Transmissions

**EmeraldRegice** · 03-09-2016, 07:27 AM

So the VR4 from what all I understand, generally has a 6 or 5 speed GETRAG transmission in it. Say in the future I wanted to swap out the transmission and put in a completely new one, what is the literally BEST transmission that would fit on the 3000gt? I usually see a lot of talk about bad 2,3, or 4th gear synchros, is that just a common thing for this car, or just this transmission, or in all cars? What causes these synchros to go bad, and is there a way to prevent it? Why are exchanging transmission so darn expensive anyway? Last but not least, ANY help and ANY information, links are great, would help out greatly to to truely understand as much as I can about the standard transmission of the 3000gt vr4, thanks!

**futurevr4man** · 03-09-2016, 08:38 AM

There are no other transmissions to mount into the car... they are all Getrag built, and all 3000gt/Stealth transmissions.

(referencing the AWD transmissions) there is a 6 speed, a 5 speed, and an automatic. The automatic is probably the 'strongest' but that's because of the nature of an automatic.

The 5 speed transmission is stronger, but the 5 speed transfer case housing is weaker (they crack).

The 6 speed transmission is 'weaker' comparatively, and the 6 speed transfer case likes to strip the gears inside after a while

So the setup, to answer your real question, that you want would be a 5 speed with a bell housing brace, and billet shift forks (at minimum). You can get LSD's too or a new center dif if your heart desires. And then get the billet housings for your transfer case and there ya go.

I'm not sure if you understand how transmissions work, but you're asking obvious questions when it comes to synchro wear. You gotta do a little research on how they work. And stuff is expensive because this is an exclusive platform. We don't have a lot of parts that interchange with other vehicles and a limited aftermarket.

**MDoe8** · 03-09-2016, 10:21 AM

Like button for above post, he nailed it....but he is still from ohio.

**EmeraldRegice** · 03-09-2016, 01:32 PM

Great information, I will have to continue my research into synchro wear, If there is any decent links that you feel I may not have come across just let me know, I would like to know what you mean by 'stronger' and 'weaker' as my take on it is that the 5 speed can provide you more HP and torque to the ground, along with longer gear throws. Can we just keep the GETRAG with only replacing the gears with ones that have longer throws? It is my understanding that the GETRAG transmission comes in a variety of vehicles, what makes "ours" the 3000gt/stealth so special from the other ones?

**Chris@Rvengeperformance** · 03-09-2016, 01:55 PM

Getrag is a brand/company name. There are tons of cars that run Getrag built transmissions even today. That said, our unique AWD transverse layout engine makes it so that no known transmissions will swap over from other platforms or cars. Unless you decide to change the drivetrain layout completely there's nothing you can do.

There are no billet forks for 5 speeds and the bellhousings rarely break. Here's kinda how it is:

5 Speeds
1)Stronger bellhousing and end case (probably at least partially due to the fact it has two long bolts on the bottom and one bolt on the top that go through all three cases and pull it together that the six speeds don't.
2)91-92 cars have a 18 spline rear output shaft that is the input for the transfer case. They break easily if you launch the car at higher rpm or dump the clutch too quickly.
3)93 cars have a 25 spline output shaft that is the same as the 6 speeds. It doesn't break as often, but can on a hard launch with good traction.
4)The transfer cases on all 5 speed cars are all aluminum and the cases themselves will split apart sometimes under aggressive launches or a lot of power. There are billet aluminum case alternatives, as well as some steel ones that are no longer in production as far as I know. A well designed transfer case brace makes this failure rare until you are in the 600+ wheel horsepower range.
5)Gears are long and far apart on the 5 speed. Some people like them for drag racing because the top of third gear goes high enough for a lot of people to not need to shift to 4th, especially if you raise the rev limit. They are harder on clutches though as 1st gear is not geared very low and makes the car harder to get launched.

6 Speeds
1)Bellhousing is pretty weak. If you race the car from a stop you need a bellhousing brace. They are cheap and cheap to install. A 13G class car or perhaps even a 9b car can split the entire trans open and ruin pretty much everything inside it.
2)1-2 shift fork seems to be weaker than the 5 speed. Supercar engineering makes a 7075 aluminum shift fork to replace this and the 3/4 one if you desire.
3)Same 25 spline output shaft as the later 5 speeds, but due to gearing differences in the transfer case ratio they don't tend to break them.
4)Sometimes under a long period of hard use the end case can split on a hard launch. It seems like this tends to affect those that like to launch at 6000+ RPM.
5)The t-case gears themselves can strip from hard launches. Some people have a lifetime of hard racing on theirs and some blow them up every few trips to the track. Redline shockproof heavy fluid may help cushion the gears and another key is to not be overly aggressive letting the clutch out. If you can afford it the RPS carbon carbon clutch seems to take it easier on the transmissions and t-cases in general.
6)The six speed gears are closer together and overall shorter. In my opinion they are more fun to drive. There is potential for better MPG at highway+ speeds as well. Some people find when you make 500AWHP or more 1st gear goes by so fast it is hard to time the shift and can have a lot of wheel spin.
7)The 6 speed has bigger diameter synchronizers on 3rd and 4th than the 5 speed.
8)The six speed is physically longer and heavier than the 5. It can be more challenging to get it installed as it wants to hit the passenger frame rail on a lip on the top of the end case. I trim off that lip and it helps a lot.

If you take care of either they both can give you a lot of good shifting life. Redline MTL or mitsubishi 75w85w trans fluid is the best combination of long life and shiftablility. Syncrhomesh can shift a little faster.

The amount of drivetrain loss between the 5 and 6 speeds should be very similar. Based on my virtual dyno results the power to the ground is the same.

Neither trans is bad or weak, except the 18 spline output shaft and the bellhousing on the 6 speeds in stock form is pretty weak. Both in good condition shift well, but usually a 20-25 year sportscar transmission is going to need a rebuild by the time you get it. Rebuilds can be expensive, but it isn't something you should have to do often.