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Replacing Transmission Mounts
 
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Pelican Technical Article:

Replacing Transmission Mounts

Time:

2 hrs

Tab:

$300

Talent:

***

Tools:

Torx socket set

Applicable Models:

 
Porsche 986 Boxster (1997-04)
Porsche 986 Boxster S (2000-04)
Porsche 987 Boxster (2005-12)
Porsche 987 Boxster S (2005-12)
Porsche 987 Cayman (2007-12)
Porsche 987 Cayman S (2006-12)

Parts Required:

Pair of transmission mounts

Hot Tip:

Use the 993 mounts and save some money

Performance Gain:

Reduced drivetrain vibration

Complementary Modification:

Replace front engine mount
101 Performance Projects for Your Porsche Boxster

This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your Porsche Boxster. The book contains 312 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 950+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Boxster owner's collection. The book is currently available and in stock now. See The Official Book Website for more details.

Some of the most common parts to deteriorate on older cars are the engine and transmission mounts. After many years, the rubber that is contained within the mounts becomes old and brittle, and doesn't perform a good job of isolating the drivetrain from the rest of the chassis. Old, worn out motor and transmission mounts can cause shifting problems because the drivetrain is no longer firmly held in its position. A visible sign that the transmission mounts need replacing is the appearance of cracks in the rubber of the mounts. The rubber will deteriorate over the years and need to be replaced, even if the car has relatively few miles on it. These mounts are also hydraulic, so if you see fluid leaking out of them, then that is also a sure fire way to know that they have failed.

The transmission mounts are fairly easy to replace. Replace them one at a time (remove and replace on one side and then remove and replace on the other side). Begin by jacking up your car and placing it on jack stands (Pelican Technical Article: Jacking Up and Lifting the Boxster on Jack Stands). Remove the pan that covers the transmission (Pelican Technical Article: Changing Automatic Transmission Fluid). Now, place a jack under the transmission to support the weight (Figure 1). Then, carefully remove the transmission mount nuts from under the car (Figure 2). You may have to use some swivel extensions to access the nuts as the exhaust components will be slightly in your way, and you will have to hold the bolts from turning at the top of the mount.

With the two bolts disconnected from the chassis, you can then remove the two bolts that hold the mount bracket to the transmission (Figure 2). These bolts thread directly into bosses on the transmission. With the bolts removed, you should simply be able to pull the mount off of the car. Installation of the new mount is as simple as bolting it back in place.

Replacement Boxster transmission mounts include the triangle-shaped bracket. At about $250 each, they're pretty expensive. While performing the installation of the Porsche 996 engine into the Boxster (see Pelican Technical Article: Boxster Engine Conversion Project), I discovered that the engine mounts from the 993 are functionally equivalent, and are sold without the triangle bracket for about one-half the cost of the Boxster mounts. You will have to carefully remove your old triangle bracket off of your old mount and install it on the new one if you decide to go this route. The stock 993 transmission mount part number is 993-375-049-05.

At the same time that you're replacing your transmission mounts, I recommend replacing the front motor mount (Pelican Technical Article: Replacing Motor Mounts). This will ensure that your entire drivetrain is stiff and firm at all times.

With the car raised up on jack stands, take your floor jack and support the transmission from underneath.
Figure 1

With the car raised up on jack stands, take your floor jack and support the transmission from underneath. Just push up very slightly on the bottom of the transmission so that you can support the weight of the drivetrain when you disconnect one of the transmission mounts.

With the transmission supported by your floor jack, carefully remove the nuts that attach the mounts to the chassis (green arrow).
Figure 2

With the transmission supported by your floor jack, carefully remove the nuts that attach the mounts to the chassis (green arrow). You will also have to hold the bolt head on the opposite / top side of the mount using a wrench. The yellow arrow shows the bolts that hold the triangle bracket to the transmission.

Here's a side view of the triangle bracket.
Figure 3

Here's a side view of the triangle bracket. The two orange arrows show the two bolts that attach the bracket to the transmission.

Here's a photo of the stock Boxster transmission mount.
Figure 4

Here's a photo of the stock Boxster transmission mount. The Porsche 993 transmission mount is nearly the same, but minus the triangle bracket (inset). If you wish to use the 993 ones instead, then remove the nut that attaches the old mounts to the triangle bracket and move the bracket to the new 993 mount.

