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240Z standard R180 diff ratios


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#1 acf321

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Posted 31 July 2010 - 01:50 PM

Hi Guys.

Apologies if I have missed this topic already, but does anybody know what the standard factory fitted R180 diff ratio fitted to the 1971 240Z was?

Also, was the diff's rear plate painted from the factory, or just straight alloy?

I have not taken my diff apart to inspect the gears, but was there a specific diff installed for a specific year?

Rgds

Adam

#2 Roberto

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Posted 31 July 2010 - 02:16 PM

In Australia, 240Z's were built with a ratio of 3.9 (R180) and 260Z's 3.7(R200)

In the USA it was a different matter (3.364 for manuals and 3.545 for autos)

Aren't we lucky.....

#3 Roberto

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Posted 31 July 2010 - 02:27 PM

In addition to that, the auto 240Z's in Australia had a final drive ratio of 3.55:1. They did not change through the years.

Don't know about the paint finish.

#4 acf321

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Posted 31 July 2010 - 02:45 PM

Awesome Roberto ... methinks the 3.9 will be just the right choice for the hornet .. that is not too intense, but coupled to a nice 250hp L24, should make for an exciting ride!

Next decision is the LSD ... will get her finished before I go down this route.. but I was salivating at the OS Giken LSD's last night.

Cheers

Adam

#5 Whittie

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Posted 31 July 2010 - 03:20 PM

The 3.9 is an AWESOME ratio, good choice!

I have a 4.4, 3.9 and 3.5 and the 3.9 is by far the best for the road in an N/A motored car. It has good accel without silly revs on the freeway. For the local track where it is not possible to go more than 200kph the 4.4 is the best with it's top speed of 220 (Silvia gearbox with longer 5th gear). I would go a 3.5 with a turbo motor tho, the extra speed would require it and the low revs on the freeway would be superb.

It sounds like you're going to have a pretty hot motor in that thing, is it going to see the track?

I would also recommend the Silvia gearbox swap, you can see my tutorial posted in the sticky in the gearbox section

http://www.viczcar.c...2.html#msg69672

It's very simple and you won't go munching boxes everytime you drive the car. Extra length in 5th gear also helps on the freeways without being too big a difference to the standard 5 speed

For the diff, I just swapped the internals from an R200 out of a silvia. For an R180 I've heard you can just take the LSD out of an STI and buy adapters from the states for about $200 to get the drive shafts to bolt on.

Also, have you thought about CV's? . I know, a million questions but it's worth thinking about all of this now before buying anything. I would recommend CV's, I've busted too many shafts at the drags to want to do anything else again if I was building a car ground up. Which CV's you use (if any) could alter what you can and can't use in terms of LSD centres, so no point buying something now to have the hassle of buying again or retrofitting to get stuff to work.

Do it right and Do it once, is my motto.

#6 MaygZ

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Posted 31 July 2010 - 05:21 PM


For the diff, I just swapped the internals from an R200 out of a silvia. For an R180 I've heard you can just take the LSD out of an STI and buy adapters from the states for about $200 to get the drive shafts to bolt on.


Whittie, they adapters for the STI diff are $500.  They look awesome.  This post goes through almost everything you would want to know about improving the diffs in the Zed, along with the standard "I just thought something so I'll post it".

http://forums.hybrid...s/page__st__100

#7 Whittie

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Posted 31 July 2010 - 05:59 PM

Whittie, they adapters for the STI diff are $500. 


Wow, unless you want the weight savings or require an R180 (Sc racing) I would go for an R200. Can grab a viscous R200 for $0 (Literally, both mine were free) from a silvia and rebuild them into a zed R200 with the crown and pinion you like for around $600-$800. Then it's a matter of cutting and welding stub axles from the zed onto the silvia stub axles, i.e. take the 'rods' from the silvia diff and weld on the flange from the zed so that the shafts botl up. Mine cost about $800 ready to go in the car for a 'brand new' diff.

Those flanges and studs after shipping (assuming about $80US here) would be roughly $700 alone, plus the cost of the STi diff.....

**EDIT** I just realised you could also just use the 'rod' from the stub axle off the STi diff and weld the zed flange on to that, same as what I did but I used a silvia diff. It cost me $50 to get them cut and welded, beats the crap out of $700 and the quality of the welds, nothing is going to break. I don't really see the need for such expensive stub axles to be honest, but that's just my opinion.

#8 acf321

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Posted 31 July 2010 - 06:11 PM

Wow .. solutions solutions .. thanks guys.

I'll run what I have (which i think is a 3.9) because the diff seems to be standard ..

If I decide I need LSD will cross that bridge when I get there, and i'm not one to burnout cars, so i'm not expecting to need anything bullet proof. My engineer James Flett uses a R180 in group SC (which he wins) and he tells me an R200 is completely unnecessary .. unless I'm going turbo power, or want to do burnouts.

Again .. will consider LSD if I need to ..

Thanks again gents ... very helpful.


#9 Whittie

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Posted 31 July 2010 - 06:20 PM

he tells me an R200 is completely unnecessary .. unless I'm going turbo power, or want to do burnouts.


He's bang on the money there, I was just suggesting that if you are considering an STi diff swap that you might consider an R200 for simplicity and cheapness if you weren't required to run an R180 such as in group Sc, no other reason. If you are happy with an open diff (you wont be for long with 240hp, let me tell you now) then it is a total non-issue.

#10 PZG302

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Posted 31 July 2010 - 06:45 PM

For mine, 20mm bigger crown wheel for near 20kg extra weight, there's no way I would bother with an R200.

I can pick up just about any R180 ratio, except 5.1, for less than $100.

As my car is circuit only, no need for LSD, just weld them up and instant traction ;D ;D

For a road car I would chase an LSD with big power, there are a few options about for reasonably cost effective solutions that are still cheaper than putting in an R200.




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