pro/con: lower weight or better weight percentage in IMCA sportmod?

**regor** · 10-22-2013, 01:39 PM

My car with me weighs about 120 lb over the minimum. I have taken all the ballast off the car to achieve that level. However, I don't have the greatest rear (53.6%) or left (54.7%) weight percentages.

So the question is: is it more important to get good rear and left percentages (by adding ballast), or more important to have a lower overall weight (but not optimal percentages)?

**Flyin Iowan** · 10-22-2013, 01:42 PM

Have the %'s right

**7uptruckracer** · 10-22-2013, 02:04 PM

You can get better left with wheel offsets and add minimal back to the rear but the right percents are way more important

**clbaker25x** · 10-22-2013, 02:06 PM

Why so much left? Most folks I know are running around 52%. We are running a few points higher on our sportmod stuff than what you are for rear percentage. Maybe move your battery further back or do stuff like that.

**7uptruckracer** · 10-22-2013, 02:12 PM

Depends if its with or without driver. we are 55 with driver and 57 rear on our mods without its way different

**regor** · 10-22-2013, 03:00 PM

These numbers are with me in the car. I'd like to get more rear and less left %. I already have the battery in the RR. The fuel cell is centered in the back.

**regor** · 10-22-2013, 03:03 PM

what can I do with the wheels/spacers to help the percentages? If I push the left sides in, and push the right sides out, would that drop the left %?

**MM90** · 10-22-2013, 03:05 PM

Put a 4" on the RR, it changed 0.5% of left side on my car.

**mod88s** · 10-22-2013, 04:02 PM

Originally Posted by regor

what can I do with the wheels/spacers to help the percentages? If I push the left sides in, and push the right sides out, would that drop the left %?

That's the opposite of what you would do. Can sportmods run different offsets or spacers??
If so, run 2" offsets on left, 4" offsets on right and see what the %'s look like.

**7uptruckracer** · 10-22-2013, 05:18 PM

No you would NOT run 2" on the left and 4" on the right they were right 4" on left 2" on right it essentially move the the chassis in relationship to your contact patches 2" backspace is from the back of the rim plate to the rim edge the shorter distance the farther it sticks it out. It's worth around 2% left side or so

**regor** · 10-22-2013, 05:33 PM

Ok so pushing the left side out will help lower the left %? Just wanting to make sure I got it straight. And to increase the rear %, is there any tips besides adding ballast?

**MM90** · 10-22-2013, 05:52 PM

I know of some A-mods with crates running around 53% rear. So I would work more with the left side weight and get it down around or below 54% with you in the car. I put a 4" beadlock on my RR for the first time from a 3" and it took 0.5% LS weight out.

**regor** · 10-22-2013, 07:03 PM

Ok so I got it backwards. Push out the right side and push in the left side wil decrease left side percentage?

**Renegade Cust Susp** · 10-22-2013, 07:23 PM

A simple way to look at it to avoid confusion. The close the tire is to the spring the heavier it will become. Make sense now?

**BlackMagic** · 10-22-2013, 07:36 PM

If you want to reduce left side % you will need to push the left side wheels further from the frame, and bring the right side wheels closer to the frame I have no idea what your current offsets are so here is just a scenario For example lets say you have 3" offsets on all 4 conners for a starting point the left sides would now need to be 2" offsets The right sides would now need to be 4" offsets if I had to guess that would be probably upwards of a 2% reduction in left side percentage, if it were me I would put a 4" on the rr and a 2" on the LR and that should drop you into a safe left side zone, put your car on the scales and mess with the offsets and see how much it effects your car getting your correct percentage numbers and having to run over weight to do so is far more important than being right on target with weight but having jacked up scale numbers.... The only way you will be able to gain rear percent is if you take weight off the front end or add it to the back.... Look for even the smallest brackets or excess length bolts or bumper bars.... Any little bit you can trim off helps, does your radiator fan have a spacer on it? Remove the spacer and move the radiator closer to the motor.... Look for little things like that.... Pounds are made out of ounces!

**setup479point2** · 10-22-2013, 07:46 PM

I guess my question would be , why do you want less left and more rear ? Those numbers aren't that bad .

**regor** · 10-22-2013, 09:45 PM

I race at a semi banked quarter mile and talking with other drivers, I had more left and less rear percentages than them. So that's what got me looking into tweaking the scaling.