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Comments and Suggestions:
cornontherob Comments: Answering the comment made on my previous question. I'm working on a 1998 boxster tiptronic. The entire bracket is removed from the passenger side, however the driver's side only has the chassis side of the mount unbolted. The transmission side of the bracket has not been unbolted due to the inaccessibility of the points. Is there any way to get better access to these bolts to finish removing the driver's side bracket? Or should I attempt to push the transmission to the passenger side enough to get the hydraulic mount over the mounting point enough to lower?
February 10, 2016
  Followup from the Pelican Staff: I usually lower it as I remove it. On 996 models the mount is similar, when the lowering the trans, it has to be pulled down then the main bolt pulled out. If not, you have to unbolt the trans side, then the flatter section of bracket more forward on the body. - Nick at Pelican Parts  
cornontherob Comments: When lowering the engine with the transmission mated to the engine automatic, should the transmission mount be slid over the mounting points? Right now the nuts and bolts are out of the mount, and they are apparently resting on the support. Do they need to be lifted and slid over before they will start to lower?
February 8, 2016
  Followup from the Pelican Staff: What vehicle are you working on? Most models with an M96 engine, require the entire mounting bracket to be unbolted, in order for the assembly to be lowered. - Nick at Pelican Parts  
Paul Comments: Does the suggested 993 mount have the same specification weight rating as the 986 non-S mount? I'm aware that these came with different ratings depending on the engine+tranny weight.
February 2, 2016
  Followup from the Pelican Staff: I don't have info on mount ratings. Give our parts specialists a call at 1-888-280-7799. They can help you find the right part.
- Nick at Pelican Parts
 
Sherif Comments: I would like to thank you Nick on your support as I had an error log from my old transmission and when I cleared it out as per your guides everything went fine thanks and best regards
January 28, 2015
  Followup from the Pelican Staff: Thanks for the follow up. We appreciate it.
- Nick at Pelican Parts
 
Sherif Comments: I would like to express my deepest regards to your support ,i had an error log from my old transmission when I cleared it out every thing went fine as per your guides thanks again and best regards
January 28, 2015
  Followup from the Pelican Staff: Thanks for the follow up. We appreciate it.
- Nick at Pelican Parts
 
Sherif Comments: I have a Carrera 996.1 3.4L and my transmission that I have just installed is working properly, but the gear indicator on the dashboard is flickering between P and 4 what is that signal and how can I fix it
January 10, 2015
  Followup from the Pelican Staff: The range switch may not be connected correctly. Check if the connector is seated properly.

Also check the DME for fault codes. If the system is not working properly, a fault code will be set. This will be your best bet when diagnosing.
- Nick at Pelican Parts
 
Sherif Comments: Comments: I have a carrera s 996.1 3.4L witha tiptronic automatic transmission zf5hp19 Hl I had a transmissin complete failure I got a used one and after installing it the engine started normally, but the lamp indicators for the gear position was on the 4 th shift and blinking and when I added the oil the indicator went off completly.and none of the gear indicators lamps are on no D no N nothing is on at all and the car does not want to start at all as if the battery is not there ,but the dach board is on and the battery is in a good condition but when I turn the key to start the engine nothing is happening as if u r trying to start the car when the stack shift is on D
Any idea what that could be
January 9, 2015
  Followup from the Pelican Staff: The range switch may be misadjusted, I would start there. You can check function using a scan tool. - Nick at Pelican Parts  
qwerty Comments: Hi,

I just replaced the transmission on a 2001 986 5-speed with a 2003 5-speed. The transmission is bolted up to the engine but I cannot mate the transmission mounts to the transmission. I have the correct mount on the correct side. Do you know of any reason this would be?

Thank you.
January 7, 2015
  Followup from the Pelican Staff: Are the transmission part numbers the same? ou may need mounts from the different year transmission. - Nick at Pelican Parts  
Pete Comments: Can we confirm that the 993 mount 993-375-049-05 will work on a Boxster S?
July 9, 2013
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799. They can help you find the right part.
- Nick at Pelican Parts
 
03B0x573r Comments: HI, love this site. Anyway, I am slightly confused. In the article, it is stated that the 993-375-049-05 mount is functionally equivalent. However, when you click the parts link, the only available mount is 986-375-049-02. Further, a quick search of 993-375-049-05 produces results calling it an "engine mount" as opposed to a "transmission mount."

I have a 2003 5-speed 986, is 986-375-049-02 the preferred part at this point if not wanting to swap out the triangle bracket as well?

Thank you.
November 30, 2012
  Followup from the Pelican Staff: Give our parts specialists a call. They will help you find the right mounts and sort out the part number confusion: 1-888-280-7799 - Nick at Pelican Parts  
Sam Comments: Nick,
Here is my follow-up info. My Cayman S is a 2010 with a 6 speed manual trans. The support bracket that bolts to the trans. has the following part number stamped on it: 9A1.161.20 ASO
Thanks.
August 29, 2012
  Followup from the Pelican Staff: Here's what I found.

