Skyline R31 Back Axle

[trsforever]

Hi, I have been looking for an alternative back axle assembly to replace the 4 speed unit and there have been comments previously about a R31 skyline being a good fit, there is a car for sale in NZ at the moment with one.
I would like to find out what ratio options there are, do they all have LSD centres, what the overall width measurement is, do you need to modify the fuel tank for clearance and are there any members that have pictures or info for doing this mod re jigs etc.
Thanks.

[Cobber]

The Oz made R31s ran a Borg Warner diff, basically pretty much the same diff (mechanically) as shit loads of Oz built Fords, Holdens etc.
Just some of the common ratios for these are 3.23:1 3.5:1 2.92:1 2.77:1.
Its relatively easy to put in a LSD centre. A diff spreader tool makes it easy.
Changing ratios is a bit of buggerising about. ( setting the crown wheel and pinion)
There are 2 pinion and stronger 4 pinion centres about.
The main difference with the R31 is the width (disc to disc) and the mounting points.
Just get the R31 assembly and trot off to your friendly local diff expert and get him to stuff the desired ratios and 4 pinion LSD centre in to it.

[Hasbeen]

The Skyline has the slippery diff as standard, & the other advantage is they come with disc brakes as standard as well. Only single pot, but they work with the same balance as the stock drums. The width is a few millimetres wider, but drops straight in with 7" alloys.

I fitted one to the 8 after my son had torn the centre apart on 4 stock diffs, 3 in a couple of weeks on one leave. This when the 8 was only producing about 175 BHP to the wheels. It now has 280 at the wheels, & he has not broken the diff.

They are 5 stud, but we redrilled the flanges with Triumph 4 stud pattern as we have nice alloys with Triumph stud pattern.

The stock Skyline diff came with a 3.08, which we find perfect for road driving, with the high compression Haltech computer controlled 4.6L V8, but any HSV ratio will suit.

HSV slippery diff centres were cheap at the time so I fitted a new one. It has only done 15,000 kilometres, but is trouble free so far, but not bad with my son driving it.

Hasbeen

[Hasbeen]

One word of warning, the Pintara had the same banjo with a lighter centre & axles. I don't know if they have the discs. Just be careful it is the skyline diff you're buying.

Hasbeen

[trsforever]

Hi, Thanks for the reply's, Hasbeen what does a Pintara look like as I don't think we have them here in NZ unless they are called something else?
I have heard that the Borg Warner LSD is a cone type and not that good any comments? this is not going to be a race car just a bit of fun.
Thanks, Scott.

[Hasbeen]

HSV use them in the hot V8 Holdens. 1.7+ ton of car with 500+ BHP.

We have had no problem, even with the loose nut behind the steering wheel, we call him Richard, my son, in the 1100KG, 330 BHP TR8. For a cost effective performance modification, they are hard to beat.

The single pot discs balance nicely with the 4 pot Volvo discs on the front. I couldn't be happier.

Hasbeen

[trsforever]

Hi, I have managed to find a R31 Skyline axle from a Station Waggon with 3.89:1 ratio, but sadly no LSD centre, But am on the track of Borg Warner cone type unit.
Hasbeen I see what you mean about the strength of these 28 spline axles, they measure 30mm at spline end compared to the 5 speed/SD1 axle's only 24 spline and 26mm dia. and the there is the good old 4 speed axle @ 20 spline and 21mm dia.
I think I have seen photos on here of a jig that was made to locate the pickup points etc. for one of these but can't seem to find it any where, could someone steer me in the write direction please.
The other thing I am trying to find info on is the working of the cone type LSD as to weather it has preload like the clutch plate units fitted to early Escort rally cars or a ramp system that locks under load when one wheel starts to spin.
Thanks for any help.

Scott.

[sydney.wedgehead]

I think I have seen photos on here of a jig that was made to locate the pickup points etc. for one of these but can't seem to find it any where, could someone steer me in the write direction please.

Rodney Wells in Victoria made jig to suit his Toyota UZ engine conversion. See TR7 V8 and Rover Differential, Rear Axle, Specific: viewtopic.php?f=4&t=16058 and related posts.