DIY: Gearbox oil change 5 Speed M/T (yes, it's different than the 6 spd)
 

First, go here to set up your car for this (level ground, wheel chocks, e-brake, etc):

https://www.rx8club.com/do-yourself-...acement-35115/
The principles are similar but our gearboxes differ slightly from the 6 speed unit.

You need:

-1 Drain pan
-1 24mm socket & ratchet
-1 torque wrench capable of ft-lbs
-1 adjustable wrench (or 1 14mm crescent wrench, and 1 12mm crescent wrench)
-Thread sealant or teflon tape. The previous owner of my particular vehicle used grey RTV. I'd not recommend that.
-2.6 US Quarts of GL 4 or 5 75w90. I used Mobil 1 because it's available locally, but Redline MT-90 is a superior choice.
-Fluid Transfer Pump, I bought mine at Advance Auto for $6.99
-Drain plug crush washer, I had to re-use my old one because not even my Mazda dealer stocks this.
-Shop towels and whatever you like to use to clean stuff. I used simple green and paper towels.

Now that your car is on level ground, the drain pan is in place, and you can safely reach the gearbox, using your 14mm crescent, remove the fill plug FIRST. Exclamation point. If you remove the drain plugs first, but can't get the fill hole guess what? you're SOL with a dry gearbox and no way to refill it. So do yourself a favor and do the fill plug FIRST.

Next, grab a 24mm socket, ratchet, and remove the primary drain plug.

While this is draining, using an adjustable wrench or the 12mm crescent wrench remove the secondary drain plug (pictured). Yes, you need to remove this. There was 1/2 quart of oil hiding here, even after I had drained all that the primary drain plug would let me.

With all 3 of these plugs removed, clean the crap from the magnets on both drain plugs.

Clean the thread sealer from the threads of the secondary drain plug and the fill plug. Get in there really good, I used a flat blade screwdriver for the big stuff, and a knife for the small stuff. If you don't get all of this, when you go to re-seal you'll end up not getting a complete seal.

With all of these sufficiently clean, your transmission should be just about done dribbling out the old gearbox oil. Take this time to clean the old sealant out of the fill and drain threads in the gearbox. I used a paper towel and the dental pick from my rifle cleaning kit very gently.

Lay a very thin bead of your thread sealer on the secondary drain plug and replace it in the gearbox. Torque to 22 ft-lbs.

With the new crush washer, replace the primary drain plug, torque to 43 ft-lbs.

Using your fluid transfer pump, fill the gearbox until it starts dribbling out of the fill hole. It'll take all of 2.6 US quarts. I bought 3 and have a little under 1/2 quart remaining.

Lay a thin bead of sealer on the threads of the fill plug and replace in the gearbox, torque to 28 ft-lbs.

With respect to the fill and the secondary drain plugs, you might end up having a few threads showing even though you're at the proper torque setting. RESIST THE URGE to keep trying to screw it in until no threads are visible. If you applied your sealer properly, leaks will not be an issue regardless of where the threads end up.

Test drive to ensure proper function. Check for leaks. Clean up and dispose of old gearbox oil in an approved recycling facility. Your trash can / storm drain are NOT approved recycling facilities. Nor is your neighbor's front lawn. Or garden.

Notes:
1. The FSM states you should replace the fill plug. Not having any in the US available to me, I decided to re-use the old one. So far so good.
2. When I was installing the engine & gearbox, I noticed that some gear oil spilled out of the back of the shift-lever hole when it was at a pretty extreme angle during installation. This indicates to my puny little brain that you could potentially refill using this hole vs. a fluid transfer pump from under the car. I found it easier to just do everything from under the car. Reading the RX7 forums (this is the same gearbox as the turbo'd cars), they say you can't fill from that hole, but then again their extension housing is different than ours.

YMMV.

Mine was not a square but a hollow like a allen head - but not . I managed to undo it with an allen key though 10mm i think .


I managed to get 3 litres in mine and that still wasn't enough !



They are right - you can't . I tried .

