Transmission Trauma II
Q My Ford F-150 has a four-speed automatic with Overdrive. Lately the trans is behaving strangely. Sometimes it shifts between First and Second or Third and Fourth gears really hard. Other times it seems to take a long time to make the shift. One repair shop tells me it's the computer while another tells me that the transmission needs to be rebuilt. Who's right? I hate to spend the money on rebuilding the trans only to find I need a new computer or vice versa. By the way, the truck has 95,000 miles on it.Jess WillisIndianapolis, Indiana
A Either shop could be right. A malfunction within the electronic control unit-the computer that oversees the functions of your truck's engine and transmission-could cause the erratic shifting. But my guess is that because of the mileage accumulated there is excessive wear of the line-pressure modulator sleeve, allowing oil to leak past this valve. If there is a lot of wear, the valve can stick, building up pressure until there is enough pressure to release it, thus causing a harsh shift. If this is indeed the trouble, you will in time reach a point where the trans may not even shift. I suspect it's time to rebuild that trans.
Bigger Gears, Or No?
Q I have a 2000 F-350 Super Duty with an 8.5-inch suspension lift and a 3-inch body lift on 42-inch Super Swampers. I have a stock Sterling 4.30 rearend. I will be towing a 21-foot boat that weighs 3,800 pounds. Will the existing rearend be all right, or should I change it?Mike KerberSimi Valley, California
A The rearend is plenty strong enough for the application, but the gearing isn't low enough for the application you mention. The 4.30:1 was the gear ratio that Ford figured it needed for a tire that was about 31 inches tall. With your 42-inch Swampers, your rolling radius has increased by about 5 inches. The practical effect is that your truck now has gears in the 3.30 range. If you think performance is lacking now, guess what it will be like with the boat in tow. To get back to factory equivalency the proper gear ratio to swap to would have to be in the 5.60:1 range. Unfortunately, the lowest ratio I could find for your Ford rearend was 4.56:1. So it all comes down to what you can live with or how much money you want to spend.
The way to lower gearing is to swap the axle out for a Dana 70 or a GM 14-bolt. To do this swap you're going to have to make some modifications to driveshaft lengths, spring pads, and brake hook-ups. Both the GM and Dana axles have 5.13 gears available. But that brings up another problem. Your frontend is a Dana 50, a hybrid that uses a special ring-gear that is about the same size of a Dana 44 but a lot heavier. According to our sources, the lowest gear ratio available for it at the present time is 4.56:1.
Air Filter Maintenance
Every four-wheeler knows the importance of a clean engine air filter. But sometimes we don't maintain this important filter properly.
While factory-style pleated paper filters work just fine, some people feel that an aftermarket oiled gauze filter offers not only better air flow for improved performance, but better filtration and longer engine life. Whatever your filter element choice is, here are a few tips that will help prolong both filter and engine life with minimum effort and expense.
After a trip over a long, dusty trail, common practice is to take a paper element out of its holder and strike it against an object to dislodge as much dirt and crud as possible. That's fine, but don't do this with such force as to distort the filter's rubber sealing edge.
Some people like to use compressed air to blow their filters clear. This isn't a particularly good practice because excessive pressure can damage the filter's fibers. If you do choose to use compressed air, always blow from the inside of the filter toward the outside, and keep the air pressure fairly low.