World's simplest 4x4 diff lock: McNamara Diff Lock

[@geoffvdw]

simple, ultra-reliable setup. nice one.

[@Lutz101]

Like the simplicity/ruggedness even though it's slow to engage/disengage. I'd use a ring wrench or ratchet wrench over an adjustable wrench.

[@davidrussell8689]

I was told the ajustable spanner was called “ the nut fucker “ 🤣but when I open the tool chest my hands still go for it 😂

[@timmcooper294]

I remember these from the 1980's ! A friend of mine got one for the Salisbury type rear diff in his 109" It was a pain to import to the USA back then ! I thought it was really cool. Later, about 25 years ago, another friend got the same type. These Salisbury versions upgraded from the standard 1.240" Salisbury 24 spline shafts to a much larger 1.500" 23 spline (early Dana 70 pattern). Oddly, the locking control was on the LH side !! This unit is still going strong behind Chevy V8 power. The smaller unit shown here uses the standard 1.240" Salisbury 24 spline pattern with a special 4 pinion differential carrier. Some of these were cast as all new third members that also used a Toyota ring and pinion. I still have an advertisement for those that I got about 1988 !!

[@vinceess4181]

Stoic Donkey You named my new truck.

[@Thiswasmeanttobeeasy]

I remember when these were around, not quite common, but you would see them from time to time. I always thought you turned the big hex, but never saw one operated.

[@gs188]

This is an interesting idea, though the explanation of how it works at the diff end doesn't quite make sense to me and I'm wondering if its entirely accurate? It would be interesting to see this half shaft removed. I'm kind of suspecting it actually works by having a slot in the end of the shaft to grab the cross pin inside a standard Rover 2 pin diff, rather than being able to somehow pass right through the diff centre to engage on the other side (most diff locks actually work by locking one output sun gear to the centre, not both outputs together, as this would still lock up the planet set and is much easier to do given the whole centre has to rotate and the cross pin being in the middle). Doing it this way, whilst a bit crude and probably not mega strong when locked would make it very easy to fit to a stock diff by just changing the shaft and drive flange which seems appropriate for what is claimed to be a cheep simple upgrade which rebuilding the diff centre would not be. Upgrading the Rover diff centre using Salisbury components also sounds dubious. The Salisbury diff normally found in the back of a 109 or 110 is a 24 spline design based on a Dana 60 crownwheel and centre which is simply massive compared to a Rover diff so I can't imagine anything could be swapped between the two. The Salisbury is a 4 pin design with a giant crosspeice in the middle to support the 4 planet gears so there's even less chance a halfshaft could slide through a Salisbury centre. Of course there are smaller Salisbury diffs out there that were fitted to smaller cars which are also of Dana design (25, 30, 44 etc) so its possible this alleged 16 spline setup features bits from one of them rather than the Land Rover Salisbury but I would be surprised if any Salisbury bits fitted a Rover diff without a lot of machining as the whole diff layout including crownwheel and carrier bearing offset is quite a different shape to a Rover. Would love to know more about the innards of this one!

[@husq2100]

I’ll add to your comments with what little I know. The half shaft/axle shaft , from old images I’ve seen looks to be splined similar each end. I suspect that it simply slides into and engages the centre of the custom cross shaft that the 4 pinion gears rotate on. Many diffs use two rebated overlapping cross shafts but some use one piece with a larger centre section. I imagine this is what is used. I’ll also guess that a Dana 44 carrier was used as these would be about the right size given crown wheel size of both the D44 and Rover diffs. While 16 spline was a Dana application the photos I’ve seen of the McNamara half shaft for these lockers looks much more like 24 spline each end…I think he just got that wrong, like the 8 spline comment.

[@husq2100]

It seems quite a few here have misunderstood the operation of this differential. Unlocked it is a regular operating open differential. Locked it is a fully locked differential. It does use a custom 4 pinion diff carrier/hemisphere that bolts in the Rover housing. As a side note, most Series were 10 spline , except the Salisbury versions which are 24 spline. There is a bit of both in front ends and rears but Salisbury were 24/24 (diff and drive flanges ) from start to finish.

