proxlamus© Posted May 1, 2009 Share Posted May 1, 2009 Just curious if anyone has any experience or seen the use of some medium expansion high density foam inside the frame rails? I'm about to weld on my bad dog frame rails and I'm considering drilling small holes and filling it with foam. Strength and seal the inside's from moisture? Quote Link to comment Share on other sites More sharing options...
ckolander Posted May 1, 2009 Share Posted May 1, 2009 I have an article somewhere where they did it, it stiffened up the frame pretty good. Other than that I have no idea. Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted May 1, 2009 Share Posted May 1, 2009 With the stock rails, you might consider doing this. With the thick/stiff Bad Dog rails, there wouldn't be any benefit. Quote Link to comment Share on other sites More sharing options...
palosfv3 Posted May 1, 2009 Share Posted May 1, 2009 There are several different types of structural foam. You really need to make sure of the one your using. Ford has one they use in the replacement of the side aperture of the Expeditions and in some rails. Had a friend fill the rails and rockers on an old Hemi Cuda drag car. It really stiffened up things but the down side is , if you ever have to remove or repair it you will wind up throwing the car away. It has the density of a 6 to 8 bag mix of concrete when hardened.The good stuff is also expensive. Last time I looked at it a caulking tube size cartridge was around $75.00. The Cuda used more than 20 tubes. This is probably not a good option for where your at with your car. Just clean the floor areas to bare metal , Use weld thru primer on the weld areas, install the rails and then spray an epoxy inside the new rails to seal and you should do well. Once this work is done the foam is a 5 minute install if you still want to go that way. Quote Link to comment Share on other sites More sharing options...
jknc90 Posted May 1, 2009 Share Posted May 1, 2009 There was an article in the Feb. '09 issue of Sport Compact Car. http://www.modified.com/tech/sccp_0902_tein_suspension_upgrades_project_s13_tech/index.html Quote Link to comment Share on other sites More sharing options...
hogie Posted May 1, 2009 Share Posted May 1, 2009 Dont use great stuff! Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted May 1, 2009 Share Posted May 1, 2009 Thin stock sheet metal might benefit from the reinforcement. But again, with the Bad Dog rails (twice as thick = 8x as stiff in bending), I don't think the incremental benefit would be noticeable. They're not anything like as bendable/deformable as stock! Quote Link to comment Share on other sites More sharing options...
tube80z Posted May 1, 2009 Share Posted May 1, 2009 Just curious if anyone has any experience or seen the use of some medium expansion high density foam inside the frame rails? I'm about to weld on my bad dog frame rails and I'm considering drilling small holes and filling it with foam. Strength and seal the inside's from moisture? I did this to a race car we used years ago. It's a good option but you need to know two things. If you ever plan to weld on the car in the foamed areas you pretty much can't. And you better make damned sure you don't have any hidden rust, as repairs are very hard once foamed. In the end rust was in my car and this more or less sealed its fate. But before that became and issue the foam did make a noticeable difference. Cary Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted May 1, 2009 Administrators Share Posted May 1, 2009 I would imagine the foam would act as a wonderful sound deadening as well, even the little bit in the frame rails should dampen a fair bit of noise. Quote Link to comment Share on other sites More sharing options...
woldson Posted May 1, 2009 Share Posted May 1, 2009 Ford's queit steel? I believe they use something similar. Quote Link to comment Share on other sites More sharing options...
junglist Posted May 1, 2009 Share Posted May 1, 2009 There was an article in the Feb. '09 issue of Sport Compact Car. http://www.modified.com/tech/sccp_0902_tein_suspension_upgrades_project_s13_tech/index.html They also had an article on it for their 300ZX project car in 1999. I still have this issue around somewhere, haha. http://www.modified.com/projectcars/0006scc_project_nissan_300zx_part_5/index.html Quote Link to comment Share on other sites More sharing options...
MoNkEyT88 Posted May 6, 2009 Share Posted May 6, 2009 I know the Honda 954 CBR has foam inside the swing arm to make it stiffer. Quote Link to comment Share on other sites More sharing options...
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