How to drag race your classic

bleedfordblue65 said:

they guy wants $225 plus shipping for a set of brand new leaf springs and used slide-a-links. I think im gonna go ahead and jump on it.

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clutch chatter, engine mounts, cracks in the flywheel, drivetrain angle...all can cause that...i had the same problem, got my flywheel re-surfaced..and bam..no more tire shake

How can I check drivetrain angle? I did a t-5 swap and maybe that threw off the angle. Do you think since Im not launching hard and it still hops than it is something other than the leaf springs? MustangMatt, did your car shutter real bad even when easing off the clutch, or only under hard acceleration?

I need major help.....

I have a drag car that is streetable, I'm building it for the strip. Its a 347 with a 671 blower, make lots of power. turbo 400 4,000 stall with a transbreak. 90/10's and moroso drag trick spings. M/T et streets 275/40/15. subframes, traction bars new leaf spring, stock one and stoack rear shocks. I have no wheel hope just wheel spin. I leave on the transbreak and spin. My best 60' is 1.7 at 11.33. I have taken boost out, i'm now at 6lbs and taken timming out to reduce h.p. I have tried everything. The car transfers weight good but the rear tires rub. Should I go with a smaller tire, so the car can squat more. How much would the cal-tracts help me? I am embarraced at the track. I broke my bracket car, so I am using this in the mean time. I know I could foot break the car and I know it has more in the car but I looking to launch the car hard.

muddslide said:

I need major help.....

I have a drag car that is streetable, I'm building it for the strip. Its a 347 with a 671 blower, make lots of power. turbo 400 4,000 stall with a transbreak. 90/10's and moroso drag trick spings. M/T et streets 275/40/15. subframes, traction bars new leaf spring, stock one and stoack rear shocks. I have no wheel hope just wheel spin. I leave on the transbreak and spin. My best 60' is 1.7 at 11.33. I have taken boost out, i'm now at 6lbs and taken timming out to reduce h.p. I have tried everything. The car transfers weight good but the rear tires rub. Should I go with a smaller tire, so the car can squat more. How much would the cal-tracts help me? I am embarraced at the track. I broke my bracket car, so I am using this in the mean time. I know I could foot break the car and I know it has more in the car but I looking to launch the car hard.

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You have outgrown your tires, tub it or don't use the transbrake, foot brake it.

I need to back half the car, but thats very costly. Like I said, I also have a bracket car with a blown motor, so it need money. It would cost around 2,000 dollars to add a 4 link or ladder bars. I'm looking for a cheaper way to get more traction. I know without a 4link I will not be cutting 1.4 60' time but would the cal tract's help? If so how many people have tried them and did they work.

muddslide said:

I need to back half the car, but thats very costly. Like I said, I also have a bracket car with a blown motor, so it need money. It would cost around 2,000 dollars to add a 4 link or ladder bars. I'm looking for a cheaper way to get more traction. I know without a 4link I will not be cutting 1.4 60' time but would the cal tract's help? If so how many people have tried them and did they work.

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Drag radials are your friend and will keep you tires from spinning.

You can get good bite with the Caltracs and the recommended suspensionparts. They are not just for wheel hop. The design, coupled with the right adjustment, helps change the centerpoint of the weight of the car on launch. They will plant the tires. No they are not a 4 link, but they can act nearly as good if you use the Calvert system of springs, shocks and their Caltracs.

Price for those item, IIRC are in the neighborhood of $850.

Good thread, as these are issues that we are preparing to tackle on my 'vert. I've had an initial discussion w/ Calvert, and hope to get the rear suspension "hookup" with him.

I might just call them and ask a few questions. If you guys are happy with them and trust them, sounds like a good idea to me. This way I could buy the set up in pieces. I just don't want to spend money on something that will not work onmy set up

steel1212 said:

How are cal tracs noisy? Do they just transmit road noise to the inside of the car? I mean I run flow 40s so they can't be much noisier than those lol.

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They run a solid aluminum bushing in place of the rubber bushing in the front eye of the leaf spring. I run a Detroit Locker w/4:11's and it was louder then my exhaust note a highway speeds. The sound travels from the diff though this aluminum bushing into the body of the car and seems to be amplified on the inside. I replaced the aluminum bushing with a delrin bushing and it took most of the noise out. If you adjust them for street use, you can hear them hit the leaf springs if you accelerate hard enough on the street.

Anyone know how much the mono leaf spring is for the 67's?

BullittStangV8 said:

Can someone post up the NHRA rules regarding roll cages/roll bars?
For example:
11 second.......need 6 point cage
10 second.......need an 8 point cage..ect.
NOTE THE CAGE SPECS ABOVE ARE NOT ACCURATE, JUST AN EXAMPLE. That way people can just search for "roll cage" in the search and find the specs, because I've been looking for months online and cant find it. (and yes, I know I should just buy a rule book).