[@ivorscruton5121]

Interesting concept, simplicity has a quality of it's own. A little inconvenient for some perhaps, but how often would it be utilised. Had factory cable lockers on two Land Cruisers, a HJ61 and BJ71, they were more reliable than electric or pneumatic type.

[@Bigcountry_littlelegs]

Wish they had of made these for Toyota's and Nissan's, great video

[@rustyshackleford6092]

Very interesting - I have never heard of a McNamara locker. Thanks for explaining how it works - I love old mechanical tech. Do you have to remove the bolt from both sides then? Or why only one wheel? I guess I don't understand that part. Lastly - I was saddened to hear "if you can find one" :-( Pity no one manufactures this product any longer. I guess if it lasts 45+ years, they can't sell enough of them in our modern era of quarterly profits driven greed.

[@Altera_Industries]

Probably the same Macnamara who built a better Air locker and sold it to TJM (the now Pro Locker) His son has a youtube channel and it has some good content Neville Macnamara Differential Specialist is the channel name.

[@pdv76]

@@Altera_Industries Great locker design, I have them back and front in my 80 series. I just wish they made them in both ratio breaks for Dana 44s like they do for Dana 60.

[@Youtubecensoredmyusername]

7:23 using a crescent wrench backwards

[@michaelwittmann2644]

I'm new to this channel, and I'm going to call you a Top Man! This is a wonderfully presented video. Voted & Sub'd👍😎. Greetings from England. P.S. Who remembers Major Leslie Hiddins AM, aka "The Bush Tucker Man" and his 110 Land Rover and trailer?

[@Mick-l7p]

Nice to have.. ive got one in my s3 swb.

[@leahheffernan4644]

right audio only

[@m1cxf]

Same effect as welding the diff gears and fitting a freewheel hub.

[@husq2100]

Not at all…

[@The_ElunduExpeditionProject]

I don't understand how this system locks the differential. From what I see, what it does is engage and disengage drive to the wheel just as a freewheel hub does except in this case it is engaging and disengaging at the differential and not in the hub at the wheel. Please explain how this locks the differential. Enquiring minds want to know.😁

[@jhoncho4x4]

Since many components of the Salisbury axles were copied from Dana axles, is it possible to build a Dana and add the Salisbury Locker?

[@husq2100]

Given the axle housing is set up to suit wheel track, spring placement and other things, it’s much more common for people to upgrade their Salisbury housing with Dana internals. D60 CW&P gives more ratio choices and there are options with D60 carriers (diffs) . Though you can buy air lockers, vacuum lockers and ATBs for the Salisbury. D60 parts will allow and upgrade in axle shaft size as well but this will mean custom stub axles, axle shafts and flanges. Of course the D60 stuff is all imperial while the Sals 8Ha stuff is metric, so again custom work is required. The downside to our LR Salisburys is the wall thickness in the axle tube and the axle shaft size (and corresponding parts)

[@timmcooper294]

Back in 1992, I built a Dana 60 front axle to match my Salisbury rear. The 8HA Salisbury is basically a Dana 60 centre with metric fasteners, and I swapped a factory series Land Rover Salisbury 4.70 ring and pinion into my custom front Dana 60!!

[@timmcooper294]

@@husq2100 Not all Land Rover Salisburys are thin tubes. Certain random Leaf sprung 109" rears have 10MM thick tubes, and the leaf sprung fronts are all thick tubes. The coil rears are stupid thin tubes !! I never understood that !

[@husq2100]

@@timmcooper294 hi Timm, firstly love your work over the years and have been following your recent endeavours with your group of friends 👍👍 The whole LR Salisbury situation is an exercise in poor engineering IMO. If they were never going to offer larger shafts than 24 spline the D44 would have been more than up to the task, had better ground clearance and less unsprung mass. And it really is disappointing the tube thickness in the coil sprung variants given the beauty of the cast in A frame ball joint mounting point. I’m currently in contact with Jesse regarding your new HD Rover diff replacement for a custom project of mine. I’m also curious how you go about fitting 40 spline stuff in the LR hubs lol. Anyway, I hope you and your family have a good Christmas mate.

