Shall I install a 4.11 diff??

[24OZ]

My mum has a 200sx turbo (the UK call them a Nissan Sivia ZX Turbo) and I have recently learnt that they came with a 4.11 diff which fits in a 240z. My mum has had this car standing for a few years and it is quite rotten, she is thinking of taking it to the junk yard and if so I might keep the diff if you all think its worth keeping.

Are there any advantages to this diff? Is it more hassle then its worth to install?

Thanks..

[2ManyZs]

Even if you don't use it, I would suggest you get it anyways... bet there would be a lot of people that would like to have one....:devious:

Have you got a ZX 5 speed in the car with the higher overdrive ratio? If so, then the 4.11 would be fine... With a 4 speed it would be too low for the street for anything longer than short trips...

[24OZ]

Hi Keith,

As far as I know it has a standard UK 240z 5 speed gearbox (type FS5C71A).

I am not too sure of the advantage of this diff. to the stock one? Can anyone give me any pros and cons?

Thanks.

[HS30-H]

George,

Your particular car would have come from the Factory with the FS5C71B ( sometimes nicknamed the "bent stick" ) transmission.

The "A" type ( "straight stick" ) was standard on the earlier UK-market HS30 models - but not on yours.

Is your Mum's car an S12 or an S13 Silvia? Be careful, as the diffs are not always a straight swap for the R180 that I presume is still in your car. And if the diff currently in your car is the 3.9 ratio ( as it should be for a UK-market car ) then you will really not notice a huge difference if you fit a 4.1................

Alan T.

[2ManyZs]

The only con's I can think of would be the work involved to change the flanges to the 240 style as I believe the 200SX Turbo's or Silvia had CV joints. Not really all that difficult, but it is a bit of work. It should also be an R-200 diff, which means changing the mustache bar and the lower transverse link as the 240 link won't give you enough room to mount the diff. You'll need the curved link such as our 280's had that came with R-200's. Of course, it is possible your Silvia's had an R-180 diff, I'm just guessing since ours came with 200's, the only ones that came here with 180's were the non-turbo's.

Pro's? Car would be substantially quicker off the line and with the 5 speed your overdrive will give you a bit lower highway RPM. All depends on if you want a little more snap in the lower gears without sacrificing cruising RPM's. There's quite a noticeable difference when going from a 3.36 or even 3.54 to a 4.11 ratio. That is if your car doesn't already have a 3.90 which would make the change moot..

[24OZ]

Hi Alan, Hi Keith,

Thank you for the information.

Alan, I had no idea there were different 5 speeds.. The information I used was from the 240Z (English Edition) Haynes manual (revised 1987). Which does not mention a B type 5 speed gearbox. However, I appreciate your Z knowledge to be superior to an under-researched English Haynes Manual, so I take your word for it.

I am not sure abot the S12 or S13, just that its a ZX silvia Turbo 1984, i think.. Anyway, you and Keith have both put me off the idea and by the looks of it saved me alot of hassle as the diff will be the original and thus a 3.9.

Thanks GUYS for shinning your torches and enlightening my Z knowledge

[HS30-H]

Originally posted by 24OZ

......However, I appreciate your Z knowledge to be superior to an under-researched English Haynes Manual, so I take your word for it.

Steady on George, that might be taking it a bit too far.........

I'm sure that the people at Haynes knew very well what they were doing - but you might need to keep in mind that some workshop manuals can tend to offer information on a "need to know" basis. ie - if they think you don't really need to know, then they might not put it in the manual..........

I can assure you that all of the UK-market cars came with the 5-speed ( and the Auto option was a VERY rare choice ), and the first of these had the "A" type. Your car ( which we think is a '73 don't we? ) would have had the "B" type 5-speed. I'm not sure if your car got an even later transmission along with its L28 engine transplant ( the gear ratios on UK-market 280ZX models were different from those in the earlier "B" boxes ) - so only a bit of research will uncover that.

Rest assured that you would indeed not have noticed much useful improvement with the 4.1 ratio diff in comparison with the 3.9 ratio.

All the best,

Alan T.

[sjcurtis]

Hi , this makes interesting reading, and I would like to add to the disscussion even though it is all just about done.

Take the diff better in your possesion than the wrecker. If it is an R180 the pinion will have an odd number of teeth not 10: 41 it will probably still have a 39 tooth crown wheel, compatible to your R180 in the Zed. These parts to a die hard four cylinder operator could be bucks or swapping power for a part you may need.

If it is an R200 it may be the same gear set but you may have an LSD optioned in. For my money investigate you need to know before it gets towed.

To the gear box I must agree with Alan, you should have a bent stick © B series box, if you have the later zx box you are also in good sted they altered the first second ratio combination to pull the taller diff ratios better. So you should be quicker off the mark with snap changes.

My2c

cheers

Steve:classic:

[24OZ]

Hi Steve!

Thanks for writting down all this research for me! I havent really re-investigated the option. The car is still parked out outside. I will check out what you've said and take things from there.

Thanks again .. Muchos Gracias