(r34) Gtr Vs Gt-t Rear End / Chassis

[Marek0086]

Hi 'fellers, can anyone in the know tell me whether or note the GT-T and GTR share the exact same diff center, diff housing and rear cross member??

[GTSBoy]

I can tell you that they do not.

Diff in the GT-T is either a VLSD or (rarely) an HLSD, both with the smaller splined 5 bolt stub axles.

The GTRs use bigger splined 6 bolt stubs.

Therefore the driveshafts are different too. 6 bolt bigger & stronger.

GTRs use alloy uprights at the other end of the driveshaft.

The R34 GTR uses either a helical (like the rarer GT-Ts) or an active diff....with a much taller ratio.

GTR diffs also use a CV joint at the input end. Other Skylines use a 4 bolt diff flange.

I actualy can't tell you if the housings are completely swappable - although they will bolt to each other's subframes and the subframes will go in each car.

Edited April 25, 2016 by GTSBoy

[dr phil]

Subframes will go in either car, but beware the subframe mounting bushes, they are different from 2wd / 4wd. 4wd has a taller centre pin in the bushes, which positions the crossmember lower in the car.

[dr phil]

GTT also has alloy uprights at the wheel end like GTR. I believe the hub is different though to suit a larger driveshaft.

[Sick_R31]

Hi 'fellers, can anyone in the know tell me whether or note the GT-T and GTR share the exact same diff center, diff housing and rear cross member??

According to FAST yes to the diff housing (gtr non v spec), no to the diff centre and rear cross member.

[Marek0086]

According to FAST yes to the diff housing (gtr non v spec), no to the diff centre and rear cross member.

So you're saying the rear cross members are NOT interchangeable??. What about power/torque capacity between GTR and GTT rear end??. What would be a relatively safe power/torque limit for both rear ends??

[GTSBoy]

So you're saying the rear cross members are NOT interchangeable??. What about power/torque capacity between GTR and GTT rear end??. What would be a relatively safe power/torque limit for both rear ends??

Just because FAST lists them as different parts doesn't mean that they are not interchangeable. What has already been posted about the crossmembers in previous posts is correct.

There is no such thing as "a relatively safe power/torque limit" for these things. What will break something in one car will be fine in another depending on tyres and usage and driver style and so on.

Suffice to say that the pumpkin, CW&P and any internal gears (sidegears and spiders in conventional diffs, or helical gears in HLSDs) will be essentially the same strength between GTR and GT-T diffs. The helical in the R34 GTR specifically is the same hardware as that in the GT-T anyway. But the viscous coupling in a normal GT-T diff is a weak point that is a waste of space. What I have said in my first post regarding which bits are stronger is still true.

[Marek0086]

Please don't call Aluminium, "Alloy". The word "alloy" has NOTHING to do with Aluminium.

[Duncan]

Hi 'fellers, can anyone in the know tell me whether or note the GT-T and GTR share the exact same diff center, diff housing and rear cross member??

So you're saying the rear cross members are NOT interchangeable??. What about power/torque capacity between GTR and GTT rear end??. What would be a relatively safe power/torque limit for both rear ends??

I think maybe your first question was not exactly your real question.....what are you trying to do? what chassis are you trying to do it to? have you broken something already or are you trying to make sure you don't break something? Are you trying to make something handle better?

[Ben C34]

Please don't call Aluminium, "Alloy". The word "alloy" has NOTHING to do with Aluminium.

I would bet cash money that the uprights GTSBoy referred to are not made out of pure aluminium. It would be an alloy. An aluminium alloy.

[Marek0086]

I would bet cash money that the uprights GTSBoy referred to are not made out of pure aluminium. It would be an alloy. An aluminium alloy.

What the hell are you talking about??... i wasn't implying that GTboy was implying that they're made out of pure Alum. ALL the metal that makes up a car is "alloyed" metal. Be it Steel, Aluminium, Titanium or Magnesium. To refer to Aluminium-alloy, as simply "alloy".... is like referring to Steel as simply "metal". Its just stupid. Language has rules... lets follow them.

