Hypertek Posted September 28, 2014 Share Posted September 28, 2014 Picked up a cusco front strut bar at the japanese classic car show today (wanted to get the rear as well, but they didn't have any). Been having this idea to triangulate it using some cheap ebay c-pillar bar. (leftover rsx bar that i used in my rx7) Thinking of how to tie it to the firewall Square tubing perhaps, bolted to the underside of the lip area (like the top-end performance triangular bar).. or to the hood latch area Seen something similar in a jdm magazine Thoughts and opinions welcomed. Why didn't I go with the top end performance triangular strut bar? Because im considering going with the bc racing coilovers with the 4 bolt camber plate option.. The cusco bar should fit (after drilling 2 holes) Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 28, 2014 Share Posted September 28, 2014 Others will argue with me, but I think these triangulated strut bars are just so much bling. They look cool but don't do much of anything. The firewall is a but flexible noodle. So, make it the blingiest bling that you can. Just remember that your little 6-cylinder motor has to tote it around. Quote Link to comment Share on other sites More sharing options...
ZT-R Posted September 28, 2014 Share Posted September 28, 2014 If i remember correctly there is a little more support from the panel behind the cowl. I would think it would make more since to tie them inline with that, but i dunno. Quote Link to comment Share on other sites More sharing options...
johnc Posted September 28, 2014 Share Posted September 28, 2014 Do a search guys. If the mounting is designed right the center of the firewall can support enough to increase front spring rate by at least 75lb. In. Quote Link to comment Share on other sites More sharing options...
ZT-R Posted September 28, 2014 Share Posted September 28, 2014 ^He seems like an Ass... Lol i read your other post the other day John hahaha. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 28, 2014 Share Posted September 28, 2014 An ass who knows what he's talking about. Quote Link to comment Share on other sites More sharing options...
bjhines Posted September 28, 2014 Share Posted September 28, 2014 Hmm... John C. is a smart guy with a lot of experience. He has made some great parts that I have I included in my own projects. I have also added a triangle brace and found that the firewall is not very strong at the top there where we all would like to add the center brace. The strongest part is 5" down where the bottom of the hood latch bracket is welded. Unfortunately the engine is in the way that low down. There have been many different approaches to stiffening this area. Here is mine http://i46.photobucket.com/albums/f127/bjhines/V8%20240Z%20project/roll%20cage/Dashbargussets.jpg ... Quote Link to comment Share on other sites More sharing options...
Nelsonian Posted September 28, 2014 Share Posted September 28, 2014 (edited) I recently had the engine bay strengthened after taking head from advice by a fellow member with roughly 500 whp that had cracked his windshield without doing any strengthening in this area. We had to remove the preexisting front shock tower bar mounts to wrap metal around the towers for a base. Here are some pics of how we approached the bars for a NON full caged car, primarily street driven car with hopes of auto crossing. Other chassis stiffening consists of 4point welded in roll bar, new floors, custom seat mounts, sub frame connectors/frame rails, stitched front frame rails and shock towers, gusseted tc rod pockets, rear shock tower bar, and soon to finish out the front with a shock tower bar. Comments, criticism, opinions, suggestions gladly wanted. Edited September 28, 2014 by Nelsonian Quote Link to comment Share on other sites More sharing options...
str8pipez Posted September 28, 2014 Share Posted September 28, 2014 (edited) I believe there is a thread where someone measured the flex of the bare chassis and they included some of this. I think. I know they covered stitch welding the seams and concluded it actually added more flex. I do love how Nelsonian's car looks. Edited September 29, 2014 by str8pipez Quote Link to comment Share on other sites More sharing options...
LanceVance Posted September 29, 2014 Share Posted September 29, 2014 (edited) Anything done to the cabin side of things here? Edited September 29, 2014 by LanceVance Quote Link to comment Share on other sites More sharing options...
