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Rb30/25 Diff Ratio

B0oStEr
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B0oStEr Mentor

B0oStEr

Posted
Posted

I've been costing a rb30/25 conversion for my r32 gtst and I reckon I should allow for a taller diff ratio to use the extra lowdown torque.

What diff ratios are available that will bolt into the r32 gtst?

What ratio are the r32/33gtr diffs? Will they fit?

Would I also need to change to gtr half shafts?

Would the 3.9:1 crownwheel and pinion from the dr30 long-nose r200 fit into my r32 diff?

If it's possible who could I get to do it and what would it cost?

What other options are there?

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RB26zcar Enthusiast

RB26zcar

Posted
Posted
all i can say is a standard R32 diff has 4.11's in it. Hope that helps. NFI about 33's sorry.

Can you tell me please if the standard R32 diff (GT-R or which) is the "long nose" R200 ?

Also, is it a clutch pack diff, or VLSD ??

I'm trying to find out which Skylines came with the long nose R200 4:11 or 4:3? CLSD.

Any help is appreciated !!!

B0oStEr Mentor

B0oStEr

Posted
  • Author
Posted
Can you tell me please if the standard R32 diff (GT-R or which) is the "long nose" R200 ?

Also, is it a clutch pack diff, or VLSD ??

I'm trying to find out which Skylines came with the long nose R200 4:11 or 4:3? CLSD.

Any help is appreciated !!!

My r32 gtst has a short r200 4.3:1 vlsd

Apparently GTRs have a short 4.11:1 mech.lsd

I have a 3.9:1 open wheel long-nose r200 from a dr30.

Higher spec dr30s had mech. lsd but I can't comment on what other ratios available.

It would be good if the short nose and long nose gears are interchangable.

Has anyone tried this?

RB26zcar Enthusiast

RB26zcar

Posted
Posted
It would be good if the short nose and long nose gears are interchangable.

Has anyone tried this?

As far as I know, you can't mix and match a pinion from another set to a ring gear of another set.

They are a matched set out of the box...

B0oStEr Mentor

B0oStEr

Posted
  • Author
Posted
As far as I know, you can't mix and match a pinion from another set to a ring gear of another set.

They are a matched set out of the box...

Of course crown and pinion are a set.

Never had one apart so I'm not sure. If the pinion is part of the input shaft it cant be done.

Cubes Grand Master

Cubes

Posted
Posted

I've looked in to this obviously. :D

The standard R32 4.363:1 diff ratio is a tad short.

My stock diff has started openwheeling, its either hang off get the bigger turbo on and see how it is when the car makes power to 6000rpm instead of 5000rpm then throw another diff in.

There's a couple of options.

The R33 4.11:1 will help slightly but the better option for the rb30det in the r32 I feel is the S13 3.9:1 diff.

So.. S13 3.9:1 it is.

Often than not you can pick up a decent cusco mech. diff for the s13's for fairly cheap. I've seen them as low as $600.

Well worth it when you consider the initial price of a s13 diff then the cost of reshimming it. That would easily equal $600 if not slightly more.

Remember once you start putting some decent power and torque down one of those wheels is going to want to break in to a tyre smoking burnout as you accelerate down the road.

Mine now does this in second from 2000rpm in a straight line. :P

RB26zcar Enthusiast

RB26zcar

Posted
Posted
Of course crown and pinion are a set.

Never had one apart so I'm not sure. If the pinion is part of the input shaft it cant be done.

I guess I didn't understand what you ment in that post... Of cource you can't use a short nose pinion in a long nose diff case. The pinion is part of the shaft.

Cubes Grand Master

Cubes

Posted
Posted

Red Drifter,

In 5th what rpm does she cruise at when doing 100km/h?

Mine sits on 2880rpm. (PFC Controller)

The 4.11 diff ratio 'should' see the car using 2700rpm to cruise at 100km/h.

A 3.9:1 diff ratio 'should' see the car using 2560rpm to cruise at 100km/h.

4.363:1 @6500rpm

1st - ~55km/h

2nd - ~90km/h

4.11:1 @ 6500rpm

1st - ~58km/h

2nd - ~97km/h

3.9:1 @ 6500rpm

1st - ~61.7km/h

2nd - ~103km/h

Which is why I think the 3.9:1 is perfect for the RB30. :)

discopotato03 Grand Master

discopotato03

Posted
Posted

Hi cubes , so S13 short nose R200 is 3.9 to 1 . Can I assume that all the late R200's are the same except for ratio and the GTR's larger half shafts .

I found a few links to people who put short nose diffs into early cars and with a bit of fabrication its not too hard . I've wondered if its possible to do this the other way round (long nose in R32) to get a 3.7 under its butt .

Do any of the auto S13/14/15 R32/33/34 used a 3.7 / 3.9 . What did Nissan use on the six speed R34 GTT's ?

Cheers A .

Cubes Grand Master

Cubes

Posted
Posted

I am 99% sure the S13's run the bigger drive half shafts. The ones that run from the diff to the wheels that is.

1991-1996 Q45 Infinity has a R200 diff with 6 bolt axles. 3.54:1 Ratio

1997 - 2001 Q45 Infinity has a R200 diff with 5 bolt axles. 3.69:1 Ratio.

Cubes Grand Master

Cubes

Posted
Posted

I was under the impression all US Spec KA24's where open wheelers?

I've driven a mild S15 making around 180rwkw.. The diff's in those are awesome and very tight, well until they get hot. They do tend to open wheel when used on the circuit. :D

  • 3 months later...
RB30-POWER Mentor

RB30-POWER

Posted
Posted

I wouldn't go any lower then around 3.7:1. (higher numerically)

With the torque of the RB25/30, you don't need heaps short gearing. Its just going to make you slower and rev the fark out of the engine on the freeway in cruise conditions.

3.45:1 is probally getting a little tall for maximum performance, 3.7:1 will give you the edge over 3.45 on a mild engine.

Can't say exactly what cars have ratio's that tall from jap land, however i can give my opinion on the ratio's as i have ran these engines in VL and R31 with the above ratio's and know how they compare/perform.

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