Winter is not the prime season for using our cars (except of course for ice racing), but these chilly months give most of us the opportunity to reconnect mechanically with them. It’s the time to modify, build and fabricate to improve their performance, handling and overall fun factor. Yes it’s cold and gets dark early, but the silver lining is that the foul weather gives us time to get ready for the race season without missing any laps on the track!
One common winter time renovation is with the transmission. Whether it’s time to rebuild the automatic or you plan to upgrade with a late model overdrive, there are probably more than a few fresh transmissions resting on the shop floor ready to be bolted under the body.
Any time you’re installing a new or rebuilt trans, there are several steps you can take to ensure its performance and longevity. We talked to the crew at TCI down in Ashland, Mississippi, about what steps you should take when swapping a trans. TCI has been building converters and transmissions for street and racing applications for about 45 year so they’ve seen just about everything when it comes to automatics.
Prior to hoisting the trans up in place, you should take a minute to inspect the flexplate and ring gear. Look for ground down teeth on the ring gear, as well as cracks or missing weights on the flexplate. While you’re at it, take a look at the driveshaft, the yoke and u-joints. These parts could cause severe vibrations or other damage that could easily be prevented.
Now is also a good time to inspect the transmission cooler and its lines. Back flushing the cooler is recommended so you start with as much fresh fluid as possible in your new trans. Also take a look at the lines for kinks and abrasion and ensure they are secured from heat or moving components. If your new trans is equipped with a vacuum modulator, now is a good time to check condition of the line and hose.
If you’re planning on running the same converter, it is imperative to have it flushed and inspected. Make sure to take it to a professional shop that can inspect the pilot and hub, the endplay and overall length compared to its manufacturer’s specs. Before installing the converter fill it with fluid. Depending on the size of converter you’re using, this may be from 2-5 quarts.
After installing the converter properly and mounting the transmission there are several more important steps to review. First is the shift linkage. It is very important, for safety and the operation of your trans, to ensure that the shifter is connected and adjusted correctly. Operating the trans between gears will cause damage and the engine should only start when the trans is in park or neutral. Also, pay particular attention to the Throttle Valve (TV) or kickdown cable installation and adjustment. Improper adjustment can cause incorrect line pressure which can quickly lead to transmission failure. Follow the manufacturer’s recommendations closely.
Once you’re ready to start the engine for the first time, it is required to have at least four quarts of transmission fluid in the trans. When the engine is running, be prepared to add the rest of the fluid (you’ll need at least 12 quarts in total). Use care not to overfill the system which could lead to foaming of the fluid.
TCI recommends starting the engine with the car on jack stands. This way you verify the shifter and cable adjustments. This also gives you an opportunity to verify the vacuum signal at the modulator (if equipped). A rule of thumb is a minimum of 12 in-hg at idle. And as the throttle position increases there should be a quick decrease in vacuum. If the signal responds slowly, the trans’ line pressure will not increase resulting in burning up the transmission. If there is too little vacuum you’ll experience harsh and late shifts.
Once you’re on the road enjoying your new trans, it is recommended to replace the filter and fluid after about 500 miles, or 20 passes for a drag car. The clutch discs and bushings inside the trans all have break-in materials that generate metallic and fiber particles. Don’t forget to re-torque the pan bolts to 13 ft-lbs as well.
For more automatic transmission tips and information, check out TCI’s web page at www.tciauto.com.