Other Articles - March - 2019

Digging Deep into the 6L45/50 Converter

Digging Deeper 6L45 featured image

It’s no surprise that, over time, converters have become more complicated and challenging to build. In this issue, we’ll look deep into the 6-speed 6L45/50 captive clutch torque converters used in the 2013- 2015 Cadillac ATS, Cadillac CTS, and the 2012-2015 Chevy Camaro.And we’ll come up with a way to rebuild the captive clutch and bring it back to OE performance.

After opening converter, my first thought was, “now this is going to be a fun one, but not impossible.” The double-sided clutch is held in by six rivets (figure 1), that you can remove using a couple different methods:

  1. Chuck up the front cover on a mill and machine the top of the rivet heads until it touches the top of the piston.
  2. Grind or sand the top of the rivet heads down to the piston (figure 2).

The second method is just as fast, if not faster.

Next, place a small punch on the remaining part of the rivet, and tap the top of the punch with a small hammer until the old rivet breaks away from the piston. Repeat the procedure on the remaining rivets until the piston releases and you can remove it (figure 3).

Once you’ve removed the piston and clutch, continue removing the old rivets. I recommend duplicating step one by grinding the rivet down to the spring so you can knock out the old rivet head without damaging the spring.

The most common problem appears to be the clutch wearing into the front cover. This reduces the lockup preload, which usually causes a converter lockup shudder.

Keep that in mind if you take a cut across the front cover. You may need to use a thicker clutch lining to maintain the preload set by the factory or use a different cover.

Another problem we found on a large percentage of these were segmented clutch material that separated and broke away at the interlock, so keep an eye out for that, too (figure 4).

Make sure to change the Teflon ring on the turbine hub; these quite often show signs of wear.

After cleaning both the piston and front cover, we’re now ready to reassemble the torque converter.

  • Slide the rivets back under spring.
  • Put the grooved clutch and piston in place and rivet them back together. You’ll need to design a small tool to slide under the rivets during crimping.
  • Once you have the piston crimped back in place, check the clutch preload. It should move freely side to side and around.
  • Press down on the piston, making sure the rivets aren’t hitting the cover, and confirm the clutch locks up.
  • Finally, finish assembling the rest of the converter to industry standards, and send it over for weld, balance, and leak test.

Captive clutches are here for the long haul, so take your time and get in there and fix the problem right the first time.