Mounting Battery in Trunk 3/8 bolts to frame? HOW did you do it???

[V6UnderPressure]

I am just curious as I am working towards getting my car at least CLOSE to NHRA legal. I am getting a trunk mounted aluminum battery box so I wont need a firewall. My question is, how did all of you get the 3/8 bolts mounted to the frame. Any opinions are welcome here!!!

Scott

 

[Scott Atk]

Scott, I don't have a current rulebook, I do however reference the rule book online. I'm not positive which year rule book that I'm reading but it states as follows:

8.1 BATTERIES

All batteries must be securely mounted and may not be relocated into the driver or passenger compartments. Rear firewall of .024-inch (.6 mm) steel or .032-inch (.8 mm) aluminum (including package tray) required when battery is re-located in trunk. In lieu of rear firewall, battery may be located in a sealed .024-inch (.6 mm) or .032-inch (.8 mm) aluminum, or FIA accepted poly box. If sealed box is used in lieu of rear firewall, box may not be used to secure battery, and must be vented outside of body. Strapping tape prohibited. A maximum of two automobile batteries, or 150 pounds (68 kg) combined maximum weight (unless otherwise specified in Class Requirements) is permitted. Metal battery hold-down straps mandatory. Hold-down bolts must be minimum 3/8-inch (9.53 mm) if battery is relocated from stock and other than stock hold-downs are used ("J" hooks prohibited or must have open end welded shut.).

Going by this the box is not required to be secured to the frame. Mine is bolted down to the trunk floor itself with an aluminum strap connecting the bolts on the underside. Hope this helps, I can crawl under and snap a few pics of my setup if it would help.

 

[its turbo time]

I always thought it was just the fuel cell that had to be mounted to the frame.

 

[fuzzyGN]

I don't think it is required but I have seen where a length of round tubing was bent into a "U", the ends welded to the frame, and tabs welded to the tube. Then the battery hold down hardware is attached through the tabs thus to the frame. None of my cars have had the frame mounting but then again none of them have gone into the 11's or faster so I am not sure they care as much.

 

[turbodave231]

Here are a couple pics:



I eliminated the spare tire well and made a bracket that mounts to the frame on one side and the fuel tank support on the other. You could do soemthing similar and keep the stock tank and go through the spare tire well.

Anyway you do it, follow NHRA rules and bolt that battery to the FRAME!

Dave

 

[Scott Atk]

Nice install Dave !
Out of curiousity, does your rulebook state something different than the excerpt that I posted? The reference I used says nothing about mounting the battery to the frame.

 

[ajt86]

i have the 04' rule book- i beleive it says it must be bolted to the frame. they dont want that 60 pounds tearing off of the trunk pan and flying all around.

now as far as reduction/trasfer- is this worth it? by the time you get a battery box, the extra cables, and put it in the trunk- how much extra weight are we talking about?

sorry if im hijacking- i just always wonderd if it was worth it to put it back there.

 

[V6UnderPressure]

i have the 04' rule book- i beleive it says it must be bolted to the frame. they dont want that 60 pounds tearing off of the trunk pan and flying all around.

now as far as reduction/trasfer- is this worth it? by the time you get a battery box, the extra cables, and put it in the trunk- how much extra weight are we talking about?

sorry if im hijacking- i just always wonderd if it was worth it to put it back there.

Well, just to throw my 2 cents in, I think it is worth it. Sure it can be costly, but it equals great weight transfer and helps even up the car a bit. The only reason is because many on this board will always ask if the little things are worth it. Such as reducing pulley weight/size, hollow sway bar etc. While each one by itself is a small gain, when you put all them together, you can shave a lot of time. If you spend most of your time saying, small gain, small gain, you might have nixxed the idea of doing 10 different things which together can shave 2 tenths off your time. I do every little bit I can from removing the AC to hollow sway bar, to any other thing I can do to gain a few hundreths or tenths. I think in the long run it pays off. Just my thoughts.

Scott

 

[ajt86]

the small stuff does add up- i have a pile of stuff i took off my car that im gonna wait untill its done to weigh it up. it just sucks somtimes because you spend so much time lightning the car up then you just add weight with battery relocation, roll bar, ext.. but yeah if you didnt lighten and added all this stuff you would be well over 4000lbs.

 

[turbodave231]

Moving the battery on a street car doesn't really make sense. But when you start getting serious about quarter mile times, moving that weight rear of the rear axle will help overall weight transfer.

NHRA does state that the battery needs to be attached to the frame. My rulebook is out in the car, but I remember reading that in the general rules section. If it is in the trunk, you need a firewall between the passenger compartment and the battery. I beleive a vented battery box can be used in lieu of at full firewall, but I have a fuel cell in the trunk too, so I built a full steel firewall behind the rear seat.

DR

 

[ajt86]

yeah my cars like 90% track so maybe ill look into doing it. i have a fuel cell too so im gonna do ahead and build the firewall in the trunk.

oh and is your firewall aluminum or steel?

 

[V6UnderPressure]

Moving the battery on a street car doesn't really make sense. But when you start getting serious about quarter mile times, moving that weight rear of the rear axle will help overall weight transfer.

DR

Dave, I see your point. But I have to differ on that it doesnt make sense. Me personally, I like street encounters. Good to have that extra traction. And less weight in front and more to the back gives the car more "balance" and can reduce the car nose diving during heavy braking etc. Its kinda common sense. But like you said, to some its not worth it. To me it is. And your right about the NHRA rules. If you have a sealed aluminum box of some sort that is bolted to the frame and vented outside the car, you dont need a firewall in the back.

Scott

 

[turbodave231]

Scott,

Moving the battery makes sense for you if you're that serious about your street performance. It is alot of hassle and it takes some time and effort to do it right. Plus you give up some or all of your useable trunk space.

I've seen alot of battery relocations that scare me! People who don't do it correctly are better off leaving the battery in it's stock location. Battery cables carry a huge amount of current and one small rub through can cause a catastrophic thermal event!