Suspension, Brakes, Drivetrain discuss the wondrous effects of boost and your miata...
Sponsored by:
Sponsored by:

NB1 Best trans/diff combo w/Rotrex?

 
Old 10-19-2018, 04:50 PM
  #1  
Newb
Thread Starter
 
Join Date: Jul 2017
Posts: 25
Total Cats: -2
Default NB1 Best trans/diff combo w/Rotrex?

Planning on buying a Rotrex S/C in a couple of years, but have a question about the best trans/diff combo? I have a 2000 LS with a 5-speed and 4.3 LSD. I bought an NA 4.1 LSD to use with the 5-speed, but have been hearing that if I wanted a 6-speed, that the 4.3 LSD would be better to have, especially if I plan on using a Rotrex later on? Can anyone confirm this?

Thanks!
Mirage775 is offline  
Reply
Leave a poscat -2 Leave a negcat
Old 10-20-2018, 07:40 AM
  #2  
Senior Member
iTrader: (1)
 
Join Date: Feb 2015
Posts: 928
Total Cats: 135
Default

Typically the more power you add, the lower numerically gear you want. Stay with the 5 speed until you need the strength of the 6 speed. 225 ft/lb give or take is the swap point. In my opinion that's also the point in which lower gears like a 3.9 or 3.6 start to make sense. First gear is just a smoke show.

You were very vague in what you are using your car for, better depends on the application.
Bronson M is online now  
Reply
Leave a poscat -1 Leave a negcat
Old 10-20-2018, 08:22 AM
  #3  
Newb
Thread Starter
 
Join Date: Jul 2017
Posts: 25
Total Cats: -2
Default

Originally Posted by Bronson M View Post
Typically the more power you add, the lower numerically gear you want. Stay with the 5 speed until you need the strength of the 6 speed. 225 ft/lb give or take is the swap point. In my opinion that's also the point in which lower gears like a 3.9 or 3.6 start to make sense. First gear is just a smoke show.

You were very vague in what you are using your car for, better depends on the application.
Thanks

I was going to do the swap now, as I'm pulling the engine out next month. I don't do much with my car, just cruising through curvy streets has been my main goal, but this year, it's been parked in the garage for the most part...
Mirage775 is offline  
Old 10-20-2018, 10:05 AM
  #4  
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,760
Total Cats: 676
Default

A friend has a 6-spd/4.3 combo, another enjoyed his 6spd 3.9. It really all depends on how you use it and what you prefer. The 4.3 guy loves autocross, the 3.9 guy did a lot of HPDE, and our local track has 2 big straights. If you love driving, the feel, the engagement, the acceleration, the sounds, have special leather driving gloves, you'll probably love the 6spd/4.3. If it's your DD for your 30 mile freeway commute, maybe even consider a 5spd/3.9.

More than likely however, you're somewhere in between. I'd probably start with the path of least resistance. Use what you've got to start, if you feel like you're running out of gear, get a taller ratio. If it feels sluggish, go shorter.
curly is offline  
Old 10-24-2018, 11:22 PM
  #5  
Newb
Thread Starter
 
Join Date: Jul 2017
Posts: 25
Total Cats: -2
Default

Originally Posted by curly View Post
A friend has a 6-spd/4.3 combo, another enjoyed his 6spd 3.9. It really all depends on how you use it and what you prefer. The 4.3 guy loves autocross, the 3.9 guy did a lot of HPDE, and our local track has 2 big straights. If you love driving, the feel, the engagement, the acceleration, the sounds, have special leather driving gloves, you'll probably love the 6spd/4.3. If it's your DD for your 30 mile freeway commute, maybe even consider a 5spd/3.9.

More than likely however, you're somewhere in between. I'd probably start with the path of least resistance. Use what you've got to start, if you feel like you're running out of gear, get a taller ratio. If it feels sluggish, go shorter.
It's not my DD. It might leave the garage once or twice a month, throughout the warmer months. Winter is stays planted in the garage or I'll tinker with it, like now. Engine and trans came out Sunday! I don't auto-x it and there aren't any tracks nearby. It's mainly used for street/curvy mountain road driving. Not worried about being a gas saver. I want something a little quicker from a dead stop and something that has good power from 2th to 4th, inn the hard curvy roads in north Alabama/south Tennessee? I can keep my 5 speed and get a 3.9 or get a 6 speed and 3.9, but the 3.6 is a little outta my price range for a car that never sees more than the street... So, what do yall think I should go with?
Mirage775 is offline  
Old 10-25-2018, 01:49 AM
  #6  
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 15,281
Total Cats: 1,997
Default

6sp/3.9 is as short as I would ever go for a Rotrex. If the car had 4.10s, I would expend exactly zero effort changing those.
__________________
Trackspeed Engineering
High-Performance Turbo Specialists - Sunnyvale, CA - 650-701-7223 - Email us!
Originally Posted by codrus View Post
Basically I've come over to the camp of "If something is a reliability problem on the track, just ask Andrew and do what he says".
Savington is offline  
Old 10-25-2018, 07:00 AM
  #7  
Newb
Thread Starter
 
Join Date: Jul 2017
Posts: 25
Total Cats: -2
Default

Originally Posted by Savington View Post
6sp/3.9 is as short as I would ever go for a Rotrex. If the car had 4.10s, I would expend exactly zero effort changing those.
Thanks. It's not a 4.10 at the moment, I just have a 4.10 wanting to go in. It was stock 4.30 with a 5 speed. I may or may not install a Rotrex in a couple of years, that's why I didn't want to pull the trans/diff out again. I was hoping to get it all done in the winter months.
Mirage775 is offline  
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Sandro351
Miata parts for sale/trade
1
02-07-2018 03:36 PM
graexodus
Miata parts for sale/trade
6
09-11-2017 05:12 PM
thumpetto007
Miata parts for sale/trade
19
08-16-2016 06:12 PM
blindboxx2334
Miata parts for sale/trade
10
04-11-2012 03:31 PM
rappadan
Miata parts for sale/trade
5
11-30-2008 10:31 PM


Thread Tools
Search this Thread
Quick Reply: NB1 Best trans/diff combo w/Rotrex?


Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.