Hello Fellow G35 owners and enthusiasts, I have to Say I have a Love Hate relationship with this car. The car is one of the most rewarding driving experiences I have had with a car how ever Working on these cars is not my favorite and the Transmissions even less. I have a question as well, my car is having a shifting problem and likley need a new Trans but I was curious to know what My options are for the Trans swap can I put a newer model G35x Trans in this car or am I stuck and or can I swap the Trans from a RWD and change out the Bell housing and transfer case?

thank you
Jak

 

Here are a few Pics of the car. it has a RWD front bumper as the donor car for the parts was a RWD.

Ouch




all Better

 

The AWD transmission is essentially two pieces, the base RE5R05A transmission gearbox mated to a transfer case.

The RWD transmission is also two pieces, the same base RE5 gearbox mated to an extension tailshaft.

The gearbox part itself is the same, however it came in two major variants and several smaller revisions. The two main differences are the electrical harness coming out of the left side. Earlier models used 3 pigtail harnesses, two had green plugs, one had a black plug. Newer models used a single large black plug directly on the transmission with no pigtail lead.

The gearbox itself is completely interchangeable, you can source one from a 350Z, M35, FX35, or G35 between the years of 2003-2007ish. They're all JATCO RE5R05A gearboxes with the same gear ratio.

The bellhousing depends on if it was installed on a 2003-2006,7 VQ35DE or a 2007-2008 VQ35HR. Gearbox was the same but the bellhousing was different. Ideally you would source one from a DE engine since that's what you have, one less component to swap.

Internally there are two other major components, the valve body, and the TCM. Earlier models with the 3 harnesses did not have the TCM installed inside the transmission. The TCM on newer models is bolted to the back of the valve body so it all basically comes out as a single piece.

You can keep your existing valve body and TCM, put them into the donor gearbox. Or you can use the donor valve body and TCM as long as that transmission came from a vehicle that had been driven. BRAND NEW TCM needs to be programmed, but if it was ever running in a vehicle it does not.

Your 2005 should have the newer style single large plug on the transmission.

If you go down to Nissan or a mechanics shop they will probably tell you that it's a VERY EXACT transmission that you need. This is not exactly true for these vehicles due to what I've explained earlier. There were a lot of small revisions from year to year as various components were sourced from different manufacturers, the car won't care though. As long as it plugs into your harness it's going to work.

I would suggest keeping your existing AWD transfer case and just buying the gearbox, keeping your existing valve body and TCM. If you happen to find a direct fit with the AWD transfer case then just swap the entire assembly if it has lower mileage. But keep your existing transfer case, valve body, and TCM for a year just in case the donor items do end up having a problem.

 

Alternately you can pull the transmission yourself, it's actually pretty straightforward compared to move vehicles. Then just have the gearbox rebuilt, probably costs $1500 or so and will usually include a new valve body. Keep your existing TCM.

However, what EXACTLY is the transmission doing that makes you think something is wrong? When was the last time you did a drain/fill on the tranny fluid? If it's been 100k or more on the stock fluid I would just do a drain/fill with genuine Nissan Matic-J or Matic-S fluid. Don't use aftermarket fluid. These transmission are sort of notorious for REQUIRING regular fluid drain/fill, it takes 4 quarts roughly (like 3.8) or they will start to misbehave. Regular service interval is 30k miles, there is no filter to replace so you just pop the drain plug on the pan, then add fluid from the dipstick tube. Quick and easy.

 

I had gotten the car running again for a time with a soldering job from the broken Valve body lead however the TCM seems to be going out now can I swap the valve body and TCM from a 2006 G35 RWD into the 2005 AWD Trans? I am getting the p1757 and p1815 codes when it misbehaves. turn it of clear codes and it works again for a month or 2 then acts up again. from what I can find it is a problem with the TCM. It would be nice to just go to the shop and have this fixed however here were we live I have called all of the shops around and no-one is willing to work on it.

 

I'm pretty sure it would work yeah, the AWD system uses another computer just for the transfer case that's tucked up under the glove box. That entire system is completely separated from the transmission controls, iirc it doesn't actually communicate with the TCM at all. The TCM talks to the ECM, the ECM sends some data via CANBUS over to the transfer case computer.

Just verify that you have the internal TCM (single large harness plugging into the transmission, not the 3 separate harness on a pigtail coming out of the transmission) and as long as it is and it came from a previously running vehicle then it should work. If it was a NEW TCM then it would need to be programmed but a used one should just plug and play.

 

Yeah looked up the AWD computer stuff in the FSM and it does NOT communicate directly with the TCM at all.