Does Downshifting Hurt the Transmission?by Dennis Lee Chapman
With the advent of the automatic transmission in the 1970s fewer people are driving manual transmissions and yet, with both automatic and manual transmissions, downshifting is an important part of driving your car. In short, downshifting does not normally hurt your transmission as long as the resulting RPMs are within the design specifications.
Downshifting for Increased Power and Speed
Downshifting increases speed and performance when variables such as wind, hill incline and towing weight impact on the car's performance in higher gears. Under these conditions, downshifting provides a boost in performance but will put more strain on your transmission. This will only hurt your transmission if you regularly abuse a specific gear to gain nominal increases in performance.
Downshifting for Breaking
Downshifting for breaking purposes will extend the life of your breaks and reserve your breaks for emergency stops. Downshifting for breaking purposes is especially useful for going down steep inclines as it is harder for your car to reach greater momentum speeds due to the positive relationship of friction to high RPMs.
Unsafe downshifting will harm your transmission. Look at the RPM gauge in your car and if the needle is near or in the yellow and/or red zones -- 5,000-7,000 RPMs on most cars -- then you are putting stress on that particular gear and risk overheating your transmission leading to catastrophic failure of your transmission.
- New car engine gearboxes image by Christopher Dodge from Fotolia.com