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06 Rubicon Unlimited. 89,000 miles, auto trans. Driving on hwy 101 near Ventura, CA at 65-70mph. I crossed an overpass, and when I hit the expansion joint the Jeep started making a grinding noise. I immediately coasted to a stop on the side of the road. With the Jeep in drive, the engine will rev but the Jeep will not move. Moving the gear selector through reverse and first/second gear yields the same results.

Oddly enough there is a tranny shop in sight so we decide to tow it there with our other Jeep. As soon as we hooked up and tried to move, we quickly found out the rear axle was locked up (engine running, shift selector in Neutral) If the engine is turned off, vehicle in N, it rolls freely.

We dropped it off at a tranny shop and they called back about 45min-1hr later and said it looks like the planetary. It was closing time for them so they’re going to look at it more on Monday to confirm any other damage, but quote repairs starting at $1700.

My questions is this..any ideas as to what caused this? Are these known failure points? Can someone explain what the planetary is/does (and is it in the tranny of transfer case?)

Does the cost of what they described so far sound reasonable? Does anyone know of good tranny shops in the Ventura, CA area?
 

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The only planetary gears that I know of in a vehicle, are in an automatic transmission. The gears in the front/rear diff's, are not called planetary gears, but ring, pinion, axle side gears, spider gears and carriers. No planetary.

The Planetary gears are a set of gears that change the gear ratio inside the auto trans. A large inner gear with 3 or 4 smaller gears walking around the outside of that first gear and a larger outer gear walking around the outside of he 3-4 smaller gears. Very complicated.

I have never heard of a planetary gear assembly exploding like you explained buy hitting a minor bump, but it is a mechanical, man made assembly so it is not perfect. Have you had this Rubi since new or did you buy it used. An automatic transmission is very strong because it shifts itself, USUALLY. If you bought it used, it may have been abused by the previous owners. I will be following to hear the final outcome on this one. It is unique.
 

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The best way to understand how a planetary assembly works is to watch a video on U-Tube. It's can be very difficult to explain or understand unless watching a video.
 

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Possible bolt(s) backed out of the ring gear in your rear diff?
I had this happen in my 04 Rubi, but only with 1 bolt.
Every now and then the bolt would work its way into the pinon and cause it to lock up - mostly when I was parked on the incline of my driveway and wanted to reverse down the driveway. Similar symptoms, in neutral it would roll, but in gear it wouldn't budge until the bolt moved. Took it to the dealer who test drove it and couldn't find anything wrong. It took a few times before it would "lockup" when they had it and then replaced the rear end.
 

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First the 231 and rubi transfer case both use a planetary gear set to achieve low so the only planetary gears are not in the tranny

Next he said engine off tranny in neutral it rolls fine so unlikely a differential issue


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In the transfer. the input gear has the sun gear
The ring gear is fixed to the case front inside
The 231 uses a cage with 3 planets while the HD version has six


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Based on him saying this
As soon as we hooked up and tried to move, we quickly found out the rear axle was locked up (engine running, shift selector in Neutral) If the engine is turned off, vehicle in N, it rolls freely.

Seems engine running makes it lock so probably only locked up when tranny has pump running
So my guess more likely torque converter/tranny than transfer case

Unless vehicle in neutral means transfer case in neutral
Gotta use less vague words like transfer case in neutral or transmission in neutral not vehicle in neutral



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Discussion Starter #8
Sorry guys..when the transmission was in Neutral, vehicle off, it rolled freely, with engine running, rear axle was locked up.

I bought the Jeep used with about 80,000 miles on it. It’s run flawlessly up until now.
 

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Planetary gear failed. There’s a broken tranny mount but he didn’t think that’d be the cause. Total overhaul with upgraded 5-pinion planetary, upgraded valve body kit, looking at about $3100.
 

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Planetary gear failed. There’s a broken tranny mount but he didn’t think that’d be the cause. Total overhaul with upgraded 5-pinion planetary, upgraded valve body kit, looking at about $3100.
3100... did you call anywhere else? Seams like a lot to me, but I honestly are not familiar with auto trannys.

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Ya it turns out we have a family friend who’s son owns a tranny shop and has done several wrangler rebuilds, unfortunately he’s not located very close. But, he did say that’s about average for a rebuild given the diagnosis.
 

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Thanks Shark I appreciate your response. We did find several rebuilds for that price range as well with warranties ranging 2-4yrs. The one thing our friend cautioned us about is how those things are done in production mode. So even with the warranty, it’s cheaper for them to send you another tranny to fulfill their warranty commitment. He suggested they likely won’t last nearly as long as one done in house by a reputable shop.
 
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