4L65E Mega Monster Transmission - Destruction and Shift Kit check balls

[nbkk43f]

Hi - Some background...I have a couple of older Chevy pickups, but my grocery getter is a 2004 Tahoe Z71 - which I purchased new, has ~270k on it and I've done all the maintenance on it through the years. I've always held onto it because I have plans of reusing the engine (5.3) and drivetrain in a project vehicle down the road, and well, it's still in pretty good shape despite it's age. Back in 2019, the tranny let go and I decided to go with a 500hp capable "Mega" trans from Monster Transmission with the Corvette 1-2 solenoid - all in preparation for the future project vehicle. The transmission also came with a shift kit installed, details of kit can be seen by clicking here. Well, about a year ago, and about 20k miles, the 500hp capable transmission let go (lost reverse, 2nd and overdrive) under my old, stock, well-worn 270k motor. Online research led me to believe the sunshell separated, common issue with these evidently.

Busy working on my other vehicle projects, I finally got around to pulling the transmission out the weekend before last and tore it down. Admittedly, this is the first automatic I've ever gotten into. The sunshell ended up being fine and all the destruction occurred with the rear low/reverse planetary - completely ate itself up. Sun gear, planetary, reverse sprag inner race, ring gear and hub all toast. The center support and sprag actually held themselves together! Not being a automatic trans guy, I'm really not sure what caused all the damage - junk rear planetary I suppose, pinions and gears were destroyed. As you can imagine, I'm not very happy with Monster Transmission right now.

Now I'll finally get to my question, the shift kit . Got all of my hard parts in last week, along with a new set of plastic (krylon?) checkballs. Put it all back together over the weekend, no issues, everything went smoothly. When I initially removed the valve body (very carefully), I took pics of the check ball locations - expecting 7, there were only 6 plastic balls on the valve body side. I was also expecting an 8th ball located under the plate on the case side, which didn't exist. There was one "captured" steel ball on the case side (sorry no photo), but that was it. My new checkballs measured .250", whereas the ones in my trans (from the shift kit I assume) were slightly larger - sorry, I don't remember the size, I believe they were .265". I put everything back together with the .250" checkballs in the stock locations. I am unable to locate instructions online for installing the shift kit that came in my transmission from Monster. Should I put the larger checkballs back the way I found them initially and move on, or am I ok with the stock configuration? Trans is back in the truck at this point - haven't gotten to installing the transfer case etc. quite yet.

Sorry for the lengthy post and thanks in advance for any advice, feedback.

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Here are some pics of the destruction if you're interested.

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[Bextreme04]

Hi - Some background...I have a couple of older Chevy pickups, but my grocery getter is a 2004 Tahoe Z71 - which I purchased new, has ~270k on it and I've done all the maintenance on it through the years. I've always held onto it because I have plans of reusing the engine (5.3) and drivetrain in a project vehicle down the road, and well, it's still in pretty good shape despite it's age. Back in 2019, the tranny let go and I decided to go with a 500hp capable "Mega" trans from Monster Transmission with the Corvette 1-2 solenoid - all in preparation for the future project vehicle. The transmission also came with a shift kit installed, details of kit can be seen by clicking here. Well, about a year ago, and about 20k miles, the 500hp capable transmission let go (lost reverse, 2nd and overdrive) under my old, stock, well-worn 270k motor. Online research led me to believe the sunshell separated, common issue with these evidently.

Busy working on my other vehicle projects, I finally got around to pulling the transmission out the weekend before last and tore it down. Admittedly, this is the first automatic I've ever gotten into. The sunshell ended up being fine and all the destruction occurred with the rear low/reverse planetary - completely ate itself up. Sun gear, planetary, reverse sprag inner race, ring gear and hub all toast. The center support and sprag actually held themselves together! Not being a automatic trans guy, I'm really not sure what caused all the damage - junk rear planetary I suppose, pinions and gears were destroyed. As you can imagine, I'm not very happy with Monster Transmission right now.

Now I'll finally get to my question, the shift kit . Got all of my hard parts in last week, along with a new set of plastic (krylon?) checkballs. Put it all back together over the weekend, no issues, everything went smoothly. When I initially removed the valve body (very carefully), I took pics of the check ball locations - expecting 7, there were only 6 plastic balls on the valve body side. I was also expecting an 8th ball located under the plate on the case side, which didn't exist. There was one "captured" steel ball on the case side (sorry no photo), but that was it. My new checkballs measured .250", whereas the ones in my trans (from the shift kit I assume) were slightly larger - sorry, I don't remember the size, I believe they were .265". I put everything back together with the .250" checkballs in the stock locations. I am unable to locate instructions online for installing the shift kit that came in my transmission from Monster. Should I put the larger checkballs back the way I found them initially and move on, or am I ok with the stock configuration? Trans is back in the truck at this point - haven't gotten to installing the transfer case etc. quite yet.

Sorry for the lengthy post and thanks in advance for any advice, feedback.

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Here are some pics of the destruction if you're interested.

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Monster transmissions has one of the worst reputations in the performance market. They are absolute hacks and borderline criminal. I would not be surprised to find that they had installed all used and bad parts and had installed no performance parts at all for their "500HP MEGA transmission". It is unfortunately a well documented occurrence with them.

