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Discussion Starter #1 (Edited)
I'm rebuilding my transmission and would like some advice on my findings. The only symptom was that my 2004 SC 4x4 (RE4R01A) wouldn't move in reverse. The major problem is that the reverse clutch oil seal on the oil pump cover supply shaft was destroyed. Since pulling it apart, I can see why it was destroyed. There is significant scoring on the supply shaft and the inner clutch hub with burr formation all in the area of the reverse clutch. For the high clutch, it is polished. See photos:


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So, this scoring is not normal and indicates metal-on-metal wearing, correct?

Is it absolutely necessary to replace these parts (oil pump cover and R clutch hub)? The vehicle has almost 200K miles, if these parts weren't replaced but the oil seals were replaced, would you guess there would be a quick failure? If they do need to be replaced, do you have a source recommendation?

What might have caused this? I imagine that the reverse clutch hub and the oil supply shaft had become non-coaxial; maybe the clutch was wobbling around the shaft? Could the brake band pull it off axis? (But then the clutch wouldn't be spinning and it wouldn't matter) The bell housing is the same thing as the oil pump housing (opposed to what the FSM says). I noticed a slight separation of the transmission case and the bell housing when I pulled the transmission out but the bolts were quite difficult to remove, most needed an 18" breaker bar, the rest needed an electric impact wrench. EDIT: This separation between the case and bell housing is expected and is written in the factory service manual. This transmission overheated likely due to old oil and a long, difficult pull months previous to the symptoms (won't move in reverse, low reverse pressure).

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I found metal filings at the rear of the transmission. There may be more wear that I haven't found yet or is it possible that the filings from the front clutch would work their way backwards?

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I need to get this back together very soon. Any input is appreciated. Thank you.
 

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Discussion Starter #3
Yes, though it seems there is a lot of variation even in the RE4R01A. I've seen a few different stators and drums all listed as compatible with the RE4R01A.

Since posting, I've realized that I shouldn't cut this corner; all that rough metal on the reverse drum will tear up a new seal pretty quickly and the worn bushing (where I put question marks; should be brass) will only cause more metal-on-metal wear. It seems the oil pump cover (also called stator) with the "speed sensor" (FSM calls it the turbine revolution sensor) port is hard to find. If I'm desperate, I might just replace the drum and try to smooth the shaft of the pump cover but that loss of diameter might be unacceptable especially where the stator meets the reverse drum bushing. I might also be able to just replace the bushing and sand smooth the stator and the seal track in the drum.

I spoke to a local transmission parts supplier that is looking for these for me. He said that loss of reverse caused by stator on reverse drum wear is a common problem of these transmissions. Here is a photo of a non-worn drum, notice the brass in the bushing and the smooth track for the oil seals.

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Yeah, a transmission rebuild really isn't a place you want to cut corners. You've got a lot of moving parts with tight tolerances. It's the type of job you want to only have to do once.
 

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With regard to the metal shavings. Due to the ATF fluid that flows throughout the transmission metal shavings will be transported all throughout the transmission, which is the purpose of the filter/screen on the intake and magnet in the pan of the transmission. Of course it is always possible that there is wear in an area you haven't looked at or noticed yet, which is why it is so important to take your time and inspect each component closely as you do your teardown. Also be sure to have a system to keep track of which components go where and in what order. Some people like to have a box for each section and possibly ziploc bags for the pieces Regardless. Take your time and pay close attention to the details. It is very easy to get your clutch pack components in backwards (plates etc).
 

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Discussion Starter #6
Thanks for the advice. I'll admit, after many days of working to get the transmission out, I excitedly started pulling it apart. I can't remember which way some of the needle bearings were. Most of it is still all in packs. sTeVeXNYCPerformance on Youtube has a lot of videos on Xterra, Frontier and Pathfinders including this pull apart
of the transmission that will help along with the FSM.

On initial inspection, I can only see the problem I detailed above (stator vs reverse drum). The friction plates look good and I wonder if I should just leave well-enough alone; I worry I might replace a well conditioned OEM part with a low quality rebuild part. I replaced the rear oil seals tonight and each one I pulled off looked excellent while one of the replacement seals was a little unsprung; I tightened it a bit before putting it on.
 

