Engine, Drivetrain & Forced-Induction
Have Technical Questions or Done Modifications to the G37? Find out the answer in here!

G37S Sedan on 3.916 Gears - OH MY GOD

Thread Tools
 
Search this Thread
 
Old 03-21-2013 | 03:39 PM
  #46  
Can'tGme's Avatar
Can'tGme
Registered User
iTrader: (1)
 
Joined: Aug 2011
Posts: 622
Likes: 16
From: Kentucky
Originally Posted by SharpByCoop
So I just secured a complete M/T VLSD diff w/ stub axles off of a 2007 G35 coupe with 13k miles from a boneyard here in CT. (I found tons of entries on 'car-parts' .com)

A call to Rich at RDZ Motorsports in Danbury, CT is securing a set of 4.08's and the install kit.

We'll outfit the assembly back here at The Shop in Norwalk.

T-minus ten and counting....

Thanks again for the straight scoop.

Coop
Coop,

I had 4.083 gears in my 350Z with 285 rear tires and basic bolt ons. I broke the right rear axle one time trying to take off hard from a dead stop. The car had almost 120,000 miles on it so I don't know if it was a fluke thing or the gears had something to do with it, but I thought I'd let you know. Heavy duty upgraded axles are available.
Old 03-21-2013 | 04:56 PM
  #47  
ap0c0lypt1c's Avatar
ap0c0lypt1c
Thread Starter
Registered User
 
Joined: Oct 2011
Posts: 127
Likes: 12
From: San Diego, CA
Originally Posted by tejasg37x
What was done to correct the speedometer after the switch to steeper gears?
If no correction was made for the speedo, you will be showing higher speed and more miles than actual...which affects mpg calculation accuracy.
The speedo is unaffected since it goes off of the ABS sensor, not the output shaft RPM sensor. Confirmed by driving past those signs that flash your speed at you when you're going too fast
Old 03-21-2013 | 05:39 PM
  #48  
SharpByCoop's Avatar
SharpByCoop
Registered User
 
Joined: Dec 2010
Posts: 554
Likes: 56
From: Norwalk, CT
Can'tGme...

Thanks. We know this. However, this is one of the better aspects of an auto.

Nothing is break proof, but there is a lot less violence to the drivetrain. We'll see.

Coop
Old 03-21-2013 | 10:32 PM
  #49  
tejasg37x's Avatar
tejasg37x
Registered User
 
Joined: Sep 2011
Posts: 678
Likes: 2
From: Burleson, Tx
Originally Posted by ap0c0lypt1c
The speedo is unaffected since it goes off of the ABS sensor, not the output shaft RPM sensor. Confirmed by driving past those signs that flash your speed at you when you're going too fast

Good to know...thanks
Old 03-24-2013 | 07:16 PM
  #50  
ap0c0lypt1c's Avatar
ap0c0lypt1c
Thread Starter
Registered User
 
Joined: Oct 2011
Posts: 127
Likes: 12
From: San Diego, CA
Update for those reading this thread:

Just changed my diff fluid after driving on these brand new gears for 750 miles. The gear oil was DISGUSTING from the break in! Bright metal flecks everywhere in the fluid and lots of shavings, but this is normal since they are new gears.

If anyone does this, change your diff oil after 500 miles on the new gears! I'm changing my diff oil again after 3,000 more miles to be sure all the break in materials are out.
Old 03-24-2013 | 09:37 PM
  #51  
CodeG's Avatar
CodeG
Registered User
 
Joined: Jan 2010
Posts: 248
Likes: 6
^^^ As long as the fluid's color has not change then you are good. Excessive metal flakes and oil color or viscosity change indicates problems.
Old 03-25-2013 | 02:46 AM
  #52  
ap0c0lypt1c's Avatar
ap0c0lypt1c
Thread Starter
Registered User
 
Joined: Oct 2011
Posts: 127
Likes: 12
From: San Diego, CA
Originally Posted by CodeG
^^^ As long as the fluid's color has not change then you are good. Excessive metal flakes and oil color or viscosity change indicates problems.
Fluid color was fine, there just was a good amount of metal from the break in.
Old 03-25-2013 | 02:01 PM
  #53  
Kojack's Avatar
Kojack
Registered User
iTrader: (2)
 
Joined: Apr 2012
Posts: 214
Likes: 2
From: nj
this is good infos
Old 03-26-2013 | 09:29 AM
  #54  
joselitopr's Avatar
joselitopr
Registered User
 
Joined: Aug 2009
Posts: 133
Likes: 4
From: San Antonio,TX
Originally Posted by ap0c0lypt1c
Hey Guys,

I just had my final drive gears swapped at SpecialtyZ in California for some 3.916 gears from a Nissan Frontier. As you may know, the standard gear ratio in this car for the autos is 3.3.

All I can say is...WOW!!!!

This is how the car should have been from the factory. Highway RPM's are only up 250-300 or so. 80mph is 3k RPM now.

However, the acceleration of the car is DRAMATICALLY improved. The car wants to go with the slightest bit of gas now! It's just way easier to get it moving. Clocked a 0-60 at around 4.5 seconds. Fantastic mod for the money, this is easily the biggest NA mod you could do to make this car "wake up" and be sporty and quick.

