30S And Taller Rwd Diffs ?

[KiwiRS4T]

I like the look of those options there. Bob was it difficult to source?

Yes interesting but I saved it from someone elses post in case I got rich. A search might find the original poster

Here ya go:

http://www.skylinesa..._1#entry5975022

and

http://www.ag-y.com/690mission.htm

elrodeo666 may be able to source parts/boxes for you

[Simon-S14]

its really easy... if you get a r200 3.7 from s14 that has 6 bolt half shafts and your r33 has 5 bolt. then all you do is knock out thr 6 bolt flanges from the diff with a hammer and then do the same with the 5 bolt and then install in the new diff. then it bolts straight in

[discopotato03]

Would it have to be a non ABS S14 diff to suit a non ABS GTS25T ?

Also do the S14s have the same viscous hub LSD as an R33 , and the larger crownwheel bolts ?

And lastly whats the story with S15 LSDs , is the helical center a Torsen LSD ?

Cheers A .

[discopotato03]

This is an interesting thread I found over as NS.com re R200 diff ratios and diff swaps .

It seems S14 and S15 diffs may be the answer with a bit of stuffing around but sounds easier than changing crown wheels and pinions . The Silvia people are trying to go to shorter (numerically higher) diffs and using R32/R33 bits to get into 4.1 and 4.3s .

http://www.nissansilvia.com/forums/index.php?showtopic=337751&st=0

The thing I don't know is about the drivers side stub shaft adapters (5 or 6 bolt bit) as in the above thread there are pics of these stub shafts in two different lengths . I think I remember reading about these in American Nissan forums years ago and the longer stub/half shaft was a viscous center thing . Fingers crossed S type and R type viscous diff half shafts are the same length internally .

Also the crownwheel bolt diameters . I know there are two sizes in H190 and possibly long nose R200s and the crossover was probably 4 cylinder to six cylinder .

Lastly note that in the NS thread they mentioned that JDM S14s had shorter diff ratios than ADM ones , I think it was 4.1 vs 3.69 . This makes me think that had R33s been sold here they probably would have had 3.9 or 3.7 diff ratios std - for our slightly higher average speeds ?

Thoughts , cheers Adrian DP03 .

Edited July 3, 2012 by discopotato03

[XRATED]

Personally I loved my 4.3 gears....

The last set up in my little 32 before I sold it was the most fun rwd engine/turbo/gear ratio combo I had ever driven! 25/30, Trust T67 on a trust manifold, 25 box and 4.3 2 way rear end. It made 350ish rwkw, but very predictable, very chuckable and fast in pretty much any gear at any speed... I never got caught 'off tap' so to speak.

Cheers

Justin

[discopotato03]

Yep I can understand that , I screwed around with H190s in 3.9 and 4.375 with the FJ Bluebird years ago . The trouble is you virtually end up with a four speed gearbox and a low speed crawler gear - 1st .

I should look up USDM S14 240SXs to see what diff ratios they used . Obviously more torque down low than an SR20DE/T cranks out so I'm going to predict a 3.58 or a 3.69 .

Will search later , cheers A .

Actually speedo drive gears for the larger 25T style box , whats available ?

[Dale FZ1]

I loved my 4.3 gears....

25/30, Trust T67 on a trust manifold, 25 box and 4.3 2 way rear end... very predictable, very chuckable and fast in pretty much any gear at any speed... I never got caught 'off tap' so to speak.

Justin you and I are on the same wavelength here. Available torque + engine response at ground speeds from 60-190 is really outstanding. Cubes make the difference but the 4.3 gearing shows it to best effect. Installing a proper diff centre and doing away with the viscous unit was probably the best change I've made of all the mods.

The trouble is you virtually end up with a four speed gearbox and a low speed crawler gear - 1st .

Actually speedo drive gears for the larger 25T style box , whats available ?

Adrian if you run the numbers of gear ratio x diff ratio you may find that a 3.7 would tend to make 5th largely redundant except as a cruise/economy gear. Main difference in the two approaches would be which gears are used more/most frequently for a given ground/road speed range. So it's generally a matter of preference/priority.

Different box ratios appear attractive, but consider the available usable torque range from a 30DET pushing between 270-330rwkW, and close ratio sets conflict with the purpose of the engine build. I'd actually think the short stroke 25DET would benefit much more than its big brother from a closer ratio set. In either case though it is fairly cost prohibitive when you see what out-of-the-box performance is available from an Evo, without dicking around with ratio changes...

For me, the 4.375 offers almost instantaneous response in 3rd gear for slower corners on track (doesn't have to drop into 2nd in those tighter corners), and a straight shift into 4th on the shorter straights without running out of rpm. So it tends to use only two gears, and changes don't go across the gate (less chance of a miss-shift). On longer tracks 5th gear is very usable but only required a couple of times.

The 4.11 ratio seemed to have it slightly off-boil in 3rd. But the car didn't really show a lack of speed or general response - it was a change made to suit my preferences.