JMortensen Posted September 29, 2014 Share Posted September 29, 2014 (edited) I believe there is a thread where someone measured the flex of the bare chassis and they included some of this. I think. I know they covered stitch welding the seams and concluded it actually added more flex. If you welded the whole seam. On a suspect test rig. STBs work. I noticed Clive the other day say that he didn't think STBs work without triangulating to the firewall. I think that is probably wrong. I had mine triangulated to the firewall on one side where the firewall was braced in the cowl, and on the other side where it wasn't (Series I cars didn't have the same bracing on both sides). The firewall had separated from the cowl after a few years, and I can tell you, for sure, that it was still doing something noticeable from the driver's seat. The real test here would be to put a dial gauge on the strut tower with a tattle tale on it and then test with and without. All the rest is really just armchair quarterbacking. Edited September 29, 2014 by JMortensen Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 29, 2014 Share Posted September 29, 2014 Johnc-I hope you know that I was tongue-in-cheek mentally linking to your other thread. If you are an ass, then I am an askhole. If a triangulated strut bar makes you happy, do one-Im not against bling. For me, it's in the way of my motor. If it were attached THRU the firewall to a cage, I would expect it to actually do something mechanically. Johnc, just for perspective, the brace let you raise the spring rate from what to what? Quote Link to comment Share on other sites More sharing options...
thezguy Posted September 29, 2014 Share Posted September 29, 2014 (edited) Although the fab work isn't as nice I did the same to mine. I should have tied the shock towers into the frame rails but I wasn't sure if I would have had the room. I'm not sure if the firewall brace I functional but it just felt like a good idea. Edited September 29, 2014 by thezguy Quote Link to comment Share on other sites More sharing options...
Nelsonian Posted September 29, 2014 Share Posted September 29, 2014 Lance, Nothing was added to the cabin side of the firewall. I am not opposed to adding in a plate on that side if it is deemed necessary. Anything done to the cabin side of things here? Quote Link to comment Share on other sites More sharing options...
johnc Posted September 29, 2014 Share Posted September 29, 2014 The front of a 240Z with just a lateral STB starts moving with a spring rate around 300 lb. in. Increasing spring rate beyond that number will not result in any significant lap time improvements, assuming the rest of the chassis is properly set up including shocks that can handle higher spring rates. Its a diminishing return thing. Adding triangulation reduces the chassis movement and lets the suspension work as it should. That allows an increase in front and rear spring rate (remember, front and rear spring rates are related) and results in measurably lower lap times. The triangulated design I used was developed on my car using FEA by Bill Savage of T-Mag. But it does move the stress loads somewhere else on the car. In my case where the firewall meets the front frame rails That part of the car started cracking (we knew that would happen, but we didn't think it would happen immediately). I reinforced the chassis with subframe connectors similar to what Bad Dog sells (this was before Bad Dog) and that solved the problem. At the end of its time with me, the ROD ran 375lb. in. front spring sand 325 lb. in. rear springs. Quote Link to comment Share on other sites More sharing options...
tube80z Posted September 29, 2014 Share Posted September 29, 2014 On my new race car I have implemented a triangulated double cross tube front structure. There's the normal cross bar at the front of the doors and another that would be at the base of the cowl, which I have made removable. This structure gives the tubes coming from the strut towers a place to feed load into. This ended up being a lot stiffer than just using a single cross bar on the cage and provides a solid spot for tubes coming from the strut tower. I'd think on a street car a similar idea could be used and would make the a-pillar stiffer in case of a side impact. When taking these pieces out of the car I was surprised at light it all was. Quote Link to comment Share on other sites More sharing options...
Nelsonian Posted September 29, 2014 Share Posted September 29, 2014 Tube80Z, If you happen to have a pic or two I would love to see. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 30, 2014 Share Posted September 30, 2014 johnc and tube80z, those answers were the best, most helpful answers I have ever seen on this site on any subject. Thank you for being complete and descriptive in your answers. I know you know what you did, but you two covered so many topics in your answers from: street vs race, roll cage design, to the "domino effect" that stiffening one part of the car without stiffening another creates, to spring rates. Guys like you are why I love this site and its on-line community. Quote Link to comment Share on other sites More sharing options...
seattlejester Posted October 2, 2014 Share Posted October 2, 2014 Mine isn't triangulated, but even my parallel ones seems to make a difference compared to other stockish cars, granted I have 2x3 frame rails so not sure how applicable my feelings are. With the bracing in the front going to the front sway bar and using a pillared mount for the sway bars, everything is connected. I will have to concede though, those cheap c pillar bars might be bling, I've been able to get a lot of deflection from the cheaper ebay bars just by pulling on them with my bare hands. Quote Link to comment Share on other sites More sharing options...
Phantom Posted October 2, 2014 Share Posted October 2, 2014 I've been running this "triangular" front strut tower brace for about 10 years now. You can see in the one photo how it mounts to the firewall area. Seems to be holding up pretty well. Quote Link to comment Share on other sites More sharing options...
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