How To Remove And Replace Porsche 944 Transmission Drive Axle Seals

THE WHY

If you're experiencing an oil leak coming from the rear of your Porsche 944 then it is probably coming from the transmission/gearbox's oil filling plugs (there are two) or more likely one/both of the drive axle seals (one either side where the drive axle meets the transmission). Other symptoms include harder than usual shifting or transmission whine due to lack of transmission oil. Having replaced the filling plugs for new ones at the last gearbox oil change it was pretty easy to trace the black greasy patch on the underside of the transmission to both the drive axle oil seals - they simply needed replacing.

THE TASK

I used the following:

8mm Spline Bit
8mm Hex Socket
17mm Hex Socket
Socket Ratchet Spanner
Torque Wrench
Socket Extension Bar
Small/Medium Heel Pry Bar or Seal Puller Tool
Seal Press or 38-40mm socket
Rubber Mallet
2 x Radial Shaft Seals (Porsche OEM Part number 016 409 399 B)
1 x Large Zip Tie or Length Of String/Rope
Spray Degreaser
Oil Drain Pan.
Stiff Scrubbing Brush
Axle Stands
Trolley Jack
Swepco 201 Gear Oil
Anti-seize thread lubricant
White Spirit
Karcher Powerwasher (optional)


THE HOW TO


(Amateur mechanic job time approx: 2-3 hours).

Start by raising the rear of the car and support on axle stands (the higher you can get the rear off the floor the easier the job becomes). As you can see from the photos below the seals on mine were leaking quite badly from both sides.

Depending how badly the seals have been leaking now might be the time to give the transmission underside a blast with the powerwasher and degreaser. The purpose of this is it makes the job a lot less messy and enables you to check for leaks once the job is complete.

Now follow my tutorial on how to remove the transmission oil, you will also need to refer to this when it comes to refilling the transmission once you've replaced the seals.

With the oil drained it's now time to remove drive axles where they meet the transmission. Start with the one that isn't under the exhaust (shown below) as it is the easier of the two and is a good way of getting a clear idea of what needs to be done when you start the slightly obstructed exhaust side.

To release the drive axle you need to undo 8 x 8mm spline screws. Make sure the spline bit goes in straight and not at an angle otherwise you risk rounding off the spline bit and probably the screw too. If you find it difficult to get a good angle on some of them then simply release the handbrake and rotate the wheel to improve the access.

With the spline screws removed you should now be able to move one end of the axle. Find a suitable place to hang the drive axle out of the way and cover the end with a plastic bag (this stops any grit getting stuck to grease in the universal joint).

The next step involves removing the flanged shaft. Start by poking an old screwdriver all the way through one of the empty spline screw holes, this stops the flange from moving when you release the 8mm hex screw from it's centre. Use a socket wrench with extension bar and 8mm hex bit to undo the centre screw as shown below.

Once the screw is removed the flanged axle should simply slide out. Give it a good clean and check there's no wear or rough areas on the axle near the flanged end.

Now we can see the large black coloured seal we are going to remove. I used a small heeled pry bar (or you can use a seal puller or other hooked instrument) to gently work around the seal and ease it out. Be careful when doing so as the blind side of the seal that you can't see contains and elasticated spring and it's easy to leave this behind in the transmission. Keep at it and the seal will eventually come out.

(Seal before removal)

(Blind-side of seal and elasticated spring)

(Seal removed)

Once removed it's a good idea to thoroughly clean the area so that no grit or muck enters the transmission when you come to install the new seal.

Here you can see the new seal (left) alongside the old seal (right)

You are now ready to install the new seal. Before you do so, take note of the small raised lip (see arrow below) that the new seal must press up against inside the seal hole. Now take a small amount of white spirit and lightly rub some of it around the outer edge of the black seal (this aids fitting and will shortly evaporate). Now press the seal squarely into the hole making sure the spring is facing in towards the transmissions internals. Now take a 38-40mm socket and a rubber mallet and gently tap the seal into place making sure it doesn't skew as you knock it in. Use your fingers every now and again to feel around the inside of the seal to see when it is fully pressed up against the lip on the inside.

Photo below shows a 38mm socket compared to the size of the seal.

And photo below shows the seal correctly fitted.

Now you can re-install the flanged axle and re-attach the drive axle shaft. You may also want to take this opportunity to refresh the grease in the CV joint at the end of the drive axle before reattachment.

Now all that remains is to repeat the procedure for the other side before refilling the transmission gear oil.

How to fit a short shift kit to a Porsche 944

THE WHY?

It has to be said that the 944 doesn't have the lightest gear shift you'll ever come across. So it makes sense to keep this part working as efficiently as possible. There are several ways this can be achieved. The first and by far the simplest is to make sure the transmission oil has been refreshed (A  job that only takes an hour, but can make your drive feel 100 times better). The second and third options involve replacing the shifter mechanism at either the gear stick end or the transmission end. Over time you'll find that wear and tear take their toll and the shift will not be as precise or as smooth as it should.

Since I had the transmission off the car and had noticed quite a bit of play in the plastic ball joint on the linkage I decided to replace it with and after market short shift kit.


THE TASK

This job is far easier if the transmission is off the car, however it is still do-able with it still attached. You'll need:

Socket set and/or ring spanners
Short shift kit (Bought mine off ebay, but you can also buy a really nice one from here)
Hammer

and maybe....

