G96 gearbox - modification of GTM gearbox subframe?

[beeman]

LS3/g96
As I have seen in other threads, the mounting location on the GTM gearbox subframe needs to be removed and modified to allow mounting of the g96. The two 1" cross tubes that the mount is on needs to be at least partially removed to clearance the hind end of the gearbox. I saw Tino had to do this in his build thread , but I can't find the final design. What is the best way to keep the subframe structurally sound?
20180328_112411-picsay.jpg

[beeman]

Spent the last few hours fabricating the g96 gearbox subframe. Recycled the FFR mounts.

[Blast3r0]

You can see many angles of mine in my google drive share: https://drive.google.com/drive/folde...W8?usp=sharing

I think what you have is plenty strong and way more metal than mine. You will have to remove the brackets from the down bars on the subframe to even come close to putting shift cables on. Let me know what you come up with for the cables because I'm not a huge fan of my setup at the moment.

[beeman]

Thanks, Blast3r0!
I actually had your pictures downloaded to my phone, I found a post of yours somewhere.
I hadn't thought about shift cables, I have the California MotorSports billet shifter, cables, bracket, etc but I have not fabbed them up. Are you talking about the brackets that the exhaust holder mounts to?

[Blast3r0]

Thanks, Blast3r0!
I actually had your pictures downloaded to my phone, I found a post of yours somewhere.
I hadn't thought about shift cables, I have the California MotorSports billet shifter, cables, bracket, etc but I have not fabbed them up. Are you talking about the brackets that the exhaust holder mounts to?

Untitled.png.png.The bracket circled is what needs removed. I was able to use the factory cable holders on the trans but I think it could be much cleaner if I had custom cables made. The link to my drive is updated dynamically as I put pictures into it and will be there as long as google is hosting for free.

[beeman]

Untitled.png.png.The bracket circled is what needs removed. I was able to use the factory cable holders on the trans but I think it could be much cleaner if I had custom cables made. The link to my drive is updated dynamically as I put pictures into it and will be there as long as google is hosting for free.

Good to know, thanks. The muffler support bracket mounts there, did you figure out what to do with that? Is the 3/4" brace that I added up to the gearbox mounting plate going to cause problems with the shift cables?

Have you dyno'd your car? That setup looks wild.

[Blast3r0]

Good to know, thanks. The muffler support bracket mounts there, did you figure out what to do with that? Is the 3/4" brace that I added up to the gearbox mounting plate going to cause problems with the shift cables?

Have you dyno'd your car? That setup looks wild.

I believe ffr wants you to mount the mufflers there but they really should be mounted to the engine/trans. My turbos are mounted to the subframe but I put flexpipes in my exhaust pre turbo to account for this. Your extra brace will not interfere with the cables.

The car has not been dynoed yet. Im hoping for a little over 600 on 93 w/ methanol ~17lbs of boost.

[beeman]

they really should be mounted to the engine/trans.

That is a great point. I'll see where I can mount them to the transmission.

[beeman]

Here's the billet cable mount that came with my CMS (California Motorsports) billet shifter. Looks like cables should clear the subframe fine.

[rev2xs]

I believe ffr wants you to mount the mufflers there but they really should be mounted to the engine/trans. My turbos are mounted to the subframe but I put flexpipes in my exhaust pre turbo to account for this. Your extra brace will not interfere with the cables.

The car has not been dynoed yet. Im hoping for a little over 600 on 93 w/ methanol ~17lbs of boost.

Just an FYI, thos mounting points are meant for a short G50 trans, not the exhaust system. I remember the build guide instructing to mount the stock exhaust via brakets to the trans itself in all cases.

[beeman]

Just an FYI, thos mounting points are meant for a short G50 trans, not the exhaust system. I remember the build guide instructing to mount the stock exhaust via brakets to the trans itself in all cases.

Interesting, I thought they were designed for the exhaust mounts. I received my chassis with these mounts already installed on the gearbox subframe, I am guessing that they are Kooks specific? They do have rubber bushings where they mount to the subframe to allow for some flex.

