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Powerflex Polyurethane Gearbox Mount Insert Fitting

August 20, 2017 - General
Powerflex Polyurethane Gearbox Mount Insert Fitting

Polyurethane Gearbox Mount Insert PFR57-530 for single front bush. What a great and relatively simple upgrade this is. Single mount is fitted to 996 3.4 and 3.6 manual models, RWD and 4WD, excluding Turbo, Tiptronic and GT2/GT3 models. Also fits 997 3.6 and 3.8 manual.

An earlier post gave details of this polyurethane insert from Powerflex (read it >>>> here <<<< and what follows is a guide to fitting one. I will relay feedback about the insert in a later post.

You will need a few basic tools to fit this insert and whilst it could be done on the floor, it is much easier with a ramp (mind you what job isn’t?). A reasonable mechanical knowledge will also help.

Disclaimer: Any work you undertake on your own vehicle is entirely at your own risk. Always follow correct safety precautions. If attempting this job on the ground ALWAYS ensure that the vehicle is correctly supported safely on axle stands on level ground. DO NOT work under a vehicle which is only supported only on a jack. Fitting of these inserts assumes the existing gearbox mount is in good condition and is not falling apart. E&OE

What will be needed:
T25 + T30 Torx and 10mm socket and ratchet (or screwdriver handle) to remove the under tray fittings. ¼” is fine for this.
7mm Deep Socket and extension ¼ Drive is fine.
15mm Short Socket ½” Drive
Extensions – Various
½” Ratchet
Long Bar
15mm Spanner
Torque Wrench
Axle Stands and Trolley Jack if doing on floor
Transmission Jack/Stand if using a ramp
Silicone Spray
Blue Threadlock
Possibly a vice

Time Required: This job can be done in about 1.5 – 2 hours (Slightly longer if you want to allow cleaning time!!)

When referring to Left and Right, it is given that this is when viewed from the rear of the vehicle. This car is Right Hand Drive, so right refers to the driver’s seat position.

Raise the vehicle. I always use a set of polyurethane jack pads, which makes it easier to locate the ramp pads underneath the car:

Jack Pads

Jack Pads

Remove the plastic undertrays to access the gearbox engine mount. Torx bits and 10mm socket required:

Undertrays

Undertrays

This exposes, as they are known in the parts catalogue, the two transmission carriers which need to be removed to gain access to the gearbox mount:

Transmission and Carriers

Transmission and Carriers

Here is a schematic diagram from the parts catalogue identifying the parts needing to be removed. Used here for reference for familiarisation with the parts:

Transmission Carriers

Transmission Carriers

Item 1 – Transmission Carrier Upper. Removed by undoing nut 6A (15mm Hex) secured to stud 5. One each side.
Item 2 – Transmission Carrier Lower. Removed by undoing nut 6A (15mm Hex) x 4
Item 4 – Bolt M10 x 110 (15mm Hex) and Nut 6 (15mm Hex) x 2 (note position)

Before doing anything else support the gearbox. As a precaution I used two transmission stands. The front one is placed just under the transmission mount, just use it to take the load off the factory rubber mount slightly. This takes the weight of the gearbox as the carrier bolts are undone and it will make removal of the long M10 x 110 bolts easier later on. The second one I used just as a precaution whilst everything was being undone:

Support the Transmission Assembly

Support the Transmission Assembly

Now proceed to undo the nuts to allow the transmission carriers to be removed. The lower carrier will be removed completely, the upper carrier will remain above the gearbox but swung out of the way.

Use some Wurth Rost Off Ice or similar on the nuts that are being undone. Allow to penetrate and give several liberal applications.

Undo the two nuts (Green Arrows Item 6A – one left one right not visible in picture below) that secure the upper carrier to the body. You may find they bring the studs out of the chassis too, this is not a problem just take care. If the nuts come off the studs, you may also need to remove the studs to allow the carrier to be swung out of the way. These studs have a 7mm hex to allow them to be unscrewed if necessary (it also allows them to be refitted easily). Be careful; the studs (99906110609) are no longer serviced by Porsche according to parts catalogue! (I found this out after I had removed them and refitted them doing this job!!!)

Next loosen the 4 x 15mm nuts from the lower carrier (Red Arrows Item 6A), but do not remove completely, just so they hold the carrier in place – this will stop it falling on the floor or your head!

Finally undo bolts securing the two carriers to the gearbox – bolt 4/nut 6 x 2 (Blue Arrows). Once the nuts are removed the bolts should push/pull out without any resistance. Support the upper carrier as it will drop down, and allow it to rest on the gearbox case. Support the lower gearbox carrier and remove the 4 securing nuts (red arrows) and remove the lower carrier from the car.