I hope you had all of those parts THOROUGHLY cleaned, preferably in a hot tank parts washer, and very carefully checked all of the hard components. I would then have contacted someone like @NickTransmissions or another reputable builder to get a real parts kit together to build a trans actually capable of holding some power. Cleanliness is key. Make sure you carefully measure and set your clearances. Make sure you vacuum check the valve body. Assume that everything Monster supposedly did was wrong, bad, or not done at all.

 

[idahovette]

I think someone with greater knowledge should look at all this carnage and advise you???........ @NickTransmissions @HotRodPC @Matt69olds ....these guys can help

 

[TotalyHucked]

Unfortunately I have nothing to offer as to if you're ok from here on but I'll reiterate what @Bextreme04 said, Monster has a horrible reputation for putting out some true junk and just ripping people off. That's good advice to just assume everything in that trans was done wrong. Hopefully someone can chime in about the valve body and you're good to go but it's not me lol

 

[89Suburban]

WOW!

 

[nbkk43f]

I appreciate the input everyone. Unfortunately, after some research I've learned the same about Monster.

As for the future of this particular transmission, some "around town" reliability would be nice, but the expectation is quite low in it's current state. Should it be utilized in a future project, it would get the proper attention.

 

[89Suburban]

I appreciate the input everyone. Unfortunately, after some research I've learned the same about Monster.

As for the future of this particular transmission, some "around town" reliability would be nice, but the expectation is quite low in it's current state. Should it be utilized in a future project, it would get the proper attention.

No pics of the pan? Would have liked to seen that!

 

[nbkk43f]

Haha, plenty of pics.

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[89Suburban]

I can't wait until Nick see this! And Hotrod!

 

[Matt69olds]

Usually that kind of planetary damage occurs when someone flat toes a vehicle with the driveshaft installed. If the engine isn’t running, there is no lubrication other than whatever was left in the pinions last time it ran. The gears get hot, give it enough time they will weld themselves to the pinion shafts.

Obviously, there is no way to tell if the gears suffered from that in a previous life. During teardown, you need to carefully inspect all the gears, make sure none wobble on the shafts, none make noise turning, and look th carrier over carefully for bluing around the pinion gear shafts. When in doubt, don’t use it.

I personally have only been involved with a single Monster Transmission, it was a C6 ford build for a Town and Country station wagon with a really wild stoker big block ford. The guy was hoping the engine would make around 700hp (family cruiser is what he called it!!) and wanted a transmission that would live. I’m not a Ford guy, I don’t know a lot of the ford tricks or the best parts to use. Unfortunately, neither is monster. In typical ford fashion, the kit he ordered didn’t fit the model year of the core transmission. I do remember specifically the spline count of some frictions were different, they had no information on servo/apply lever compatibility, basically zero tech support. I had to spend some time on a few online ford groups. I then had to take a long drive in the Olds to get the ford funk out of my mind!!

I do remember not one part in the “Monster in a Box” was any different than what anyone could order from a reputable vender. In this case, I would have been time and money ahead buying parts from a ford specialist. They would have had the technical support I needed picking out the best parts to use.

 

[HotRodPC]

I was first thinking it likely started from a failed Sunshell and went from there. Looking again, that's not it. But I do see thrust issues in the planets. I see an imprint of one of the planets where it was being thrusted against the inner race to the center support. It's as if a torrington bearing/thrust washer was left out allowing to much clearance and that planet just beat the hell out of the inner race causing worse issues behind the planets being beat on also. I have an exploit here and maybe you can make out what I mean. I'm guessing part #250 was either left out, or became destroyed. That allowed the front of #584 to beat on the back of #664. You can even see the planet spindle locks impression beat into the back of #664 in your pic, so I think that's where you problem started.

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[HotRodPC]

BTW, going back together, 4L65-E is OEM with a hardened sunshell. Maybe even updated the Smart Shell by now. IF it's not, do be 100% sure to replace with the SmartShell and follow the install instructions. That is not only intended to deal with stripped splines in the sunshell, but it does also handle that heavy thust problem and it actually moves the thrust to another part that's stronger and can tolerate the abuse, or maybe spread the torque out is a better description of the cure. Sonnax is bad ass in their engineering. They are some smart dudes over there. Don't beleive me, just search engine GM Smart Shell and read about it, what it does and why, and then tell me if it probably wouldn't have saved this transmission. You didn't post any pics of your sunshell, but I'd be interested in seeing it too. Although it may not be damaged, if you don't have the smart shell, I wouldn't be afraid to say, the sun shell also played a part in this catastrophic failure.

 

[HotRodPC]

Hey, just 1 more post. Thanks so much for posting these pics. Sorry it had to happen to you, but I just love love love carnage pics. They tend to make my sticker peck out. Makes me wanna go wreck ole' girls uterus and cause some more carnage. Know whutta mean Dawg?!?!?

 

[Nasty-LSX]

ha, JUST WOW!!!! Not really. Dont surprise me anymore. Monster has the worst rap. Anyone remember MAD DOG transmissions? They were
as bad if not worse than monster. Thats crazy you had to go through this with them.. Hope your next move is better

 

[Nasty-LSX]

I can't wait until Nick see this! And Hotrod!

Nick is going to have a ball with this!!