Front upper chassis bar won't line up to bolt holes. Force it?

[Cobra4B]

EDIT 2 - Could someone please measure their chassis? Panoz says the chassis is supposed to be 32.5" outer edge to outer edge, but ours is clearly 32.25" everywhere

EDIT - See posts 3 and 4... our chassis is square, the bolt hole spacing on the piece we received is 0.25" too wide. I assumed it had sagged inward on the top before taking actual measurements.

The shop that put the crap 347 in the car also put on a screwy accessory setup (even when we told them to do '94 GT accessories) which got in the way of the bolt-in upper chassis bar. To make it work they welded it in at the front.

I cut it out and put it back the way it was to get the engine/trans out and make the car easy to access/service in the future. Then went ahead and ordered the a new part from Panoz. The new part doesn't line up. It's off by 1/4". Muscling it I can get it to be off only 1/8" but nowhere near bolting up. Anyone else run into this? I'm sure I can make it work with some improvisation, but should I?

The old bar was round tube and adjustable with heim-joints at each end vs. this one being fixed.

New GTS bar not fitting.



Old bar welded in place with band-aided SBF accessories in the way of where it should have been bolted in.



Before when it was bolted in.


Thanks,

Brian

[gamacdon]

i am not an engineer but to me flexing the frame to fit the bar is not the way to go. i am leaning toward round bar with adjustment. on the other hand 1/4 inch is not much and it is the top of the frame where it should not make much of a difference. i know this reply is not much help but hopefully something to think about.

[Cobra4B]

I was able to spread the upper chassis with a scissor jack and piece of metal. This allowed me to get the bolts in just fine. However, after doing that i measured and found the top of the chassis was now wider than the bottom.

I removed the upper tie bar and took some measurements. With the bar unbolted the chassis is perfectly square. The main longitudinal square tubes are 32.25" outer edge to outer edge uppers and lowers. I measured at multiple spots from the firewall all the way to the tips. The bolt holes in the chassis are 30.5" center to center. The bolt holes on the chassis bar I was sent are 30.75" center to center so it is exactly 0.25" too wide.

Any chance someone could take some measurements on their end? Did I just get one that was made a bit off? Or, are there variances across the cars? I expected my upper chassis rails to be slumped in, but the tape measure proves otherwise.

I've emailed Panoz to see if I got a bad one or if they have any of the other style ones in stock.

[Cobra4B]

Can anyone else verify the frame rail outside-to-outside measurement?


Upper rail 32.25"


Lower rail 32.25"


Upper chassis bar bolt holes @ 30.5" on center (makes sense since the square tube is 1.75"... 32.25 - 1.75 = 30.5)


Upper bar Panoz sent @ 30.75"

[Cobra4B]

Could someone please measure their chassis? Panoz says the chassis is supposed to be 32.5" outer edge to outer edge, but ours is clearly 32.25" everywhere.

[Fast Viper Dan]

Originally Posted by Cobra4B

Could someone please measure their chassis? Panoz says the chassis is supposed to be 32.5" outer edge to outer edge, but ours is clearly 32.25" everywhere.

I don’t know why your frame uprights are less than they should be. It was made by a human or something was bent at one time. But if they are square, this is what I would do.
Cut the cross bar in two, cut ¼ inch off one of the halves, have your machinist buddy mill a piece of cold rolled steel bar (1018) 2 inches long to fit inside the tube. Drill a 3/8 hole about ¾ inch in from the cut end of each half of the bar so that with the 2 inch long steel bar inserted into the cross bar, it can be seen thru each hole. Weld the inserted bar at the hole so that you have the 32.25 inch spacing that you need.

Or, go back to the adjustable bar.

You should not force the bars apart. Under vibration this will encourage other welds to crack. Should go together with minimal pressures added.

Good Luck.

[NZGTRA17]

Originally Posted by Cobra4B

Could someone please measure their chassis? Panoz says the chassis is supposed to be 32.5" outer edge to outer edge, but ours is clearly 32.25" everywhere.

Brian, measured mine, 32.42" across same dimension with bar bolted in place.

My car uses the GTS bar and while heavier I like this better than the round heim jointed item. Far stiffer.

Kel.

