FAQTech

Why is a chromoly cage lighter than one made from mild steel?

The weight loss is directly related to the tubing wall thickness. Chromoly due to it's metallurgical makeup is a stronger material, so NHRA allows for a smaller wall thickness with no loss in strength when compared to mild steel.

What is the weight difference between a mild steel and a 4130 chromoly cage?

For 1 5/8" tubing, mild steel (ERW seam tube) has a typical wall thickness of .134" and weighs 2.134 lbs per foot. 1 5/8" 4130 chromoly tube has a wall thickness of .083" and weighs 1.367 lbs per foot. Doing the math that shows a weight difference of 36%. Your average 10 point cage has approximately 65' of tubing. Built from mild steel the cage would weigh 140 lbs. The same cage built from chromoly tubing would weigh 89 lbs.

How quick can I run with a roll bar?

NHRA allows cars to run as quick as 10.00 (with stock firewall and floors) with a 6-point roll bar. A roll bar is required when your car runs quicker than 11.99 (13.99 Convertible). Roll bar diameter requires is 1 3/4" where as roll cages are made from 1 5/8" tube.

How quick can I run with a 10 point roll cage?

NHRA allows a 10 point cage to run as quick as 8.50 in the 1/4 mile. From 10.0 to 8.50 the cage must be NHRA certified and the driver to carry a NHRA license.

What if I want to run quicker than 8.50 in the 1/4 mile.

Depending on the class and type of car build, you then get into the SFI certified cage specs. These include SFI chassis spec 25.5, 25.4, 25.3, 25.2 and 25.1E. These specs cover door car construction and there are other SFI specs to cover dragsters, altereds and funny cars.

Does HFR offer kit or "off the shelf" fabricated parts?

No, not really. We specialize in building custom, one off cars & parts. Every car is different to some degree and each car that comes in is used in a slightly different way, or has varying degrees of power. We pride ourselves in offering our customers services to cater to their individual needs. For those who have a part that is damaged and looking for a replacement, we can often duplicate that part or make updates/changes based upon the customers needs. We are a dealer for many of the current products and components available these days. We feel combining our skills in custom car and component building along with todays huge aftermarket parts suppliers is a win-win situation for our customers.

What are some of the door car SFI specs?

  • 25.5 - Full Bodied Car Stock or Modified/OEM Floorpan and Firewall with OEM Frame or Uni-Body Construction – 7.50 to 8.49 Seconds; 3,600 lbs. Maximum. May be Mig or Tig welded mild steel or Tig welded chromoly.
  • 25.4 - Full Bodied Car Tube Chassis – 7.50 to 8.49 Seconds; 3,600 lbs. Maximum. May be Mig or Tig welded mild steel or Tig welded chromoly.
  • 25.3 - Full Bodied Car with Aftermarket Body Shell and Tube Frame, OEM Body Shell and OEM Frame with OEM or Modified Floorpan and Firewall, or Uni-Body with OEM or Modified Floorpan and Firewall Roll Cage - 6.50 to 7.49 Seconds ET; 3,600 Lbs. Maximum. Must be 100% Tig welded chromoly.
  • 25.2 - Full Bodied Car Tube Chassis – 7.49 Seconds & Quicker; 3,200 lbs. Maximum. Must be 100% Tig welded chromoly.
  • 25.1E - Full Bodied Car Tube Chassis – 7.49 Seconds & Quicker; 2,800 lbs. Maximum. Must be 100% Tig welded chromoly.

Are drag cars the only cars you do work on?

No, we do work on all types of cars. If there is a roll bar or cage we can do it all, we need is the specs for the class your running. We have done work for road races, mud bogging and monster trucks.

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