ap0c0lypt1c

GTM has a high strength Aluminum shaft that supposedly handles 800hp (It's $600 though )

The reason I'm concerned about the stock driveshaft is that it doesn't bolt directly into the flange, but you'll see it bolts into a cylindrical rubber dampener that then bolts into the flange. My rubber dampener already has surface cracking, and I'm afraid that is the weak link.

SharpByCoop

Got it. Thanks for pointing out that damper. I haven't been under there enough to remember.

I talked to Sam directly about the alum driveshaft, and he was suggesting that at 600whp it might not be such a good idea. 800 whp? I need to look if they have updated the HP figure with a stronger build. for me the $600 price tag is nominal. This conversion is going to cost me over $2000.

Again, thanks for YOUR info, and I appreciate you allowing me to update my build into this thread as well.

Coop

ap0c0lypt1c

I read somewhere it was good for 800 but I'd take Sam's word over something I read on the internet! Looks like it's carbon fiber or nothing, although I'll probably eventually get the GTM shaft simply because I'll be staying NA.

I'm glad I could help you! I was sick of all the gear swap threads that had misinformation or conflicting information that never got clarified or resolved so I wanted to do it right and have a good thread the community can refer to.

SharpByCoop

^^^ Exactly.

I dropped the unit off to Rich at RDZ Motorsports in Danbury, CT this evening. Great guys, clean shop, lotsa performance cars!

They verified it's a VLSD (from salvage yard), and the gears and flange are scheduled to arrive early next week.

I've read the output flanges may need work? The holes are threaded, but need to be bores? Where did I see this? Do you (or anyone) know?

Rich will drop it off down at The Shop, also to visit Jimmy K. (The owner. They went to HS together and haven't seen each other in twenty years!)

I'm stoked!

Coop

ap0c0lypt1c

I'm glad it's coming together for you! I mentioned it very briefly at the beginning of the thread but from what I understand 350z/g35 diffs have threaded output flange holes and 370z/g37's have smooth ones, so the g35 diff you have will need the holes in the output flange bored and smoothed out most likely, it shouldn't be a big deal at all. My diff I used was off a G37 so I didn't have to go through that step.

White G37

iTrader: (1)

Hmmm... mine are at about 3200 at 80mph on a coupe. I did buy the car used so maybe someone already swapped the 4.08 gears into my car? I average 20.3-20.6 MPG on a tank. Another user said that his RPMs are at about 3100 at 80mph, though.

This is off-topic, but..

I did a 155 run, and I thought that I'm supposed to reach 155 in 5th. When you're going that fast you're not paying too much attention to where exactly your RPMs are at, but I know I didn't hit 155 in 5th and I shifted out of 5th pretty damn near the rev limiter cut off. It was a little bit after I got into 6th that I got to 155, the speedo needle actually went 1-2 miles past 155 and I never actually felt the governor kick in.

On a side note, the G37 is stable at high speeds.

SharpByCoop

I just checked and you are exactly right.

The two flanges will meet up OK, but it appears later years used the axle flange as the threaded bore and the output flange is a smooth larger OD bore for the bolt to slide through.

On this diff I picked up, the opposite is true: Output flanges threaded, axle flanges smooth larger OD bore. (Looks like a 10 x 1.25 mm thread?)

You cannot draw the halves together if BOTH are threaded, so one has to be loose. I'll notify Rich at RDZ. I can't imagine this will be too easy, as those shafts are hardened. We will see.

These autos really are a pain to convert.

Jim

NBE-ON'D

Hope everythig was lashed proper.

JSolo

iTrader: (14)

It is very possible the tach is off on our cars too. My camaro was like that, tach showed 2K, but actual was ~1700 (top gear, 80 mph). The actual was based on a obd reading. I'll have to repeat the same test one of these days with torque (tm) connected and see how well the tach rpms match what the computer is picking up.

AFAIK, sedan/coupe/370z all share the same drive line and same gear ratios including final drive.

ap0c0lypt1c

@White G37: 4.08 gears in a 7AT 370z at 80mph is around 3300 RPM. iirc the 6MT's 6th gear isn't as long as the 7AT's 7th gear so on a 6MT I imagine your RPM at 80mph with the gears would be even higher.
See:

@SharpByCoop: Yep! That's one of the reasons I spent a couple hundred extra bucks on a diff out of a G37 so I didn't have to worry about that issue. SpecialtyZ made it sound like it wouldn't have been a huge deal either way though.

@NBE-ON'D: Everything was, there is no gear whine or anything like that. Just normal break in wear. The real test will be when I change the fluid again in 2500 miles. If it still has a lot of metal I might be in trouble lol

NJ Torque

iTrader: (5)

Say if I could source a 'S' vert rear diff, should bolt into my sedan, no? assuming said sedan was RWD?

ap0c0lypt1c

If you have the S sedan it will bolt directly in. I never had luck finding a vert diff though.

NJ Torque

iTrader: (5)

What if a base/journey sedan?

ap0c0lypt1c

I think you need a different stub shaft on one side of the diff because of the VLSD. I'm not too sure exactly what part # it is or anything like that, or cost.

SharpByCoop

OK, so Rich has contacted me via email, and the completed diff with 4.08's and auto output flange is all set. He's trying to make time to drive to The Shop and drop it off and visit with Jimmy (the owner and long time schoolmate).

Strangely, the output shafts were NOT threaded. He sent me a photo. This is odd, only because the extra two axles the salvage yard included (with the same car stock# G35) also have no threaded bores. When I responded above, it was only by looking at the axles which I still had. I'd left the diff with RDZ and didn't look.

The only way they could mate is with through bolts and nuts? Anyway, this is irellevant to my needs right now. (When my axle breaks it will become relevant if I want to use them.)

Getting anxious. Getting close.

Coop