Lightweight SWB: Undercoating or no undercoat?

[911hunt]

I am falling deep down the slippery slope of a lightweight SWB project and currently the chassis is off being cleaned and dipped in Oregon. I am doing EB Motorsports fiberglass front fenders, bumper, hood, rear bumper, and deck lid. I will also do lightweight perlon carpet. My question is whether or not to do undercoating or simply paint the bottom of the chassis body color. This car will be 99% street with spirited driving. I know shaving ounces off a car using and it for street driving is like taking crazy pills but I have already started and there is no going back. Is the car going to sound like a tin can inside without undercoating or is it going to sound like that even with undercoating? I would greatly appreciate any opinions or feedback!

[911r67]

Black chassis lawyer like factory race car...you can add a thin film of wax...but nothing else

[Longballa]

Absolutely undercoat the bottom and the wheel wells. You'll regret it if you don't. You don't have to go as thick as the factory did. I do a medium coat.

[911hunt]

Absolutely undercoat the bottom and the wheel wells. You'll regret it if you don't. You don't have to go as thick as the factory did. I do a medium coat.

Enough said! Sounds like the small weight penalty is worth it and I can always just drill a few more holes!

[1QuickS]

I removed mine and never regretted it. Most of noise is from open intakes and then open exhaust. If you want a quiet car then get a Lexus.

[Longballa]

To each there own but even the Hot Rods I build with medium undercoat you can here the rocks coming up with sticky tires. Take a poll I guess. I could see no undercoat for a track rat but I'll never do it for a street rod.

[JackMan]

If I had one Porsche and it was always driven on the street -- I'd be in the no undercoat street rat camp. I have a 1989 944S2 race car, It's seam welded, strung out on crystal, and no coatings expect paint and patina. I used to drive the car stock and then it evolved into a race car. A car communicates differently with you when you remove the undercoat and when you drive it -- the viceral explosion of driving takes the driving experience to a diff level, especially if you are running headers with no heat and more specially if you have a 67s on Sterroids like Pauls.

[1QuickS]

Exactly, a car built for "spirited driving" is more alive when you hear all aspects talking to you. Save your music listening and chatty conversations for your Lexus.

I believe a sports-purpose, SWB 911 should be: visceral, urgent and responsive. Chips and imperfections from driving are well-earned patina.

[NickP]

When Scott built and painted my ST he put his medium coat of undercoating on the underside and wheel wells. My car is used mostly on the street for weekend back country runs, group rallies (street), around town once in a while and 4-5 track days per year. That means most of my miles are on the street and I’m happy with the set up. It would be much louder and I think uncomfortably so without some degree of sound dampening and protection from the undercoating. In particular, if you are running TB15’s they throw up so many rocks and debris in the wheel wells I think it would irritate the sh*t out of me if there was no undercoating. At the end of the day it really depends how you use you car and what floats your boat. My 2 cents...

Nick

[911hunt]

When Scott built and painted my ST he put his medium coat of undercoating on the underside and wheel wells. My car is used mostly on the street for weekend back country runs, group rallies (street), around town once in a while and 4-5 track days per year. That means most of my miles are on the street and I’m happy with the set up. It would be much louder and I think uncomfortably so without some degree of sound dampening and protection from the undercoating. In particular, if you are running TB15’s they throw up so many rocks and debris in the wheel wells I think it would irritate the sh*t out of me if there was no undercoating. At the end of the day it really depends how you use you car and what floats your boat. My 2 cents...

Nick

At some point this car will be your neighbor on Solana Circle so you can see the final product!