[@theyetti8811]

Now I have to Google an internal diagram to see what is actually going on inside.

[@hughbatchelor8599]

Is there one on each side or do you only engage it on one side?

[@championn3c574]

This isn't to disengage the diff, it's to lock it. As I understand it, there's an overlong halfshaft on that side of the car which normally just engages with the R/H diff side gear. When you remove the bolt, a spring pushes the halfshaft through the centre of the diff so it engages with both diff side gears, so locking the diff.

[@noelfrankland9060]

YES IT WAS A GREAT DIFF LOCK I FITTED ONE TO MY 1980 SERIES 3 LWB THAT WAS THE BEST LANDY I EVER HAD I HAD 22 2A LANDYS MANY I FITTED WITH HOLDEN MOTORS THEY WERE TOTALLY USELESS GUTLESS MOTORS FINALLY WOKE UP AND PUT A 4.1 CROSSFLOW ALLOY HEAD FALCON ENGINE BEST CONVERSION EVER. GREAT ECONOMY AND AWESOME POWER. WITH THE JACK MCNAMARA DIFF LOCK WAS UNSTOPPABLE

[@craigtomkinson2837]

Lovely ep and setup, My dad had ten brand new SWB land Rovers in a row, From the first ones bought into QLD in the late 40 or early 50s to the 80s, I learnt to drive in one of his 4wd around 1970 onwards, Then Dad saw the light and bought a Toyota and never went back to LRs, I owned a series 2a could not sell it quick enough. and owned Toyotas from then on,

[@edwardlloyd2430]

Another yellow puddle in the sand.

[@78a67h]

I presume you are referring to FJ-40 Toys. Based on your 1st hand experience It would be interesting to see a comparison you can make of the 2 vehicles with pros and cons either side.

[@craigtomkinson2837]

@@78a67h Yes my brother had a new FJ40 with 2f 4lt motor brillant 4wd, but a tad thirsty, , Dad had the near new SWB 2,3lt Rover was the Leyand one what a heap of shirt it was motor was rebuilt in a couple years was hot stunk of fuel and gutless, And the steering was all over the shop, Toyota was serpera in every way, Then he bought the first diesel 3,6lt HJ45 or 47 that was a awesome 4wd. and many more toyotas after that, our neighbours had the later Rovers they seems fine,

[@JohnDavies-u9z]

There has to be some modification to the Diff itself for it to still work as a diff should in normal use otherwise I am sticking with original conclusion.

[@will7its]

So they grow on gumtree's??? 🤠

[@Mat-hh6hj]

If only the still made them

[@garthrichert5256]

Dear Geoff. From what I see, you are just pulling the half shaft out of engagement with the diff and and allowing the wheel to roll freely. That's just like a free-wheel hub Perhaps I have not understood how it actually locks the diff.

[@brunoterlingen2203]

Same here, there is no true explanation, a white-board would have helped.

[@overlandready]

interesting unit, but the large lump on the outside I bet got hit a few times. the Rover axle is 10 spline on Series, 4.1:1 raito, and the later Rover diffs were 3.54:1 and can be swapped out. The Defender were 10 spline to late 93 and then went to 24 spline. Salisbury axles were mostly 24 spline. So does this work with a modified ahaft and gear? when the shaft slides it goes through the diff centre into the other side gear?

[@husq2100]

4.7-1 was the ratio for the vast majority of the Series vehicles. The exception being the Series 3 stage 1 with 3.54-1 as it used the LT95 gearbox/transfer case out of the RR and 101FC. All Salisbury were 24 spline at diff and drive flange (except for the limited Salisbury front axles with a CV and the unique axles in the 101FC) All front CV axle assemblies were either one piece drive flange and stub shaft or 24 spline at the drive flange. Series 2a & 3 fitted with the Salisbury from factory had 24 spline front drive flanges as well, and late Series 3 they went to 24 spline drive flanges on all vehicles. The locker in question uses a new shaft etc. you can google it and see the parts quite easily.

