Thread: Series 3's and aftermarket diff lockers

Originally Posted by isuzurover

True...
Even if you could fine one, you could probably get a lockrite for a similar amount.

The salisbury model seems very strong, but if you get a rover one and something breaks...

Isuzurover would you seriously recommend someone to put a lockrite in a rover diff? The company that made them even realized how bad this combination was and stopped selling them! All the extra loads of a diff lock without removing any of the weaknesses of a rover diff!

As for something breaking in the rover diff lock, the only thing likely to break is taking teeth of the crown wheel, which shouldn't cause any issues with the diff lock. My brother had an ex-army 2A LWB with 253 V8 and bolt rear diff lock. When he put the 36" Silverstones on it, he started breaking crown wheel and pinions left right and centre, none of these failures resulted in damage to the diff lock. Eventually he put a McNamara hypoid diff in the rear with the same bolt operated diff lock centre and that stopped all those issues.

Originally Posted by navigation2000

I'm interested in acquiring a McNamara bolt type diff lock for the rear of my series 3 ex army.

Question though, I've seen mentioned elsewhere, about "fully" locked, meaning both front and rear diffs. Is this the go?

I can see the advantages of locking the rear on it's own, but is it really necessary to lock the front as well? Fully locked would be pretty awesome I reckon, depending on terrain of course.

Dunno if I'd ever "need" "fully" locked.

Any advices?

It's a bugger that you have a Series 3, as I have one to suit a rover diff in a vehicle that I'm no longer using, but your vehicle has a Salisbury, so it's no use. If you want to lock the front diff, you either need an auto locker like a detroit or an air/vacuum operated as they never made the bolt diff lock for the front axle as I don't think it would work as the it was make the uni joint on the axle go out of alignment with the king pins.

Depending on what you are doing will depend on whether you need a front diff lock or not, just a rear diff lock will make a big difference to the vehicles capabilities.

Originally Posted by cmurray

Isuzurover would you seriously recommend someone to put a lockrite in a rover diff? The company that made them even realized how bad this combination was and stopped selling them! All the extra loads of a diff lock without removing any of the weaknesses of a rover diff!

As for something breaking in the rover diff lock, the only thing likely to break is taking teeth of the crown wheel, which shouldn't cause any issues with the diff lock. My brother had an ex-army 2A LWB with 253 V8 and bolt rear diff lock. When he put the 36" Silverstones on it, he started breaking crown wheel and pinions left right and centre, none of these failures resulted in damage to the diff lock. Eventually he put a McNamara hypoid diff in the rear with the same bolt operated diff lock centre and that stopped all those issues.
.

What size are the axles/splines in your locker? Does it have a completely new centre? Or just a new cross shaft? 2-pin or 4?

As you yourself stated, in rover 4.7s, the CW&P usually breaks first. I have broken 2 rover 4.7 CW&Ps, but never broken a diff/hemisphere. IMO many diff breakages in SIII and later vehicles are actually caused by the circlip falling out.

Given the above, IF I was using a rover rear in a series, and IF I wanted the cheapest option, I wouldn't have a problem fitting a lockrite.

Originally Posted by isuzurover

What size are the axles/splines in your locker? Does it have a completely new centre? Or just a new cross shaft? 2-pin or 4?

As you yourself stated, in rover 4.7s, the CW&P usually breaks first. I have broken 2 rover 4.7 CW&Ps, but never broken a diff/hemisphere. IMO many diff breakages in SIII and later vehicles are actually caused by the circlip falling out.

Given the above, IF I was using a rover rear in a series, and IF I wanted the cheapest option, I wouldn't have a problem fitting a lockrite.

