R200 Ratios and the DR30RS

[discopotato03]

Back again . My DR30 has an open 3.9 ratio R200 . I thought all these cars came with an LSD center . The Bluebird had an R200 3.9 ratio LSD that had the internal spacers flicked and a full set of plates fitted , I think 3 sets of active plates per side insted of 1 . The pre-load was about 67 ft lbs and too much for a road car .

My point is I want to try a 3.7 ratio diff to give the engine more to load up against .

I've noticed that when loaded down with lots of weigh ie extra diffs/drive shafts/struts/A arms/X members (basically another car in the boot) the engine basically says bring it on , more more more . Has anyone used the 3.7 ratio and what did it come out of , swapping in the lsd is no issue .

Also nearly forgot DR30 R200's can use a very expensive replacable uni joint found only in the middle of some Navara 2 piece tailshafts . I believe there is a pinion flange that is larger off I think a Z31 or a 280ZX that uses a larger replacable and cheaper uni joint . Anyone out there know for sure ?

Thanks for your thoughts A .

[V8skylineMAN]

your lsd is probably sha99ed, as far as i know all r200's are lsd(but im probably wrong, i usually am)....

just rev it higher b4 u drop the clutch, both will spin...lol

[Duncan]

my understanding is that there are non-LSD R200s as well so be careful.....anyway a 20 year old diff is pretty tired by now, may need a rebuild.

[0HR-30T]

If your DR30 was originally a non-turbo, (or has a non-turbo diff in it) then it would only be single spinner.

[discopotato03]

My car has too many std intercooled turbo bits I reckon to be retro . It is white under the bonnet and two pak silver elswhere ie no lairy decals behind the doors or black lower down .

Its more likely that it was changed in Japan after being abused or it was too good to sell with the car . As I understand it R200 LSD's are not cheap but can be fitted into later cars (the center hemisphere) . In the early 80's Nissan changed the crown wheel bolts from 10 to 12mm , early centers can be drilled out to 12mm or late ones can have 1mm thick bushes fitted to 1 or 2 bolts just to torque it up .

Anyhow I want a 3.7 open diff to put my LSD in to give the engine more load to work against . I hate the 1-2 ratio spread in the Nissan gearboxes (too wide) and there is no easy way around this . Some RB25DET gearboxes are slightly better but are very expensive to buy and substantially heavier . I'll have to look into Z31/32 NA gearboxes as I vaguely remember one of them having a 3:1 1st gear .

Gotta go cheers A .

[boj01]

R200 diffs also came in S12, S13, S14, S15 - R30, R31, R32, R33. If you investigate all the types of R200's, you should find the ideal one for your application. Being a DR30, the smaller R200's such as S13 etc will probably be your best option as the R33/Z32 diff centres are the larger type.

[discopotato03]

Not quite sure what you mean by larger type . I know S13-15 and Z32 , R32/33 use a slightly different variant (shorter snout and pinion shaft plus different mounting system) I think the basic hemisphere dimensions are the same ie carrier bearing journals and the register that locates in the crown wheel .

When I mentioned Z31/32 I was refering to gearbox ratios .

[0HR-30T]

I *think* VL turbo boxes have a 3.5 1st gear ratio? And from memory,720 ute (Z20) also had a low 1st. Personally,I feel 1st is low enough in FJ's standard!

[discopotato03]

My point exactly , FJ box is 3.32 1st and 1.906 2nd . With the wide gap the 2nd gear baulk ring cops a hiding and the engine revs are too low to pull cleanly , am currently researching into Z32 and GTR gear sets .

[0HR-30T]

Well,if that's your point exactly,you wouldn't want to go lower again with 1st gear,would you? Would it not be better to try and lower 2nd's ratio?

[Boof]

wouldn't it be better to try to raise 1st gears ratio so its closer to 2nds?? So there isnt such a big gap??

[discopotato03]

Boof yes . When I had the Bluebird (L20B bored and stroked to 2340cc pre FJT) Stewart Wilkins built me a gearbox using Aust spec 260Z mainshaft and lay gear , also converted to warner syncros . 1st was 2.906:1 and the rest the same as FJ20 . 1st was a touch tall but once rolling it was brilliant . I still have this box but unfortunately the gears are all narrow as in all early Nissan 6 cyl 71 series boxes . I reckon the FJ would kill it in short order .

[0HR-30T]

Or failing everything else,you could just push another 100hp That'd close that ratio gap up!

:jk:

[Adam_RSX]

no, another 100nm would though

[V8skylineMAN]

It would appear that some have an incorrect understanding of gear ratios. So FYI here's how it works:

for example, old mate has a 3:1 first gear a 2.5:1 2nd, a 2:1 3rd, and a 3.9:1 diff ratio.

He feels that 1st gear is "too low" (ie car hauls a55 in 1st but bogs down when it hits 2nd)

He could change the diff ratio to a higher 4.11, (higher number= lower ratio), this would give the impression of the gears being closer together, but at the same time rather than fixing the problem he is just masking it. with the downfall being less overall top end.(more torque would fix it properly though, as Adam_RSX said.)

The solution is to lower the ratio of 1st gear,(raise the number) to maybe 2.8:1

He is raising 1st by lowering the ratio, bringing 1st closer to 2nd.

Higher the number, lower the ratio.......

PS if you all already knew this then maybe i just got confused along the thread...

Jason

[0HR-30T]

no, another 100nm would though

picky picky

Cheers Jason,for clearing that up.Unfortunatly,I think Disco wants to go higher ratio diff (3.7:1) as well as tinker with the box ratios....

[V8skylineMAN]

I think Disco wants to go higher ratio diff (3.7:1) as well as tinker with the box ratios....

Yeah, i know....i was just clearing it up for someone who appeared to not get it properly....

also, i dunno bout r30's onwards but the older dattos that had auto trannys were all 3.7 ratio diff......try looking in an auto r30/32/33/34 maybe?

[Ghostrider]

Boof yes . When I had the Bluebird (L20B bored and stroked to 2340cc pre FJT) Stewart Wilkins built me a gearbox using Aust spec 260Z mainshaft and lay gear , also converted to warner syncros . 1st was 2.906:1 and the rest the same as FJ20 . 1st was a touch tall but once rolling it was brilliant . I still have this box but unfortunately the gears are all narrow as in all early Nissan 6 cyl 71 series boxes . I reckon the FJ would kill it in short order .

The answer to your diff question is 260Z, they came out standard with a long nose R200 open 3.7:1 ratio.

The gearbox might be a little different, but my sources tell me the Zed rally guys are now using R31 gearboxes behind their L series engines, just have to change and modify the bell housing.

I have an RB20DET box that I am going to set up to suit the L Series if I go that way.