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SkinnyG 12-28-2012 01:48 AM

Tips on changing a transmission
My 5-speed transmission was making some NASTY disintegrating bearing noise under low rpm load (lugging), as well as deceleration most noticeable in the lower gears. Methinks cluster gear bearings, but I had another tranny kicking around. And the hunch that the clutch was dying. So......

I reviewed AllData first, to see what I'm getting into. According to AllData, there are two steps:
1) Remove shifter (remove boots, and remove internal snap ring holding ball/shift-lever.

2) ( and I quote: ) "Remove transmission"
Not the most detailed of instructions. Thanks, AllData. </sarcasm>

My favourite tools for this job was a 3/8" drive butterfly impact, impact universal, and long extensions. The job is entirely accessible from underneath, and not that bad as far as trannys go.

Well, ok, the hoist was welcome too.

TIP: Disconnect the NEG battery cable. I didn't, but I'm a gambling man.

I removed the shifter assembly (six fasteners) as my existing boots were better than the ones on the replacement. I gave the carpet a good-old "heave-ho" to access the boot screws. I always hate doing this. Removing the carpet would be easier. I know some people just slice the carpet in the corners to access the screws better. A stubby Philips helps get the two forward screws.

I removed the driveshaft and carrier bearing.

I disconnected all electrical connections, and unclipped the harness from the transmission.

I removed the starter bolts.

TIP: Remove the upper starter bolt first. A standard length 14mm works best, with the handle angling towards the firewall. ~Then~ do the bottom bolt which is so much easier to get to.

I removed the four large engine-transmission fasteners, as well as the two wee ones at the bottom of the bellhousing.

I supported the transmission with a transmission jack (which proved useless), and removed the transmission crossmember. There are nuts on the topside of the crossmember you need to hold with a wrench. I pulled the entire transmission rubber mount as well, as the replacement was better.

Give the transmission a hefty tug rearward, and it should come off the engine nicely. The transmission, at this point, was still supported by the tranny jack.
It looks like there might be enough room to just shove the transmission back on the torsion bar crossmember, and have complete access to the clutch without removing the transmission from the vehicle. However, my tranny was toast, so it had to come out.
Seeing that the tranny could not be dropped straight down because the torsion bar crossmember was in the way, I ditched the tranny jack and supported the tranny on my shoulder, and lowered the bellhousing end out the bottom.

TIP: To clear the pressure plate, you may need to rotate the transmission slightly clockwise (as viewed from the rear).

TIP: If you're pulling the transmission, you might as well change the input shaft and output shaft seals. They are not expensive, and "you're in there anyways."

============= You're In There Anyways =============

While you're in there, you might as well do the clutch.

CDN pricing from my local Nissan Dealer: $380 in parts.

I picked up a "Premium" clutch kit from LordCo for $160 (list was $272).

TIP: To remove the pilot bearing, pack the crankshaft cavity with grease. A 1/2"-drive extension is about the right diameter (5/8") to place inside the existing bushing, and drive it in with a hammer. The grease has nowhere to go, so the hammer force causes the grease to push the old bushing out.

To put the new bushing in, I made a simple slide-hammer weight out of a washer and a heavy 3/4" drive socket. These slid onto the 1/2" drive extension I used previously, and using the old bushing as a spacer (to clear the flywheel bolts), I progressively hammered the pilot bushing in. Using the extension helps you hammer straight. The bushing was finished flush by tapping it flush with the drive-end of a deep socket and a hammer.

My clutch disc was contacting the rivets on the pressure plate side. The flywheel side was fine. It's usually good to pull the flywheel and send it out for surfacing. It's a stepped flywheel, so it'll be a bit more expensive.

I scuffed the flywheel with a 3M surfacing disc on an angle-die-grinder (This was a bad gamble - the new clutch chatters).

TIP: The "raised" portion of the clutch center faces the pressure plate. Don't get that mixed up or your clutch won't work.

I love that the clutch kits come with a clutch aligning tool. Way back in the bad old days they didn't. Golly that was misery back then.


I got the next transmission ready to install, and heaved it up onto my shoulder. Tail end in first, slight rotation, and shove it into the clutch. Thread a fastener in by hand just to hold it there while you jimmy the thing home and thread the rest of the fasteners in.

TIP: Make sure the transmission is fully seated onto the engine block before you start tightening the bolts. Using the bolts to "draw" the two together may break the bellhousing.

Re-installation is straight forward, nothing to report.

Except the "new" transmission has a different bearing noise. Probably input shaft bearing. Figures.

TIP: Pour 2L of gear out in through the shifter hole before you put the shifter back in.

TIP: Use ONLY a GL-4 gear oil. I have had good success with gear oil that is rated for BOTH GL4 AND GL5. I have had BAD success with GL5-only.

Sorry no pictures. I was under a time constraint to get the job finished.

I was unable to remove the old Vehicle Speed Sensor from the old transmission, so I ended up machining a plug to seal the hole until a new sensor comes in.

SkinnyG 01-19-2013 05:04 AM

Bumping this, just because of all the recent posts about transmissions and clutches.

I finally was able to remove and swap the old VSS. A combination of soaking it with WD40 for two days, soaking it with MoovIt for another day, and careful application of a propane torch.

Sensor survived the ordeal and tested good for signal and resistance, so I put it in the new tranny and fabricated a new method of holding it in place since I had broken the mounting tab off it. *sigh*

uno's_hb 01-19-2013 08:49 AM

Nice write up Skinny, lots of very useful info. I like the "tips" too, its always good to hear it from someone who's done it instead of just reading the manual.

OnAir88 01-19-2013 12:50 PM

skinnyG this was a great write, very detailed.

I was told by my uncle who did transmissions for 30 years said that the output shaft seal was irreplaceable.. I'm not saying your wrong by no means. But this is what I was told.

SkinnyG 01-19-2013 07:24 PM

You can't say I'm wrong by any means. :)

Input seal: National #1981 (SKF #11615)
Output seal: National #710324 (SKF #13907)

U-Joints are non-replaceable. Except you replace them with Rockford 430-10 (86-89) or 430-12 (90-97).

hrd_bdy 01-19-2013 07:32 PM

just out of curiosity, what makes the U-joints non-replaceable on these? on my Supra i was told the same thing, that it was manufacturer designed that when the U-joints were bad you just got a whole new driveshaft. that used to be the case, but nowadays you can get around it and replace them i guess. i got them done on the Supra but they said it was a bear to do (hence why i took it to them and never did it myself lol)

all-data just says remove shifter and remove trans because most rear drive transmissions are basic and include removing the same items, some are worse to remove than others *cough*BMW*cough*

Dragthatsht 01-20-2013 02:53 AM

Best advice i have is take it out the bottom.

OnAir88 01-20-2013 03:23 AM

See he told me that I cld bore the hole and get a seal.. But it was non replaceable.
Thanks G!

SkinnyG 01-22-2013 02:57 PM

Kurtis_With_A_K took pictures when he did his clutch:

Boozehero 01-23-2013 12:59 PM

First off, thanks for the great write up.

Funny coincidence... I replaced my GRENADED :facepalm:
POS 5 speed about the same time as SkinnyG did. I have done so many tranny in/outs that this one was a breeze. The main tip is to clock the tranny to the passenger side on the way out and in and if you take apart the d shaft, it has to go back together the same way.

As you probably know, I don't have much of a good opinion for the D21 (junk) tranny.

Oh, and BTW HRD_BDY, try removing a tranny from an early Sunbeam Alpine or Rover 2000 TC... They don't come out from the bottom...
You have to pull the whole wad out of the top.

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