993 Faq Frequently Asked Questions about the Porsche 1994-1997 993



Filed under: Do It Yourself (DIY),Transmission — Jeff 993TT @ 12:47 am

Changing my transmission oil was pretty easy and my shifting action is much smoother.. It also gives me more peace of mind. There aren’t any filters in the trans! Really the hardest part was jacking up the car onto 4 jack stands.
I used 4 quarts of Amsoil 75W90 syntethic oil. Interestingly, it was pretty difficult to find Mobil 1 gear oil, which was my first choice. I found mostly Amsoil and Redline in shops. This oil wins the more colorful prize. It was a light blue color.

The manufacturer recommends doing this change at 30K, but at 19K miles, my trans oil was pretty dark and murky. There were a few shavings on the magnetic plug, which I cleaned off. ( See pic below. )

Thanks to Robin for a wonderful DIY. It helped me tremendously. Here are a few tips for the first time DIY’er that would be helpful.

a) You may need to put blocks under the rear wheels while jacking up the front of the car. With the front already on jack stands, the jack has less clearance to get under the tail of the car. My car isn’t lowered, but I needed the cinder blocks in the picture to get the jack under there. I used the rear engine jacking point without problem. The hockey puck trick worked great!

b) Definately use a 10 MM allen key socket. I had to purchase a 3/8″ to 1/2″ drive adapter to use a bigger ratchet handle. Those bolts are on pretty tight.

c) Robin’s DIY recommends that you remove the filler plug first, which is a good idea. However, it makes more sense to just make sure that you can loosen both the filler and drain plugs. You don’t have to remove them right there, otherwise, trans oil will start to flow out of the filler.

d) If you wait about 1/2 an hour for all the old transmission fluid to drain out, it will take all 4 quarts of the new fluid without spilling out of the filler tube. Just keeps things a bit cleaner. I liked the “oil bong” technique. It worked great. I used 7/8″ tubing and shaved down the end a bit. I then screwed it into the filler plug. If I were to do it again, I would have purchased an extra quart of AMsOIL to run through the transmission case to flush out any extra impurities.

e) Also, you will have to take off the driver rear wheel. I ended up taking off both rear wheels, becuase I couldn’t tell in Robin’s picture which one to do.

Here is a link to the gallery:


Short shift kits

Filed under: Transmission — Jeff 993TT @ 5:46 pm

There are several aftermarket short shift kits available from various vendors. The kit that comes closest to “factory” is the RS short shifter from Schatz Motorsport.

The DIY for the C2 short shifter can be found here: Short shift kit installation

The installation for the C4S/TT requires a modification to the tunnel cover. The physical shifter is longer than stock, so a teardrop impression must be made in the tranmission tunnel cover.


RS clutch and LW flywheel

Filed under: Transmission — Jeff 993TT @ 4:44 pm

The lightweight flywheel (LWF) is a great way to improve the quickness of your 993 and make the car more fun to drive. A normal 993 uses a “dual mass” flywheel and clutch (think of it as two pieces of metal with a rubber layer between them). While it generally works fine, the rubber can fail.

The RS version of the 993 used a different flywheel that weighs about 30% less than the standard flywheel and it’s one piece of metal with no rubber to fail. Less weight means an engine that revs faster, with most noticable improvements in the lower gears. When replacing the dual mass with the lightweight flywheel the clutch must also be replaced.


How long will my clutch last?

Filed under: Transmission — Jeff 993TT @ 4:43 pm

Pretty reliable units some listers have gone 100K miles on original clutch!

Euro gearing

Filed under: Transmission — Jeff 993TT @ 4:39 pm

A great perfomance upgrade is to reduce the gear ratios in your transmission. The USA cars all have “tall” gearing to maximize fuel economy. This is the G50/20 transmission. In Europe, the ’94 to ’96 cars got a different transmission, the G50/21, with closer gear ratios. Closer ratios mean less rpm drop between gears and it allows you to stay in the power band of the engine better than the taller gears of the /21 transmission. This means the car will be quicker.

The RS and RS CS (club sport) also use gears similar to the /21 (their transmissions are /31, /32, or /33).


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