GT4 to RWD?

[Mos]

Getting back on topic, there is nothing technically impossible with locking the centre diff.
The ST185s have a viscous coupling that's separate to the centre diff. This coupling can either be welded up or a piece fabricated to lock the two shafts that it engages. The centre diff does not need to be removed to be disabled.
An ST185 Rally Car (that I once owned) had such a machined component in place of the viscous coupling.
This would then provide full torque to either axle - removing the front shaft should also be technically possible.

The drive, however, would be running through two hypoid gears, which while reasonably strong, offer a non-trivial rotating resistance. As many have pointed out, the two hypoid gears (one in the read diff) aren't terribly strong by RWD standards.

So while technically possible, it isn't something that would ordinarily be considered worthwhile.

While turning the engine 90 degrees and fitting a W5* series gearbox would be the "preferred" solution, I can't fathom how that is possible without firewall/tunnel/floorpan modifications. There is a steering rack mounted to the firewall occupying the same space as a flywheel/clutch does in a RWD application that would need to be moved to another location.

Furthermore, the tailshaft housing of the transfer case on the 4WD gearbox could be considered of similar size as the extension housing of the W58; that is all the space that is afforded in the ST185 tunnel at the firewall, hence the bulk of a W58 gearbox would not be able to fit in the same factory space.

Mos

[clubagreenie]

Not that I am agreeing or disagreeing but generally a hypoid type diff is considered an "upgrade" in the off road 4WD world and considered stronger since there is a larger surface area between the crownwheel and pinion.

[Norbie]

What Mos means is the direction of the drive is being turned 90 degrees twice, which introduces greater power loss than a conventional FR setup which only does it once.

[JustenGT8]

Hey it's a Mos, i thought you were extinct? Good to see the polite post with the hidden barb is alive and well.

Does the FMIC bump your cred up enough to show your face again ;-)

Mos is also referring to the small size of the diffs? right Mos? as by any FI RWD comparison they are considered tiny and very fragile. I broke mine in AWD for with approx 200kw at the wheels. The torsen housing is a real weak point.

[Classique71]

is that when you got the TRD rear justen ??

[JustenGT8]

In the White AWD car yes ,that's when i went with the TRD rear LSD.

In the red car i blew the stock diff into tiny little pieces and had the same fear for the Super JZA70 torsen so again i went with a full TRD rear gear set and LSD.

[Norbie]

If your little display leaving the Dubbo show'n'shine was any indication, the TRD diff works quite nicely.

[Draven]

norbie - are you planning to fit an a-series diff to your bastard-hybrid, or just the v160/1?

[Norbie]

Just the transmission for now; the diff won't be upgraded unless I break it, at which point I'll seriously consider an A or B series.

[Mos]

Yep - 2 90degree changes of direction.
And yep, the hypoid is small when compared to a circa 1400kg conventional RWD vehicle.

What I probably should have said was "the two hypoids *used in the ST185* aren't terribly strong by RWD standards".

Justin - it is my understanding that the hypoid design sacrifices transmission efficiency for strength as opposed to a bevel type joint that is more efficient at the expense of strength (and noise) - would that be correct? (Vague recollection)

Justen - lets just say there's some degree of inspiration with my other road car

Mos.

[JustenGT8]

Ah i love inspiration, i'm often inspired, i believe i was inspired at the time of leaving the Dubbo Show n Shine.

This thread appears to be done? agreed?

[Mos]

Aww I wanted to post a photo of the ST185 firewall - there's one about 3 minutes away without an engine in it - thought it might be useful.

Other than that, it's done

Mos.

[JustenGT8]

Once again it's well clear what's what and what's not Mos Those that haven't figured that out will keep listening elsewhere and probably pay the price

[clubagreenie]

Justin - it is my understanding that the hypoid design sacrifices transmission efficiency for strength as opposed to a bevel type joint that is more efficient at the expense of strength (and noise) - would that be correct? (Vague recollection)

Mos.

Just so we are on the same track.

Hypoid = pinion entering high or low in the case not centre. AFAIK the surface area of the gears is far greater, for example the pinion on a F100 McNamara hypoid centre is 24mm longer than std and also larger in diameter. They are noisier though, can say from experience. I can only see efficiency changing through extra friction.

[Raceflo]

Ok the VR4 the the monkhouse boys were sliding had an specially made gear box from PPG gearboxes in it, unsure as to the modification done