Which sunshell did you go with?

Reprise

Lifetime VIP Donor
Supporting Donor
Member
Jul 22, 2015
2,724
Whenever I see discussions about these, the one that always comes up first / best is the Beast.

I have one in my rebuild; as soon as I started talking to the shop about rebuilding mine and that I wanted the weak points addressed such as the sunshell, he asked if I had heard of the Beast (I had, and was going to spec it had he not mentioned it)

With some of the other items to beef up, there are multiple options. But the Beast is the shell everyone seems to go with. I've never heard of one breaking, and these are in vehicles built for high HP applications (upper hp limit on a 4L60e being about 750hp, IIRC)
 

6716

Original poster
Member
Jul 24, 2012
821
With some of the other items to beef up, there are multiple options. But the Beast is the shell everyone seems to go with. I've never heard of one breaking, and these are in vehicles built for high HP applications (upper hp limit on a 4L60e being about 750hp, IIRC)

The interwebs suggests that the 4.2 makes 275 hp at 6000 RPM.

Anyway, I read one review that said the instructions were (because the thing is so beefed up) to build the transmission, spin it a few times, and see if the sunshell was marking up other components.

Did you have that experience?
 

Reprise

Lifetime VIP Donor
Supporting Donor
Member
Jul 22, 2015
2,724
The interwebs suggests that the 4.2 makes 275 hp at 6000 RPM.

Anyway, I read one review that said the instructions were (because the thing is so beefed up) to build the transmission, spin it a few times, and see if the sunshell was marking up other components.

Did you have that experience?

My reference to what (a built) 4L60e can handle, hp-wise, is related to putting it behind a built motor, NOT the stock LL8 / 4.2L. If GM was selling 750HP inline sixes, I think they would've sold a lot more GMT360s (and no need to offer a V8 or a TBSS).

I didn't build my transmission myself - I had a builder do it (because I didn't have the room in my garage to do it safely, nor the expertise.) As much as I would have preferred to have either assisted or witnessed the build, I didn't get to do that, so I had to trust that the builder knew what he was doing. All I can say is that the trans has worked flawlessly since it was rebuilt (and I still have another year left on the warranty). I don't go racing; rather, I had it built for towing.

Looking further, it appears there are some other options besides a beast - if you like Sonnax, they make a 'SmartShell' that's supposed to 'out-beast' the beast. And the GM replacement shells are supposed to be heat-treated since about 2003 (although by the accounts just on this forum about the OEM ones stripping or breaking, I don't know if any went into GMT360s as a stock part).

Also, I did find evidence that people *did* experience failures with their beast shells - but it was traced back to the manufacturing vendor incorporating an unapproved design change (switching to a 3-piece from a 2-piece assembly, as the originator / patent holder designated). The owner switched vendors back in 2009 to correct this, and recalled the bad ones. Since then, all of their shells have 'SAP' stamped on them - as long as you get a Beast with that stamping on the outer casing, then it should be a reliable part.

Here's some info on the Sonnax...

Stripped or cracked shells in GM 4L60, 4L60-E, 4L65-E and 4L70-E units are a common problem, but strengthening the shell alone does nothing to address the equally common problem of a failed rear planet captured bearing. Sonnax SmartShell heavy-duty reaction shell kits prevent damage to the rear planetary assembly, as well as provide a reinforced shell. In the OEM sun gear shell, the thrust load passes from the shell through the sun gear, then overloads the small captured planetary bearing. To protect this bearing, Sonnax took the smart approach and replaced the OEM black plastic washer with a large thrust bearing and roller clutch race. This re-routes the thrust load directly to the carrier, completely bypassing the delicate bearing. The Sonnax SmartShell heavy-duty reaction shell kits avoid the substantially increased weight found in other aftermarket shells. They include reinforcing the hub area with an electron-beam welded collar. A final machining process after welding ensures precision alignment. SmartShell splines undergo an advanced machining and heat-treating process, and the lugs which engage the drum are heat-treated, as well, to avoid flaring.
 

6716

Original poster
Member
Jul 24, 2012
821
Good info, thanks.
 

Forum Statistics

Threads
23,271
Posts
637,476
Members
18,472
Latest member
MissCrutcher

Members Online