Removal Points Arrowed

Removal Points Arrowed

Lower Transmission Carrier Nuts

Lower Transmission Carrier Nuts

Upper Carrier Securing Nut and Stud (Left)

Upper Carrier Securing Nut and Stud (Left)

Upper Carrier Securing Nut and Stud Removed (Right)

Upper Carrier Securing Nut and Stud Removed (Right)

Gearbox Mount Bolts

Gearbox Mount Bolts

Below is a closer shot of the gearbox mount nuts/bolts. Both 15mm hex head. You may find if you have applied to much load to the transmission support stand that you have to drop is very slightly to aid removal of the bolts. Note the orientation of the bolts. DO NOT lower the stand too much and never remove the load from it completely. Take extra care if the car is 4WD that you do not load up the propshaft/cardan shaft (maximum 20 degree deflection angle). If your car is 4WD it is an ideal time to check and inspect the flex disc on the cardon shaft:

Gearbox Mount Nuts (Right Side)

Gearbox Mount Nuts (Right Side)

Gearbox Mount Bolts (Left Side)

Gearbox Mount Bolts (Left Side)

Lower gearbox carrier nuts removed, now the carrier can be dropped out of the way.

Lower Carrier Nuts Removed

Lower Carrier Nuts Removed

And the factory mount pads can be removed, which will no longer be required. Note the upper carrier just resting on the gearbox snout:

Factory Pad In Situ - Remove This. One Each Side.

Factory Pad In Situ – Remove This. One Each Side.

Factory Pads Removed

Factory Pads Removed

And this is what you have with the both carriers and the pads removed:

OE Gearbox Mount Both Carriers Removed

OE Gearbox Mount Both Carriers Removed

OE Gearbox Mount Both Carriers Removed

OE Gearbox Mount Both Carriers Removed

Now we are almost at the point where the polyurethane insert can be fitted, but just some housekeeping first…..

Did the upper carrier studs come out with the nuts, like below?

Studs and Nuts Seized Together

Studs and Nuts Seized Together

These received another thorough soaking (or three) in Rost Off Ice and the 7mm hex end was held in a vice securely (take care not to damage the head) and the nuts then loosened and removed from the studs. The stud threads (both ends) were then cleaned up using the wire wheel ready for refitting (note the threadlock for later). This was to remove old threadlock on the captive end and any rust on the exposed end:

Studs and Nuts Serarated

Studs and Nuts Separated

Other securing nuts and bolts. If there is any rust on the threads clean them up using a wire wheel :

Securing Nuts and Bolts

Securing Nuts and Bolts

After that small amount of housekeeping the polyurethane inserts can now be fitted into the gearbox mount itself. Spray the inserts on the surfaces that sleeve into the factory rubber mount and also spray the OE mount voids as well. This will make it easier to push the inserts into the OE mount. You will need to swing the upper carrier backwards out of the way slightly to aid fitting. Once fitted it looks like this. Note how the upper carrier is angled out of the way slightly:

Poly Inserts Fitted

Poly Inserts Fitted

Poly Inserts Fitted

Poly Inserts Fitted

Poly Inserts Fitted

Poly Inserts Fitted

The above three pictures also show a little more clearly how the gearbox has been supported under the factory mount location.

Now the studs can be refitted through the upper carrier and screwed into the underside of the chassis. Use some blue threadlock on the threads into the chassis and screw in by hand to ensure they do not get cross threaded, then tighten fully home, but take care not to over tighten. Now loosely screw on the securing nuts to hold the upper carrier in place. Line it up with the holes through the gearbox mount.

Next refit the lower carrier and tighten the retaining nuts by hand, again lining it up with the gearbox mount.

Then refit the two M10 x 110mm bolts through the carriers and the gearbox mount, paying attention to the orientation. The bolt head is on the left hand side viewed from the rear.

Tighten all nuts and bolts to correct torque, which is 48 lb ft. Transmission Carriers to underbody and gearbox mount. Check several times. It is worth noting that there will be witness marks in the carriers where the nuts and bolts were previously fitted. These can be used as a guide for refitting.

On another not my lower carrier had a little surface corrosion on it. Whilst it would have been great to wire brush it down and repaint it with Plasti Kote metal paint time did not allow for this, so a generous covering of Dinitrol 1000 will have to suffice for now. That should keep any further corrosion at bay.

With the inserts fitted and the carriers back in place:

Just the undertrays to go back on:

Undertrays Refitted

Undertrays Refitted

After a quick clean of course!!

Undertrays Before

Undertrays Before

Undertrays During

Undertrays During

Undertrays During

Undertrays During

And After:

Undertrays After

Undertrays After

You get the idea. I didn’t have enough time to give the undertrays a thorough clean but a wipe down to remove as much of the old dirt as possible and a wipe over with some trim dressing will suffice for now.

And it now goes without saying, lower the car safely from whichever supporting method was being used and enjoy.

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