Transmission bracket M10
Tightening torque 65 Nm (48 ftlb.)

Transmission mount M12 external Torx screw
Tightening torque 120 Nm (89 ftlb.)
- Nick at Pelican Parts
 
986Rick Comments: Wow...found out something else that both "101 Projects" and the Bentley manual do NOT cover:

The transmission mount bracket for the 6-speed manual on the Boxster S at least on my 2000 model is COMPLETELY different than anything in this article and available from Pelican or other Porsche parts dealers. The bracket was not an "A" bracket specific to each side, but, rather a single large "C" shaped bracket that went over the top of the tranny, connected to both sides of the trannie in a similar fashion to the "A" bracket, then attached to the mounts.

The good news? The "986-specific" mounts that come without the bracket worked with this S-model linkage. The bad news, I had to remove far more from the bottom of the car to do the replacement...made for one hell of a weekend.
July 30, 2012
  Followup from the Pelican Staff: Thanks for the feedback and info about the specifics of your vehicle. Glad you got it done. - Nick at Pelican Parts  
Sam Comments: 986Rick,
Wayne may have a exact answer for the Torq size, but I simply used a standard 19mm 6 pt socket and it fit like it was meant too. A very close fit and zero damage to the corners of the special nut. Don't try a 12 point socket. I have no idea what they are good for except rounding off corners.
July 18, 2012
  Followup from the Pelican Staff: If I remember correctly it is an E24. - Nick at Pelican Parts  
986Rick Comments: Wayne-

What is the size of the TORX socket used to mount the replacement mount to the bracket? there is ZERO info out there, and I have my car in the air, with a useless E6-E16 Torx socket set I bought for the project...

Thanks,

Rick
July 17, 2012
  Followup from the Pelican Staff: I'm not 100% sure. I have a larege set of female Torx sockets, and I just grabbed one that fit from there. I will copy this question to the forums and perhaps someone can definitively say? - Wayne at Pelican Parts  
Sam Comments: Anyone know what is the bolt torque spec for the two bolts that attach the triangular bracket to the side of the transmission housing case?
July 7, 2012
  Followup from the Pelican Staff: Not knowing the exact year of your car I had to shoot for a mid-production year vehicle. Here are the specs for the mounts along with bolt size.
Hydraulic mount on support side part M8 25 Nm
Hydraulic Mounts To Carrier Side Part M8 23 Nm
Transmission support to transmission M10 65 Nm
If you send me year and transmission type I can be more sure of the specs.- Nick at Pelican Parts
 
ST Comments: Hello Wayne:

I was wondering if you have any pointers for tiptronic mounts? I managed to get the drivers side replaced, but the passengers side has been a PITA to get out. It appears I may have to remove the ATF cooler It says Modine on it, I guess thats what it is. Any pointers?
January 28, 2012
  Followup from the Pelican Staff: Have you tried lowering the transmission a few centimeters and moving it to the side. It should be able to come out atthat point. - Nick at Pelican Parts  
Rick Comments: Regarding re-use of the old bracket, please elaborate on your statement "carefully remove old triangle bracket from the old mount". Any special procedure involved or just remove the torx bolt being careful not to bend/deform the bracket. I will be re-using the old brackets and replacing the mounts. I assume I will be removing the entire assembly, one at a time, from the transmission, install the new mount to the old bracket, and then install the refurbished assembly. Thanks.
August 31, 2011
  Followup from the Pelican Staff: You're not supposed to put any torque on the new mounts, as they are hydraulic, and then can leak. They have a square section at the top that mates into the triangle bracket, so that when you tighten them to the bracket, they should be secure and not move. If your old mounts are really worn out, it's possible they might disintegrate when you try to remove them. I've never seen this personally on these cars, but other cars that are older can be troublesome like this. So, yes, simply remove the old torqx nut from the old mount / bracket assembly. - Wayne at Pelican Parts  
BoxsterS Comments: Hi,

I was wondering if the procedure is the same for a tiptronic? What would be a good point to put the jack under the transmission for supporting the weight?
November 29, 2010
  Followup from the Pelican Staff: It should be similar, I think the transmission mounts are the same part number, although I haven't replaced them yet on my wife's Tiptronic Boxster. I would follow the procedure in the "jacking up" article, where you put the jack under the rear suspension points. It's much easier to do that. - Wayne at Pelican Parts  

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