[@JohnDavies-u9z]

Bloody silly idea! The only way this works is that the diff itself has to be permanently locked and when the pull bolt is in the Landy is then just one wheel drive when in normal high ratio and all drive loads are through that one wheel/half shaft. I guess it would be OK with the Stronger Salisbury axle and if Landy spends most its time on loose/gravel surface it would be fine left locked and one would only need to fit the bolt when going on hard surface.

[@robinhamilton9939]

So you saying it isn't a locking differential at all? Just a means to disengage the drive to one half shaft? If that's the case, the other half shaft would need to be permanently driven with no differential function at all .

[@alexjohnward]

No John it's conventional when unlocked.

[@arijanlesicar]

I dont understand either, if disengaged, and transfer case is in 2WD, you will have no drive, it would be like removing one drive flange on Defender. Unless differential itself is swapped for what would be a spool.

[@pdv76]

I think it locks splines that mesh the axle to the diff carrier effectively locking the diff . When tightening the bolt into the axle it must move splines past the corresponding splines in the carrier to only engage on the sun gear of that side of the diff? Or that’s how I would imagine it would work?

[@robinhamilton9939]

I could imagine splines on the half shaft which normally sit outboard of the diff, sliding into engagement with splines in the crown wheel or bevel gear carrier (I don’t know which side the crown wheel is on).

[@AquaMarine1000]

Mother said not to point.

[@johncunningham4820]

Diff disengagement on REAR axle ? Why ? Seriously , I'm curious .

[@championn3c574]

This isn't to disengage the diff, it's to lock it. As I understand it, there's an overlong halfshaft on that side of the car which normally just engages with the R/H diff side gear. When you remove the bolt, a spring pushes the halfshaft through the centre of the diff so it engages with both diff side gears, so locking the diff.

[@johncunningham4820]

@@championn3c574. How ? For an overlength Half-shaft to engage with the OTHER Side gear , One , there's a Spider-gear carrier in the way , and Two , it would have to displace the Half-shaft on the other wheel to engage that spline .

[@championn3c574]

@@johncunningham4820 Good point, the Rover diff does have a spider. There must be more too it than just Salisbury side gears in a Rover diff, perhaps a spiderless diff with an extended L/H side gear? I can't think of any other way it could work. Unless it somehow locks the R/H side gaer to the diff cage.

[@gameon6159]

I don’t trust Dave Hickman!!!!

[@noelfrankland9060]

NOT ONLY THAT JEFF IS THAT THEY WERE CHEAPER THAN OTHER DIFF LOCKS ALSO DIFF LOCKS FOR LANDROVERS WERE NOT AVAILABLE WAY BACK THEN

[@johnb9394]

it sticks out too far. it would get taken off.

[@blacksheep6888]

Put wider rims and tyres, problem solved

[@blacksheep6888]

Not shifter its a crescent wrench

[@sambeazley3900]

Nope, it’s a shifter in Australia mate

[@blacksheep6888]

@sambeazley3900 crescent wrench, is the correct terminology even in Australia

[@brunoterlingen2203]

What a PIA, too much work each time to engage/disengage. Vacuum lockers are, I think, the way to go. Please learn how to use a shifting spanner correctly.

[@78a67h]

Terribly labour-intensive and grossly inconvenient considering that you have to cancel diff-locks immediately after traversing the obstacle or else you are in trouble. I would fit a diff-lock that is easily engaged / disengaged at the flick of a button or lever whilst I am still seated behind the wheel, even if that may eventually falter after X years of service, or even permanently go open-diff than use the McNamara as you describe.

[@one1shot1shaun]

Just Cause you're not a real one my guy 🎉

[@richardvalitalo3670]

Seems a silly type of locking hub. How would it drive when unlocked? Does it drive only on the other side? That's not differentiating & would pull to one side. Dumb & inconvenient.

[@husq2100]

You have misunderstood. It is a normal open differential in the unlocked position and a fully locked differential in the locked position.

[@032254855]

isn't the rear diff still open though