Rollbar

G.R. · #1 (**permalink**) 02-04-2004, 04:52 PM

I'm going to be installing a rollbar on my NAF 289 FIA:

1) What is the aprox "Rake" or angle toward the back of the car based on pictures I've seen of the original cars there appears to be some. Aprox degree of rake?

2) How far back from the cockpit edge to the front of the driver tube leg-on the (passenger)right side--2"--3" ?

My car has the mounts attached for the hoop and front leg to the frame--was delivered w/o a rollbar originally.

The rear cockpit bulkhead is flush to the rolled edge of the cockpit , no "parcel tray" set back.

Anyone?

wtcobra · #2 (**permalink**) 02-04-2004, 10:47 PM

G.R.- I would say no more than a few degrees. You are going to make it functional right?

Wayne

maxrpm · #3 (**permalink**) 02-05-2004, 12:00 AM

I frequently drag race my car and learned the hard way that with a helmet on, my head actually hit the rollbar during a hard launch. I returned to the pit area to find all my so called 'friends' in tears laughing because they actually heard the clang of the helmet over all the noise, and watched me trying to reposition my helmet between gears so I could see where I was going(it pushed the upper edge of the helmet down over my eyes) I've since reset the rollbar angle to quiet the laughter,and uh...so I can see where I'm going. Sucks having an open top car at a track and you know all eyes are on you, only to look like a stooge.

Thats me in the middle....

G.R. · #4 (**permalink**) 02-05-2004, 12:14 PM

Thanks Wayne for the confirmation. Yes the bar will be functional.

How far back from the cockpit edge to the front of the rollbar tube? I think on my SPF it was about 2".

maxrpm--that had to hurt the ol' ego

wtcobra · #5 (**permalink**) 02-05-2004, 10:43 PM

G.R.- on mine it is only an inch, but my roll bar is partially exposed thru the rear bulkhead. I have seen them about anywhere, but most are 1 to 3 inches back from the bulkhead lip, I would say. Doesn't really matter as long as it protects your noggin.

Wayne

Double Venom · #6 (**permalink**) 02-06-2004, 05:01 AM

GR,

In case you didn't know....to be legal per NHRA the bar has to be at least 2"s above your helmet when you are buckeled in. Also it should be at least a wee bit higher than the windshield.

Set back is basically where you want it. Some are directly behind the seat-forward of the cowl, others go through the cowl as little as a 1" back from the edge.

Max, couple of hints

neck brace if you didn't have one, and a chin strap hooked to the front lower section of your helmet!

DV...the old been there, and it hurts!

GeorgiaSnake · #7 (**permalink**) 02-06-2004, 05:44 AM

You might want to check the NHRA rule book for open cockpit cars. The criteria is based on the et's you run if I'm not mistaken. I was told 5 point cage if quicker than 12 seconds. Fire suit as well.

Anybody know anything different?

Randy

GeorgiaSnake · #8 (**permalink**) 02-06-2004, 05:52 AM

I was wrong about the et check this link

http://www.nhra.com/contacts/tech_faq.html

Randy

Double Venom · #9 (**permalink**) 02-06-2004, 06:19 AM

GS...well done!
We have found each "tech" even at the same tracks will interpret the rules a little differently.

They have approved our "down bar" consistantly and is made to be removed or added in minutes. It fits in the car so nice without interfence to the driver or passanger we have found that the owners install them an just leave them in. The diagonal behind the driver is NOT needed, unless you start running some very serious times.

If we pop into the 9"s this season, and we fully expect too, then we will have to add a "halo" and side bars. Now that will be a little tricky and still keep it street useable!

DV
PS..the owner of this DV II is rather tall, thusly so is the main hoop to meet the 2" inches higher than the helmet rule!

maxrpm · #10 (**permalink**) 02-06-2004, 08:35 AM

Quote:

Originally posted by Double Venom

Max, couple of hints neck brace if you didn't have one, and a chin strap hooked to the front lower section of your helmet!

DV...the old been there, and it hurts!

DV, yes I did have the collar on but it was my first pass and I wasn't anticipating the car to hook all that well with street tires. I watched the video in slow-mo, 1.50 60ft threw my upper torso back and compressed the seatback enough to allow contact with the rollbar. When I installed the bar I didn't take into account the helmet or gs, I went for visual aesthetics. This was a few years ago.
I have other issues to look into. The local track where I run always considered my three bar hoop legal because it was their view that it was a (wink,wink)'factory design'. Well that track is closing this summer after 54yrs because LI needs more golf courses. My problem will be fitting a NHRA cage into the car, I don't think I will go that route, and will probably stop racing the car, or even sell it. It's funny because I started out building my cobra as a track only car (halo and all) and decided 1/3 of the way thru to make it a street car and cut the cage back out.
I'm thinking about taking up golf....

Double Venom · #11 (**permalink**) 02-06-2004, 11:46 AM

Max,
You wont like Golf! You just can't get the sound or the RPM's out of those clubs! 1.50 60' is exactly what a DV turns! That should put you at well over 1G at launch. Like I said, been there and it hurts!

DV...Golf...give me a break!

