I thought I might share my recent transmission mount upgrade experience so that others that might be interested might benefit from my own experience.


My car is still pretty new to me, but having owned 3 other 5 speed Porsches, I have always felt like the 6 speed transmission was shifting a little rougher than I would prefer. I asked the shop owner that did the PPI down in Atlanta about it, and was told it seemed normal to him and since he has far more experience than I, I bought it and brought it home. When I had the Kline exhaust installed locally I asked the shop owner about the transmission and he commented that they all seemed to feel similar to him, and I should just be deliberate in the gear selection. We checked the tranny fluid while it was on the lift, and it was full and clean, so I eliminated that as a possible cause of any concern.


I read a number of comments here on 6 speed and elsewhere about the poorly designed transmission mount used on these cars, and how others noticed smoother shifting and better handling from an upgrade of the OEM 996tt transmission mount. So I decided I would make the upgrade but then labored a little over going to any of the performance oriented urethane semi-solid transmission mounts, or just using the 997 transmission mount that was claimed to be a far more robust design. I decided I was looking for primarily the best balance of street use comfort and quiet ride with a lower emphasis on increased handling performance, so I ordered the 997 transmission mount part number 99737503303


http://suncoastparts.com/product/99737503303.html


I followed the super helpful DIY post originally made by quick968.
https://www.6speedonline.com/forums/...ml#post4510695

I also borrowed a couple photos from the post to help with illustration.


I torqued the (2) larger primary tranny mount bolts to 85 pounds as in the DIY post, and the (2) smaller bolts and all the transmission bracket bolts to 48 pounds.


I took my time and was able to install the new tranny mount in about 3.5 hours start to finish with several breaks for a tired old sore back. I was not really sure what to expect, and really did not take pictures along the way, but realized afterwards I probably should have.


I had also read many posts about using urethane window weld to repair or strengthen the tranny mount, so I opted to make my 997 tranny mount just slightly more firm than stock and filled in the voids in rubber with 3m window weld. Clearly the 997 design has much more rubber and is vastly superior to the 996 design, so adding the window weld may not have been responsible for much improvement, but it may have reduced flex and made it slightly more firm than stock.


Given the fairly low mileage on my car when I removed my 996 tranny mount I really expected it would most likely be intact, but I was a little surprised to see it was showing signs of possibly already starting to fail. The photos show a couple of cracks in the rubber, and I think it is pretty reasonable to suspect the mount must have been flexing more than I would have expected. For those that have experienced any similar symptoms of vague and occasional rough shifting, I share this experience as my tranny upgrade transformed my car to a totally different feel.


Now shifts are far more precise and I don't need to be as deliberate as the gears changes require much less effort. And an added and less expected bonus, the car's handling is noticeably improved. This is a little difficult to quantify, but the car feels a little more secure and balanced, and I suspect the reduced flex in the driveline is partially responsible for this.


I am so pleased with the results I highly recommend others may want to consider this upgrade, I think the window weld is probably optional.
I marked up a photo with red to show the areas where I added window weld to just fill in the voids in the rubber. But regardless of that, I believe the big difference is the more robust design of the 997 mount, coupled with the age of my car's old mount.


Trust me, this has been the best $250 investment I have made in the car so far.

I hope others can benefit from this post, and just let me know if there are any questions I might answer.

Cheers, Dave

 

Thanks for the write-up. I'm getting ready to do this as well. What year and mileage on your car?

 

I'm sure you will be happy with the new tranny mount, my car is a 2002 with 25,700 miles.


Cheers

 

was gonna ask about your mileage.. my t-mount didn't get changed until about 75k!! and ALL the rubber bits were like cookie crumble! but once i swapped my engine mounts for semis and a new 997 oem t-mount.. ALL lateral slop was gone. i also refreshed my trans, so she's a tight ship.

i'm sure yours is as well for at 25k?! she's barely broken in! enjoy it!

 

Im waiting till I can access a lip to do mine. I tried to do it with just jack stands and could not get enough leverage to break it loose from the trans.

 

I hear you my man...


I jacked my car using a floor jack with a hockey puck on the sub-frame cross member. I set my jack-stands on the 3rd lowest setting so I could have enough room to move around pretty freely, but it was still fairly cramped under the car.


For this job I used my 1/2" drive Craftsman ratchet set, but with such limited leverage, I was not able to break the larger bolts loose.


I pulled out my 1/2" drive torque wrench for extra leverage, and that broke them loose fairly easily. The wrench was set to click at 85 pounds at the time, and it clicked well before I was able to break them loose. I would guess it took perhaps 110 pounds of torque or so to break the factory Loctite...

 

would be interested in the old trans carrier mount if you could stand to part with it for a few bucks to cover it & ground shipping. want to start a pay it forward deal where I remove the old tattered insert aluminum races if the next guy wants to do more of the SS mount install.

 

Great video, but it doesn't apply to the 996 Turbo. Transmission mount design is completely different.

 

So are the poly inserts just as good or better than this updated carrier w/HD rubber bushings? I'm seeing poly mounts for ~$150...vs $250 for the new carrier. Just curious what is the better value...I'm leaning towards to the poly inserts if the carrier itself isn't different. Thanks and great write up OP!

 

I don't think the poly are worth it as I put a set in a year ago. Lots of noise and vibration introduced into cabin. Reminded me of a 996 GT3! If your car is a track car do it as it does help with shifts and drivetrain movement. I'd do over with 997 updated mount if I could.

 

window weld 20$

 

Really Steve? Just window weld? What are the results of just window weld?

 

74 durometer rating same as the aftermarket stuff for next to nothing. remove the mount clean it amd fill it with w/w encapsulate all the cracks fill everything. smooth it out with your fingers soaked in soapy water. let cure for 48 hrs, install. if you dont like it your out 20$

heres mine after 3 yrs and countless hard launches at the track. not a single crack

 

Do you do this with a new mount or can you "refurbish" a used one?

Also, whats the window weld product called and where can you get it? Or do you have a pic of the tube?

 

Found this on amazon - 3M 08609 Window-Weld Super Fast Urethane Black Cartridge $23.96.

Good question ^^. Can I do this with my 74K mile mounts?