What you are supposed to put in that housing is a bit of a mystery though ...

Its torx (T-50), and that's not the fill hole. It's an inspection port. For what I don't know. You can fill through it, as long as you leave the primary (lower) fill port open, and stop filling when the primary port starts drooling vs. filling all the way to the large torx head port.

See above comment... and the PM. It's above the fill hole so it stands to reason you'll be able to get a bit more in there. As per our PM conversation, I'm not sure what an extra 400mL will do, good or bad. My workshop manual said 2.6 US QT, so when it started dribbling from the fill hole at 2.6 QT's, I figured it was done.

The RX8 FSM and workshop manuals say nothing about this, but after digging around on RX7Club.com I found this:
http://www.rx7club.com/3rd-generatio...4/#post1558372

And he's right. Go to the 1993 RX7 Workshop Manual from foxed.ca, open section J which is gearbox, and scroll to page 62 (the last page in sect J). It talks about using grease on the pivot for the shift lever, and filling the "change control case" with 80 - 95cc's of "specified" oil which I assume means gearbox oil.

In theory, since there's no way to drain the change control case, you should never have to fill it... but if you're doing a rebuild or installing a fresh gearbox, I can see why it would need to be filled.

Hope this is helpful.

page from the Rx-7TT R15M-D trans manual:

https://www.rx8club.com/attachment.p...1&d=1360519737

^^^ Or that plus this (below) if you find yourself needing to refill the change control case.

i know i am reviving an old thread but can't seem to find my answer.

I have 5 speed transmission and it takes 3.75 liters and after that it starts dribbling. Is that normal? According to above pics by Team RX8, maximum is 2.5 liters for 5 speed but mine never starts to dribble until after 3.75 liters. What should i do in this case?

I had the same thing ...........See comments from McKenna above ...

Massive thank you for this - I know I am reviving a zombie thread but I don't think that a thank you, even 4 years after the last post and nearly 7 years after the original post is something to be missed.

I also need to highlight this YouTube video as it shows the process on a series 1 five speed gearbox.

I have to say that this was a bigger pest than I had imagined. I did gearbox and differential today (with the help of my 10 year old daughter who was amazing!) and the first pain was getting the car on 4 axle stands on my shingle driveway. I had to get some OSB board for the trolley jack to go on as the wheels of the jack just dug in the stones.

Second thing was that on my 2004 192 car I am pretty sure it hasn't had a gearbox or differential oil change in its life. So trying to get the torque required to undo that square fill plug was tough. Eventually gor there with a 17mm socket and a breaker bar. Sump plug needed the breaker bar as well.

The crush washer was destroyed. How some of you guys manage to reuse yours I don't know.

The biggest pain was the differential. It took me forever to seat the fill plug after replacing the oil.

Anyway, took it for a drive along some country roads where I can warm it up and then give it the beans - my daughter seemed very happy with her work!

Reminder of rule #1:

***ALWAYS*** remove the fill plug first, then the drain plug.

unless you can afford to be stuck with it drained of oil and can’t get the fill plug out ...

the person in that video should consider their self fortunate :)

6-speed fill plug is different type and position fwiw

.

Oh for sure - undid the fill plug first in both cases. We've got a few spare cars but didn't fancy the shame of calling the garage and asking them to come and help. But the gearbox fill plug was on unbelievably tight. The sump plug and secondary drain plug were pretty easy to crack.

I'd watched a fair few YouTube vids and then came across this thread. The image that you posted in October 2013 confused me because the gearbox plugs on the videos didn't look anything like your image - and then I saw the video that I popped into my reply.

Anyway, I've got some cardboard sitting under the car and I'll check it in the morning for spots. The crush washers that I used were slightly larger bore than the originals so were a bit sloppy on the plug.

ok, so that's not your video? My bad then. Because the person there clearly didn’t do that. Having the fill plug out also let’s the oil run straight out quickly rather than glugging away like that too.

As long as the sealing surface around the full perimeter on both sides is in contact with the crush washer then it should seal fine