Just thought I'd share :P
Does the car feel better to drive? Does the transmission feel better. I cant drive my car in Normal mode it just pi$$ the hell out of me ,and I feel like selling the car every time I do so, so I just drive in manual mode 100% of the time.If it help with the horrible trans I may give it I try cause I just got the pics to put it for sale.
Old 03-26-2013 | 10:33 PM
  #55  
SharpByCoop's Avatar
SharpByCoop
Registered User
 
Joined: Dec 2010
Posts: 554
Likes: 56
From: Norwalk, CT
Got the complete G35 VLSD diff and (2) spare axles. ($425) I'm guessing/hoping the G35 coupe and mine are the same? Nice to have a backup.

I'll be dropping it off to Rich at RDZ motorsports in Danbury for the gears R&R. Jimmy and his men at The The Shop will swap rears when it's finale.

For me the 4.08's will not be such a dramatic change. I already have 3.69's. It's only a .4 change in ratio. That said, this will be just right.

I'm looking forward to the completion. Probably about two weeks, or a bit more.

Stay posted.

Jim
Old 03-27-2013 | 02:54 AM
  #56  
ap0c0lypt1c's Avatar
ap0c0lypt1c
Thread Starter
Registered User
 
Joined: Oct 2011
Posts: 127
Likes: 12
From: San Diego, CA
Originally Posted by joselitopr
Does the car feel better to drive? Does the transmission feel better. I cant drive my car in Normal mode it just pi$$ the hell out of me ,and I feel like selling the car every time I do so, so I just drive in manual mode 100% of the time.If it help with the horrible trans I may give it I try cause I just got the pics to put it for sale.
Car feels like it has more torque low end (that's the main purpose of the gears) but it also provides more acceleration in each gear. This makes the car feel faster than with stock gears. Transmission still has its moments but overall is much better imo. It might be worth a shot but I would hate for you to spend 1.5k on this and still be dissatisfied with the car.
Old 03-27-2013 | 03:02 AM
  #57  
ap0c0lypt1c's Avatar
ap0c0lypt1c
Thread Starter
Registered User
 
Joined: Oct 2011
Posts: 127
Likes: 12
From: San Diego, CA
Originally Posted by SharpByCoop
Got the complete G35 VLSD diff and (2) spare axles. ($425) I'm guessing/hoping the G35 coupe and mine are the same? Nice to have a backup.

I'll be dropping it off to Rich at RDZ motorsports in Danbury for the gears R&R. Jimmy and his men at The The Shop will swap rears when it's finale.

For me the 4.08's will not be such a dramatic change. I already have 3.69's. It's only a .4 change in ratio. That said, this will be just right.

I'm looking forward to the completion. Probably about two weeks, or a bit more.

Stay posted.

Jim
Do you have an aftermarket driveshaft? I hope the stock one can handle that crazy torque multiplication haha. I really want to see what times your car ends up running when this is done. Your car is the big budget version of what I would do to mine if I had the funds so it would be cool to see the result.
Old 03-27-2013 | 03:23 PM
  #58  
SharpByCoop's Avatar
SharpByCoop
Registered User
 
Joined: Dec 2010
Posts: 554
Likes: 56
From: Norwalk, CT
More importantly: Can an AFTERMARKET driveshaft handle the torque? So far there are zero available offerings. Although a carbon shaft would be nice, I don't think the OEM heavy driveshaft is the weak link. Awaiting word on the carbon driveshaft thread to evolve.

I'm now on the search for the OEM automatic flange. In order to properly set it up on the bench with the crush sleeve, it needs my auto flange. That would require the car being laid up on a lift at The Shop for the duration.

We are scouting for a new or used one, so this is literally a bolt over.

Coop
Old 03-27-2013 | 04:45 PM
  #59  
Ivoidwarranties's Avatar
Ivoidwarranties
Premier Member
iTrader: (7)
 
Joined: Nov 2008
Posts: 2,078
Likes: 28
From: Omaha
I've been looking at this mod for a while now. So much conflicting information out there. One guy on here said they put the 4.08s in his automatic's differential no problem. Another guy on here (or 370zforum) said his cruise control still works and he has an automatic. If I can find a used differential at a decent price I'll be doing this mod this summer.

Originally Posted by SharpByCoop
For me the 4.08's will not be such a dramatic change. I already have 3.69's. It's only a .4 change in ratio. That said, this will be just right.
I'm sure you already know this but it's not looked at as a .4 change in ratio but more correctly as a 10% change in ratio. That's pretty big by the way. A 10% increase in leverage is what everybody needs.
Old 03-27-2013 | 07:55 PM
  #60  
SharpByCoop's Avatar
SharpByCoop
Registered User
 
Joined: Dec 2010
Posts: 554
Likes: 56
From: Norwalk, CT
Good clarification. I'll take 10%. My point is that there are some who go from 3.3 or the 3.5 ratio to 4.08's, so my 10% isn't as severe.

Hey, Nissan has 4.36's if I'm feeling greedy!

Gears ordered, automatic flange ordered ($125), and all systems go. I'll deliver the diff to the shop this weekend.

I'll report back MY trials as well. T-minus 6 and counting.....



All times are GMT -4. The time now is 12:47 PM.