Hex rod and two rose joints (see foot of post)
Hacksaw (see foot of post)
Thread tapping set (see foot of post)



THE HOW TO

(Amateur mechanic Job Time approx: 1.5 hours (off the car) or 2+ hours (on the car)

Firstly identify the original shifter linkage and support arm attached to the gear box. If your transmission is still attached to the car the linkage sits on top of the transmission. You'll also need to slide back the rubber boot and undo the bolt that connects the linkage to the shift rod that runs through the car before you can continue.

Now remove the black rubber boot completely by sliding it off the linkage rod (you'll need to re-attach this to the new linkage later).

Next undo the nut and bolt at the top of the linkage where it joins the support arm. At this point the bolt on mine sheered as it was so old and rusted. If the same happens to you then you can either buy a replacement from Porsche or make you're own alternative support arm using some hex-rod and a couple of rose joints (See end of post for details on this).

Assuming you've not had problems undoing this nut and bolt you can then proceed to remove the small bolt that fastens the linkage to the shifting stub on the side of the transmission (Note: the flat side of the shifting stub that the bolt presses against). Having removed the bolt a small tap to the side of the linkage with a hammer should remove it from the stub and the transmission completely leaving only the support arm attached to the transmission at one end.

Here is a photo of the new linkage (left) beside the old one (right).

Installation of the new short shift linkage is the reversal of removal, taking care to line up the flat side of the shift stub as you slide on the linkage and do up the bolt. Then reconnect the support arm to the linkage and finally slide the rubber boot back on.

Here's what the finished article should look like.

Now for those of you that are interested in the support arm (The orange rod in the picture above). Having researched the short shift kit on the web before I attempted this modification there are several manufacturers all offering roughly the same piece of kit at varying prices. Some of the short shift kits come with a support arm similar to the one I made and some (like the one I went for) just make you use the original arm (and had the bolt not sheered then I would have reused the arm).

To make the arm you will need to source a length of hex-tube / hex-rod. In the UK this is easier said than done as most hardware stores don't stock it. Fortunately because I have been going Karting since the age of sixteen I happen to know that hex rods are used as the steering track arms on these vehicles. So a quick search on ebay for 'Kart track rods' brings up a number of results right away and at some very reasonable prices. The good news about buying them off ebay is that they usually come with the rose joints already attached at either end. If they don't then you'll need 1 x 8mm Left Hand Thread rose joint & 1 x 8mm Right Hand Thread rose joint (They are also known as 'track rod ends').

If you've bought your Kart track rod then you'll instantly notice that it has an 8mm thread cut into it at each end, one will be a left handed thread and the other will be right handed (Right handed threads are standard on virtually every screw you've ever come across). We need to make the rod shorter which means cutting off one of the ends. Leave the left hand threaded rose joint attached to the track rod and measure it up against the original support arm. Mark the length and use a hacksaw to cut off the standard right hand threaded end (we don't need this bit). You will now be left with left handed threaded length  and will need to re-tap an 8mm right hand thread into the sawn end. Once this is done attach the right handed rose joint and you'll have an adjustable support arm. By simply using a spanner to turn the rod you'll notice it'll pull the rose joints inwards and by turning the other way it will push them outwards.

Simply attach it in place of the original support arm using a couple of 8mm Allen bolts and some washers as shown in the photo above (Using Allen bolts instead of normal hexagonal bolts allows the rose joints to move more freely).

How to change transmission oil on a Porsche 944

THE WHY?

If your 944 is 25 years old like mine with just over 120,000 miles on the clock then you may have noticed that the gear changes are not as smooth as they once were or maybe your gearbox is whining a bit. Then it's quite possible your gearbox / transmission needs some fresh lubricant.

THE TASK

Quite a simple one really. This is what you'll need.

17mm Hex bit
Torque wrench
Anti-seize thread lubricant
Swepco 201 gear oil (Approx £50) - You get 3.8 Litres in the bottle, the transmission needs 2 Litres
A large syringe
Bowl to catch old lubricant

THE HOW TO

(Amateur mecahnic Job Time approx: 1 hour)

If your transmission is still attached to the car then it's probably best to give it a 10-15 minute drive to warm the old oil up so that it flows out more easily. My transmission was already off the car so I just had to make sure it was on a level surface. The transmission is located under the rear of the car. Take an empty bowl and place it under the left hand-side of the transmission ready to catch the old oil. On the left side of the transmission you will find two identical oil drain plugs situated to the right and below the drive shaft mount.

Start by cleaning off any dirt or rust around the threads on both drain plugs, give them a spray of penetrating oil too. Remove the upper plug first (in case the lower one is seized then you haven't lost all your oil with no way of putting fresh oil back in). Then remove the lower plug using a 17mm hex key, the oil should then start to flow out. Once all the old oil has flowed out stick your finger in the hole and feel around checking for metallic particles left in the bottom of the transmission. If there are then your tranny may need a little more attention than just an oil change. Now is a good time to inspect the condition of the drain plugs. Mine were pretty old and roughed up so I decided to change them for new ones, only a couple of quid each from Porsche. Notice the tapered thread on the drain plugs.

Now apply a little anti-seize thread lubricant to one of the drain plugs and tighten it into the lower hole to a torque of 20Nm. Now fill the syringe with Swepco 201 gear lube which I bought from here and pump it into the upper right hand hole. Repeat until the oil comes level with the bottom of the hole you are putting the oil into. Once you're there apply the same anti-seize thread lubricant to the remaining drain plug and tighten to 20Nm. Job done.