HighPlainsDrifter · #12 (**permalink**) 02-06-2004, 12:12 PM

Hi,
a certified NHRA track will make all convertables under 14.00 ET have a welded in rollbar with a driver's side bar[bolt in is OK] Bar must be wider than shoulders and 3" taller than head, Also all covertables will need a certified 5 point harness, snell 95 full helmet, arm restraints, SFI gloves, SFI jacket[neck brace optional ] neutral satety switch, proper battery holddowns,master battery cut-off switch,driveshaft loop, dual carb return springs.
This is good to 11.00 ET for automatics, a manual trans needs a scattershield if faster than 12.00
You can see my rollbar in my pic gallery, and yeh you NEED the headrests if you ever take the MRS out in the car,if she bangs her head on the rollbar,you'll never have sex again.Perry.

maxrpm · #13 (**permalink**) 02-06-2004, 12:13 PM

DV, But I get to wear those cool clothes & ride around in one of them carts!.....I was getting 1.5s on 28x12.5 Mickey T SportsmanPro street tires @18psi hot. I never had a slick on it at the track but I might try 10.5 slicks this spring. I have a weird hop at the start that I can't lose: it bites, the front tires go about 6-8" in the air then the rear susp. unloads, front comes back down- then it hooks wheels up again and goes. I'm hoping slicks cure this, what do you think?
And I'm gonna look into a chin strap.

HighPlainsDrifter · #14 (**permalink**) 02-06-2004, 02:25 PM

DV,
You will need a full cage to go faster than 11.00 and a full SFI 3 layer jacket/pants/boots/gloves. Also to go into the 9's you will have to get an NHRA competition license [3 slow runs and 3 full runs] You will also need a solid axle, no independent rears allowed if you have one.
Also a rated parachute for your weight.
Good Luck,
Perry.

Double Venom · #15 (**permalink**) 02-06-2004, 03:31 PM

Perry,
Yup, but I didn't know they actually passed the 3" high-over the head rule. They told me about it last year, but it hadn't been officalized if you will. Haven't had a chance to read this years rules yet.

Since DV II's use (almost always) an independant rear we knew they were/would shut us down at 9.99. But, you gotta do it just once if you know what I mean. The car is actually set up for more of an autocrosser but ya just gotta know what you gotta know! If you know what I mean is?

When my DV, with all the safety equipment listed as far as clothing, wrists restraints, 5 point harness, helmet, etc., hit 11.00
They asked me if I was going for 10.99? I just smiled and told them we would be ready! We ARE ready!

Max, it sounds like you have one heck of a small block! Maybe you have to much bite?? Maybe pinion angle is off a little, this will certainly create "wheel hop". Maybe a different shock set up all the way around, maybe a lot of things. Sure wish you were closer, I'd love to be in the pits with ya though!

MT sponsored my DV, and told me to dump the slicks and go with their MT/ET's. 9.5 lbs. cold, nose lifts, rips out 9" rear ends by the pinion, blows Vipers away at launch, ( and at the end) and hooks like you wouldn't believe. Scond gear is almost as violent as first. I launch at 3,900 to 4,800 RPM.

Here's an idea for you, have someone with a "good" video camera tape your launches for you. Record everything for that launch: temp., air pressure, RPM at launch, even the time of day. If you can get the track temperature so much the better. Have the video taken from the back 3/4's to the front. Then some at the front head on. Well you know what I mean. After 60' you really don't care what's happening. Watch the rear wheels in their opening. See if the right rear especially is actually moving rear ward at launch. Are the front wheels coming up pretty even or is the left front visibly coming up faster and higher than the right.

On my DV the right rear was actually moving backwards in the tub, even though we were using bushings from a Ford 250 truck! Now gone to poly's!

Been shown a lot, but still my favorite picture!

DV...Not a Pro by any means, but I sure have fun!

HighPlainsDrifter · #16 (**permalink**) 02-06-2004, 05:21 PM

DV,
You're having Way too much fun, wish I was there.
Just don't push it till it breaks.

Maxrpm,
To go in the right direction.....
Replace your rear coilover springs with 140# springs and pre load the pass side rear with 2 extra turns,that will help the tires stay planted.
Also add a panhard bar, [5th link] will keep you straight at the top end.
Perry.

Double Venom · #17 (**permalink**) 02-06-2004, 06:12 PM

Highplainsdrifter,
You mean like this? Our first attempt at -10.99. Ripped the housing in half. Didn't put nary a scratch on the pinion or gear!
Someday I'm going to get all the pieces chromed

DV..somebody stop me. I need Spring to be here!

maxrpm · #18 (**permalink**) 02-06-2004, 06:50 PM

The front comes up evenly on launch and when it bites again. So what you see is a quick double wheelie at the start. It's not wheelhop, more like the rear squats and digs in, front comes up, then the rear suspension sort of unloads and rises then digs back in. The front actually rises higher on the second bite. No real wheelspin but you can see in the slow-mo the tire sidewall 'grip' around the "8 o'clock" area of the pass.wheel,4-drivers side, then disappear then wrinkle again. The 1-2 shift is fine, front tires comes up evenly(approx4") I thought about lower tire pressure but I'm 'ascared' with such a short wb car. I've run other cars with tire press. as low as 8-10psi. but not in a 2100lb, 90" plastic car! I must be getting old...I'm starting to actually worry about consequences.
Thanks for the help guys, I feel like I stole G.R.s thread

G.R. · #19 (**permalink**) 02-06-2004, 07:39 PM

Naw learned a couple of things besides rollbar--haven't drag raced in nearly 30 yrs---things sure do change

HighPlainsDrifter · #20 (**permalink**) 02-06-2004, 10:22 PM

Wow ! What a great trophy that would make for DV IV. Put it on a 8 x 8 piece of wood and a plaque for the tuff luck award.

I'm not as brave as you, I only launch at 1/4 throttle[1.66 60']
and short shift, I have a 95 mile roundtrip to the track and don't want that to happen. But maybe I should get an award for the 1st car to run 11's on REGULAR gas !
What a hoot,
Perry.