Jacks Transmissions likes to engineer solutions which make sense. To make the GR6 more reliable, we perform several modifications as standard procedure during the rebuild process. As part of this process, we modify the factory shafts to accept a thicker and more robust heavy duty retaining ring.
The small and thin factory retaining rings are known to work their way up and fail, causing catastrophic failure of the unit. Please note that when the OEM ring distorts, this will also damage the splined teeth on the end of the shaft. Our retaining rings are good up to 16,000 pounds of thrust, which means your car would have to make over 10,000ft/lbs of torque to break them! This allows the retaining clips to work like they should and never have a failure.
We like performing our own retainer upgrade as we believe it to be superior and more reliable than gear locks. It's a lot more work, but worth it to have the peace of mind that it's done correctly without the added complication of a lock.
Retaining clips in the pictures below. OEM clips on the left and right. Jacks Trans Spec clip in the center. Note how much thicker and bigger our retainer is compared to the OEM:
Jacks Trans HD retaining clips installed: