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Discussion Starter #21
Rebuild Part 2:

I did not disassemble nor do anything with the valve body; I removed it to get the last piston (low and reverse brake) out and replaced the o-rings on the solenoids. I just didn't want to mess with it as I didn't think it was part of my problem and I could access it at any time later if there was a problem. I do regret not checking/cleaning the "pilot" filter inside it.

To compress the piston springs in the clutch drums, I planned to use c-clamps. This didn't work very well; they kept slipping off and tilting, maybe I used them once. I had to fabricate a spring compressor out of wood (careful of particulate) and a giant screw. This was especially useful for the finger-spring of the reverse clutch drum; I used some PVC pipe with my spring compressor to get this spring. I think a puller tool of some kind might have been useful but I couldn't find one at the time.

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One lip seal I had trouble with was for the reverse clutch piston. To re-seat these pistons, you twist while pushing it down. Some of the pistons I had to use my body weight to get them to seat but I couldn't get the reverse clutch piston down. I used the C-claps which seated the piston while also inverting and clipping the lip seal -oops. I had to slam the drum (wrapped in plastic) against a pad to get the piston back out. I put the old seal back in (great condition) and it seated easily. It could have been that the new seal was too big.

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When replacing the steel plates in one pack, they were too thick causing the retaining plate to snap ring clearance to be too small. I used the old steals which put it back in spec.

75902
 

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Discussion Starter #22
Rebuild Part 3:

There is a rear support (low one-way clutch) and a forward support (part of the stator ie pump cover). The supports hold oil seals for the drums that fit around them. The FSM says to use petroleum jelly to hold these seals in place while you slide the drums over them. It was very warm in my garage and my petroleum jelly was quite runny and wouldn't hold the seals in place. I had to put the supports and jelly in the fridge for a while to keep the jelly thick enough to hold the oil seals.

Sometimes as you're putting on a drum, a washer or race might fall off. I placed a long thin screwdriver though the center so that if something fell off, it would be caught by the screwdriver instead of falling down into some hidden part of the transmission.

When assembling the oil pump, I was confused by this step and thought it didn't apply to me so I almost skipped it until I realized that this metal "friction" ring could be removed on the bottom side of the cam ring.
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Make sure the spring seat in the oil pump isn't upside down or you won't be able to put the pump cover back on fully.
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A mechanic on YouTube talked about bur formation on the control piston (wiper arm?) in the oil pump. This would cause the arm to get stuck. He said he would take a file to the edges to remove this burr. My control piston seemed to have beveled edges on the bottom side possibly to avoid this problem.
75905
 

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Discussion Starter #23
Rebuild Part 4:

Park-Neutral Position Switch:
I didn't realize that my transmission over heated until I decided to test the PNP switch. I saw someone tested theirs and as I was waiting for shipment of hard parts fortunately I decided to test mine for continuity. The results were inconsistent with shorts sometimes where there wasn't supposed to be. I pulled apart the PNP switch looking for the cause of the shorts but didn't see a problem. I also scraped off a lot of the insulation looking for problems; this was later packed with silicone putty. Here is what it looks like inside:

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And the other side:
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You can see as the selector is moved, the 3 rods on the sweeper arm cause some of the opposing plates to establish continuity. No sign of problem here.

When I was cleaning the exterior of the transmission, I noticed what I thought was a melted crayon that might have kicked up from the road and landed under the PNP switch where it melted. I finally realized this was a pool of melted wire insulation. As I moved the cable, all the wires were coming in and out of contact.

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I couldn't find a replacement and didn't want to wait for one so I cut all the wires (one at a time), put heat shrink over them and soldered the wires together.
75910


Tested again and works great.
 

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Discussion Starter #24
Rebuild Part 5:

Total and reverse clutch end play:
If you replace certain hard parts, you're supposed to measure and adjust total end play and reverse clutch end play. I don't think any shop does this. I called around trying to borrow the special tool needed to measure this and no one had heard of it. Not even the Nissan service centers (they don't rebuild your transmission, they'll just replace it). Transmission shops said they just do it by "feel". Well, I put so much work into this rebuild, I wanted to do it as best I could so I bought the tool (J-34291). I'll post a lot of information about the tool and the plungers later.

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I took multiple measurements of each end play (at different angles) and found that they fell within a range of 0.15 mm. This doesn't sound like much, but when the total allowance is 0.25 - 0.55 mm (total end play) and 0.55 - 0.90 mm (reverse end play), it was quite large (about 50% of the allowance). It's an unwieldy tool perched on unstable objects trying to measure minute differences.

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I'm glad I did these measurements; it put my mind at ease but I don't know how useful it was to do. I know I can resell the tool for more than I paid for it; eBay has them for about $200, brand new they are $3500 (hah!).

Based on the clearances you measure, you're supposed to select a bearing race or a plastic washer of a specific thickness. I bought a variety of washers from Cobra Transmission. I think they only had one thick bearing race (metal) so I bought it and grinded it down (by scraping it on the concrete under my shoe for an hour or more then sanded smooth) to fit the thickness I needed.

The FSM says to install/adjust the brake band after measuring end play but the reverse clutch drum moved too much so I did it before measuring these clearances.
 

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Discussion Starter #25
Rebuild Part 6:

When I pulled the transmission, I noticed a separation of the bell housing and transmission case and thought it was in error. This is supposed to be like that.
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Opposed to what the FSM says, the pump housing and the bell housing are one piece and cannot be separated.

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Also, there is no brake band strut.
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Much of the plastic corrugated tubing near the engine was brittle. I replaced it and wrapped it with heat shielding tape (the tubing on the transmission too). You can also see here how I increased the length of the crank position sensor connector cable.
75916
 

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Discussion Starter #26
Rebuild Part 7:

Hard Parts:
I realized before pulling the transmission that I might have to replace some "hard parts" like drums. I contacted a local transmission supply to ask if they had a part (I think I asked for a piston in the reverse clutch drum) and they said no. That was all the prep I did for this. I should have done better.

When I pulled apart the transmission, I found that the stator (oil pump cover/rear support) and the reverse drum were wearing on each other and were damaged beyond use. This is supposedly a common problem with these transmissions. A local transmission supply got me a used reverse drum ($60) though the bearing needed replaced; they didn't have a usable stator. Buffalo Engine Components (www.buffaloengine.com) had a good selection but also didn't have a stator. I had to resort to eBay for a stator where I only found a stator/drum set for $260 shipped -ouch.

The drum they sent me was immaculate and I ended up using it over the local one. The stator however was slightly different than mine and than the auction picture (see previous posts). They sent me another one that matched perfectly except it was damaged (the support had a chip in the end holding the bearing). They sent me another one that had been dropped on the other end deforming the teeth so they wouldn't engage in the torque converter. I was sick of waiting for parts so I decided to use the one with the chip on the support. It didn't look like it would cause any problems because there was a machined space on the other side. I filed and sanded the chipped area.

75918


75919
 

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Discussion Starter #27
Miscellaneous:

With the transmission off, I replaced the rear main seal and the rear engine oil pan gasket. I wrote it up here:


I took the chance to sand and repaint much of the lower oil pan. It looked brand new by the time I was done. Sorry I didn't take photos of the finished pan but you should plan to do this too. I also repainted (at least partially) the transmission/fly wheel dust covers, the oil pan, the torsion bars and parts of the frame.

75920
 

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Discussion Starter #28
Aftermath:
I had no problems for a couple weeks. One cold morning, I heard a buzzing noise for a few seconds after starting it from cold; it wasn't accentuated by shifting gears, forward or reverse. The noise was similar to this:

A couple weeks later when the weather turned cold, the buzzing came back and lasted longer. It would eventually go away when it warmed up.

Diagnostics pointed to the oil pump. I read a BMW forum where many said they got this buzzing after installing a new filter. It was mentioned that the aftermarket filter was out of spec and was starving the oil pump.

