99 Silverado 4x4 Z71 Transmission Issues

[stick64]

My son has now gone through 2 transmissions over a 114,000.00 of use. He is not an off-road user nor drives a lot of miles. Jus back and forth from high school. This last transmission only lasted 14k miles. My transmission guy is sympathetic, but not completely as far as fixing for a reduced price. We do not know what is going on here. My son has large tires and a small lift kit. This was what the original owner had. Should there have been a a gear change with larger tires ? Could this in anyway be a result of early transmission failure if the gear change did not take place with larger tires ? Any help or advice would be appreciated.

[j cAT]

I'm sure your son drives responsively....with large tires and a heavy foot in the texas heat alot can occur..

the use of a very large trans cooler and frequent fluid inspections and filter/fluid replacements should reduce this...

having a high school student destroy a transmission or two is normal ...been there done that..

[stick64]

Originally Posted by j cAT

the use of a very large trans cooler and frequent fluid inspections and filter/fluid replacements should reduce this.....

So an upgrade from the factory tran cooler would be in order ? Do the coolers fail from time to time ?? thx

[2000CAYukon]

Do you know what failed each time? Was it the Sunshell? Was it the 3/4 Clutch pack? There are aftermarket upgrades for both of these. Gears can help reduce the stress on the tranny given the larger tires.

//2000CAYukon

[stick64]

Originally Posted by 2000CAYukon

Do you know what failed each time? Was it the Sunshell? Was it the 3/4 Clutch pack? There are aftermarket upgrades for both of these. Gears can help reduce the stress on the tranny given the larger tires.


//2000CAYukon

It was the clutch pack, thx

[2000CAYukon]

The Transgo HD2 Shift Kit (see https://www.700r4l60e.com/store/prod...&cat=64&page=1) helps prevent 3/4 clutchs from burning up.

//2000CAYukon

[bigbadram51]

Depending on how big of tire, and what the gear ratio is, can def. help tranny life. large tires and tall gears can make it shift alot at higher speeds. Part of the blame is the 4L60E, which although not a terrible tranny, not the strongest of the bunch. What size tire is he running?

[stick64]

Originally Posted by bigbadram51

Depending on how big of tire, and what the gear ratio is, can def. help tranny life. large tires and tall gears can make it shift alot at higher speeds. Part of the blame is the 4L60E, which although not a terrible tranny, not the strongest of the bunch. What size tire is he running?

Tire size is LT305/70R16. Tires were new when we bought the truck so I do not know if previous owner had any problems. We will pay a lot more attention to RPM and what speeds shifting is taken place at. Transmission guy should be able to have an idea here with test drive ? thx