Getting a 3.9 R200 in the UK..

[Robotsan]

.. is beginning to look like a tall order!

I currently have a 3.545 R200 diff in my '76 4 speed 280z, according to this:




According to this thread on zcar.com, the only cars that come with a long-nose R200 are the following Z cars (nothing from any other marques?) - and only 4 of these came with a 3.9 ratio:

75-76 280Z, 3.545
77-78 280Z, MT 3.545
79 280ZX MT,4 Spd,4 Seater 3.364
79 280ZX MT,5 Spd,4 Seater 3.7
79 280ZX-GL 3.7
80 280ZX MT,4 Seater 3.9
80 280ZX-GL 3.9
81-83 280ZX Turbo - all 3.545
81-83 280ZX MT 3.9
84-86 300ZX MT and A/T 3.7
84-86 300ZX Turbo MT and A/T 3.54
87-89 300ZX MT and A/T 3.9
87-89 300ZX Turbo MT and A/T 3.7 CLSD


Looking at the S130 280zxs.. I can't find any info on whether the ones listed above were sold with a 3.9 in Europe, or whether that's just USDM info above. Anyone know? According to this thread on Hybridz all '81-83 non-turbo ZX's had a 3.90 - but does that apply to European cars as well as US?

Looking at the Z31 300sxs.. according to this: http://www.xenonzcar.com/z31/differentialinfo.html only the US 87-89 non-turbo had a 3.9, - so none of the European cars would have it, which surely makes that very improbable to source here?

How often do these diffs become available in the UK?

I'm tempted to just go with a 3.7 as they seem fairly plentiful in the UK, but then I'm thinking will going from 3.54 to 3.7 even be that noticeable?

Thanks for any insight.

George.

 

[ALN]

So here's the comparison in terms of speed (MPH) for using the 1976 4 speed gearbox ratios on say a 225/55/15 tyre at 3500 RPM for each diff ratio:

3.545 Ratio Diff @ 3500 RPM
1st - 20.21mph
2nd - 32.31mph
3rd - 51.29
4th - 72.58
4th @ 6000 RPM - 124.6mph

3.7 Ratio Diff @ 3500 RPM
1st - 19.36mph
2nd - 30.96mph
3rd - 49.14mph
4th - 69.54
4th @ 6000 RPM - 119.21mph

3.9 Ratio Diff @ 3500 RPM
1st - 18.37mph
2nd - 29.37mph
3rd - 46.62mph
4th - 65.97
4th @ 6000 RPM - 113.1mph

I hope the above helps!

 

[jonbills]

Go for the 4.6

NISSAN Cedric 1993 Rear Rigid Differential Assembly 3830005V00 [PA72762713] | eBay

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[Robotsan]

So here's the comparison in terms of speed (MPH) for using the 1976 4 speed gearbox ratios on say a 225/55/15 tyre at 3500 RPM for each diff ratio:

3.545 Ratio Diff @ 3500 RPM
1st - 20.21mph
2nd - 32.31mph
3rd - 51.29
4th - 72.58
4th @ 6000 RPM - 124.6mph

3.7 Ratio Diff @ 3500 RPM
1st - 19.36mph
2nd - 30.96mph
3rd - 49.14mph
4th - 69.54
4th @ 6000 RPM - 119.21mph

3.9 Ratio Diff @ 3500 RPM
1st - 18.37mph
2nd - 29.37mph
3rd - 46.62mph
4th - 65.97
4th @ 6000 RPM - 113.1mph

I hope the above helps!

Thanks that's very interesting. Where did you get that from?

I could live with a top speed of 113! But I wonder if 70mph would be a bit noisy, if it's already at 3500 at 66mph?

I'm guessing the s13 5 speed I've bought would help a lot in that respect. But just need to find the right diff.

 

[Robotsan]

Go for the 4.6

NISSAN Cedric 1993 Rear Rigid Differential Assembly 3830005V00 [PA72762713] | eBay

Find many great new & used options and get the best deals for NISSAN Cedric 1993 Rear Rigid Differential Assembly 3830005V00 [PA72762713] at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

Wow. Didn't even know they went that high/low.