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2005 rules NHRA Only 1/4 mile (1/8 mile)
Driveshaft loop req. 13.99 (8.59) or quicker w/slicks
Driveshaft loop req. 11.49 (7.35) or quicker w/o slicks
Roll Cage req. 10.99 (6.99) or exceeding 135 mph (6 pt)
Helmet req. 13.99 (8.59) or quicker (Snell or SFI approved)
Fuel line; Max of 12" total front to rear of rubber fuel line. No fuel lines in drive shaft tunnel.
Catch can req. all clsses.
SFI jacket req. 10.00 (6.40) to 11.49 (7.35)

thehueypilot said:

2005 rules NHRA Only 1/4 mile (1/8 mile)
Driveshaft loop req. 13.99 (8.59) or quicker w/slicks
Driveshaft loop req. 11.49 (7.35) or quicker w/o slicks
Roll bar req. 10.99 (6.99) or exceeding 135 mph
Helmet req. 13.99 (8.59) or quicker

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You need at least a 6 point cage & a single layer jacket @ 11.99 or quicker.

washMO66 said:

You need at least a 6 point cage & a single layer jacket @ 11.99 or quicker.

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that's a negative on the cage. they changed the rule sometime last year.

When do I need a roll bar or roll cage?

A roll bar is mandatory in all cars (including T-Tops) running 11.00 to 11.49, in convertibles running 11.00 to 13.49, and in all dune buggy vehicles running 12.00 seconds and slower. The rollbar must conform to the diagrams referenced in the NHRA Rulebook.

A roll cage is mandatory in cars running 10.99 or quicker or any vehicle running 135 mph or faster (regardless of E.T.). In full-bodied cars, with unaltered firewall, floor and body (from the firewall rearward, wheeltubs permitted), running between 10.00 and 10.99, roll bar permitted in place of roll cage. In convertibles running 10.99 or quicker or exceeding 135 mph, roll cage mandatory. Cars runing between 7.50 and 9.99 must have chassis inspected every three (3) years by NHRA and have a serialized sticker affixed to the cage before participation. Plating of chassis prohibited for all cars manufactured after 1/1/2003. Rear-engine dragsters must conform to SFI Spec. 2.7A; vehicles running 8.49 to 7.50 and/or exceeding 180 mph must meet appropriate SFI Spec for body used. All others must conform to specs for body style used, as listed in General Regulations 4:11, 10:6 of the NHRA Rulebook.

via http://www.rockfallsraceway.com/techfaq.shtml

Didn't know they changed it, thanks for the heads up, I was going off of the following which has obviously been modified.

14.99

To prevent radiator overflow from leaking onto the track, NHRA requires an overflow can of at least one pint in volume. This can be as simple as routing a radiator overflow tube into a windshield washer reservoir.

All cars should also be equipped with a proper battery hold-down, even when the battery is in the stock location. Factory stock hold-downs are acceptable in this case. Otherwise, bolts of 3/8-inch diameter must be used to retain the battery. Lug nuts are another area of concern, especially with aftermarket wheels. NHRA recommends all cars be equipped with open-ended lug nuts to allow the inspector to verify the length of thread engagement.

Obviously, all lug nuts and studs must be in place. For slower cars, this isn’t a critical point, especially when using O.E.M. wheels. But with faster cars and aftermarket wheels, the concern is that the lug nut engage the threads of the stud for a distance at least equal to the diameter of the stud. Inquire at your local track as to what the tech inspector will accept.


Since fire is an ever-present threat, NHRA specifies no more than a total of 12 inches of rubber fuel line in the fuel delivery system. This includes the rubber line between the pickup and an external fuel pump and also between the fuel pump and carburetor. In the case of an accident, rubber line is susceptible to damage that could cause a fire. Investing in either steel hard line or braided-steel fuel line is both wise and far safer than using rubber fuel line. Some type of reverse lockout for aftermarket shifters is also required for all cars.

13.99

NHRA requires a DOT, SNELL or SFI helmet for any car quicker than 14.00. There are a number of different specs so you should check with your local tech inspector.

For cars that run e.t.’s between 12.00 and 13.99, all of the above requirements apply along with the addition of a driveshaft loop. A new-for-’95 rule exempts cars running 13.00 and slower when equipped with street tires. Since traction is the key to going quick, this places more strain on the driveshaft. To prevent the driveshaft from breaking at the front U-joint area and perhaps coming into the interior of the car, or digging into the track and pole-vaulting the car, NHRA mandates that a steel loop be placed just behind the front U-joint of the driveshaft. A universal driveshaft loop is available from Lakewood that bolts to the floorpan. A rollbar is required in this e.t. bracket only if the car is a convertible.

11.99

By the time a car is capable of running between 11.00 and 11.99 seconds in the quarter-mile, safety requirements are especially important. Up until this point, factory seatbelts are acceptable, but in the 11-second-and-quicker time zone you need a quality safety harness. The minimum requirement is a 3-inch-wide, five-point harness meeting SFI spec 16.1. The 1995 National Hot Rod Association Rulebook outlines the proper way to mount the shoulder harness and belts.