I replaced my filter during the rebuild so I decided to put the original back in. I flushed the old one over and over with gas then rinsed it with acetone. I pulled the new one I had just put in a few week prior and found this:
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Now, I knew my rebuild wasn't done in a clean room and I expected some particulate such that I put cheaper ATF in at first and planned to change it out after a few weeks. What I found however was much worse than I expected. Fortunately, this makes the cause of the problem obvious. The clogged filter was starving the oil pump especially when the fluid was cold and more viscous.

The original filter was put back in and all the fluid that would drain out was replaced with Valvoline Maxlife Dex III synthetic (5 quarts). Then another 4 quarts of that was replaced with synthetic. The buzzing is gone. I'll probably clean this filter and put it back in within a few months just to be safe.

No other problems so far (about 2 months after completion).
 

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Discussion Starter #29
J-34291
I'll post a lot of information about the J-34291 for anyone that might need the tool for the many uses (even outside of Nissan transmission) that it is intended. Hopefully with this information, you can make your own tool or do your own estimates so you won't need to buy this expensive, hard to find tool.

It was originally made by Kent-Moore which has been purchased by Bosch. I've seen at least 3 versions of this kit (same product number). As time went on, more manufacturers requested more plungers be designed and included in the kit. I've seen between 5 and 13 plungers in the kits. It seems the kits are $3500 brand new or about $150-$300 on eBay for unknown amounts/types of plungers.

The kits have 2 legs connected by a bridge, a gauging cylinder (holds the plungers) and various plungers. The legs are 200 mm; the plunger holder is 165 mm and the plungers are of varying lengths but the shafts all seem to be 68.5 mm (this isn't important as it just fits inside the cylinder). The long side of each plunger is between 34 and 35 mm. Some plungers have a ledge and a short side so the plunger can abut a smaller area. This short side length varies too.

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To make a measurement, you connect the legs and bridge and gauging cylinder. You set the legs on the specified surface (like the case-oil pump mounting surface) then you let the gauging cylinder rest on the point you want to measure, tighten it's position. Next you put the specified plunger in the cylinder and turn the assembly upside down placing it on the other side of what you want to measure. You let the plunger drop against the point and you tighten it's position. You then measure how much the plunger fell out of the gauging cylinder.

You'll notice that if your plunger is 35 mm (35 mm plunger + 165 mm gauging cylinder = 200 mm same as legs) and the gauging cylinder drops by 50 mm in one direction then there will be a 50 mm space on the plunger side. If you're using a 34 mm plunger and the gauging cylinder drops by 50 mm in one direction then there will be a 51 mm space on the other side. In this way, you can see that a certain amount of space is built into the measuring process.

For example, my RE4R01A reverse clutch drum end play spec is 0.55 - 0.90 mm using the J-34291-23 plunger (34.5 mm). When I put the tool into place, the gauging cylinder drops by X (unimportant) amount and rests on the reverse clutch drum thrust surface. We now know that on the plunger side, we have 0.5 mm + X amount. More importantly, we know that the space we want to measure if we didn't have the tool would be between 1.05 mm and 1.40 mm (0.55 + 0.5 and 0.90 + 0.5). So, if you could build a tool that would measure the difference in drop onto the drum vs drop onto the washer, you would expect these measurements. If you didn't get them, then you change the washer thickness.

Here are the measurements of the plungers that I had in my kit. I used a cheap (Harbor Freight) caliper so my measurements may be a little off but I measured these over and over to get the same result. The first measurement is the "long side", if the plunger has a ledge, the second measurement is the short side. Subtract one from the other to know how much of an over-hang the plunger can handle.

