I believe it was Tom that found some popped spot rivets (someone saw/found some). That would be from too much flexing. Folks need to remember that it is an acknowledged fact (and in print) that the structural integrity that was designed into the car was compromised by the former GM exec's decision to insist it be a targa top car instead of a T-top car. The car's design team and folks on this board (and elsewhere) have been dealing with that decision since it was made.

The stuff will fit on an '85, you will just need to drill holes and put in the rivnuts.

If you buy a bar from E-M, there is the chance it won't line up correctly. Mine didn't and I had one hole welded up and redrilled. I refit it (working with metal was my first career). There are lots of other folks who didn't have that issue.

Between the camber brace and the harness bar, I believe we got the most initial benefit from the harness bar. My wife was immediately able to tell that the car didn't squeak/rattle as much.

Has anyone following this thread had the vette-to-vette/Gordon Killebrew bars installed on a long term basis AND still have the car ? If so, have you looked underneath and checked the condition of the spot welds to see if there has been any ill effect from them being under tension ?

I have been wondering since I have been reading/learning from a lot of you, this forum, stuff I saw on a car show about modding a Mustang, how it would work out to put on the X-brace with the vette-to-vette or similar construct added. that would create another "box" structure with cross-bracing. In the spring when I put the x-brace in, I am going to have it boxed and I am going to see if I can have some type of lateral bracing added that would run lengthwise out at the end of the "x".

 

https://www.redline360.com/cipher-au...rsal-CPA5000HB


found this as well - seems to be set up differently - not sure it would add the rigidity and horizontal support like EM's

 

I wouldnt buy one of these, they have no rigidity.
I have seen photos of a crash involving one of these harness bars (being used with a harness) and it collapsed inside of itself. The EM bar costs twice as much for a reason.

 

agreed the more I looked I wanted to retract my post - I could not see structurally how it could be rigid and adjust that much at the same time

 

While I dont have the kit, I am seriously considering it. From what I can tell you arent REALLY putting anything under tension. At least not under any tension it wouldnt be in if the top was on the car. From what I can gather you put the car on jack stands, install everything then take it off the jack stands and measure front to back and corner to corner on the roof install points(or there abouts), THEN you put it back up in the air and tension the rods to match those measurements, then you put it back down and "in theory" everything is still in line. So "to me" nothing is really in tension, its just being held in place from twisting, so the car, again in theory, acts like its sitting static. This shouldnt cause any undo stress on any parts and in fact should reduce stresses on all the fasteners, spot welds, etc... as they, again, in theory, shouldnt be allowed to twist or move.

I dont know. Just ruminating on it.

 

from their site

If if is putting the frame rails in compression, it is putting stress on the spot welds. I was watching a show about building Mustangs, they put in sub-frame connectors, then welded a square tube to the pinch welds and then put lateral braces from that bar back to the subframe connectors. Everything was welded in when the car was sitting level on a drive on lift so there was no frame/unibody flex/twist welded into permanency,

 

2 questions - does the harness bar from EM install in a similar way to r-d cross brace (NLA ?)?

and is it worth the $300+?

if it is as good as it sounds and helps firm up some of the "loose in the cage" problem. -- - maybe it is

thanks

 

What do you mean by R-D cross brace ? the em harness bar attaches to the upper 2 seat belt bolts and the 4 bolts that hold the targa top holders in the rear hatch

That will/would be up to you. I am satisfied that I spent the money.

You should take up the offer to come ride in my car. NOT A SCARE you ride, just a nice, at speed limit ride so you can feel what it feels like

 

that style of bar WILL tighten up the rear of the car,
is it worth $300 - I had to make my own and I would have gladly paid $300 to buy one if I could !

 

Is there solid evidence that this will in fact tighten up the chassis? It seems like it would only stiffen the halo's movement in a diagonal direction. In the thread I posted Tom400 tested frame deflection (not scientifically but pretty solidly and with video evidence) and the frame was flexing all over the place. Even from the rear rails to the halo. Maybe these bars stiffen a specific part of the car that makes it feel tighter but from what I saw I think the rest of the frame is flopping around the stiffened section. It sure is a step in the correct direction though. These cars seem to have too much flex in the frame to be fixed easily.

 

Not being an a**, just going to make a statement so you maybe will say Ah Ha, but what is behind the back seat of most 4 passenger cars, regardless of 2 or 4 door ? A bulkhead that ties the two sides together. Back when I was into Fox body Mustangs it was well known that the notch backs were stiffer than the hatchbacks because they had a big wide open area like we have, as opposed to a bulkhead welded into the structure.

Is it a cure all, of course not, that is why they did what they did with the C5 and the hydroformed frames, but if it takes away (for speaking purposes) 15% of the chassis slop in certain planes of movement, well that would be enough to be felt.

 

This is my experience with using a harness bar - I use my car for hillclimb, in the street reg class we are allowed to have a harness, a friend of mine who runs in the under 2000cc street reg class put a race seat and a harness in and made big gains (re set the class record) due to the bumpy track we run at.
So it was a no brainer, get a harness in, but of course the c4 being a fibreglass pod you will need a harness bar, did my research and the EM bar seemed the best so I copied the design and made one.
First meeting - the car was suddenly power over-steering out of corners where it was neutral before. But the car was about 2/10ths quicker.
Had a chat with my suspension man - while I thought that the car was power oversteering because I was strapped in and getting on it harder, he thought the harness bar had stiffened the rear of the car up, his suggestion was to swap out the 24 mm rear bar for the smaller 19 mm and if that cures the oversteer then the harness bar has stiffened the back of the car up.
Next meeting with the 19 mm swaybar the car was neutral again, and another 3/10ths quicker again - so while I put the harness bar in purely to be able to strap myself in nice and tight, it appears to have had another positive effect.
People who have raced c4's will tell you that they can be quite sensitive to even small changes in rear swaybar size, but this was a huge drop.

 

quick question - is the sway bar thing anything I would have to worry about - or is that an adjustment for harder race based driving?

 

For just driving around, enjoying the car, you won't need to worry. Now if you are going to be really pushing into it somewhere, then tuning the suspension via changes like that moves into a whole new level.

5/10's quicker. Now we are getting a bit of evidence of what postive changes can be made to a C4 with the different components.

 

as above dont worry too much about it.
the effects go up with how hard the car is being driven - its just that when a car is being driven at 10/10ths (as in raced) every little thing matters a lot.

 

thanks everyone - bit the bullit - 15% off coupon on eBay helped - exotic muscle had one listed on there so I saved a couple of pennies with the coupon - I should see it in a couple of weeks

thanks again for the help once more of the engine stuff is done I will probably look to the front end for the camber brace or derivative

Sean

 

Keep us posted how it goes and what your findings are

 

thanks - will do

 

If you have fitment issues, give me a shout, a pm, send me your phone nbr. I had some fitment issues with the EM harness bar I bought and it cost less to fix than the postage to send it back

 

thanks I appreciate that - hopefully it will go smoothly - but if not I will definitely be in touch