[rev2xs]

Yeah its this weird little bracket which has its own bushes. Its original Porsche equiptment for the short trans types

[VRaptor SpeedWorks, LLC]

Yes, the Kooks system was originally designed to mount there when they first developed it (which I had no part in). We never mount the Kooks there....we always attach the muffler stands to the transaxle. And yes, those chassis brackets are there for certain Porsche transaxles that have a large cast alum member that spans across there.....I've never seen one in person.

[beeman]

Thanks again, guys.
Shane, have you ever made an exhaust mount for the g96? There aren't a lot of available free mount points on the transmission... I should be able to figure something out.

[beeman]

There is a usable mount point on the passenger side. There is a solid tab on the driver side that I can drill through for a mount site. The gearbox mount has a reinforcement plate on top as well that could be drilled and used as a mounting point.

[VRaptor SpeedWorks, LLC]

Sorry, the only mounting brackets I've done is for the G50, G96-50 and the Mendeola. I assume yours is a G96-01...is that right?...that's a whole different breed of cat. All of the transaxles I've done...the rear of the trans (about where the point of that green fabric (welding blanket?) has a bolted on rear section, and we use those bolts/studs to mount a separate bracket to mount the muffler stands to. That web on the center section you have circled in your photo....if you can get the muffler stands to line up with that web on both sides, that would probably be the easiest point...and then just cut the muffler stands down and re-weld the bolt to the bottom so it is the right height. That's essentially what we do for the stands on the Mendeola.....cut them down to a shorter length (a bit shorter than you think you need) and then we weld a 1.5" bolt back to bottom of the stand and then we can washer/shim the stand up or down to get to the height we want.

[jamesfr58]

There is a usable mount point on the passenger side. There is a solid tab on the driver side that I can drill through for a mount site. The gearbox mount has a reinforcement plate on top as well that could be drilled and used as a mounting point.

IMG_1517.JPGIMG_1518.JPG

I haven't posted here yet, but took deliver of my GTM in September 19th of last. I had hope to be further along bu had to take 2 months off to assist my parents bu back home now and back at it.

[jamesfr58]

I have not posted anything yet but got my GTM in September of last year. Here are some picture of my modifications to mount the G96 6 speed in my GTM behind a LS3. Not a pretty as some but is fully functional or at least I hope it will work as designed.IMG_1517.JPGIMG_1518.JPG

[beeman]

James
Thanks for the pictures!
Are you mounting a wing to the plates on your subframe?

[jamesfr58]

Beeman

Yes I am mounting the wing to the plates on the welded to the side of the frame. VRaptor supplied the parts to mount the wing to the frame

[beeman]

For you guys running the g96, which axles did you use? I have no axles, I need to buy some. Get the FFR ones? Or is there another reasonably priced option? I did receive the inner/transmission joints with my transmission, I just need the axles with the outer GM joint.

[crash]

As far as I know, the junk yard is your best bet. I know from talking with others that the replacement axles from GM are only available complete and are expensive. If you have to go the factory route, then you may as well run the www.myraceshop.com replacement/upgraded parts as they run a bit more on the initial cost but are stronger and easier to service in the long run.

[beeman]

Wait, are they C5 Corvette axles /outer CV's?? I thought they were proprietary. Does the porsche inner joint attach directly? I have a donor Vette with rear end intact (automatic)...

[crash]

You will need the FFR supplied "adapter" half shafts. If you don't have those, you will need to contact FFR and get those, THEN get some Vette axles for the outer CV. Sound like you have the Vette axles, so you will need to contact FFR for the half shafts...assuming that the G96 is the same width as the G50? If not...I guess we'll be talking! LOL!

[jamesfr58]

You can get the Porsche G96 Companion Flange and CV Joint Kit that will mate up with the FFR have shaft for the inner CV joints and used the ones from the donor you have for the outer CV joints. Make sure when you order the Porsche CV joints you also order the companion flanges. They are not included with a CV joint kit and are required, they have area for the rubber boot to attach to and they cover the one end of the CV joint. The CV joint kit will have the joint itself, the boot and the end flange. Pelican Parts carries Porsche parts that will match up to your G96, but sure there are other place to obtain the parts as well.