[Marek0086]

I think maybe your first question was not exactly your real question.....what are you trying to do? what chassis are you trying to do it to? have you broken something already or are you trying to make sure you don't break something? Are you trying to make something handle better?

Ok, so here's my [dirty] fantasy. I want to get an R34 GT-T (2 door) and put an LS2 in it, with a 4L65E behind it.

Do you guys know of anyone who has done an LSx conversion in an R34??

[GTSBoy]

What the hell are you talking about??... i wasn't implying that GTboy was implying that they're made out of pure Alum. ALL the metal that makes up a car is "alloyed" metal. Be it Steel, Aluminium, Titanium or Magnesium. To refer to Aluminium-alloy, as simply "alloy".... is like referring to Steel as simply "metal". Its just stupid. Language has rules... lets follow them.

Steels are alloys. Despite the fact that there are hundreds of different alloys that are steels, we use just the one term to refer to all of them. We don't go about calling it iron carbon alloy, because that would be annoying. We don't go about referring to each individual steel by the exact type/number/brandname unless we need to be very clear exactly what we mean. Because otherwise it would be annoying. Inconel is an alloy, also having a convenient name, despite there being a number of different 600 series alloys knows as inconel. It's 60% nickel, making it a nickel alloy (and not a stainless steel as most people think it is). We don't call it nickel chromium iron alloy, because that would be annoying. Brass is an alloy. But there are many many different ways to make brass, not even using the same ingredients. We just call it brass, because getting into more detail is annoying.

Aluminium alloys are commonly referred to as just "alloy". And perhaps surprisingly, people know what we mean when we're using that simple shorthand, because of the context. If someone was talking about a turbine in a jet engine and said it was made of alloy, almost no-one who knows anything at all about turbines would assume that the thing was actually an aluminium alloy, or that the person talking about it meant it was an aluminium alloy. Context is EVERYTHING. So when we're talking about car parts, like diff housings or suspension components, the context fairly reliably tells you that the placeholder term "alloy" is referring to aluminium alloys.

You're correct. Language has rules. It is also very flexible and surprisingly robust. It is possible to be both excruciatingly precise, and also it is possible to be slightly more vague in the exact words used yet convey all the information required.

[GTSBoy]

As to the question of whether GT-T rear end components are strong enough for an LS2. Of course they are. Plenty of RB25 engines putting out more power and torque than an LS2. Will it last forever? Nup. They're strong, but everything in the driveline becomes consumable once you start down that path.

You're going to want to use a GTR diff though, or at least the gears. 4.11s will be very short behind an LS2, especially in such a light car. You're going to want the ~3.5 gearing from the GTR. Once you have the GTR diff, then you're committed to the bigger, stronger axles anyway. There are no other differences that matter.

Importantly, if you do use a GTR diff, you ARE NOT GOING TO WANT the active diff. And it seems a shame to destroy a helical diff by putting in a 2-way. So you'd be well advised to get a helical and see if it can hold the power without turning inside out. They're pretty good, but I've seen high power Supras turn their helicals into small pieces, and the Supra ones are (supposed to be) tougher than the Nissan ones.

[Marek0086]

Would i have to do any cutting/beating of the chassis to get the 4L65E in??

[Duncan]

Right now we are talking.

I take it that is a holden auto? NFI about fit there, there tunnel is not huge. The motor fits but apparently having headers, a starter motor AND a steering rack is a big ask.

All of the r chassis rear ends are pretty good strength-wise compared to any average car, and there is a lot that is interchangeable. Personally I'd go with the gtt rear end and see if something breaks.

If it does take a 32 or 33/34 non vspec rear end from hub to hub and throw that in. Only issue might be difference in ABS sensors. And you may want a different ratio as GTSBoy said