Jason Staley

Well, I finally had some time to get underneath the car and figure out a frame stiffener that is of some help and is reasonbale to fabricate. I'm not sure how much is "enough", so any opinions are welcome.

1) semi- X brace using 1.75" x .125" thick tubing +8% torsional stiffness, 21 lbs
2) roll bar using 1.75" x .125" thick tubing +10% torsional stiffness, 35 lbs
3) 1/8" thick plate welded to outside of frame (orange area) +7% ,13 lbs
4) TOTAL: +25% stiffness +68lbs

The roll bar was just an estimate. If anybody has real dimensions, I could revise the model with them (i.e. width, hieght, tube size). I tried a backbone approach, but there just isn't enough room to get past the rear end - at least that I could tell. I did try a model using 2 tubes (same as above) down the middle of the car from the rear crossmember to just behind the engine. It didn't seam to be a big improvement ... ~ 2% increase in torsional stiffness.

I didn't make a perfect x-brace because the driveshaft and 2 exhaust pipes are running down the middle of the car. So I connected the 4 bars to the tranny cross member just outside the exhaust tube holes. I also connected the bars together underneath the crossmember with a 1/8" thick plate of steel. Not the easiest to fabricate, but I'm sure it can be done.

If anybody has any suggestions, please throw them out. I'd appreciate dimensions too, so I could build it in the model. Thanks.



http://temp.corvetteforum.net/c3/greatwhite/

:cheers:

SmokedTires

That's a pretty neat model that you've come up with :yesnod: . Your rollbar's pretty accurate to the one I installed into my own car. I did weld plates to the frame 1st though, then welded the rollbar to the plates for better mounting to the car. Instead of just a 4pt rollbar, how would an 8 point measure up ? It seems that the extra points to the forward section of the frame may allow for not needing the X bars underneath, though I may be wrong :)

Don't forget about the crossbar between the shock towers that's available thru VB&P ;) .

Another area is motor plates mounting the front of the engine block directly to the frame rails :) . :cheers:


[Modified by SmokedTires, 9:09 PM 3/9/2003]

metal tech

Did you use software that can actually estimate these changes? With several companies being able to mandrel bend rectangular tubing, a frame with no welded together sections "should" be stiffer. The C5's hydroformed frame for example. As Mike mentioned, motor plates, at the front of the block and at the bellhousing area will help stiffen the front section. I've read about some structural foam that can be injected into a hollow frame rail to provide more rigidity. Just food for thought.

Al

FinnShark

Good work Jason! Your stiffening work is really interesting! :cool:

I suppose that the semi X-bar is as close to X as it can be? If I'm correct the trans is comming pretty close and it is not possible to do real X stiffener there? Can you see from your model how flexible the rear frame and center frame connecting area is? I mean the area where the rear frame vertical beams are connected to horizontal parts. Do you think there might be some places to add stiffeners? :thumbs:

NHvette

Those plans look great !!
But, us automatic gys are left out. We can't weld up to the tranny crossmember.
Do you think a bolt-up scenario would be worthwhile ?

Keep up the good work.
:cheers:


[Modified by NHvette, 1:32 AM 3/10/2003]

aussiejohn

Dear metal tech and Jason,
I only posted a reply the other day re chassis strengthening. James Pierce in Melbourne did a full seam weld on his 1968 roadster chassis, then had it powder coated and filled with foam and this made it incredibly rigid. Definitely worth doing if you pull the body right off.

Reghards from Down Under

aussiejohn :cheers:

PROSOUTH

TTT

I just got in from a week long trip and have missed several good topics it seems. This is one that I have been waiting on. I would like further information and major discussion on the methods shown. Thanks JIM

SmokedTires

Filling the frame with the foam stuff seems to work really well without the expense of a lot of weight :yesnod: . :cheers:

mayberg

Have you considered gusseting the frame according to the ChevyPower publication?