Axle housing leak
 

Just curious what's involved in fixing this. Do I have to drop the whole axle or is there a short cut? It's bad enough that there is a pool of gear oil under the car right now.

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From what i can see it appears the sealer between 3rd member and housing is failing. Can be serviced in car. Drain diff,remove axles,driveshaft-plug tailshaft of trans with bottom half of plastic water bottle to keep oil from seeping out while driveshaft is out. Remove all the retainer bolts for pumpkin out of diff housing. Get a 4x4 block of wood and 48 oz hammer and smack one side of pumpkin,then other and alternate til seal is completely broken. Pumpkin needs to come out completely straight or it won't clear housing and come out. You'll see what i mean,lol.
Even more important to get back into housing.
Pro tip,lol get some long 8mm x 1.25 mm x 55 mm bolts and cut heads off,round down end where head cut off to bullet shape and cut a slot in that end. Need at least 3. Screw them into housing and use them as lineup dowels to assist in reinstalling pumpkin. Really helps if doing this on the ground=no lift.

Clean off sealing surfaces of pumpkin and housing of old RTV and wipe down with carb cleaner.Apply a layer of Gear oil RTV (gray) onto sealing surface of pumpkin@1/16"-1/8" thick and put it back together.Get all bolts in and snugged down handtight then use a screwdriver and pull lineup studs out and put remaining bolts in and tighten to @ 28-30 ft lbs. Should be left with a perfect bead of RTV squeezed out around circumference @1/16" thick. Don't be tempted to wipe this away,actually helps seal last longer.

Now a good time to check/renew u joints/replace driveshaft/replace axle bearings and seals. Also a good time to change final drive gearing,see where this is going...

^^^ That's exactly how the job is done. I love the idea of installing a few locating studs to aid in installation. The only thing I deviate form is that I use brake clean on the housing's mating surface as some carb cleaners can leave behind a residue. Other than that, that writeup is spot on.

What you do need to be aware of is that you may have to use a slide hammer bolted to the axle's face in order to remove the axle from the housing. I would also encourage you to replace the axle seal on the housing. This will ensure that you have no leaks past the bearing. Also, after you install the differential, give the RTV plenty of time to set up and cure. This iwll also ensure the differential is leak free.

Awesome write up. So yeah, my next question was gonna be whether I should just plan to put that 4.77 in that I've been thinking about...and it sounds like the answer is yes. Unfortunately I wanted to get one more dyno session in before making significant changes so I could test a few things. I know the dyno can adjust for the diff ratio, but it's still a variable in the results.

I have replaced all of the bolts (except the long one) with studs on my car. A decent hardware store will have metric studs that will work for this. That way you don't have to spend time cutting bolts. Take time to make sure the vent on the housing isn't plugged because that can cause leaks. Also, since you are pulling out the axles, replace the axle seals.

Changing the rear bearings if never been done before would be good while the axles are out.

If you mess with the gearing its a whole another ball game to get the lash and so forth setup right and requires more parts and you probably want to replace bearings and theres a sleeve on there that has to be replaced as well. Haven't done all this yet but will be doing it soon (as in next year LOL) as well.

you might check the torque on the bolts before you rip it apart, they like to loosen up if you beat on the car...

Agree about some carb cleaners and residue. I pretty much use Berkible 2+2 carb cleaner exclusively for the fact it leaves no residue. I have used it for final washdown of small parts after glassbeading and using compressed air to dry before putting in my"paint booth" for coat of etching primer. I normally use acetone for this,but after running out,the 2+2 has been a good substitute to continue working til get opportunity to get to body shop supply store. It's not economical,lol,but allows completion of a near done batch of parts'

I have found that at @65-70 degree garage temps that by the time the rest of parts have been installed back in car and it's time to fill differential,enough time has gone by for sufficient curing of RTV. Working outside in colder temps,i would wait maybe a couple hours before refilling.

^^^ this

If you have complete 3rd member or chunk,now's the time. If you have a new ring and pinion you will need to replace bearings,pinion/carrier. You will need an assortment of shims to set pinion depth/backlash,new crush sleeve,i prefer a crush sleeve eliminator as it keeps preload/backlash settings very close to how you have differential set up.
This pertains more to high horsepower cars but also here on cars that are run hard,drag strip,autocross,road course. The shock load of a launch,with/without slicks can deform crush sleeve over time,same for the harsh full throttle on/off on some tracks/surfaces. As crush sleeve deforms,the preload/backlash settings are lost and these clearances add up to clunking that can be felt in off/on throttle apply and take a toll on gearsets and bearings shortening their life. For those that just cruise and run thru the gears this is overkill,but for serious use should be considered.
There's a skillset involved in setting up differential gears,clearances,preloading components for a reasonable and quiet service life. Bolting parts together and hoping for the best pretty much insures you're revisiting this soon. I have done this trackside to keep competing instead of going home,some broke after couple passes(expected)some lasted longer before grenading, you do what you have to do before it's trailer time.

So...short answer...take the axle and new gear set to a pro. This sounds like it's above my pay grade.

Take out the 3rd member and sublet that for refit,same as you would do to reseal leak.Leave housing in car=much less work,replace axle seals while axle shafts out,axle bearings if not done recently.
You will need front/rear pinion bearings and races,carrier bearings and races,crush sleeve. Shims for pinion/carrier,gear marking compound.

No shop will do a regear with intent of using current bearings,even if bearings are still "good" chances of distorting/stressing them in r&r process not worth the time. I recall your car to be low miles but still require above parts to do job. I don't recall if yours is a GSL,if so,consider having LSD clutch packs gone thru while out and apart-lot cheaper at this point. If a GS and no LSD,adding one would be beneficial for both street and track time. Maybe shop in classifieds for a LSD 3rd member and have that overhauled and your new gearset set up in that. If you're like me,you can't be without 2 or more chunks with different ratios to suit different needs.lol. You can use car in meantime til newly acguired/refitted 3rd member is ready for install.

For now,put car up in the air and drain diff,check tension on retention bolts on 3rd member,clean it off and smear some gear oil RTV on housing/pumpkin,let it set up overnight if you have to,then refill. This will buy you some time,how long? Depends how clean you get surfaces,think wire brush/shiny metal. Assuming tech inspection at your track,don't know how much detail they go into...

IDo your research on shop you'd like to do the work,don't just drop it off anywhere. Driveline shop specializing in Japanese transmissions,diffs best. Any quality driveline shop should be able to do a regear with clearance/adjustment specs supplied,source brand name bearings/races the shop will use. They may/may not want to/be qualified to do a LSD rebuild. You will have to interview ask questions.

If you were closer...

Car is at 40k right now, GSL with the LSD. Maybe I'll try to clean it up and smear some RTV on it as you suggest and see if I can get the summer out of it. I'm still poking around in the engine bay working on stuff as we speak. I keep waffling about the final drive because I enjoy using it around town and back and forth to work which is a lot of highway. I also want the speedo to work properly and I don't know that there is a drop in speedometer gear for the 4.77.

After doing it a couple times,you can swap one chunk for the other in @hour.
Or you can go down the road i did and buy a car trailer...see where this is going? Oh,now you need something to pull the trailer with...