[Cobra4B]

Thanks Kel & Dan - FWIW Panoz says I should just spread the upper chassis and that it's not an issue at all. They said they do it to cars all the time. Also, said they moved away from the heim-jointed adjustable bars because they would get some inward sag from the upper chassis over time.

Others have also said that you want to "jack" in some preload to that upper part of the chassis to account for the loading of the suspension etc.

I've decided to buy a new tubular bar from Coleman, but go one size larger than the original one that came on the car. This way I can bolt it up, then turn the bar a couple of turns to expand it (LH and RH threaded heims like the trailing arms etc.) and slightly load the chassis. IMO it's the best overall option.

I can then remove tension for easy removal of the bar vs. having to break out the scissor jack and a metal bar every time I want to remove/install it.

Kel - Did you measure the lower part of your chassis to see if it matched the upper? Curious if yours is spread out at all with the bar installed.

[NZGTRA17]

Originally Posted by Cobra4B

Thanks Kel & Dan - FWIW Panoz says I should just spread the upper chassis and that it's not an issue at all. They said they do it to cars all the time. Also, said they moved away from the heim-jointed adjustable bars because they would get some inward sag from the upper chassis over time.

Others have also said that you want to "jack" in some preload to that upper part of the chassis to account for the loading of the suspension etc.

I've decided to buy a new tubular bar from Coleman, but go one size larger than the original one that came on the car. This way I can bolt it up, then turn the bar a couple of turns to expand it (LH and RH threaded heims like the trailing arms etc.) and slightly load the chassis. IMO it's the best overall option.

I can then remove tension for easy removal of the bar vs. having to break out the scissor jack and a metal bar every time I want to remove/install it.

Kel - Did you measure the lower part of your chassis to see if it matched the upper? Curious if yours is spread out at all with the bar installed.

Brian, measured bottom and pretty much the same as the top. May be 1mm in it. The bolt centers in the removeable member I have appear to be around 30.75".

I mentioned I like the GTS brace because it is stiffer, I meant in compression and bending. Tension is not the issue between the heim jointed item and the GTS item but the 2 other load scenarios are.

I am not a fan of preloading the chassis unless this is a must for fitment and cannot be remedied easily. If the GTS bar is used and is a good fit, once it is torqued in at 90ftlbs any movement due to suspension deflection will be due to other load path factors or member deflection.

My time with aircraft engineering taught me that preloading normally leads to stress cracking once a dynamic load is applied (i.e. where the direction of load may not be in the same plane as the preload force, unlike torqueing a fastener, where the preload is in the same plane as the force experienced by the fastener).

Just one mans opinion of course!!

Kel.

[Cobra4B]

10-4.... then I'm definitely going to get the proper heim-jointed bar from coleman with 3/4" heims and call it a day.

[feqrags]

that's why we read your post..thanks..

[boothkc]

You will find that not much is "standard" on these cars. Just about everything requires some custom fitting or messing with. Simple stuff just doesn't fit and this is a good example.

I would cut the square bar and reweld it to your length needs. Any good welder should be able to do this and stiffness is important.

We found it was easier to make much of the metal stuff rather than futz around with stuff from Panoz that took hours to fit. We did replace the entire front frame (fire wall forward) once and they did a nice job of making that up for us.

Kevin

[panozracing]

I rarely have fitment issues with Panoz Parts??? Weird...

Maybe your cars are bent :-)

[boothkc]

Brian,
we have 3 of them and even moving parts from one car to another is often a struggle. Some stuff is easy (Coleman suspension), but other stuff is more of a PIA. There is a quite a bit of hand building etc with these cars and newer parts (if available) seem to be "rougher." Body panels are very crude, new fron clip required lots of time to fit and when we smashed up the radiator and support there was a ton of time to get the metal work all correct. Cars could be "bent" but not likely too much.... they are all bent a bit!

My point is that stuff like this post should be expected in a "custom made" race car and you just have to be expecting it. Everything seems to take more time in boats and race cars.

Kevin

[Cobra4B]

It's not that this type of stuff surprises me with a small-run custom racecar, but more as to the best way to deal with it. I.e. spread the upper frame to make it fit or get another adjustable bar. I'm not 100% comfortable with spreading the chassis 1/4" considering it's square top to bottom and I don't like that I have to bust out a scissor jack and metal bar every time I want to take that bar on and off.