That has made me think what about 4.1 diffs though.. are they any easier to get hold of in R200 form by any chance?

 

[Mr Tenno]

Maybe you're missing the obvious one - get a diff from a UK 260z. Should be a straight swap if the year is late enough?

 

[Robotsan]

Maybe you're missing the obvious one - get a diff from a UK 260z. Should be a straight swap if the year is late enough?

Really? I thought 260s only had a max of 3.7?

 

[Mr Tenno]

Really? I thought 260s only had a max of 3.7?

Ah no, you're correct. That would make it 'euro spec' for a 5-Speed though.

Alternatively maybe an r180 swap could be an option?

 

[Robotsan]

Ah no, you're correct. That would make it 'euro spec' for a 5-Speed though.

Alternatively maybe an r180 swap could be an option?

Hadn't thought of that! So would that mean swapping to 240z/260z half shafts too? And any other things?

 

[AliK]

I’m with @jonbills - I have a 5 speed stock 260 box with a 3.9 I found in Arizona on eBay and arranged my own DHL pick up / delivery. Amazing how from finding to delivery was less than 3 days from across the ocean! Total cost as about £350 IIRC but it was 5 years ago.

! Went from a 3.54. It’s more alive but if I did it again, I’d opt for the 4.11 or what Jon posted.

I guess it depends a lot on the torque curve of your engine and your driving style.

Edit: I’m not sure the S13/14 is going to help that much more (as I don’t know the 4 speed to 5 speed comparison for the S30 boxes) - but my yet to be installed S14a has a second gear that is 10% taller than my 260z box - so putting that in would negate the benefits of a 3.9 which is 10% revvier than a 3.64.

 

[Robotsan]

I’m with @jonbills - I have a 5 speed stock 260 box with a 3.9 I found in Arizona on eBay and arranged my own DHL pick up / delivery. Amazing how from finding to delivery was less than 3 days from across the ocean! Total cost as about £350 IIRC but it was 5 years ago.

! Went from a 3.54. It’s more alive but if I did it again, I’d opt for the 4.11 or what Jon posted.

I guess it depends a lot on the torque curve of your engine and your driving style.

Edit: I’m not sure the S13/14 is going to help that much more (as I don’t know the 4 speed to 5 speed comparison for the S30 boxes) - but my yet to be installed S14a has a second gear that is 10% taller than my 260z box - so putting that in would negate the benefits of a 3.9 which is 10% revvier than a 3.64.

Not bad! Unfortunately shipping rates have gone insane since then. I managed to source a 3.9 from a 280zx in the end - £175 to a chap in Washington State. He's then posted it to STS Imports who are charging a decent £80 to ship it over and another £30 to get it to me in Manchester.
Not bad all in all. Won't be here till October as we just missed the last boat, but there's no rush as it probably won't get installed until next year.

So re: the S13 5 speed box, surely for me it will be better than using my long geared US 4 speed?

I've sourced one of those for £200 in the UK too, but the seller has been a bit odd. Long story but no money has changed hands yet!

 

[AliK]

I don't know much ab out the 4 speed as mine is a 5, but everyone I know who has done the swap to the more modern S gearbox says it transforms the driving experience and they won't go back.

I was giving mine the beans the other day and I have to say, I still like the character of the old box and for now, it's still shifting fast and smoothly enough to enjoy. So my S14a box is currently in store for that rainy day when the synchros / bearings on mine finally give up.

Well done on the shipping / finding one. When you get it, check the backlash on it and tighten if required. Mine having come out of an Auto N/A 280ZX with 90K miles on it, was unbelievably unworn. I didn't even change the bearings. I'm hoping you will find the same. The NA ZXs weren't particularly torquey or high powered and the R200 is a very strong diff so I would be interested to see if yours is also in the same state.

