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GT Motorsports Automatic to Manual Transmission Conversion
We are in the process of designing our site, so please bear with us. Until then, we will make the introduction of our product and project overviews here.
We have recently started converting 5AT G35’s to 6MT configurations. Here, we’d like to present to you, the G35/350z community, the illustrated project of such a job, why it can be a viable option to many of our valued customers, and how dramatic a difference it can make on the “sport” factor of the car.
So far, four complete conversions have been performed. Two conversions have been done on G35 sedans and two on G35 coupes, including an especially extreme case, Gurgen’s 2003 5AT G35 Sedan (described below). We have therefore perfected and streamlined the process down to a science. Now, the end result is a completely OEM-quality setup that makes the car indistinguishable from a factory 6MT vehicle.
Interior:
The fitment of the transmission requires custom fabrication of the car floor to ensure OEM-like fitment of the shifter/boot assembly. As illustrated below, the floor is cut with a plasma cutter, and a new opening is fabricated, complete with factory middle shifter boot & bracket thread locations. The latter ensures that the car seamlessly receives the new MT center console.
Below is the orignal piece plasma-cut out of the vehicle so we may install our custom fabricated peice shown above.
Below are custom brackets fabricated to fit the clutch slave cylinder:
Drivetrain:
Additionally, the driveshaft also requires changing, due to the different lengths of the automatic and manual transmissions. Fortuitously, for people with built engines and forced induction, the 5AT’s 3.357 final drive ratio is preferred, to enhance traction. However, a new differential can be fitted if requested (MT model’s 3.537 final drive ratio).
This is also an ideal time for a clutch upgrade (no additional labor charges). Here you see the ATS/Carbonetics® Triple-disk carbon clutch installed.
Electronics:
To ensure good fitment and functionality of the setup, the engine control harness (aka EGI harness) is replaced. The lead outs of all factory engine sensors are hence preserved, and the engine management and control is seamless. There are a few wiring additions required, namely the clutch ignition switch. These are wired in a high quality OEM fashion to the EGI harness to preserve that safeguard. The major exception to this is the type I sedan (early 2003 model 5AT) that employ a completely different ECU and wiring harness. A much more involved rewiring is required on these cars, as we learned from Gurgen’s conversion project. The ECU requires replacement as well, to prevent the drive-by wire system from going into limp mode (due to the absence of the 5AT).
Instrument cluster functionality is completely preserved (tachometer, odometer, speedometer, fuel level, and coolant temperature gauges) with the exception of the presence of the gear indicator window being still illuminated orange and the “AT Check” warning light remaining lit. This can also be disabled at the customer’s option.
Here are some additional pictures of the finished product.
This conversion option is for those enthusiasts that are already deeply involved in the modification process. Namely, customers who had originally opted for the 5AT vehicle and have since advanced into forced induction and perhaps built engines. For these customers purchasing new cars and transferring over the upgrades is almost always prohibitive. It is for these customers that the current upgrade path is especially viable.
Availability:
Now
Turnaround Time:
4-6 weeks
Prices (GTM® M/T Conversion):
Labor: $3700
Parts: $5000
Optional upgrades (no additional labor at the time of conversion):
GTM® Spec Exedy® Twin-Disk clutch assembly: $2485 (Currently on Sale!)
Thank you.
Coming soon:
GT Motorsports® 4.5L VQ35HR N/A Stroker Kit
GT Motorsports® Fully Built Automatic Transmission Upgrade
The above mention vehicle is a 2003 G35 Sedan, the owner of the car is GurgenPB below is a dynograph showing what he car made when it come to us on the 5A/T, then we have once we a recent tune to compare.
Specs on car:
2003 Infiniti G35 Sedan
Power Enterprise Twin Turbo Kit
GTM Stage 1 Shortblock
GTM Stage 1 Heads
GTM Turbo Spec Cams
HKS FCon VPro Standalone Engine Management System
Dual bank Innovate LC-1 Widebands with feedback to VPro
Custom 3" T.D. catback
Automatic Transmission 3rd Gear pull:
Manual Transmission, 5th Gear Pull:
Overlay of both Dynographs:
The cars are not plotted identically because of the difference in tranmissions. The before graph was on 91 Octane at 12 psi with the Emanage Ultimate, then after is on appox 93 octane with 13 psi and the FCon VPro.
BOT - great way to give the AT guys an option to cut over "seemlessly." Great job Sam.
Our shop car has been running on the AEM EMS for the last 7 months we have these units on the shelf and ready to go. We will be installing and tuning a car that is being shipped to us as we speak with the AEM EMS. Expect to see a press release in the next couple of weeks. (hopefully)
GT Motorsports® Fully Built Automatic Transmission Upgrade
Ooh..Moar info.
__________________
Turbo Cars are like hot women. A little edgy, every guy wants one, some guys can't handle them and if you throw a little alcohol in the mix they'll rock your world!!