An NHRA-legal rollbar is also required in the category. Recent rule changes have reconfigured what NHRA classifies as a rollbar. The classic four-point bar is no longer acceptable. The new standard is mild-steel tubing of at least .120-inch wall thickness (most chassis companies, like Art Morrison, use .134-inch wall tubing) that includes a forward-running side bar from the main hoop past the driver’s shoulder. This bar is only required on the driver’s side, but most systems include both sides for a six-point rollbar.

An SFI-approved scattershield is also necessary in this e.t. category. NHRA requires the scattershield to have an SFI aluminum-foil sticker. According to Red Roberts of McLeod Industries, older bellhousings can be certified by sending the scattershield and block plate to the original manufacturer. The company will inspect the housing and if it passes, it will receive an SFI 6-1 certification. Most SFI certifications are good for five years. Contact your manufacturer if you’re not sure.

The clutch and flywheel must also be SFI certified. The main consideration in this area is to avoid using a cast-iron flywheel. According to Roberts, sometime in the mid-’70s most of the new car companies began using nodular iron flywheels that are much safer. Most, if not all, current high-performance aluminum and steel flywheels are safe when used in conjunction with an approved scattershield, but the rules state that the pressure plate and flywheel need an SFI certification number. Roberts says the best plan is to record all your SFI numbers in a logbook. This makes it easier for the tech inspector and it shows the inspector that you understand the importance of the inspection process. This e.t. level also requires steel valve stems in all wheels, along with arm restraints for open-cockpit cars like roadsters.

10.99

Cars running between 10.00 and 10.99 need all the above-mentioned safety equipment, plus driver’s protective clothing, aftermarket axles and an SFI-approved harmonic balancer. The driver needs to have at least a single-layer, SFI-approved jacket such as those sold by companies like Diest, Simpson, RJR and others, as well as long pants and approved driver’s gloves.


The aftermarket axle requirement also extends to installing a C-clip eliminator kit in any rearend that uses a C-clip to retain the rear axle, such as the GM 10- and 12-bolts and the Ford 8.8-inch rearends. While the current NHRA axle rule does not include an SFI spec for axles, experienced axle manufacturers such as Summers Brothers, Mark Williams, Strange and others offer axles intended for this kind of abuse.

Harmonic balancers first became a subject of concern on blown cars that placed enormous loads on the balancer driving the supercharger. Now, any car running quicker than 10.99 needs an SFI-approved harmonic balancer to be legal. Companies like Vibratech, TCI, BHJ and others can supply the necessary legal part.

A new NHRA safety rule change for 1995 states that cars running between 10.00 and 10.99 must have a rollcage unless the car has an unaltered firewall, floorpan and body (except for wheeltubs). This means if you have a street car with a stock floorpan and firewall but have tubbed it for bigger tires, all you need is a five-point rollbar until the car runs quicker than 10.00. Of course, a rollcage is perfectly acceptable if you wish to install one.

9.99

Now we’re into the really quick cars, those running from 9.00 to 9.99 seconds in the quarter. These cars are blazingly fast and capable of speeds approaching 150 mph. Significant improvements must be made to the car in order to step into the 9-second zone. Foremost among these is a rollcage. The cage must be constructed of mild-steel tubing at least 15/8 inch in diameter, with .120-inch wall thickness. It can also be chrome-moly tubing of .083-inch wall thickness with a total of eight attachment points. These eight points refer to the placement of the cage surrounding the driver, including the two rear support bars. NHRA does not require bars that run forward to the front suspension, although many cage designs include them. All cars running 9.99 or quicker must have the cage certified by NHRA and have the NHRA certification sticker attached to the cage.

Attached to the cage is a window net to keep the driver’s arms inside the car. The driver must also wear a neck collar and fireproof clothing meeting an SFI spec. Additional requirements include an NHRA competition license, an external electrical shutoff and a flexplate/automatic transmission shield. If your car can run over 150 mph in the quarter, as many of these cars do, then NHRA also requires a parachute to help slow the car down. Now that we’ve primed the pump, your best bet is to obtain a 1995 NHRA Rulebook for $10 and carefully read the E.T. Bracket General Regulations section. The Rulebook specifies exactly what will be required depending upon your car’s e.t. capability. Drag racing with fast street cars is tons of fun. It’s even better when you do it safely

The 11.99 rule actually dropped to 11.49.

anyone running the mono springs?

Well, after a few more bad launches at the track, I ordered everything today from Cavert Racing.I hope it helps, I will keep you posted.

when you say "everything" what all does that include?

I got the rancho 9000 and the mono springs, I didn't need the cal tracs. I also ordered new rims, with the correct backspacing so the tire shouldn't rub anymore.