Three thoughts remain:

1. I flushed mine with some sacrificial oil to make sure it was totally clean
2. Use Hylomar Blue Gasket sealant on the cover (@Huw advised this and I have to say he was spot on)
3. Depending on what you intend for the car or your budget / driving style, this may be an ideal time to drop in a Quaife LSD. I now regret not doing it when it was off the car (I can easily light up the rear inside pulling out hard on a right turn out of a junction (but I do have quite a modified engine with adjustable Koni inserts setup to three quarters - read firm)

Nissan R200 300Z/240SX ATB Differential

The Nissan R200 280-300Z/240SX ATB Differential is the perfect upgrade of choice for car owners and motorsport competitors looking to improve their vehicle’s traction.

shop.quaife.co.uk

 

[Alphabettispaghetti]

Thanks that's very interesting. Where did you get that from?

I could live with a top speed of 113! But I wonder if 70mph would be a bit noisy, if it's already at 3500 at 66mph?

I'm guessing the s13 5 speed I've bought would help a lot in that respect. But just need to find the right diff.

Simple answer is to drive at 60 on the motorway, the. Have the enjoyment of fun gearing everywhere else

 

[Robotsan]

I don't know much ab out the 4 speed as mine is a 5, but everyone I know who has done the swap to the more modern S gearbox says it transforms the driving experience and they won't go back.

I was giving mine the beans the other day and I have to say, I still like the character of the old box and for now, it's still shifting fast and smoothly enough to enjoy. So my S14a box is currently in store for that rainy day when the synchros / bearings on mine finally give up.

Well done on the shipping / finding one. When you get it, check the backlash on it and tighten if required. Mine having come out of an Auto N/A 280ZX with 90K miles on it, was unbelievably unworn. I didn't even change the bearings. I'm hoping you will find the same. The NA ZXs weren't particularly torquey or high powered and the R200 is a very strong diff so I would be interested to see if yours is also in the same state.

Three thoughts remain:

1. I flushed mine with some sacrificial oil to make sure it was totally clean
2. Use Hylomar Blue Gasket sealant on the cover (@Huw advised this and I have to say he was spot on)
3. Depending on what you intend for the car or your budget / driving style, this may be an ideal time to drop in a Quaife LSD. I now regret not doing it when it was off the car (I can easily light up the rear inside pulling out hard on a right turn out of a junction (but I do have quite a modified engine with adjustable Koni inserts setup to three quarters - read firm)

Nissan R200 300Z/240SX ATB Differential

The Nissan R200 280-300Z/240SX ATB Differential is the perfect upgrade of choice for car owners and motorsport competitors looking to improve their vehicle’s traction.

shop.quaife.co.uk

Good, that's the consensus I'd picked up on too.

My 4 speed doesn't feel great even with the new bushes and crunches going into reverse, so I think its days may be numbered. I will change the oil in the short term though. 5 speed and diff swap won't be for a while.

OK thanks, how do you check the backlash? Can that be done with the diff off the car?

Thanks for the tips, will have to find this thread when the time comes!

LSD would be nice, but this car will be stock power for quite a while I think! I can always do that in a few years - and there will always be a market for the 3.9 gubbins from this one I guess.

Mine came out of a manual N/A '81 280zx with 70k on the clock. Seller said it was nice and quiet in use, but we'll see when it's here. He did crack it open and sent me some photos but I don't know if you can tell much from them!

 

[AliK]

The factory service manual has a procedure for it - so I won’t write an essay here

But yes you have to do it off the car.

Sounds like you’re going to end up with a decent diff without too much wear - fingers crossed. Nothing I can tell you from photos - you have to measure the backlash when it arrives using a dial gauge and some engineer’s blue in the teeth.

Keep us posted!

 

[Robotsan]

Okey doke, we shall see then. I'll get back to you in October

 

[Huw]

OK thanks, how do you check the backlash? Can that be done with the diff off the car?

Unfortunately no, I would suggest to check the backlash you really need the unit isolated from the drive train. Much easier on the bench.

On the LSD upgrade, best Upgrade I’ve ever done.

https://zclub.net/community/index.php?threads/r200-diff-quaife-atb-lsd-conversion.27184/