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With all repairs (especially critical ones) it's generally best to go with quality parts from either OEM or a company with a proven track record for quality and reliability. I think the transmission falls well within this group. The alternative is doing it more than once. When it comes to seals I will always replace them "while I'm in there" as they are one of those items that can look to be in perfect condition, but still leak. Don't forget to do your rear main seal on the engine before you pop that trans back in.

With regard to the clutch packs, it's kind of a personal choice, but assuming you are using quality parts and the X has 120k+ miles on it I'd probably swap out the packs and other parts that are typically provided in a rebuild kit (as well as other worn or damaged parts). DO make sure that you clean out the entire casing and all parts very well before reassembling as it is so important that you get the bits of metal out of there.. Don't forget to lube things as you assemble them as a "dry" startup (before the fluid is flooding through the fresh transmission) will cause wear on the new parts (lube your seals)

Steven's videos are always helpful. I've used them for a number of things on my X (like timing belt). There are also a number of other good videos online. I know that there is a whole series by a young man that rebuild his that is many many videos long showing his tear down and rebuild in great detail. I like to look through a number of video sources before starting a new job and also read through the FSM a few times to familiarize myself with it. WHen there's a discrepency between the videos and hte FSM the FSM wins, unless there's a "special NISSAN tool" involved and the videos show an alternative to buying a $400 tool or the tool is only available to the dealership.
 

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Discussion Starter #8
Thanks again. I do have a rear engine oil leak. I haven't pulled the flex plate yet; those bolts are just laughing at me and my 18" breaker. I'll take a torch to them sometime. I have an RMS kit that I hope will solve the issue though the oil pan is rusted and I worry that may be the cause.

Yesterday while I rewired the crankshaft position sensor that I ripped out, I replaced a lot of brittle and melted wire loom and provided extra metal tape insulation.
 

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Discussion Starter #10 (Edited)
The rebuild is going slowly though progressing. I realized that the brake band I got from Rock Auto was the wrong size. It was the only one listed as compatible so I just assumed that it was the correct one. I needed the larger band (2 3/8") but got the slender one (1 1/2"). Could anyone comment on the condition of my old band (190K miles) and why I should or shouldn't worry about reusing it?


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Thanks!
 

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Discussion Starter #11
I had time to buy another band. The old one looks good but is fairly smooth which may be a little glazed.
 

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Discussion Starter #12
I received a good-used stator which is slightly different than the pictures I was shown before purchasing it which is not cool because I paid much more because I thought it was an exact fit. Does anyone know if this difference is significant? I don't really want to wait another week+ to get another.

My stator:
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Stator I was given:

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This is the rear of the stator that faces the reverse drum. In the case where this meets, the area is pretty open:

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Let me know if you have any input.
Thanks!
 

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Discussion Starter #13
The supplier sent another stator that was an exact match so I wouldn't have to worry about this difference. In the end, I would have installed the different stator as I didn't think the differences were significant but any time I felt something odd from the transmission, I would have thought it was because of this stator.
 

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Discussion Starter #14
Whelp, I suppose I'm ready to put down my thoughts on rebuilding the RE4R01A in a 2004 4x4 SE. There will be a lot of information here so ignore the many posts. Hopefully this info will help someone in the future.

For some background, here is a thread regarding my initial problem (no reverse) and finding the likely cause:
 

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Discussion Starter #15
Rebuild Preparation:
First off, the rebuild took much longer and was more complex than I initially estimated after spending weeks reading posts, watch videos and studying the factory service manual. Just removing the transmission took about 5 long evenings. The work of rebuilding it was pretty straight forward but was greatly delayed (about 3 weeks) by trying to find the parts that I didn't know I needed until I took it apart. Putting the transmission back in took about 4 long evenings. I spent much more time reading and preparing for this work than actually doing the work. Become VERY familiar with the FSM sections from "Removal and Installation" to the end.

All of the work I did was by myself with an occasional tool fetcher. An adjustable transmission jack was extremely helpful. I bought the 800 lbs one from Harbor Freight and resold it after the job. I actually rebuilt the transmission on the jack as it was too heavy to move to the table (until I gutted it).

