h4nsm0l3m4n Posted August 10, 2009 Share Posted August 10, 2009 I've been wanting to install strut bar braces for my car for quite some time. Rather than simply buy one, I thought it would be more fun to design my own brackets and piece together the kit. For reference I used the s30 chassis dimensions (two in particular) and physical caliper measurements from my car. I also used various previous designs off this forum for inspiration. Here is what I've come up with. The whole bar assembly (front bar shown, rear bar will be similar but shorter) Close up of bracket setup As you can see the bracket is designed so it can be used on either side of the car. This should make both fabrication and assembly easier. The vertical part of the bracket itself can be achieved by bending the bracket 90 degrees or welding it. I am still deciding what material and thickness I would like to use which will dictate where bending or welding will be preferred. The heim joints and threaded tubes will possibly be replaced by something more simple. The bracket itself will be laser cut by a local shop, known for excellent work at great prices. Side note here, if people show interest it may be possible to order a bunch of the brackets at a discount price. Sourcing the heim joints, etc. should be easy. If you are interested in this let me know. I expect the design to change a little bit as I work on it this week. Many dimensions are not finalized, this is something I basically just threw together in about 20 minutes. Still, I am interested to hear people's inputs, I think this should work well but any advice is always appreciated. Quote Link to comment Share on other sites More sharing options...
skib Posted August 10, 2009 Share Posted August 10, 2009 sweet Id be down to get some brackets Quote Link to comment Share on other sites More sharing options...
Xnke Posted August 10, 2009 Share Posted August 10, 2009 Same here, brackets premade would be great. Quote Link to comment Share on other sites More sharing options...
tube80z Posted August 10, 2009 Share Posted August 10, 2009 I expect the design to change a little bit as I work on it this week. Many dimensions are not finalized, this is something I basically just threw together in about 20 minutes. Still, I am interested to hear people's inputs, I think this should work well but any advice is always appreciated. If you don't make it double shear then you should change the strut bar mount to a clevice. This will make it stiffer than a rod end. Quote Link to comment Share on other sites More sharing options...
260DET Posted August 10, 2009 Share Posted August 10, 2009 About time I asked the a previous question once again - why design a strut brace with joins that allow movement? Not picking on you h4, strut bars with movement allowing rod ends are quite common. So you are excused The whole idea of a strut bar is to prevent movement, its not that hard to fabricate a solid bar with no adjustment and bolt it solidly to the towers. If captive nuts for the bolts can be welded in then better still. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 10, 2009 Share Posted August 10, 2009 About time I asked the a previous question once again - why design a strut brace with joins that allow movement? Not picking on you h4, strut bars with movement allowing rod ends are quite common. So you are excused The whole idea of a strut bar is to prevent movement, its not that hard to fabricate a solid bar with no adjustment and bolt it solidly to the towers. If captive nuts for the bolts can be welded in then better still. We've done this argument before, but the strut tower brace is VERY weak in the axis that the joints allow movements in. If you want to keep the struts from moving up and down in relation to each other, a thin long bar attaching the two is not the way to do it. I would go so far as to say that your typical strut bar is next to useless at preventing this kind of movement. For this design I like Cary's clevis idea but it's not as snazzy looking, so most people would rather have a rod end in there. Quote Link to comment Share on other sites More sharing options...
langfordchuck Posted August 10, 2009 Share Posted August 10, 2009 Yes, I just put one of those on my 86 MR2. As I was installing it i thought, this wouldn't be hard to fabricate for my 260z... I would be interested in the brackets if some are getting made up. It seems clear to me that the point of the strut bar is to limit side to side movement, not up and down movement. But torisional stiffness is not exactly the high point of zed design, especially for those of us that have compromised frame rails and have not yet replaced with bad dog parts... Quote Link to comment Share on other sites More sharing options...
h4nsm0l3m4n Posted August 11, 2009 Author Share Posted August 11, 2009 If you don't make it double shear then you should change the strut bar mount to a clevice. This will make it stiffer than a rod end.Thanks for the suggestion, if the design doesnt change I will definitely make this change on my own setup. About time I asked the a previous question once again - why design a strut brace with joins that allow movement? Not picking on you h4, strut bars with movement allowing rod ends are quite common. So you are excused The whole idea of a strut bar is to prevent movement, its not that hard to fabricate a solid bar with no adjustment and bolt it solidly to the towers. If captive nuts for the bolts can be welded in then better still. We've done this argument before, but the strut tower brace is VERY weak in the axis that the joints allow movements in. If you want to keep the struts from moving up and down in relation to each other, a thin long bar attaching the two is not the way to do it. I would go so far as to say that your typical strut bar is next to useless at preventing this kind of movement. It seems clear to me that the point of the strut bar is to limit side to side movement, not up and down movement. But torisional stiffness is not exactly the high point of zed design, especially for those of us that have compromised frame rails and have not yet replaced with bad dog parts...While I definitely agree that these bars will be quite flimsy along the axis of the bolt in the joint I approached this design from Chuck's perspective. I also thought that strut bars first and foremost are supposed to stop sideways motion, which I think these will do reasonably well (better still with the clevises in place of rod ends). That being said there is nothing wrong with more stiffness in the chassis. My main goal is to make a reasonably effective, inexpensive and easy to put together (and tear down) strut bar setup. I think what I have now is close, but I will take another look and see if I can come up with something equally simple but without the same problems. If you were interested in getting some brackets, we might work something out later this week, or next once I'm more finalized with the design, fitment, and have gotten a quote for the fab work. I'm not anticipating these to be that expensive. Thanks for all the replys! Quote Link to comment Share on other sites More sharing options...
