Thread: Foam Filling the chassis......

05/30/2011

Due to demand, I am turning this into an Official How To Foam Fill Your Chassis Thread starting on post #118. I started this thread as an inquiry looking for input on foaming my chassis. After very helpful input from the forum, I did indeed foam the living hell out of my chassis. I did this with my body-man during extensive body-work being done on my vehicle. However there is no reason that you cannot do this in your driveway or garage in about four (4) man-days. No special skills necessary, I am positive I could do this again myself with a helping set of hands.

Give me a couple of weeks and I will have everything in order and easy for you to follow (posts 118-125) to properly foam-fill your chassis.

Shawn B




This is where and how the thread actually started back in 2008...

Here is the link to the Suspension Thread with Steves and Mikes wisdom on chassis-grade foam:

http://www.sr20-forum.com/suspension/1801-b13-b14-b15-suspension-information.html#post24091

And a direct link to the SCC article by Mike K:

Project Nissan 300ZX: Part 5 - Project Cars - Sport Compact Car Magazine

Anybody done this recently to a B13?

My car is at the body shop as we speak, body repair, sunroof delete, and IKEA brace. Interior currently completely gutted, nothing but the dash, steering wheel, pedals, and stick-shift shaft.

Next week it goes to the mechanics shop for the engine bay fixes, afterwhich I can test drive it.

Then the Classic goes back to the body shop for a damned $eriou$ paint job. All trim, windows, lights, everything off the vehicle. All new window/door seals, shiney new bad-ass Nissan OEM black paint job. Spending stupid money, I might add.

I am seriously considering foaming the chassis during this re-birth process. I'm already soooo deep into this financially, what the hell is another hundred bucks worth of structural foam? According to Mike K, you can never get the chassis "too stiff." And because the car is going to be freshly repainted after I did the foaming, I don't have to freak out so bad about an accidental drip or spill. Apparently, if you get this stuff on pretty much anything, it is a bitch and a half to get off.

1) Already armed with an IKEA brace, AT RSTB, and Cusco FSTB, should I still see (feel/hear) pretty noticable improvements in lessening NVH with the chassis foam?

2) Being that I am mechanically inept, what is the best place(s) to foam-fill in a B13 chassis? Ie...what places make sense to fill in? Rocker panels are fairly obvious and mentioned by Steve and Toolapcfan. Should I just do the rocker panels only? Mike did both the rocker panels and the frame rails on his 300zx.

3) Steve mentions that if I use too strong of a foam, I can actually bend the metal (outside the cavities) of the places I am trying to fill in. The foam expanding with enough force to "push out" the sheet metal. Yikes! I do NOT want to fuxor this up.

4) Are there any places in a B13 that should definitely NOT be foamed due to wire-runs or any other reason?

Thanks for any input or advice.

Have you considered seam welding? Too costly/time consuming?

Yessir, I believe that it would be both too costly and time consuming. I wouldn't know what the hell to do with a welder, and I cannot imagine the cost involved at the body-shop.

However, I want the car to feel as tight as a drum. Like new, or actually better. I am also adding some weight (Egads!) and installing Elemental Designs fancy-ass sound deadening to the cabin, doors, and trunk. I don't really care if I lose a 1/10 in the quarter mile that I am never going to run. A small weight concession for a less "tin can" feel/sound to the vehicle.

shawn! glad to see you're still around and kickin!

here's the quote from mike's article on my car back in the day:

"With the interior stripped, I took advantage of its condition to inject Foamseal Catalyzed Urethane Foam into the car's unibody. Foamseal foam is pretty amazing stuff. It can increase the stiffness of the cross section chassis members by up to 40 percent. We have used it in several project street and race cars to stiffen unibodies with good results. The Foamseal foam was injected into every major frame section through the factory access holes. Foam injection is a popular mod in Japan to stiffen the chassis, but few are aware of it here in the States. Do not try to duplicate this with cheap hardware store spray foam, which won't harden inside the framerails of a car and has no structural properties. "

it's not THAT detailed but when i've gone through the car, all cavities are filled. also, i've stripped several b13's and iirc there arent any wires running INSIDE the actual cavities.




the chassis foam should SIGNIFICANTLY increases the chassis rigidity. you should be happier with the ride as well since the shocks will be forced to do their job.

