ST-R to VR4 drivetrain differences

[MunkyWrench]

A few people have made st-r to vr4 conversions, partial or full.

Can any of those people comment on the differences, what was swapped, what was missing, driveshaft hoop?, etc?

I have a pfl vr4, so I have all the parts.

I am building an engine. It will be too much power for the ayc diff.
One option is an STR diff case with some rs or cusco gear in it.

The reason I am thinking of a whole STR and not just a diff, is that I might be able to get an STR shell in better nick than my VR4 is in.
i'd like to have a tidy project overall. it feels like i may be putting my motor in a bit a of a mule at the mo.

I have a linkplus g3 to go in, so loom/computers etc is not important.

It is really the drivetrain and suspension I am concerned with. mostly drivetrain. hence this part of the forum.

knowledge sharing appreciated.

[scott.mohekey]

You should be able to swap the drive train from the vr4 to the str, and keep the str's open diff casing with an lsd head. Most bits and pieces are interchangeable. Springs may be slightly different between the two, but shocks and suspension are identical. Oh, brakes might be different, but easy enough to swap.

[Adam.Findlay]

also i was told the transfercase has a physically smaller casing and does not have the viscous center lsd. I have never confirmed this though.

[scott.mohekey]

I was going to mention that, but I'm only sure that the transfer case on the auto st25 is smaller. I don't know about the str.

[wintertidenz]

The ST-R diff is smaller too.

[Adam.Findlay]

the diff is the same as a type v vr4 diff just because it is not ayc.

[scott.mohekey]

Only because the AYC has more going on in it, mainly the clutch packs. The actual diff in it is probably smaller than the open diff in the str. Adam has an open casing with an lsd head in it and it seems to be a lot stronger.

[Adam.Findlay]

in saying that i have never had an ayc crown wheel and pinion and a st-r crown wheel and a type v crown wheen next to eachother. as crown wheel size is the most commonly refered to "diff size" comparison

[scott.mohekey]

Neither of them are a 9 inch ;)

[Adam.Findlay]

6 inch 6.5 at most :( why i have broken 3 of them lol

[scott.mohekey]

I wonder if a 9 inch could be made to fit? I don't mean a solid axle either, I'm talking 9 inch head in a custom casing and custom axles.

[Adam.Findlay]

putting a hilux independant front, diff in out rear subframe. main issue would be ratios

[scott.mohekey]

One of the nissan diffs might be an easier fit (both space wise and ratio wise).

[Adam.Findlay]

well you have a st-r on your lawn and a r32 diff in your garage so we can experiment with fitment when im back in chch

[scott.mohekey]

Kinda what I was hinting at! Unfortunately, its an R150, so its one of the smaller nissan diffs.. an R230 would be nicer (a tad over 9 inches).

[Adam.Findlay]

r200 will be way more then enough for a 4wd setup. r230 if you did a high powered rwd conversion

[scott.mohekey]

Yeah, I was thinking of the R230 for the 1uz.

[Adam.Findlay]

ahh i see. r200 would be easier to get a lsd for would it not? correct me if im wrong but arent r200's gtr diffs

[scott.mohekey]

I believe so. I'm not really sure what comes from what, just what is roughly available.

[crazydriver81]

A few people have made st-r to vr4 conversions, partial or full.

Can any of those people comment on the differences, what was swapped, what was missing, driveshaft hoop?, etc?

I have a pfl vr4, so I have all the parts.

I am building an engine. It will be too much power for the ayc diff.
One option is an STR diff case with some rs or cusco gear in it.

The reason I am thinking of a whole STR and not just a diff, is that I might be able to get an STR shell in better nick than my VR4 is in.
i'd like to have a tidy project overall. it feels like i may be putting my motor in a bit a of a mule at the mo.

I have a linkplus g3 to go in, so loom/computers etc is not important.

It is really the drivetrain and suspension I am concerned with. mostly drivetrain. hence this part of the forum.

knowledge sharing appreciated.

Suspension isn't an issue to worry about. It's dentical and you can fit any VR-4 aftermarket suspension you like.

Rear axle isn't an issue either. If you are going to use the ST-R shell you just have to swap engine / gearbox / transfercase. That's it. Been there, done that.

[Nick Mann]

http://www.fqperformance.com/shop/index.php?cPath=22_145_372&osCsid=4823ed5f1f5d34b61af0251254855127

These guys show a couple of lsd options for the evo 7/8/9, one of them states it is for models with AYC which I assume means you can fit it to the AYC driveshafts. Either way, the price doesn't seem outrageous for what it is, although maybe I am missing something.

[scott.mohekey]

It's not clear whether it goes into the standard AYC casing alongside the AYC workings, or whether it replaces the whole unit. I can't really see the point of having it alongside the AYC system (unless I'm missing something).

[Kenneth]

I read on a manufacturer website (possibly KAAZ) that you can use it alongside the AYC. If the AYC is able to perform some degree of LSD duties (big if) it is going to work very hard if you are pushing it hard. Presumably an LSD will assist so that the AYC is able to spend more time doing its job rather than trying to be an LSD. I doubt it would be ideal to have a tight LSD though, as that could just hinder the AYC operation.

[Adam.Findlay]

i though the ayc lsd packs you buy require you to disconect ayc. so only the new lsd unit is doing all the work but woring inside the ayc casing

[MunkyWrench]

Suspension isn't an issue to worry about. It's dentical and you can fit any VR-4 aftermarket suspension you like.

Rear axle isn't an issue either. If you are going to use the ST-R shell you just have to swap engine / gearbox / transfercase. That's it. Been there, done that.

i just read your str -> vr4 swap thread. very good. and i hear (from that thread also) the alloy sub frame from the STR fits the manual vr4 gearbox. can you confirm the auto fits as well? i wasn't sure if I understood your post correctly in that thread.

suspension was all the same in terms of strength/bulkiness of arms etc?

[crazydriver81]

i just read your str -> vr4 swap thread. very good. and i hear (from that thread also) the alloy sub frame from the STR fits the manual vr4 gearbox. can you confirm the auto fits as well? i wasn't sure if I understood your post correctly in that thread.

suspension was all the same in terms of strength/bulkiness of arms etc?

ST-R alloy subframe will fit fine with either AT or MT gearbox +engine of the VR-4.

Suspension components like arms and geometry of the struts / shock absorbers is identical. Cannot say if the springrate of the OE springs may differ, as I have a coilover suspension fitted.