You've got to be kidding me! A lockrite just replaces the planetary and sun gears in your existing diff carrier! They didn't even replace the cross shaft! So you still have issues of the carrier allowing the crown wheel to flex away from the pinion, which causes teeth to be broken off the crown wheel! Plus all the issues around the cross shaft. Installing into a Salisbury is ok as the standard diff is not really a weak point, but in a rover diff, they do not remove any of the weaknesses in the diff.
I have broken one rover diff, which was in the front of my 90, and the cross shaft ended up in 3 pieces, and I didn't think I was giving it a hard time.
I have seen a rover diff in a 2A shorty let go when the cross shaft in the rear diff snapped in two. I've also seen the actual carrier fail in the rear diff of a late 70's Rangie, it tryed to spit what was left of the planetary gears out of the rear of the housing.
The bolt operated diff lock comes with 24 spline axles and is a 6 gear hemisphere as opposed to the rover 4 gear hemisphere. The one thats fitted to the my old 86" never gave me an issue. I can remember axle tramping my way up a hill in 1st low, no issues at all, I can remember thinking while I was doing it that I was glad I had the diff lock in the back, as without it, the rear diff or an axle would have broken for sure.

I agree - A lockrite is the probably the weakest option. But it doesn't make anything weaker than it already is - i.e. you aren't going to be breaking more CW&Ps (may put more stress on the cross shaft). So they may be an option for some - i.e. people with a gentle right foot and standard size tyres - that haven't even broken anything with a standard setup.

A lockrite costs about $300? (from US). A detroit is what - $800? An ARB is about 1.1k and a McNamara (air) is about 2k? If you have a lockrite in a series 4.7 (rover) diff, replacement halfshafts, CW&Ps, and diff cross shafts are dirt cheap. So if you are happy to replace those if/when they break, then that may be an option for some.

The original poster sounded like they wanted a cheap option - as probably do others who have a series and don't want to spend lots of $$$ for a locker. You only have 1 McNamara locker, and by the sounds of it a few takers. It isn't like they are common. However - from what you have said, they sound quite strong - I didn't realise they supplied a whole new casing/hemisphere with the locker.

Personally, I prefer manual lockers (MD/ARB/JM), and wouldn't run an auto locker. But I also wouldn't run a rover rear diff either.

If I had a series shorty that I wanted extra traction for on the cheap, I would modify the axle casing to fit toyota 8" centres, and cut down some toyota 1.3" 30 spline axles to suit. If you wanted to be really cheap, you could even run shimmed toyota LSDs...

Originally Posted by cmurray

You've got to be kidding me! A lockrite just replaces the planetary and sun gears in your existing diff carrier!.

Have to agree here, the Lockrite merely cams on the original cross shaft

You'd be a fool to fit one to a rover centre and I've fitted them to a few things

The cross pin nor carrier can handle to punishment of a lunchbox locker

And cross pins break alot, because they snap in half, aswell as missing circlips, flogging pin centres in the carrier and just general crap materials/design

I've probabaly broken more rover centres here than most

Originally Posted by rovercare

Have to agree here, the Lockrite merely cams on the original cross shaft

You'd be a fool to fit one to a rover centre and I've fitted them to a few things

The cross pin nor carrier can handle to punishment of a lunchbox locker

And cross pins break alot, because they snap in half, aswell as missing circlips, flogging pin centres in the carrier and just general crap materials/design

I've probabaly broken more rover centres here than most

Agree 100% - however you have(/had) a lot more HP than most

However, for someone in a series with 50Hp on a GOOD day!, pizza-cutter wheels and a pile of spare diffs and axles (series bits are usually sold for scrap value...)...

Originally Posted by isuzurover

Agree 100% - however you have(/had) a lot more HP than most

However, for someone in a series with 50Hp on a GOOD day!, pizza-cutter wheels and a pile of spare diffs and axles (series bits are usually sold for scrap value...)...

Had

But I wrecked most in the stockers I bought to wreck

Don;t think you could find a lockrite for a rover centre anymore

Jacmc, bolt operated locker is very retro

Mates old man had one in a 2A 30 years ago, with a 225 slant then 265 hemi

So, if i do manage to get my hands on a mcnamara bolt-operated diff locker, i should look into some more heavy duty axles to go with it? is the rover centre on the SWB series III up to the challenge?

This is all new to me, having only had the old girl for about six months and just looking into things now.

thanks everyone for your input, its awesome to have this kind of knowledge on tap for a novice