does the ambient sensor and circle cut out work? How did you retain this? Do you have to fabricate something? Or am i missing something? Seems like a pain to retain.
3) I have a hotchkis sway bar that included a reinforcement plate that goes on the studs that the tray also uses for a mounting point. Curious if the stud is even long enough to fit both? Anyone have both? I recall it being very close with the current reinforcement plate.

[jayjaya29]

I can only answer question 2 confidently. This panel does not replace the front lower wheel well liners, so nothing needs to be done for the ambient temp sensor. The panel will simply butt up against the lower portion of the wheel well liner.

[Driver407]

I can only answer question 2 confidently. This panel does not replace the front lower wheel well liners, so nothing needs to be done for the ambient temp sensor. The panel will simply butt up against the lower portion of the wheel well liner.

Thanks! Had no idea how that worked.

[cobra]

What I can say from putting a big aluminum plate on the bottom of a motorcycle (skid plate) was that it's possible to increase the noise substantially with one of these. And it's not a good noise, more like a twangy buzzy echoey sound as the plate vibrates and reflects engine noise upwards, compare to the stock plastic tray.

[01SG]

Seems like more trouble than it's worth. That piece has to come off any time you do anything under there, and the easier the better.

Plus I can't think of any legitimate advantage of having this.

[WOLFN8TR]

I have this panel on my M3. It did not induce any noticeable noise from being aluminum vs plastic. I didn't use the hardware for up front, only the sway bar brackets and the rear screws. It fits under the front bumper area, I added a few screws to keep it in place. It takes a few extra minutes to remove it but not a big deal.

[Driver407]

Thanks wolf. Was wondering if I could run it without the front screws. Good to know. (think the guy i was talking to didnt have them anyway lol. Not that i couldnt get replacements at ACE)
Your pic also helped me see that the sway bar bracket is faced outwards so you have easy access to the lower screws to undo them. Way more room than i thought too.

Is going on my track car that I do maintenance on all the time. Trying to not complicate panels more than needed. However this doesnt look too bad with the ~5 screw setup.
My OEM plastic tray is also getting beat up from the track and bits are starting to flake off. Metal will hold up much better over time. Is also a lower profile (1in~) and wont drag/scrape on steep track corners.

Think that scratches most the questions I had. Thanks all.
If anyone happens to have a Hotchkis sway bar and can confirm the bracket fits with the reinforcement plate. Let me know! Cant go out on my car and check for a few days.

[WOLFN8TR]

I think this would be perfect on a track car. 👍

[bigjae46]

I had this awhile back, it's the way to go if you want something that lasts. The downsides...

1. The OE part probably has a very small aero advantage.
2. I think the OE part supports the bottom of the front ducting to the oil cooler which is flexible.

The contours of the OE part is a bigger deal on the E9X M3 since there is an oil cooler vent with a gurney flap. Not much of an issue with the E46.

My biggest complaint was the hardware which does make it a total PIA to remove. Bolts, nuts, washers...do yourself a favor and use stainless rivet nuts to make removal and installation MUCH easier.

[Driver407]

Found a video that show the studs - post install with the hotchkis plates.
My memory was pretty spot on. Pretty sure there is not enough room for the motion bracket and the nut to fully thread. Stud has a stepped threading at the top.

Guess i may need to rethink getting the tray. 😠
Figured id post for anyone else that may go down this path later on.

[mrgizmo04]

I don't like Hotchkis brackets and bushings, so I replaced mine with Turner brackets and bushings keeping the Hotchkis bar.

These look like skidpads if you like going offroading on track .

Sent from my SM-S911U1 using Tapatalk

[Driver407]

I don't like Hotchkis brackets and bushings, so I replaced mine with Turner brackets and bushings keeping the Hotchkis bar.

These look like skidpads if you like going offroading on track .

Sent from my SM-S911U1 using Tapatalk

What about the bushings and bracket did you not like?
I just installed my hotchkis the week before we were out at Sonoma Drift together a few weeks back. First track day since i installed this saturday. So will see how it works out.

[Bry5on]

CSL bushings also fit the Hotchkis bar just fine. About a half millimeter less compression of the rubber if memory serves. I ran that setup on my car.

[Gearhead55]

Any information about weight difference?

[Driver407]

Any information about weight difference?

If you are talking about the weight of the motion tray. It is heavier than the OEM plastic one. Think i heard 7-8 pounds total.