rsicard Posted August 11, 2009 Share Posted August 11, 2009 Stephan: I like your design as far as it goes. I am going to fabricate a front strut bar with three attach points. One from side to side, another from side to center firewall and lastly one from side to forward and down to frame rail. Thinking also about a X cross brace just forward of the engine running parallel to the side to side strut bar. This will likely necessitate running one more brace from each strut forward to a strengthened radiator top bulkhead. Sure would like some graphics such as you have done but with more attach points on the strut plate. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 11, 2009 Share Posted August 11, 2009 It seems clear to me that the point of the strut bar is to limit side to side movement, not up and down movement. But torisional stiffness is not exactly the high point of zed design, especially for those of us that have compromised frame rails and have not yet replaced with bad dog parts... Ladder frames and subframe connectors aren't very good in torsional rigidity. They might help, but having braces to the strut towers in 3 dimensions is the way to increase rigidity. If you search for "chassis stiffening" you'll find some good ideas on the subject. Or for a basic rundown read Chassis Engineering by Herb Adams. To the OP, the strut tower bars will help a lot in terms of improving handling, they just don't control the up and down movement of the strut very well. Don't take that as a knock on the idea though, it's just that a strut tower bar is the wrong tool for that job. Quote Link to comment Share on other sites More sharing options...
h4nsm0l3m4n Posted August 12, 2009 Author Share Posted August 12, 2009 (edited) Stephan: I like your design as far as it goes. I am going to fabricate a front strut bar with three attach points. One from side to side, another from side to center firewall and lastly one from side to forward and down to frame rail. Thinking also about a X cross brace just forward of the engine running parallel to the side to side strut bar. This will likely necessitate running one more brace from each strut forward to a strengthened radiator top bulkhead. Sure would like some graphics such as you have done but with more attach points on the strut plate.I'm not sure how much I can do for you but take a look below at an updated design. The main update has been additional holes to facilitate additional bracing. I may add more options still, that will be dependent on how much things will cost to fab. The brackets should still mount on either side of the car but some welding will be required to put the vertical tab for the side brace in place. Nothing most people on this forum can't handle. Here's some updated pictures of the design: Some general notes on the progress. I'm leaning toward using 1/8" or 1/4" steel plates. Dimensions are slowly being finalized. I'm looking for diameter of the 3 strut tower bolts, I'm not at home with my car so I cant check this dimension. If someone can check it for me that'd be great. The brackets will still be laser cut, I will send out a quote request tomorrow or Thursday to get a price estimate. I'm going to build a mock up this weekend out of cardboard or wood to check fitment on my car and will post pics. Stay tuned and as always any input is always appreciated. Just realized my previous pics blew up when I switched albums on photobucket. For reference all pics for this project are here: http://s233.photobucket.com/albums/ee194/h4nsm0l3m4n/datsun/strut%20bar/ Edited August 12, 2009 by h4nsm0l3m4n Quote Link to comment Share on other sites More sharing options...
skib Posted August 12, 2009 Share Posted August 12, 2009 I like the new design Quote Link to comment Share on other sites More sharing options...
MAG58 Posted August 12, 2009 Share Posted August 12, 2009 Agreed, I think they look very good. I drug out the drill gauge and took it to the top of my hats. It's in In and a 3/8 wouldn't quite fit through but 25/64 was perfect. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 12, 2009 Share Posted August 12, 2009 I would warn you that you might need to extend the mounts to get the bar higher, as the valve cover is higher than the strut towers. In other words, the CAD drawings are great, but go figure it out on the car before you commit to having a bunch of parts machined. Also, if you're redesigning the whole thing, you might make it double shear and have the attachment point right in the middle of the strut tower so it is best positioned to handle the stress it will receive. With double shear I'd go back to a rod end. Also, the braces back to the firewall are a decent idea, the question is where to attach them and have it be strong enough to really make a difference. Pull the cowl panel and take a good look at the firewall and you'll see what I mean. There isn't much back there. bjhines did a good job reinforcing his cowl to deal with the stresses from the strut tower bar, but without that reinforcement I'm not sure how much good those will actually do (and I say that having had a similar set up on my car for years). Quote Link to comment Share on other sites More sharing options...