I have been thinking of doing this myself Shawn, thanks for posting up. Sorry I don't have any input though.

Interesting times my friend. Overwhelmed best describes it.


So, talk to my mechanic (or body guy) and use common sense? I figure either guy (pro's) should be able to give me a hand and advice.

This seems like a no-brainer given my goals for the vehicle, and its current state of disassembly.


Actually, that thought was input. You've been considering the idea.

I was wondering why (apparently) more folks don't do this. The weight penalty seems minor for the additional chassis stiffness provided. Mike K's 300 and Steve's S13 (S14?) both done, and both gentlemen very impressed with the results? That is a consensus enough for me, any day of the week. I think I'd be stupid not to do this at such an opportune time-frame.

It seems like it would greatly benefit daily drivers, auto-x, and road racers. The only folks that would possibly not benefit would be 1/4 mile afficianados where the weight is absolutely critical.

Maybe I've missed the threads, but I never see anyone else follow what Mike and Steve unanimously agree upon. We spend money on FSTB's, RSTB's, and dream up new 3-point versions of the same. Further, we weld in IKEA braces. Yet seemingly very few folks do this recommended $100 major overall chassis stiffener.

Quite frankly, as mechanically inept as I am, the thought was a bit daunting to me. However, now I have seen how (pain in the ass and time consuming) easy it is to really strip an interior. Not that hard, I only needed a little help in some spots from my mechanic. Which means that anybody else on this forum could do it in half the time with zero help required.

Here's the link, the website still works. Looks like I will call them on Monday during normal business hours and find a local distributor in Houston:

I'm officially "going for it." The guys at both shops will think I am nuts. Er...more nuts.

I think your situation is a good place/time to give the foam another shot. I think most people get overwhelmed with the idea that the foam could damage their paint - if repainting, you have nothing to worry about.

I would think rocker panels, "A" pillar, "B" pillar, and "C" pillar would be the best spots to do it (if all of those places are accessible).

Off-topic: Shawn, if you want a non-sunroof roof you can have mine if you come get it - it is already cut off.

Josh

I am excited to see how this goes. I'm hoping there is going to be a full fledged thread with pics galore about this overhaul of your car!

The car is going from the body shop to the mechanics tomorrow (I hope). While the car is getting wrenched on, I am going to do some foaming. The car then goes back to the body shop for final painting. Anything I screw up, the body shop guys can clean up before they paint.


That is easy enough, thanks for the input. We shall see what I find out.


Thanks, but my sunroof is already gone. Seam welded panel, then some "metal containing super goop", then bondo to smooth everything perfect. I did not want a sunroof from the get-go in '93, I couldn't find an SE-R without one.


I am going to go buy a digital camera tomorrow at Target for just that purpose. I'll start snapping pics. Gotta run by the body shop, then (hopefully) sending the vehicle to the mechanics.

One thing that is tough to locate is a damned non-sunroof headliner.

Once located, I am going to have it recovered and match it to the back window shelf-thing, and the panels in the doors. All in some charcoal/black material.

From my motorpsort and engineering experience you have this main issue to attack.


Pillars twist - they twist in the sense of rotating and not flexing.

Everytime you take a corner or bump, energy its stransferred through yoru shocks and struts to your chassis. Resistance is given on all points of contact with the ground, so the energy will travel the furthest it can until something gives (noramlly the body twisting).

If you can stregnthen all parts where energy can be trasnferred from one direction to another (eg floor to pillar - pillar to roof) you give the enerygy no where to go but back to where it came from.


So for the sentra chassis, i think getting some fender bracing, foam filling the front rails. Foam filling the front a pillar section and boxing in the strut towers is your first step. There is not much room to foam at the base of the sentra B pillar, so maybe foaming in conjunction with a B pillar brace would be very handy. Linking that B pillar brace directly to the rear strut brace would tighten the rear up immensly. But again your not left with much area to foam fill in the rear section. If you already run lower control rear and strut top rear the rear end will be very tight already.

The main achivement is to somehow work out how to link the a-b-c pillars. Our chassis are pretty good for a factory car.


The NISMO n15 vzr's use a special rear beam, with special rear link arms. I can only imagine they were stronger and the rear link arms may have been boxed in to reduce twist and improve rear end response.

sorry for the waffle and slight OT parts. Maybe it can help you?