My thinking for our little dirt car is to use strong springs on the right with weaker springs on the left. I know this is unconventional thinking, especially with a crossweight of only 29 percent, but you must understand that at this point the car has only made laps around the house. Initially this setup looks OK, but we haven't been to the track yet.
Jim McFarland suggested using...
Jim McFarland suggested using a larger plenum in the manifold. I got 2 two-barrel to four-barrel adapters and put them back to back to form a plenum. There was a small gain, but this told me I would need a huge plenum for a cure. Not practical in this case.
The Honda has a locked (welded) differential. With the track tires, only about 2 inches of stagger is available. I heated and bent the steering arm on the left-front spindle to increase the Ackerman effect. I think I want the left-front to do most of the work. That means as little weight as possible is transferred from side to side. All this is intended to make the front end stick down in the turns and not have the car push up. The crossweight (the wrong direction for a rear-wheel drive car) is intended to keep the left front of the car heavy.
We came up with an unusual way to adjust the weight of the car. The best way to do this is to use the AFCO adjusting sleeves that are made for coilover applications. If you have a few extra bucks, get them. Some sort of spacer is required because the AFCO racing springs are shorter than stock. That is good because it leaves room to raise and lower a given corner.
Already over budget, I went to the muffler shop. I ordered up several pieces of 211/42-inch tailpipe of lengths between 6 and 12 inches long. Then I had the muffler man form some flanges that would fit over the straight pieces. The flanges are welded to the straight parts at different measurements. Rather than use a screw-type adjustment, I now change out the tailpipe parts to achieve different heights at that corner-certainly not convenient, but cheap.
I made a dedicated wrench that fits all the nuts required to remove the coilover unit. At the bottom attachment point, I drilled the threads out of the mount. The bolt was cross-drilled for a hairpin clip. At least on the rear, a spring change or height adjustment can be made in about six minutes.
Replacing the needle under...
Replacing the needle under the squirter hold-down screw with a ball and a spring did the trick. A 0.155-inch steel ball and half of a ball-point pen spring was used. Once the spring was close, I adjusted the tension by washers under the squirter.
Currently, the spring setup is as follows:
* All springs are 10 inches tall* Right-front: 550 pounds
* Right-rear: 450 pounds* Left-rear: 120 pounds (cut stock spring)
* Left-front: 300 pounds
The car weighs 1,534 pounds. This is to make it legal for the 1 pound per cc rule at East Bay Raceway. During construction, I was concerned it might be heavy, so I built light. As it turned out, the car was light by a bunch. One benefit is that weight can be added where it will be most beneficial.
A&A Manufacturing makes clamp-on-tube lead weights. Each pair weighs 25 pounds. You should consider using these instead of home-brewing lead weights because there are no dangerous lead fumes from melting wheel weights and no time spent finding lead-just bolt these on and go. We used 250 pounds of these weights placed as close to the left and front as possible. Another nice feature about these is that there are no brackets required. Just clamp them to any tube and move them around as you want when making adjustments.
FWD cars on a dirt track have a propensity to push in the corners. The front wheels point into the corner while the car points out. I want the car to be going the same direction as the front wheels. My logic tells me that if the left-front has enough weight, stagger, and Ackerman, this will happen. Granted, there are those racers with this type of car going fast with far different setups, but nothing gets improved unless other things are tried.
With so much weight on the front, the rear could be sensitive to spinning out. However, the right-rear is also heavy (crossweight), which should help. Also at the right-rear, the upper link was shortened 11/48 inch. This gives a few degrees of camber to this wheel.