.Sam..the #'s for the 5at dyno was done in 3rd gear...I've always dynoed my auto in 4th because thats the 1-1 ratio for the autos.The 5AT #'s would of been higher if dynoed in 4th,is that correct...Looking at his mods(built short block etc.)when he was 5AT if he would of dynoed in 4th he should of went over 400whp, in my opinion.
Correct me if I'm wrong, just for my future dyno's
Thanks
Last edited by coachk; 06-12-2007 at 08:29 AM.
Reason: correction
Very nice work guys. I'm very encouraged that finally there are more options for us 5AT guys. We'll see how my SGP built trans works out. Will you do a separate thread for the built auto details or can you provide some now?
__________________
Turbo Cars are like hot women. A little edgy, every guy wants one, some guys can't handle them and if you throw a little alcohol in the mix they'll rock your world!!
Our shop car has been running on the AEM EMS for the last 7 months we have these units on the shelf and ready to go. We will be installing and tuning a car that is being shipped to us as we speak with the AEM EMS. Expect to see a press release in the next couple of weeks. (hopefully)
sam
GT Motorsports
Any comments on the HKS vs AEM?
__________________ Yes i'm a DoucheBag: But Admit it.. my posts excited you
Nice job but i agree with coach k those numbers should be still a bit higher on that 5at. If you do the math the 5at is losing a little over 28 percent of power to the ground compared to the manual that is alot don't you think. Well that is a clean swap for sure and good job. I also hope people look into beefing the auto trans up. I know that manuals can put more power to the ground but the auto has benefits once going forced induction like keeping the turbo spooled up between gears. I know in the supra community the fastest supra's in a straight line are auto's usually.
We have been planning to post this information for a while, and this was a perfect time since I just got the exhaust on and it was a good opportunity to release what is possible with a full out 6MT with optimal exhaust, engine management, etc...
A few thoughts:
I am not sure if the original 5AT dyno plot was done on 4th or 3rd gear. In fact, i am inclined to think that it was in 4th. I can assure you that the difference was minimal...since this was over a year ago, i cannot remember for sure what the number was, but when we were dynoing the car, we did both 3rd and 4th gear runs, and the difference was no more than 12-15hp in my case. Also, the temperature difference is significant (see below), and i would guess that the car head 20 or so hp more with cooler temps (when it was on the eManage Ultimate!).
Another thing, is that this is hardly an apples-to-apples comparison.
5AT configuration when dynoed:
Stillen 2.5" exhaust (with a single 3" bottleneck x-pipe)
LaBree 2.5" test pipes
Scott Performance FI cams
eManage Ultimate EMS
12psi
91octane 102 degF weather
Also, this is on a really nicely built engine by Sam. Still 9:1 compression.
As a side note, the car feels incredible. It becomes a truly potent track car. That was the number one (perhaps number two) motivator for me to push forward with this mod, i got into tracking more and more and realized that 5AT is nowhere near adequate. As you can see the torque curve is much more linear, with the car pulling much nicer toward redline.
I also wanted to have a very conservative setup to 1) not do the engine ever again and 2) have the engine last a VERY long time, regardless of how overbuilt it is.
That's the beauty of GTM, Sam will truly make a car that you want without any guesswork as to whether it is overbuilt enough or will last a long time, it will! He is a genius when it comes to this. As many of you know, I do my research and homework diligently, and watching Sam tune the car, even I feel that I would be way over my head... and I thought that I knew my stuff. Experience is everything, my friends. If you want your car built RIGHT, this is the only place to go.
i drove Gurgen's car last weekend with the manual conversion: WOW. i've driven it before in automagix mode and now with the 6speed. its really a great conversion. felt like it came with a manual tranny.. good job Sam & Crew on the swap.
__________________ Cheston s Sponsors: TechnoSquare|Cosworth|StopTech|Toyo Tires|OS Giken USA|KW Suspension|Koyo Radiators|Motul|GT Spec|K&N|HAWK Performance|Performance Nissan|Rays Engineering|Finishline Autocraft. Thanks: Z1auto|VIP Status. Join the Salad Bar Club. Castrol Syntec Top Car Challenge '09: 2nd Place (Team Super Street). Sport Compact Car Magazine Ultimate Street Car Challenge 2008: 2nd Place.
GT Motorsports: 5A/T to 6M/T Conversion *PICS!*
s Sponsors: TechnoSquare|Cosworth|StopTech|Toyo Tires|OS Giken USA|KW Suspension|Koyo Radiators|Motul|GT Spec|K&N|HAWK Performance|Performance Nissan|Rays Engineering|Finishline Autocraft. Thanks: Z1auto|VIP Status. Join the Salad Bar Club. Castrol Syntec Top Car Challenge '09: 2nd Place (Team Super Street). Sport Compact Car Magazine Ultimate Street Car Challenge 2008: 2nd Place.
