Subframes and Roll Cage or not?

[Fastmax32168]

I would like to get some opinions on just what I need to do in order for my project to not twist itself up like a pretzel when I hop on it hard.
Here is my current direction. 77 Monza Hatch, Ford 9" rear with a 235 ET street on it, Turbo 350 trans, 400 CI motor that should make close to 500 Crank Hp.
Now this is not a drag car, just a hot street ride that I may take to the track once in a while to play. I simply want it to have enough traction that it will have the ability to go straight and be safe when I nail it.
I was originally wanting to do Subframes and no roll bar but I keep rethinking my plan.
Now what I am wondering is If I go ahead and install a 6 point rollbar do I still need to do subframe connectors or will this stiffen it up enough to accomplish my goal?
Thanks

[greg72]

Roy I ran my 72 Vega with a 350 and muncie 4spd with just a 6 pt rollbar for years on the street without any problems . Granted my 350 probably only made 300 HP, but i was a 20 year old street squirrel and was not easy on the car .

I think the key was that I never put slicks on it , so rather than torque the car too much it would often just over power the tires --- again being a young kid, this was perfect !

Also at the time (early 80's) you would hear stories of guys popping out windshields from v8 Vegas due to twist. But the only time I ever saw evidence of that ...the car was an original Northeastern vehicle with much of the original sheetmetal rusted away!

I think with the combination of a solid car with street tires - either a welded in 6 point roll bar or frame connectors would be ok. Of course doing both wouldn't hurt . The cool thing about frame connectors versus the roll bar would be the stealth factor --- but with 500 hp small block ....well stealth can be a relative term anyway

In the end i think it really just depends on which way you want to go. With my Mirage I am going with frame connectors rather than a roll bar..... again the engine in my Mirage is not making the HP yours is ....also i am thinking the car will look more stock without a rollbar and that is the direction i am going with mine. Yours sounds more radical , which is cool. I am looking forward to seeing it when done !

[NixVegaGT]

I would put the subframe in either way if you're looking for opinions. Ray (peterpan) is currently welding all the spot welded flanges on the chassis. I'm betting that will do a great deal to stiffen the chassis. I know doing this on the early Mustangs garners big results.

Have you thought of fabing a 3-link? Here is a couple nice shots in a recent post:

http://forums.h-body.org/viewtopic.php?t=19036

They make this set up for the RX7 crowd.

[monzaS/P]

At a minimum I would suggest frame connectors. Roll bars will provide a little more support but then your giving up a little space if you still plan on using the back seat. Just my .02 cents

[myvega]

Well, you asked for opinions, so here is another one. I doubt very much if your ride gets out from under you that your sub frame connectors are gonna save your ass. Put the 6pt. in and incorporate sill bars into the design and you've got the best of both worlds. My car has over 600 passes on it since I started racing it in 1999 and it has no frame ties, just a 6pt. with sill bars and it hooks hard, goes straight, and has kept it's structural integrity better than some new cars.The doors fit perfectly, the glass hasn't popped out, nothing, and I've gone as quick as 9.71 with 1.35 60ft. times. If you're like me, if it's under your foot, you're gonna use it, so think about the safety factor a bar gives you, but, then again, it's only my opinion.

[Fastmax32168]

Thats some good info and food for thought you guys have given me.
Jim, It sounds like what you built is exactly what I had in mind.
I figured the low sill bar was serving the same purpose as a connector would.
Greg, the main reason I was going with the subframe connectors was in order to keep that stock mirage look, so I guess we thought the same.. But I figure it is so far from stock mechanically that it really doesnt matter to me now. Unlike my other cars that come and go, and I always think about resale, this one is just for me, so why am I worried about it? I am going to make it the way I want it. Since I found this 9" ford rear to bolt into it, now I can put some sticky tires on it, and now with all that power I need to make sure it goes straight, so I was leaning toward the rollbar.
Nix, I was also planning on doing a bit of stitch welding. Between this and the rollbar, it just seemed like subs also was just overkill for a street car.
Monza S/P, I was planning to work around and be able to keep the back seat. I guess we find out after I start bending and welding!
Roy

[myvega]

One other thing you can do to really stiffen up the car is....(don't laugh, it really works) pump the rocker panels full of expanding foam. I got access to mine from the rear wheel well area and used a long piece of medical grade clear hose fed the entire length of the rocker, and as I pumped it in I pulled the hose out. Yeah I know, it sounds really stupid, but it adds a LOT of strength with almost no weight. One can will do each side.

[Fastmax32168]

Jim, I wouldnt laugh about that, I actually started a post a while back,(I think we were still on V8 Monza) about that but it got a lot of skepticism.
They actually make a structural foam just for this purpose, the Ricer guys do it all the time. Here is a link to an article about it.
http://www.stormowners.com/GSOPDatacent ... iew/id/110
Roy

[myvega]

Cool!

[NixVegaGT]

That's a really cool idea! I love it. I'm doing this one for certain. Roy that is a great article. The foam is water tight closed cell. It could help keep water out of voids... I'm going to use this in my frame rails too.

Jim/Roy, Thanks for the idea!

[greg72]

That is a cool idea. I have added this to my stock pile of articles and tech tips.

Thanks guys !

[dANNYbOYs]

I had my 1980 Monza coupe backed halfed, looks pretty cool I have a motor that has an estimate of 350-400 hp I have a 400th trans which the mounting points won 't match for my turbo 400 so do I have to tie my frame for a 350-400 hp motor, if not how do I get a 400th to work with out tying the the frame from back to front. Thanks everybody for your time.

[chevyart]

that 3 link kit on the mustang site(think it was a mustang site) will probably be great for traction, but will only help to flex your chassis(floor pans) more go with some sort of frame connector to strengthen front to back. this will also give you a good strong point to add any crossmembers for tranny support, driveshaft loops, or any other base to support your floor pans. good luck chevy art PS once you add slicks and get bite your car will start showing all the weak links in chassis and suspension. beef everything up if you can

[waybad]

Well, you asked for opinions, so here is another one. I doubt very much if your ride gets out from under you that your sub frame connectors are gonna save your ass. Put the 6pt. in and incorporate sill bars into the design and you've got the best of both worlds. My car has over 600 passes on it since I started racing it in 1999 and it has no frame ties, just a 6pt. with sill bars and it hooks hard, goes straight, and has kept it's structural integrity better than some new cars.The doors fit perfectly, the glass hasn't popped out, nothing, and I've gone as quick as 9.71 with 1.35 60ft. times. If you're like me, if it's under your foot, you're gonna use it, so think about the safety factor a bar gives you, but, then again, it's only my opinion.

Could you post some pictures of the roll bar and it's mounting points? does it hinder the pass. comfort?
any videos?.. nice car
ThanksTC

[chevyart]

hey myvega what exactly are sill bars and where are they installed, and what do they hook to.. i understand chassis and frame very well and probably call your sill bars by another name. always willing to learn thanks chevy art