For you, perhaps the taller diff ratio might make a lot of sense and 1st/2nd very usable in traffic. Could be that a 3.7 diff with a 0.85 5th ratio change in the box would work well. Different application, different requirement or preference. Hope that clarifies my general thinking.

[WHITER33GTS-T]

I have a 3.7 crown wheel and pinion from a S14 but just havent got around to fitting it to my spare diff yet.

[urtwhistle]

I been quietly following your convo cos I been thinking about doing this. Not sure if it helps any 1 but I quickly knocked up the attached spread sheet. You only have to update the yellow cells to suit your config and it should tell you what you want to know.

GEAR CALCULATOR.xls

[discopotato03]

Interesting to plug a few numbers into that table , the differences are greater than I thought though the 3.9 ratio diff puts me about where Id like to be based on revs in 5th at ~ 110 - about 2700-2750 vs around 2900 . I just find my car feels undergeared and I'm always short shifting it and it pulls 4th and 5th around at low revs really easily . If an RB25 can do this then an RB30 should be able to do the same or better with slightly taller gearing ie a 3.9 .

My RB25 isn't factory and the things done to it were intended to make it a bit stronger everywhere than std . Things like its head was cleaned up by Harris and has oversized exhaust valves and was decked to give ~ 9.3 static CR , 256 cams and a GTRS . You accelerate out of corners in first and second with less than full throttle and it wants to spin the first two gears in the dry as soon as it makes any meaningfull boost . PITA if the road isn't straight and it wants a bit of someone elses lane as well , ole' goat like me gets strange looks driving one of these things when it gets a bit out of shape ...

Anyway my next searches are going to be for info on R200 crown wheel bolt sizes , I think Skylines used the larger 12mm bolts at least in GTRs all /R33s /R34s . I've seen some peope posting that S13s use 10mm bolts and the S14 and 15 turbos 12mm bolts . If I do start playing with a short nose not ABS 3.9 R200 I'd like the larger bolts so that nothing is a backwards step strength wise compared to my std one .

Cheers A .

Edited July 3, 2012 by discopotato03

[KiwiRS4T]

Interesting to plug a few numbers into that table , the differences are greater than I thought though the 3.9 ratio diff puts me about where Id like to be based on revs in 5th at ~ 110 - about 2700-2750 vs around 2900 . I just find my car feels undergeared and I'm always short shifting it and it pulls 4th and 5th around at low revs really easily . If an RB25 can do this then an RB30 should be able to do the same or better with slightly taller gearing ie a 3.9 .

Cheers A .

What ratio final drive do you have now to be doing 2900rpm at 110? Is it a 4.363 or 4.375? If so that explains why you are looking at 3.7 or 3.9 but if you are happy doing 2700 at 110 I am doing that now with my 4.1 GTR diff (which is not very different from the 4.08 Stagea diff it replaced) and 255 40 17 tyres....and both those diffs are readily available. And my RB30 pulls well from 2000 in any gear - torque now with another 5 - 8lb of boost to come (2000rpm is approx 40km/hr on this chart):

[discopotato03]

Try punching 2838 revs into that table above and you get 110.2 something revs in 5th gear , I was just going by what my gauges said which looked like 2900/110 . I'll try the table again with the 3.9 and 3.7 and see what comes up at 110 .

Partly what started me thinking about expressway cruise was driving an XR6 back from Goulburn recently and it was sitting on about 1750 revs at 110 by it gauges . I realise that these have a 4L engine and late auto but its not a lot of revs to cruise most places at 110 .

The trouble is I've never had the RB30DET experience so I'm only guessing how much extra torque they'd make in the 1-3000 rev range . If I did one I'd want every Nm I could squeese out of it in this range because getting more further up goes with the territory .

I think a 30 to my 25s spec but with a slightly higher 9.5-9.6 static CR should feel significantly stronger at part throttle which is where my car spends 85% of its time . With all else being equal I think unintentional traction loss would happen more often and its already a slight issue and thats just running off actuator pressure , actually I tkink the FC was set at 12 for the OE dryer .

Obviously I'm different from most SAUers in that I'm not looking for a million Hp just more average torque , I doubt I'd ever track this car and just want something strong enough to get in and out of the traffic and breeze down the highways .

As I said it would have been interesting to see how Nissan would have done a 33 30 combination .

The closest thing I can think of is the 2JZGTE Supras and I'll search their gearing as well .

A .

Edited July 4, 2012 by discopotato03

[urtwhistle]

Out of curiosity have any of you ever herd of some 1 fitting a EatonTrueTRAC into a R200? A mate has one of these in his IRS Falcadore and he swears by it. They are massivly cheaper than some of the Jap brand diffs.

[JonnoHR31]

Aren't the TruTrac's mechanical lockers designed for 4WDing? If it's the ones I'm thinking of they'd be good for burnouts but not much else

[Dale FZ1]

Torsen design. Same as you get from Quaife. Often found installed in BDA Escort rally cars. Quite smooth in operation ie. no clunking. Not sure how they perform in a high torque environment eg behind a 30DET, or XR6T. JZA80 Supra uses a Torsen centre and there are reports of those losing effective LSD action behind high output 2JZ engines.