h4nsm0l3m4n Posted August 12, 2009 Author Share Posted August 12, 2009 I would warn you that you might need to extend the mounts to get the bar higher, as the valve cover is higher than the strut towers. In other words, the CAD drawings are great, but go figure it out on the car before you commit to having a bunch of parts machined. Also, if you're redesigning the whole thing, you might make it double shear and have the attachment point right in the middle of the strut tower so it is best positioned to handle the stress it will receive. With double shear I'd go back to a rod end. Also, the braces back to the firewall are a decent idea, the question is where to attach them and have it be strong enough to really make a difference. Pull the cowl panel and take a good look at the firewall and you'll see what I mean. There isn't much back there. bjhines did a good job reinforcing his cowl to deal with the stresses from the strut tower bar, but without that reinforcement I'm not sure how much good those will actually do (and I say that having had a similar set up on my car for years). I was almost waiting for someone to suggest doing double shear from the middle of the strut tower. The reason its not this way right now is due to my 4 barrel manifold setup. I have a 9" (I think) diameter air cleaner so it extends forward to be basically right inline with the middle of the two strut towers. To clear it now the bar has to come slightly forward, but not too far since room under the hood gets scarce and theres the big hump in the front of the valve cover and oil cap to contend with. I might be able to find a smaller air cleaner to swap out, in which case I'll definitely make the change you mentioned. Either way I plan on making a mock up over the weekend to make sure I have good fitment before anything is ordered. As far as the firewall brace, you make a good point. Additional bracing back there will definitely be needed. I mostly made that change to accomodate the possibility of such a brace. As you say its been done before, I'll do some more research on this and see if I can come up with something. Agreed, I think they look very good. I drug out the drill gauge and took it to the top of my hats. It's in In and a 3/8 wouldn't quite fit through but 25/64 was perfect. Thanks for that. I guess the bolts are 10 mm. I'll dimension the holes .41 or so, the laser shouldnt have any issues with that. Can you (or anyone else) measure how far they stick up out of the strut tower? This will help determine how thick to make the brackets. I'm leaning toward 10 ga or 6 ga CRS now. Quote Link to comment Share on other sites More sharing options...
h4nsm0l3m4n Posted August 17, 2009 Author Share Posted August 17, 2009 I've been a little busy with various projects on my car and at work so am a little behind where I'd like to be on this project. I made some changes to the design, take a look below. Things will be tight on assembly but if you're careful with your welds everything should come together fine I think. I have not gotten a chance to make a mock up but I am hoping to take care of that soon as well. I am sending out a request for quote, if you are actually interested let me know so I can take that into account. Quote Link to comment Share on other sites More sharing options...
skib Posted August 17, 2009 Share Posted August 17, 2009 when you find out shoot me a PM, Id be interested in the whole strut bar set up depending on the price Quote Link to comment Share on other sites More sharing options...
MAG58 Posted August 17, 2009 Share Posted August 17, 2009 I'm down for some brackets after a quote... PM Me Quote Link to comment Share on other sites More sharing options...
h4nsm0l3m4n Posted August 17, 2009 Author Share Posted August 17, 2009 Just sent out the RFQ, should be getting numbers back monday or tuesday. Just FYI, the rod ends, pin and threaded tube will not be included in this kit. If/when we end up getting something going all I would provide is the bracket that mounts onto the strut and the two vertical plates. I will likely order the bracket this week since it pretty much set in stone. The vertical plates will be ordered next week after I had a chance to make my own mock up over next weekend. You'll have to weld the vertical plate(s) on in the position of your choosing and figure out how you want to do any of the linkages yourself. I will provide general support and advice on how to mount everything up including part numbers and vendors used after I've successfully completed my install. But the beauty of this design is you are essentially free to pursue whatever meets your needs/budget once you have the bracket. You could bolt a wooden dowel in there if you really wanted to... Quote Link to comment Share on other sites More sharing options...
langfordchuck Posted August 17, 2009 Share Posted August 17, 2009 I'm in for a set. Only question I have is that in your last diagram the vertical braces span the centre hole for the strut assembly. While this seems better for double shear, it does't leave a lot of meat to weld the uprights to. I assume that in your mock up you looked at this, and are confident that there is enought surface area for a good reliable weld? Either way put me down for a set. thanks for your work on this. Quote Link to comment Share on other sites More sharing options...
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