Friday, September 20, 2013

Powerglide band adjustment tips

The powerglide transmission has a single band.  It is used to hold the clutch drum during low gear operation.  If the powerglide band is not adjusted properly the following things can occur:
  • Band failure (burning of clutch material)
  • Slipping in low gear or no low gear function at all
  • Shift flare between low and high gears
  • Car rolling backwards when the transbrake is applied
The powerglide band should be adjusted to the following specs:
  • Tighten the band adjustment screw to 72 inch lbs
  • Unscrew the band adjuster three and a half turns (3.5)
  • Tighten the band adjustment screw's locking nut
The band should be readjusted on a semi regular basis throughout the racing season.  BTE recommends using a heavy duty band adjustment screw to prevent band failure.  Stock band adjusters can bend and warp under heavy duty conditions.

See also:

BTE Kevlar Powerglide Band
BTE Wide Powerglide Band

Friday, September 6, 2013

What are the limits of a factory, stock or OEM powerglide case in a racing application?

For more than 30 years, racers have relied on a variety of OEM parts to complete their cars due to budget or due to a lack of suitable aftermarket parts.  In the last 10 years, this has started to change dramatically with the availability of aftermarket cases, housings, gears, and just about every other high performance transmission (or engine) component.

Aftermarket powerglide cases bring a lot of advantages over stock cores:
  • Greater strength
  • Revised oil channels optimized for racing
  • Improved wall thickness to meet SFI safety requirements
  • Elimination of non essential areas and features for OEM usage
However, stock cases still have plenty of applications in budget and entry level racing.  With the addition of a SFI approved bellhousing and case shield, a stock case be ready for competition.

What are the practical limits for the stock cases?  What are some important tips to remember when using a stock case?

BTE recommends using a polyurethane transmission mount.  Solid, rigid mounts are often too stiff for a powerglide case when a heavy car launches hard.  This will often lead to a crack in the case.

Also, stock cases are more prone to failure if a driveshaft, rear end, or u joint is not properly configured or faulty.

Finally, it is important to monitor line pressure when using a stock powerglide case.  Pressures over 245 lbs can cause leaks or cause cracks to form in the thin die cast aluminum found in some of the various casting versions.