I bought quite a lot before starting the job because I didn't want to wait on shipping products while it was torn apart. During the rebuild, I think I ended up with two more purchase orders outside of buying the damaged hard parts (stator and drum). This also meant I spent more than I initially anticipated. I didn't keep track but I probably spent around $750 total (rebuild kit 200, hard parts 250, oil $100, band/bolts/filter/exhaust gaskets/etc maybe 200). I spent more on other tools that I wanted to buy anyway (like a new jack, breaker bar, torch, etc).

I had lists and lists of procedures, what I needed to buy, what I needed to be attentive of during the rebuild. A lot of preparation went into this. The JPAT parts list was very helpful in finding part numbers to find hard parts, filter, washers and races. The FSM was helpful in knowing which version of the RE4R01A I had. Rock Auto was a main source of parts at first but I found they sent me parts that didn't fit my transmission though they were listed as compatible (small brake band). You need to know more specifically what parts you need rather than trust that someone else knows.

JPAT sample:
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FSM model code:
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Finally, how did I get in this situation? Because I'm lazy and because the car didn't tell me there was a problem. I should have changed the transmission fluid; it was old (probably very old). I checked the color (which, in retrospect, I didn't evaluate very well) and the level before taking a very long drive and then taking an even longer drive while pulling a heavy trailer over mountains. The transmission overheated, hard parts wore on each other and an oil seal failed. In the dash, there is an "ATF Temp" light that should have lit but didn't (I have the 4x4 SE). I'll have to investigate this problem later.
 

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Discussion Starter #16
Rebuild Regrets:
In the grand scheme, I probably should have bought a transmission from a junk yard ($120ish) and rebuilt it. Then swapped it into my car and rebuilt my original one and sold it for good money. This would have drastically cut down on the time (almost 4 weeks) that my vehicle was out of commission.

Though I had a master rebuild kit (rubbers, frictions and steels), I was wholly unprepared for dealing with galled/worn bushings. I wish I had bought a bushings kit and had investigated how to replace them. Unfortunately, when putting the transmission back together, I can't say that I was completely happy with all my bushings:
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I should have changed the knock sensor while the transmission was removed. My knock sensor is about 8 years old. I read that someone changed theirs while the transmission was off; other than that, I have no idea how feasible this is. I was planning to change mine later (head gaskets) so I didn't look into this much and now I'm not sure I'll have to do my head gaskets.

There is a selection of plastic washers and metal bearing races of specific thickness that you'll need if your replace certain hard parts. You don't know which thicknesses you'll need until you put the transmission back together. I would recommend buying a variety so you'll be prepared. I found Cobra Transmission to have the widest selection though still incomplete.
 

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Discussion Starter #17
Transmission Removal/Install:
Every bolt is a chore to remove or get back in. It's really frustrating. Cursing at the bolts encourages them to do what you want. Hitting a wrench with a 2 lb rubber mallet freed up so many seized bolts. I used that thing much more than I anticipated. The rubber mallet proved invaluable.

Though the list of steps to remove the transmission in the FSM is basic, I found it pretty helpful. I just followed it step by step.

I didn't remove any exhaust pieces. I didn't want to deal with rusted bolt globs. If I did it again, I would have removed the passenger catalytic converter. This thing was always in the way and prohibited me from removing the ATF cooler lines until I got the flex plate off. I had plenty of room on the driver side with the front drive shaft removed.

Though the FSM says to remove the transmission and transfer case as a unit, I removed them separately. Together they would be too heavy to manage for me alone; also, I wouldn't be able to drop it because the tail of the transfer case sits above the exhaust Y-piece that I didn't remove. Rotating the transfer case to the driver after disconnecting it allowed me to get it around the Y-piece.

Installing the transfer case:
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Disconnecting the transfer case from the adapter/transmission, was made more difficult because many of the top bolts were blocked by the form of the transfer case. You couldn't get a straight shot on them with a socket; you didn't have enough room for a wrench. I had to use 2 u-joints to get around it.

