Opinion wanted For strut bar mounts

[280zjoel]

I was just wondering what everyone's opinion was for having a strut bar with only one bolt mount on the strut tower. If its not a big issue I could get a couple of sets for the z cars for a good price(If there is interest). Im just worried if since the bar will only have one mounting bolt on each side, if it will sheer the bolt off. Any input would greatly be appreciated. Here some pics of what im talking about.

The front bar has a semi-flat shape to it, the rear strut bars are actually round.

Let me know what you guys think.

Thanks in advance.

[cockerstar]

I don't have anything to back my claim up, but my gut tells me that they're lacking some reinforcement.

I'm planning on offering strut bars this summer along with a few other suspension components once I get quotes back from my machine shop, so I PM'd you with an idea.

[MONGO510]

IMO they are useless without a complete redesign of the mounts. Also, I think you will find that the bar itself is not stiff enough to be effective.

FWIW

Mongo

 

 

 

I don't have anything to back my claim up, but my gut tells me that they're lacking some reinforcement.

I'm planning on offering strut bars this summer along with a few other suspension components once I get quotes back from my machine shop, so I PM'd you with an idea.

[johnc]

Per some FEA analysis done by T Mag about 10 years ago, the strut towers twist and bend inwards. The setup above will do little to nothing to prevent this.

[cygnusx1]

 I too thought that the strut tower bars would have helped.  I figured it would keep the towers from moving in and out towards each other in bumps and turns.  As it turns out, I never realized what I was missing until I got a triangulated bar that tied into the firewall.   Having pivots at the mounts makes them even less effective, unless you triangulate to something solidly tied to the unibody, like the firewall.  The rear bar can be triangulated down to the floor of the hatch or at the base of the strut tower. 

Edited April 23, 2010 by cygnusx1

[z-ya]

This is what we fabricated for the front of the race car.

 

 

If you were do something similar for the street I would make the square tubing at the firewall longer so that you can keep the stock hood latch. We have a pinned fiberglass hood on this car so it doesn't really matter.

 

Pete

[JMortensen]

� I too thought that the strut tower bars would have helped. � I figured it would keep the towers from moving in and out towards each other in bumps and turns. � As it turns out, I never realized what I was missing until I got a triangulated bar that tied into the firewall. � Having pivots at the mounts makes them even less effective, unless you triangulate to something solidly tied to the unibody, like the firewall. � The rear bar can be triangulated down to the floor of the hatch or at the base of the strut tower.�

This has been discussed before several times, a search would probably have negated the need for this thread entirely, but I'll make the argument against Dave's argument again. I had bars tied to the firewall and only after I was taking them off did I realize how flimsy the area of the firewall was that I had attached to. The firewall itself was separating from the cowl on my car, so I really think the firewall did next to nothing on my install. Still, adding strut tower bars (with pivots) made a HUGE difference in my car.

 

The pivot thing is a red herring. Yes, it means that the struts can move up and down or back and forth relative to each other and the strut bar does nothing to try and resist that motion, but the fact is that the strut bar is a pretty crappy device to use for preventing that motion. I believe I previously used the analogy of holding on to the base of a diving board trying to prevent motion at the other end.

 

The strut tower bar should keep the space between the top of the struts equidistant. If you want to prevent fore/aft motion or twisting, you need something else in addition to the STB. Tying to the firewall is pretty useless IMO unless you beef up the firewall (see bjhines's STB). Another idea is tying to the frame rail where the sway bar attaches. This has the dual benefit of strengthening the frame there and should provide some resistance to fore/aft movement.

 

For the OP, I would suggest a welded in mount in double shear and a taller boxed mount with a straight bar. In order to clear the L6 valve cover the mounts have to be fairly tall and long, so you need to do a good job of making them stiff to really get the most out of it. STBs bent to clear the valve cover are inherently much weaker, and single shear mounts or mounts bolted to one hole are also bad designs.

[z-ya]

For the OP, I would suggest a welded in mount in double shear and a taller boxed mount with a straight bar. In order to clear the L6 valve cover the mounts have to be fairly tall and long, so you need to do a good job of making them stiff to really get the most out of it. STBs bent to clear the valve cover are inherently much weaker, and single shear mounts or mounts bolted to one hole are also bad designs.

 

Jon, your right, anything bolted on (not welded) that has bends in it isn't ideal. Especially those pivot style ones. The one we have on the race car originally used the three strut bolts before we put camber plates in. So the little welded on tabs and single bolt arrangement was an afterthought. Still, it makes a big difference in handling, and is far better than any two point pivot style.

[cygnusx1]

    The top edge of the firewall has a sharp 90 degree edge which is also backed by the drainage tray for the wiper area.  The drainage tray has many compound angles making it stiff in the fore and aft direction. Nissan thought it strong enough to mount the hood latch there.  On either side of the hood latch area, behind the firewall, in the drainage tray, there are two fore-aft vertical gussets that complete a semi-box section just under the windshield.  I beg to differ that the area is inadequate for assisting in strut top location.  Sure it also depends on where and how you mount to the firewall.  The bar I am using is not the only bar on the market that makes use of this convenient area.   Don't forget, it's not for handling "roll-cage" forces.  It's just a position locator.

 

 

 

 

 

Now look at this!  You likely aren't going to find a much stiffer box section anywhere in the car.  Looks like wing structure from a Japanese Zero!

 

Edited April 24, 2010 by cygnusx1

[JMortensen]

The early cars like mine only have the brace you show on the passenger side. I took the advice of a guy who knew Z's without pulling the cowl panel off to check and welded the bracket where the brace should have been and it wasn't there. My car was pretty rusty where the bottom of the cowl box is spot welded to the firewall and this area was separating pretty badly under the force of the strut bar. I don't think my car was unique in this respect. Put it there if you want, but I think bjhines' solution is a LOT better.

Edited April 24, 2010 by JMortensen

[crazyoctopus]

Any photos of bijines set-up that you have on hand? I can semi visualize it and am too lazy to search for it; not to mention it would be a nice visual comparison in the same thread.