So would you guys recommend a 3.69 vlsd over a 3.90 open diff?

 

From you current 3.3, upgrading to 3.69 is about a 10% difference. About the same as manuals upgrading from 3.69 to 4.08. From what I have read and hear, that upgrade for you is perfect. I went from 3.69 to a 3.916, a 6% difference, is its a nice bump, but I would like to go 4.08 eventually.

 

Our first gear is so short, after 3.69 it just becomes ridiculously short. Like hurts launch times short. If you are making over stock power it is not the best choice, IMO. However, if we were able to launch in 2nd gear...

 

I gotcha I think I'm gonna just go with 3.69 and vlsd seems like the easier swap overall.
I'm planning on adding Z1 HFC, CBE, Z1 CAI and tune after the gears go so that should give me a good bump in useable power.

 

Hands down 3.69. I do think the 3.9 will be faster overall but it's too short for daily. There's a noticeable difference going to 3.69. Get a KG stamped on for the OEM vlsd and 3.69. Needs to come from a 2007-2008 G35S auto. Not super hard to find but not exactly easy.

 

Thanks for the all the suggestions I've decided to go with the 3.69 vlsd. I haven't located one yet so I went ahead and picked up a set of sways and hopefully I'll spot a good used diff soon.

 

So I'm having a helluva time finding a low miles vlsd 3.69 diff..I found one out of a 2007 g5 for $125 but it has 120k on it which is 40k more than my car..should I wait or take a chance on it?

 

Ask them to send a video to you of them spinning the input and see if both axle flanges spin the same direction. If they do I'd take a chance on it.

 

It's at a local LKQ I'll check that when I get there thanks

 

Just FYI lkq is notorious for pulling the stub axles so if those are missing I'd walk away

 

Thanks I'll call them and see before I drive there.

 

2015+ NISMO 370z autos came with a VLSD and 3.69 as well. They will most likely cost more but you have much better odds of finding one with less miles.

Here's a chart to help some: Z1 Final Drive Gear Ratios

 

Dude those diffs are like $900 everytime I found one. Remember that the 370z all had manual diff flanges. The one he's looking at now is better if it comes with the stub axles. Fyi get the bolts for it as well or you'll be at advance Auto getting some new ones as you can't reuse the ones on your car currently.

 

Swapping flanges is not difficult. Options are options, and I've seen them as low as $450 shipped; which is what I got mine at three years ago. If he is looking for low miles he is most likely going to have to pay for that.

 

Then you lose the guide pin/centring pin. It may not vibrate with it gone but it's not the "right" way to do it.