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Transmission/Differential Fluid Flush
Transmission/Differential Fluid Flush
| Question: |
"Why is my transmission so hard to shift in the winter?" |
| Answer: |
"Because you're using old, gunky transmission fluid." |
| Level of Difficulty: |
Medium |
Intro:
No matter what the manufacturers say, transmission/differential fluid gets dirty.
There are some very good reasons for wanting to change the gearbox
and diff oils on these cars, these are: better shifting especially when cold, the oils
over a period of time will not provide as much protection as they used to and of course
oil technology has improced since the mid eighties when these cars were first made and
like with engine oil they do break down after a while and will not protect your gearbox as
well.
If you just want to check the level on the box or diff then the procedure is the same.
First remove the filler plug and then if oil runs out of the hole then you are ok, if it
does not then add a little at atime until it just starts to weep of the hole. Re install
the filler plug.
To start with you need to either get a 17mm hex allen key or 17mm drain plug removal tool
( I prefer the 17mm tool as it can take more torque when undoing the plugs). Looking at
the gearbox first it is best to warm the oil up by driving the car for 5 to 10 miles to
get the oil nice and warm as it drains out better this way. Next you need to jack up and
correctly support the car. Underneath you will see on the left hand side of the box about
half way up the filler plug, remove this first, why I hear you ask? It's simple if you
drain the oil first and then can't the filler out then you got a big problem. Chances are
it will be in quite tight, best thing to do is to clean it out first. Next up is to drain
the oil out of the centre diff attached to the back of the box, the drain plug is located
on the bottom of this, be careful here as the oil does tend to gush out and it won't smell
all that great either. Now if you got the time I would leave it an hour or so drain out
properly, you won't get it all out but try and leave it as long as possible.
Whilst you are waiting for it drain out now is a good time to clean the plugs as they
should have little magnets on them to catch bits of metal. On re filling put the drain
plug in and then fill the box with your oil, I have a suction pump for this very purpose
which holds 0.5 litre at a time, i have heard of people using turkey basting syringes as
well, or you can squeeze it out of the bottle and end up with it running down your arm.
Once you are sure you have enough in the box, i.e. it's just dribbling out of the hole
then reinstall the filler plug. Whilst you are under this end of the car have a look at
the gear linkage that sits on top of the box next to the bellhousing, it's well hidden so
maybe a work light will help. Now if you have a spray can of grease sray the linkage well,
in particular the part with the ball joint on. This makes a big difference to gear change
quality, worth doing anytime you are under this end of the car. The other job well worth
doing id lubrcating the centre propshaft bearing, for this you need a grease gun and some
patience as it is a bit on the fiddly side, once the grease nipple has been located then
attach the grease gun and go for it.
Ok now it's the rear diff's turn, don't forget the tip about taking the filler plug out
first, drain and refill the same as you did for the box. Note that the oil for the rear
diff is different to the oil for the box. In my experience it's best to cheak the level of
the gearbox and rear every 6 months, as low oil kills these very quickly.
What about the fluid, man? What do I use?
From "TM"
Subject RE Correct Trans Fluid for '86 4KQ?
Date Mon, 10 Dec 2001 104638 -0500
Brandon- I am not a transmission expert, but I know that you
should _only_ use a GL-4 rated gear oil in your transmission.
You should follow the specification as provided in your owner's
manual and in the Bentley manual as to the actual weight and spec.
Redline MT90 is one gear oil that is within spec- MTL is too light.
Do not use a GL-5 oil in your transmission. You also cannot go wrong
with the factory Audi oil- that's what came in the transmission. I
cannot get a straight answer from Amsoil, so I would personally not use
their 75W90 oil in a transmission without confirming that they have a
GL-4 spec oil.
That said, I have Redline MT-90 for the transmission and Amsoil 75W90
for the rear diff waiting for me to replace the current oils in both.
Taka
From Gil Bourcier
Date Mon, 27 Sep 1999 103437 EDT
Subject RE Changing tranny /diff fluid in 4kq
Paul,
Having just done this 1k miles ago, it's still pretty fresh in my mind.
You'll need a 17 mm Allen wrench or Allen socket (hard to find, got the
wrench @ Sears for $9.) I would recommend Redline fluids (www.redlineoil.com
to locate dealer near you,) use GL-4 MT-90 for the tranny and center diff (3
quarts) and GL-5 75W90 for the rear diff (1 quart.) When you start the front
and rear operations, make sure you remove the fill plugs first to allow
proper draining. Fill plug is halfway up transmission on drivers side of
trans, trans drain plug is almost below it on same side, diff drain is on the
bottom. Drain, reinstall drain plugs, and add two quarts of fluid, lower car
to just above ground. Move shifter around to knock out air pockets. I used
a funnel and 18" rubber hose to refill, holding funnel just above the left
engine mount. Should take 16 to 24oz more fluid before running out fill
hole. Reinstall fill plug move to back, repeat for rear diff (fill plug on
passenger side, halfway up diff, drain on bottom, should take 0.8 quart.) I
found shifting to be like butter after the Redline treatment, which was
recommended by the list a while back. Email me if I can help further.
Gil Bourcier
Columbia, MD USA
87 4kcsq- 84k
Notes: I completely ripped this off from Iain & Ralf's Coupe Quattro Homepage. The file has been changed to make it more "integrated" into
my site.
