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Manual Transmission Output Shaft Seal Replacement
 
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Pelican Technical Article:

Manual Transmission Output Shaft Seal Replacement

Nick Czerula

Time:

7 hours7 hrs

Tab:

$50

Talent:

*****

Tools:

18mm socket and wrench, flathead screwdriver, E12, 30mm socket, seal puller, 3-jaw puller

Applicable Models:

BMW Z3 (1996-02)

Parts Required:

Manual transmission fluid, output shaft seal.

Hot Tip:

Warm transmission for 3 miles before beginning

Performance Gain:

Remedy a fluid leak

Complementary Modification:

Replace manual transmission fluid

In the BMW Z3 longitudinal drivetrain configuration, the transmission output shaft is at the rear of the transmission and connects, via a flange and the rubber flex-disc (guibo) to the driveshaft. For the flex-disc removal procedure, see our tech article on driveshaft flex-disc replacement.

The transmission output shaft seal can leak over time as the sealing lip wears. You may notice a leak toward the rear of your transmission. Be sure to check the shift selector shaft seal as well. See our tech article on manual transmission selector shaft seal replacing. When looking for the source of an oil leak, always look for fresh clean oil. This will direct you to the problem area. If you see dirt gathered around the output shaft seal and a clean oily area, this indicates a leak at the seal. I suggest that you replace the transmission fluid when you replace this seal.

In this article, I'll go over the steps involved with replacing the driveshaft output shaft seal on BMW Z3 models with a manual transmission.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches. 

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability. 

Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Jack up your vehicle and support using jack stands. See our tech article on jacking up your vehicle.

Remove driveshaft and Giubo. Once the driveshaft is removed, clean the transmission thoroughly.

In the beginning of the article I mentioned removing your driveshaft.
Figure 1

In the beginning of the article I mentioned removing your driveshaft. I donÂ't always do it this way. Depending on the vehicle condition, especially the exhaust studs near the manifold, I will drop the exhaust down, then drop down the driveshaft. You can see I have the driveshaft hanging and the exhaust supported (see next photo for jack placement on exhaust). This allows access to the output shaft (green arrow).

This photo shows the jack (green arrow) supporting the exhaust.
Figure 2

This photo shows the jack (green arrow) supporting the exhaust. Allowing access to the shift rod.

Once you have access to the transmission output flange, remove the 30mm flange nut.
Figure 3

Once you have access to the transmission output flange, remove the 30mm flange nut. You will have to counter-hold the flange while loosening.

I like to use a 3-jaw puller to remove the flange from the transmission.
Figure 4

I like to use a 3-jaw puller to remove the flange from the transmission. Install puller and tighten until flange is free. A lot of times I find I can tighten the puller by hand, no ratchet required.

Then slide flange off transmission output shaft.
Figure 5

Then slide flange off transmission output shaft.

Now it is time to remove the seal.
Figure 6

Now it is time to remove the seal. I use a seal puller and slowly lever the seal out. You have to stick the puller into seal, then lever it out. Now be careful not to damage the transmission housing and work gently and slowly.

To install new seal, slide it over the output shaft and press it in by hand.
Figure 7

To install new seal, slide it over the output shaft and press it in by hand. Then slowly install the seal until it is flush with transmission housing. You can tap it in using a rubber mallet or a hammer and an extension (as shown in photo). Be careful not to bend the seal or seal lip. Install flange onto output shaft. Then install the flange nut, use Loctite 243 on threads of the nut. Install drive shaft to transmission, see our tech article on driveshaft installing for more info.

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Comments and Suggestions:
Ron Comments: What to do if the flange nut is stuck?
September 7, 2016
  Followup from the Pelican Staff: Use a breaker bar to loosen it. 3/4" drive if needed. - Nick at Pelican Parts  
Ruprect Comments: The Haynes manual specifies that the output shaft nut actually has some fairly specific torque specs.

Step 1 : 170 Nm 123 ft lbs.
Step 2 : Loosen
Step 3 : 120 Nm 87 ft lbs.

My concern is that the Haynes manuals are fairly old i'm not sure they revise them so are these still valid torquing instructions... i.e. did BMW improve the nut so that this is not necessary?
July 2, 2016
  Followup from the Pelican Staff: No, torquing is still necessary. The Bentley Manual will have the most current specs. I would grab a Bentley repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 

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Page last updated: Fri 12/9/2016 02:06:45 AM