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Removing the upper transmission-engine bolts required linking over 3 feet of extensions together. I accessed all the driver and top bolts from the driver side leaving only 2 bolts (trans-to-engine) to access from the passenger side.
 

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Discussion Starter #18
Transmission Removal/Install Part 2:

When I dropped the transmission, I didn't see the crank position sensor. It isn't shown/mentioned in the FSM and I thought I had them all in mind. My Chilton manual mentioned it but I thought it was calling another sensor by another name. Because I didn't realize it, I pulled the wires out of the sensor and I had to rewire it. The wires were short so I also added some length to them. The connector is similar to a fuel injector. I found a YouTube video that showed me how to disassemble the connector by searching for a code (E02) that was printed on the connector.

FSM, the CPS should be drawn here:
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My CPS:
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CPS:
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I also didn't notice that the driver post-cat O2 sensor wire was connected to a transmission bracket and I ended up yanking on it trying to get the transmission out. Careful of that.

To get both the transfer case and transmission out from under the vehicle while still on the transmission jack, I had to lift the rear axle with my floor jack (19.5 inches) to make room. The front was on jack stands with the tires lightly contacting the ground so I was able to chock the front tires. It was still extremely dangerous, so be careful if you do this. It was not an option for me working alone to pull either of these off the jack while still under the vehicle.
 

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Discussion Starter #19
Transmission Removal/Install Part 3:

Dip stick tube:
When you're putting the transmission back in, get it very close and then insert the dipstick tube loosely. I didn't do this and had an extremely difficult time putting the tube in after the transmission was mounted. There were too many restrictions. I had to drill a hole through the floor pan (near the AC drain) and pull the body inward with a bolt and crowbar to make room for the tube to fit in. I also sawed off about a half inch from the bottom of the tube. This took over half a day but was much better than disconnecting the transmission and reconnecting it again which probably would have taken 2 days. I read that someone put the tube in after mounting the transmission by just tilting it all backwards by the weight of the transmission. This didn't work for me; maybe I didn't dare let too much weight tilt the engine back.

Underbody:
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Passenger Footwell:
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I filled in the holes with RTV and painted the underside.


When putting the transmission back on, I wrestled with it for a LONG time. One dowel would go in and then I would try to fit the other side in and the first side would come out; over and over. Finally I focused on getting the torque converter to engage first and the dowels on the side went in easily. I had to tilt the engine backwards to do this though by lifting the front of the engine with a bottle jack.

Putting the breather hose bracket and bolt in the top of transmission was difficult, I couldn't reach up there and get it in. I was able to push the breather bracket close to position and from the top-back of the engine reach down and put the bracket in place and thread the bolt.
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Discussion Starter #20
Rebuild:
The FSM was a little confusing to follow. In general, there is a disassembly section followed by many component specific sections (ie oil pump, control valve, reverse clutch) then an assembly section. I found that as I was assembling, I would flip back and forth between the component specific section and the assembly section for that component. This helped assure that I had rebuilt that component properly and was assembling it properly.

When removing components from the transmission or from other components (front planetary carrier from the forward clutch drum), I would recommend marking the height of the component on the inside of the case with a permanent marker. When you put everything back in, this would be helpful so you know if you have seated each component fully. When seating the components, you have to lift/twist/seat to get the teeth to engage with all the friction plates. Don't be afraid to pull it back out to check that you had seated it fully. Check that all the friction plates are aligned. Mark how far it went in so you can repeat it or do better.

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I rebuilt most of the transmission as it sat on the jack, this was because it was too heavy to move until I gutted it; being able to tilt it on the jack helped some installation steps. Only after I removed everything did I put the transmission on the table and remove the pan/valve body. Of course, it was also the first thing to be put back on. This is out of order from the FSM but I was still able to do it even though some assembly instructions discussed reaching through the bottom (where the VB should have been removed) to help seat things.

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All these components should have been placed in a clean plastic sack after removal and shouldn't be stored on the floor (mine was very clean but still). I later put things in bags but probably too late; see "aftermath" section to follow. Yes, there is actually an order to how they are placed. You'll need a lot of room so you can keep your components organized.
 
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