Odd Ball Diffs.
EARLY Series 1 80" - 4.88:1 Casing is unique as it is longer than a Long Nose diff, rare and expensive and odd ratio V8 90s came with 4 Pin Centres, rare, fetch a premium, but beware these are at best near 30 Years old, and they do wear - hugely sometimes !
LSD units - even rarer I know of the current location of a 4 Pin LSD 4.7:1 Long Nose 10 spline diff!
The "Long Nose" Diff - Our Bread n Butter
Land Rover Diffs come in a 'range a flavours', the main ones are as follows :
This unit is fitted in various guises and ratios to all Series 1 2 3, 90s, Defenders, Range Rovers Discos etc etc
The Main Ratios are 4.7:1 for Series, and 3.54 for just about everything else....These Diffs ARE NOT all the same.
The main differences are that there is an "Imperial Casing" and a "Metric Casing", Imperial tends (not always) to be 4.7s, and the Metric tends, but again not always to be 3.54. Mixing the guts of one type into another type can be done but its not striaght forward and frankly should be avoided, and can be spendy
Some Imperial Casings and some early Metric Casings have filler plugs on the Diff Units, as the axles are sealed, later Metric have no filler plug on the Diff Casings, as they are on the Axles, .....be carefull !
Some EARLY Series Imperial Casings have a separate "Nose" which has to be shimmed, these can be spotted by a ring of bolts around the top of the casing where the Pinion seal exits. EARLY Dihfs also have locking tabs on the Crown Wheel Bolts and also some have locking wire around the 4 x Carrier Bolts.
Early Imperial Diffs Carrier Bolts are a different length and thread to Metric Carrier bolts, however the Crown Wheel Bolts are all the same ALL Imperial and Metric casings the Crown wheel bolts are UNF, as are Heavy duty replacement units from the likes of KAM and Ashcroft a improved and stronger Crown Wheel Bolt is FTC5150, these are 12.9 ton, Flanged head bolt, once ONLY use, and around £1.30 each you need 10x of them. they will fit ALL Crownwheels, however,
Heavy duty Crownwheels like KAM and Ashcroft need a Longer bolt to enagage the wide Crownwheel threads completely, the STANDARD bolts FTC3586 (early number superceed to this) are 1.25" long, the FTC is 1" long, fine for the 3.54 or 4.7 standard crownwheels - is debatable on the wider ones as the thread is .25 too short, there was a longer Flange bolt but LR No longer make it......
On Crown Wheels and Pinions every pair IS A MATCHED SET, you'll see numbers etched into the end of the Pinion and the same number on the Crownwheel back face DO NOT MIC CROWN WHEELS & PINIONS Up from differing units, they are always a Pair, and are ground & matched to each other.
Rebuilding a Imperial Casing will require different Carrier Bearing to Metric- and they are more Spendy, all Metric casing use the same carrier bearings RTC3095, if you are planning to upgrade to a Locker etc, the casings generally regarded as the "Strongest" are the Imperial OR Metric ones with "Ribs" over the carrier caps, vs the very late TD5 type casing which has a Flat Cap. If your also pegging the strength is massively increased on both, so is less of an issue
Carrier Bolts Imperial or Metric are prone to stretching and bending, most are 8.8 or less, 12.9T is a huge improvement, with Loctite !
The 4.7s are 10 spline centre, ie take 10 spline shafts, the 3.54s can be either 10 spline or 24 spline.
All Long Nose casings fit all axle tubes and are interchangeable, fitting 3.54 units to a series axle sometimes requires a dowel or 2 to be removed from the series casing. All 4 bolt flanges fit, even when like say the TD5 "Round type" look different.
3 Bolt flanges and donuts are a superb LR modification and partly involved the work of the devil, and yes you can swap over a 3 bolt to 4 bolt, BUT the 3 bolt has a spacer/ collar as part of its unit, the 4 bolt flange has a separate collar so must be fitted.
Swapping over flanges does not affect pre-load or pinion height, and can be done on the vehicle if carefull. Use a new Nyloc if is is that type, can be a castleated nut with a split pin, or even a bolt into the end of the pinion, its a LR things are designed to all look the same and then catch you out
10 spline diffs are no stronger and 24 spline diffs, both are weak as they are a 2 pin design. 24 spline shafts ARE stonger than 10 spline shafts, more later in video. Ratio wise a Rover 3.0 Coupe has 3.9:1 CW&Ps if you can find them - and you'll need 2 x of them Early Rover cars have 4.3:1
same applies !
Just to complete the abortion of bolt types, the 2 x bolts that hold the steering damper in place on a diff casing are BSF !
Thats a quick whizz around Long Nose units, now
Short Nose Diffs
This differential causes all sort of questions and queries, so lets start with
This unit will NOT fit into a Long Nose casing. The PCD of the bolts is completely different. No, don't try cutting off the mounting flange on your long nose diff, and fitting a short nose ring, a tad out of 100% alignment (which you will be) will cause major drive train issues.
NO the centres are not interchangable, more later. These differentials are fitted to P38 Range Rovers, all models, and LATE TD5 110 Rear Axles, and come in 2 flavours
ALL are just one ratio - 3.54:1. and the 2 x flavours are the cheap and somewhat nasty 2 pin, and the heavier Duty 4 Pin. MANY people have looked at using the Short Nose 4 pin centre into a Long Nose casing, it is NOT a straightforward step, and to do it properly (yes it can be done) requires a large amount of machining time, and some serious skill to get it right, however, done right it is a VERY Strong cheap unit
The Short Nose 2 pin is fitted to all P38 Front and Rear, but the 4.6 V8 has a 4 pin Rear Diff as does the 110 Rear, the 110 front diff is a good old standard
2 pin Long Nose type unit
So, that's a quick whiz around Short Nose stuff
Salisbury
Ah yes the Salisbury. Frankly I don't like them.
Consider that you have to "Stretch the casing open" just enough to get the centre out, and too much = 1 x scrap casing - I mean WTF !.
Also Salisburys are hideously expensive to rebuild (head bearing is around 8x the costs of a Long Nose unit) and there are again different ratios and Flavours, there are drum braked Salisburys, disc braked Salisburys and 4.7 and 3.54 ratios,
On 110s, a quick upgrade is to by a Short Nose late TD5 110 axle, 4 pin flvour, and prop and swap the lot over. Salisbury axles are stong, the diffs can take a lot of abuse, but the axle tube themselves are prone to shearing off where they exit the diff unit.
Pretty much nothing on a Salisbury fits either a short nose or Long Nose assembly !
Video
Diff Pegging