J-34290-3: 34.3 mm
J-34290-4: 34.3 mm
J-34290-6: 35.0 mm
J-34290-7: 34.9 mm; 14.7 mm
J-34290-8: 34.5 mm
J-34291-6: 35.0 mm; 27.2 mm
J-34291-7: 34.1 mm; 20.0 mm
J-34291-12: 35.0 mm
J-34291-13: 34.8 mm; 15.7 mm
J-34291-14: 34.2 mm
J-34291-15: 34.6 mm; 20.0 mm
J-34291-20: 35.0 mm
J-34291-23: 34.5 mm; 15.6 mm


Note:
I needed the J-34291-23 plunger but unfortunately it didn't come in the kit I bought. I contacted Bosch who was able to connect me with an engineer who told me that the entire plunger was 4.06 inches (103.124 mm) long; the short side was .6092 to .6087 inches (15.47 mm to 15.46 mm) and the long side was 1.3592 to 1.3587 inches (34.52 mm to 34.51 mm). I used other plungers because I knew their lenghts and calculated the measurements I would have gotten.
 

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Discussion Starter #30 (Edited)
I'm really glad I did this project. It was pretty difficult but very rewarding. When there's a global pandemic and you have more time than money on your hands, it was a great opportunity. In between all this, I did some other projects: power steering hoses to stop that slow but messy leak, reconditioned (heat and chemical) the exterior soft plastics, painted the exterior hard plastics, painted the rear bumper, waxed (hiding the mountain pin-striping, I should polish these out), reconditioned the headlights and scavenged junk yards for miscellaneous broken pieces. I'm really happy with this 16 year old vehicle now.

Future projects are redo the falling headliner, fix the A/T Temp warning light (or find another way to monitor the temp), dent repair, front suspension work with alignment, adjust headlights, replace shocks (8 years old), rebuild the power steering pump (it's getting whiny) and maybe replace seals on the PS gear box, (something leaked but isn't now).

I'd be happy to answer questions and help anyone out that is taking a rebuild on or tracking down a transmission problem with the RE4R01A. I don't frequent the forums but I should get an email if you reply to this thread even years from now. I'll respond but it may be slow.
 

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@QuinE
Sir, my hat is off to you, not only for doing the job, but also for the immense effort to take the pictures and write it up!

I honestly don't expect to ever do a trans rebuild, but I actually found your write-up to be an interesting read.

I hope your work continues to reward you with many trouble-free miles and tons of fantastic experiences.
 

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Fantastic write-up! As I've been dealing with transmission issues myself the past couple of weeks, your research has been so very much appreciated. The attention to detail and hints on potential screw-up points (Like the spring that you don't want to install upside down), is fantastic.

I've come across a lot of the same threads and videos that you've mentioned (the Frontier forum posts, various R31 / skyline posts, the youtube videos, etc) in my googling and found a lot of additional manuals/guides in the process that would be great to store somewhere for future use in addition to the FSM for the AT. Perhaps this thread can become a master for transmission repairs/rebuilds and stickied? I know it would have been super helpful for me to have been able to find a ton of resources in one place. I've got a youtube playlist dedicated to the RE4R01A videos I've found thus far, that I will break out in link form in a following post.

Some of the guide /manual pdf's I found that could (should?) probably be stored in a google drive or something for future reference by unfortunate Xterra / Nissan owners:

  • ATSG Technical Service Information - Nissan RE4R01A (90 pages)
  • ATSG Nissan RE4R01A (104 pages - I'm not sure how much overlap there is with the above)
  • JPAT Parts Reference Guide - (As you mentioned/shared, it's a great part # reference with images)
  • 1990 Nissan 240SX Auto Trans Diagnosis - RE4R01A , RE4R03A , RL4R01A (I'm sure not everything will apply, but a great resource, nonetheless)

For future readers: I've found that it's easier to find transmission information, posts, guides, videos, etc by searching the transmission part number ( RE4R01A ), given how much it's been used in various vehicles over the years. Just keep in mind there have been numerous revisions and modifications.
 

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I would suspect that it's not so much that the replacement filter was out of spec, but that the new clutch packs etc. were throwing debris as they got seated and broken in (this is to be expected). Ideally this would get picked up by the magnet, but the magnet can only do so much. This goes to show that after rebuilding and a break in period the filter should be changed. I would hope that the original filter would have also caught all of this material (and likely been plugged up). If not, it would have been recirculating through the transmission and all of those nice new parts.
 
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