Ausmini
It is currently Sun Jul 06, 2025 2:13 am

All times are UTC + 10 hours




Post new topic Reply to topic  [ 8 posts ] 
Author Message
 Post subject: Diff selection help?
PostPosted: Thu Jul 24, 2008 2:30 pm 
Offline
848cc
848cc
User avatar

Joined: Tue Jun 12, 2007 8:28 pm
Posts: 229
Location: In Hell
I have orderd a new set of straight cut gear from the UK (Three months ago :evil: :evil: and they are still on back order) I have been told that first gear is very tall so it may be a little hard to get off the line.
If any one runs straight cuts on the road what diff are you running to compensate for the tall first gear?


Top
 Profile  
 
 Post subject:
PostPosted: Thu Jul 24, 2008 2:37 pm 
Offline
998cc
998cc

Joined: Tue Sep 06, 2005 1:26 pm
Posts: 817
Location: Adelaide
I ran a factory sc/cr 3 synchro remote box in my Cooper S for years on the road, along with a 649, Browriggs and 45 Weber. I always used the 3.44:1 diff with no problems, and that was coping daily with Melbourne traffic. Gives you a great take off range before you need to change into second.

_________________
Slide
1965 Mini Van (1360)
1970 Mk2 Cooper S (1310)
1978 Rover SD1 V8 (4.6)
1996 Land Rover Discovery V8 (4.0)


Top
 Profile  
 
 Post subject:
PostPosted: Thu Jul 24, 2008 4:56 pm 
Offline
848cc
848cc
User avatar

Joined: Fri Mar 03, 2006 11:04 am
Posts: 441
Location: Brisbane
I have a spread sheet I put together to illustrate gear ratios with diff ratios etc. pm me your email and I'll send it too you...


Top
 Profile  
 
 Post subject:
PostPosted: Thu Jul 24, 2008 4:58 pm 
Offline
1098cc
1098cc
User avatar

Joined: Fri Jan 14, 2005 9:08 pm
Posts: 1683
Location: Bris Vegas Occupation: Engineer
I have a 3.44:1 and it's a biatch to drive on the street in traffic, not that I do that anymore...

Daniel

_________________
Videos - Turbocharged A-Series on Dyno & at Wakefield
Mafs waz not my strong subgeckt at skkol


Top
 Profile  
 
 Post subject:
PostPosted: Thu Jul 24, 2008 9:52 pm 
Offline
998cc
998cc
User avatar

Joined: Sat Dec 03, 2005 2:23 pm
Posts: 955
Location: Canberra, ACT
You can try this web site....

Has an online calculator just put in the various details (geraing, wheel size, diff ) and it'll show the data...

http://www.guess-works.com/Gearbox/Technical/ratio.htm


Top
 Profile  
 
 Post subject:
PostPosted: Sat Jul 26, 2008 2:47 pm 
Offline
848cc
848cc
User avatar

Joined: Fri Mar 03, 2006 11:04 am
Posts: 441
Location: Brisbane
Mine is similar to that but I grabbed a dyno plot to show torque versus speed and the overlap in each gear :D
It's not very accurate because each engine is different but its actually really interesting to mess around with...


Top
 Profile  
 
 Post subject:
PostPosted: Sat Jul 26, 2008 4:36 pm 
Offline
998cc
998cc

Joined: Mon Jun 18, 2007 9:00 pm
Posts: 1127
Location: Down South
Hi,

We ran a 3.4 diff in Targa one year and a 3.7 the next with a four syncro SC gearbox. The 3.7 was my choice, the 3.4 is too tall and makes hill starts a killer expecially on really hot engines.

I know the English tend to run really low diffs...I don't think this suits our roads as well - mind you I am not an expert!

Cheers

Rich


Top
 Profile  
 
 Post subject:
PostPosted: Sat Jul 26, 2008 9:10 pm 
Offline
848cc
848cc
User avatar

Joined: Tue Jun 12, 2007 8:28 pm
Posts: 229
Location: In Hell
I just had a close look at my 3.44 diff pinion gear shaged. I think 3.7 would best suit what i want to use the car for thanks for your input.

Cheers Tony


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 8 posts ] 

All times are UTC + 10 hours


Who is online

Users browsing this forum: No registered users and 92 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  

© 2016 Ausmini. All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.