Basic modifications for newbies
(→The first modifications to be made to your vehicle) |
(→The first modifications to be made to your vehicle) |
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With a front-motor, rear-drive vehicle, the chassis twists diagonally upon application of power. The left front gets lighter and the right rear gets lighter. The right front and the left rear get heavier. This is why you will see the right rear tire spin while the left rear hooks up on a car with a "one-legger" or "open" type differential. The right rear is light and needs additional weight applied to it. This can be accomplished cheaply and easily by installing an air shock on the RIGHT REAR ONLY to replace the conventional shock absorber on that side. Experimenting with the air pressure in the shock will allow you to equalize the weight applied to both rear tires on acceleration and "hook up" both tires without going to the expense of installing a locking device in the differential. Just keep adding air pressure to the shock until you have two equal-length black tire stripes on the pavement when accellerating from a stand-still. I've done this many times and have seen other racers do it with equal success. An additional benefit is that the car will be easier to drive at the strip with an open differential that has been "weight equalized". | With a front-motor, rear-drive vehicle, the chassis twists diagonally upon application of power. The left front gets lighter and the right rear gets lighter. The right front and the left rear get heavier. This is why you will see the right rear tire spin while the left rear hooks up on a car with a "one-legger" or "open" type differential. The right rear is light and needs additional weight applied to it. This can be accomplished cheaply and easily by installing an air shock on the RIGHT REAR ONLY to replace the conventional shock absorber on that side. Experimenting with the air pressure in the shock will allow you to equalize the weight applied to both rear tires on acceleration and "hook up" both tires without going to the expense of installing a locking device in the differential. Just keep adding air pressure to the shock until you have two equal-length black tire stripes on the pavement when accellerating from a stand-still. I've done this many times and have seen other racers do it with equal success. An additional benefit is that the car will be easier to drive at the strip with an open differential that has been "weight equalized". | ||
| − | Now, with the rear end nailed down and operating, it's time to move on to the middle of the car and take a look at the transmission and torque converter. | + | Now, with the rear end nailed down and operating, it's time to move on to the middle of the car and take a look at the transmission and torque converter, assuming an automatic transmission will be used. If the transmission is a manual shift, then overlook the following information and go stiffer on the rear gear (4.10, 4.44, etc.) |
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| + | If the car is very light (under 2,800 lbs with driver aboard), then a 2-speed automatic will work fine on the dragstrip and should work on the street as well. Heavier cars should use a 3 or 4-speed auto. If fuel mileage is a concern in your world-beater, then a 4-speed overdrive auto is probably the better choice. I'll leave it to someone else to go into detail about the choices here, but the GM 700R4 has shown to be a good choice for non-computer applications. They can be beefed up to take considerable abuse. | ||
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| + | The next component to be addressed is the torque converter. It is mandatory that the converter is matched to the camshaft you'll be using. As was stated earlier in this article, stock converters will stall at around 1,200 to 1,400 rpm's, depending on the amount of torque produced by the motor among other things and that's fine when you are using a stock-type cam that begins making power at idle. But when you change the cam out for a longer duration/higher lift model, you're no longer making power from idle and the car will be a dog until the rpm's increase to the point where the motor is making power. One way around this is to install a converter that stalls higher than stock so that the motor comes up on the cam quicker and the car accelerates faster. Any cam you install in the motor will have an operating range of about 3,500 rpm's. In other words, it might make power from idle to around 4,200 rpm's (stock cam) or from 1,500 to 5,000 rpm's or 2,000 to 5,500 or 2,500 to 6,000 or 3,000 to 6,500 or 3,500 to 7,000. I'm sure you get the idea. It works in a certain "window" of operation and is inefficient below and above those rpm's. So, if you install a cam that operates between 3,500 and 7,000 rpm's and use a converter that stalls at 1,200, you can see that the motor will not be producing enough torque from 1,200 to 3,500 to move the car efficiently. The car will be a D-O-G. On the other hand, if you use the 3,500-7,000 cam with a converter that stalls at around 3,500, then when you nail the loud pedal, the motor will rev up close to the stall speed of the converter and you'll be making power and applying torque to the rear tires sooner. (PLEASE NOTE THAT EACH APPLICATION IS DIFFERENT AND THAT A PROFESSIONAL TORQUE CONVERTER MANUFACTURER SHOULD BE CONSULTED FOR THE EXACT CONVERTER FOR YOUR APPLICATION). If I could get a little plug in here, I know Jim Hughes personally and have for many years and I can, without question, recommend Hughes Converters. Jim is a man of integrity, both personally and professionally. | ||
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