Available from Quaife to suit a lot of FWD transaxle/diffs. Reputedly do best on tarmac or smooth gravel (eg rally) where the wheels are on the ground most of the time.

Probably worth a closer look for those who require OEM levels of NVH but something better than the viscous centre. Are they available to suit the R200 diff?

[urtwhistle]

Your both thinking along the same lines. They are used on some 4wd's. I have herd that they do destroy them self if you get extreme wheel hop. A mate has 1 behind his 5L that is pretty much a skid pig and it is unreal how smooth it is at locking up and damn predictable at flicking it around corners.

Harrop make alot of kits for Falcadores that use Truetrac's so they can't be rubbish. They don't list any thing for the R200 but thats not to say that it can't be done. I will try and ask the diff builder who is doing a mates 4wd.

[discopotato03]

The only std Torsen diff center I know of came in S15 200SXs .

This is an interesting article someone put up in an American 240SX forum , USDM S13s and 14 came with KA24E and KA24 DEs just in case anyone didn't know and as is mentioned they had a 4.08 R200 std .

http://www.ka24development.com/vlsd.html

Note the second pic shows two nose lengths used in "short nose" R200s , the 3/4 inch longer one has a speed sensor in the nose and uses a shorter tailshaft . I'm guessing this was for 3 chanel ABS and later 4 chanel ABS had sensors on each half shaft adapter ie 5 or 6 bolt bit .

My R33 is a 96 non ABS car and it'd be good if someone can confirm if ABS GTS25Ts used speed sensors in the front or sides of the diff . Fingers crossed its the sides because then the case lengths and tailshafts will all be the same - manuals anyway .

Again to try and sum up I think it works like this for "short nose" R200 non GTR diffs .

1) I think all short nose diffs use 12mm crownwheel bolts .

2) Half shafts are 5 or 6 hole .

3) Viscous LSD units have different length half shafts . Open center ones are same length and same spline as long nose R200s .

4) There are two lengths of short nose case and pinion , front sensor ABS and the shorter non nose sensor type .

5) The critical thing to find is the ratio you want and the correct nose length , see point 4 .

It occurs to me that once you have the desired ratio and case length the half shafts and carrier from your standard diff should transfer in easily enough which gets around the spline and half shaft compatability issues . I've been here before years ago and compared to H190s R200 are easy to pull the carrier swap crownwheels and drop the assembly back in . 200s are easy because the spacing/preload spacer shims are outside the carrier bearings outer races and you can select fit them with the bearing caps off . The only unknown is any carrier offset differences which exist in some diff families to work around the diameter differences in pinion gears . If ratio differences are set by the crown tooth count rather than big differences in pinion teth numbers/diameters the carrier offset problems aren't as great .

A .

[discopotato03]

Another article from Zilvia Net in the US .

http://zilvia.net/f/s-chassis/200226-shimming-r200-j30-vlsd.html

I would NOT do this viscous hub "overshim preload" business because I think its a cheap rather than a long term way to have a partially locked diff center . The reason I'm posting the link is because it shows in pics how to remove the carrier from a short nose R200 and how to open up the hemisphere to get to the viscous hub . Also on the second page someone posted an exploded diagram from a WSM of a 350Z short nose R200 .

I must have joined Zilvianet and was last there 5 1/2 years ago , I searched "R200 VLSD" in the S platform section and have about a weeks reading to do .

I really want to open our world up to these later R200s because most Aussies don't seem to know all the variations and what can be cobbled together to suit everyones needs - like a 3.7/3.9 VLSD bolt in for R33s . Or even aftermarket LSDs .

A .

[urtwhistle]

Hey I looked up quaife and they list a centre for the R200 but its roughly the same price as buying a Cusco. which I don't want to pay 1000-1200 for.

[discopotato03]

Sigh , I didn't want to look at GTR rear diff parts but you chase enough Nissan forums and the R vortex soon drags you in .

I don't know if this deserves its own thread but I suppose stronger/est rear diff bits goes with RB30 territory .

So far I've read that GTR R200s are short nose diffs without the ABS sensor and slightly shorter (for short nose R200) non 3 chanel ABS snout .

The main difference seems to be larger splines and stub shafts , and the 4 channel speed sensors on these stub shafts . Also the output flanges are 6 individual hole ones .

People say these can be fitted to S13/S14 and I'm guessing R33 GTS25Ts if you use GTR half shafts . Theres also talk about GTR alloy hubs which I think must be uprights that use larger rear wheel bearings . Do RWD R33s get these too but with 5 hole stub axles ?

Anyway I think it may be possible to graft a GTRs hemisphere into a GTS25Ts or S14s R200 but you have to change stub axles half shafts and not sure what else out at the knuckles/uprights .

Thoughts , cheers A .