Stage 12

Front Axle conversion to Toyota internals

I have only ever broken 1 front axle in a Land Rover. I have also broken a front Ring and Pinion Gear in a mate’s Range Rover [sorry Larry]. If you are anything like me you hate breaking things, especially in a competition setting.  Over the years I have used Maxi Drive Axles, front & rear and Ashcroft Axles in the front. Whilst I never broke either of these two brand axles, I have been with people who have broken them, in particular one Defender 90 driver I know, who should remain nameless, broke 3 of them in one day [Sorry Carl , but I think by now everybody worked out it was you].

In preparing the Discovery Short Ass I upgraded the rear axle to a Salisbury with whopping 35 spline axles, but what to do for the front? I had a standard set up with an ARB and 4.10 gears but standard axles just don’t like competition punishment. From my investigations I had 2 choices:

  1. Upgrade using Heavy Duty Rovertracks Axles [or MaxiDrive Axles] and Defender 110 CV’s [or similar Longfield CV's] or
  2. Change the front internals to Toyota running gear.

Option 1 above was feasible, All I’d need were the axles and CV’s which would cost me about $1,000 or so. Remember I had an ARB and the rest of the gear already. The downside was that whilst the Defender CV’s are strong they do get broken regularly in competition situations and I wanted to minimize the amount of spares I took. Also I had broken 4.10 Ring & Pinion Gears before so my confidence in them being strong enough was also limited.

Option 2 was going to be expensive, can I get away with it without telling the wife? If I sold my old axles, ARB from the front, my spare ARB taken out of the rear, the 4.10 Ring & Pinion Gears in the front diff and ARB air compressor I could raise most of the money to do the Toyota conversion. This would mean settling for a Toyota E Locker instead of the ARB. Yes a downside but I could live with it. I prefer the ARB locker as it has an instantaneous lock compared to the E Locker which only engages when everything is lined up perfectly. It also meant a lot more work and time was short.

Ok I like to have the best irrespective so I went for Option 2. Just do not tell my wife how much it cost her, I mean me.

To many the use of Toyota internals inside a Land Rover Axle housing may seem sacrilege, it shouldn’t, most of us run a variation on a Buick engine. Besides, unless you pull it apart you cannot really tell the difference.

While similar in size, the Toyota Diff has a higher Hypoid offset and much bigger Carrier and Pinion Bearings. Add to that the Differential housing is very strong, and well gusseted. These three things together make a differential that is perhaps more than 50% stronger than a Rover type. Next time you cat a change check out a Toyota 4.10 Ring & Pinion Gear next to a Land Rover set. the difference will surprise you. Even more when you choose to run really low gears.

Removing the Old Axle

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Assuming you pursue Option 1 above, Rovertracks developed a kit using the time tested Longfield Chrome Alloy/300M 30 spline CV joint [they can also get you the Defender CV's]. They provide axles, CV’s, Bushings and drive flanges. Machine work is required to fit the Toyota pattern  [read Longfield] CV to the Rover Spindle (stub axle). As part of the kit you send them your spindles or they can send you a pair already set up with your old ones being a change over after you have fitted everything up.

This part of the installation is as simple as changing broken CV’s. OK Assuming that this was all you do, now the CV’s and axles are the strongest part of the front end so what would logically break next?

The ring and pinion gears! Yes I have experienced this [Sorry Larry]. Unfortunately Land Rover differentials are not the strongest particularly when you move away from the 3.54:1 Ring & Pinion gears to say 4.10:1s or you are ambitious enough to want 4.75:1’s. What can you do? And Now for something completely different [Yes I Like Monty Python]. Put in a Toyota diff! Rovertracks can provide the same components as the Longfield CV kit [mentioned above] to fit a Toyota third member. It all comes as a kit so as long as you have an angle grinder and know someone who can weld a few studs for you it is a simple enough swap over.

In addition to axles, CV’s, Flanges and the bushings you need and get a Sewer cap diff cover and Panhard rod plus the special tools, templates and fasteners to put a Toyota FJ 80 diff in you Rover housing. They also do the required machine work to fit the bigger axles through the Swivel balls and fit your Rover driveshaft to the Toyota pinion flange, This results in a very strong front axle!

Building the New Axle

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It is all well and fine to contemplate an upgrade such as this but is it really doable by the average Land Rover Owner?. The simple answer is yes! If I can do it anyone can! Ask anyone how bad a mechanic I am and if they are being kind they will say I an almost useless. You, as I did, will need help with a little welding if you cannot weld. The rest is pretty straight forward.

To Fit the 30 spline Toyota third member into the Land Rover Axle housing is where the majority of the actual work comes in [other than the removal and refitting process]. This is easier if you remove the diff cover from the axle housing first. I used a Sawsall but a suitable cut off wheel will do the job, cut off the cover leaving about ˝” of the stock cover. I actually cut mine off flush as I had a great welder to do the welding for me hence the ˝ inch lip was not needed. In most cases leave the lip. This will leave you with a nice place to center your new sewer cap diff cover to weld it on.

Next the bolt pattern and size of bolts that hold the carrier housing need to be modified. Firstly you punch out all bar 2 of the studs [the kit shows which ones to leave in]. The kit comes with a template [that must be returned upon completion] to allow you to mark the axle housing by use of a transfer punch. Mark the Differential mounting holes on Land Rover housing. You can then bolt the template down firmly to the axle housing using the remaining two studs and punch mark and drill the new Toyota holes in the housing. Make sure you drill as straight as you can. A couple of my holes were a little off vertical which meant a lot more fiddling with Diff alignment when I was ready to put things together.

Now put the 10 supplied 5/16-24 screws into these new holes [from the inside out] and bolt them down using the non-nyloc nuts that come in the kit. Have a competent welder Tack weld these bolts to the housing with about a dime size tack on each side of the bolt. You can then unbolt and remove the template and knock out the remaining Rover studs.

The upper and lower bolts closest to the ring gear face will not be used. We welded these up however it is not mandatory and some guys who have already done the conversion run without them, your choice.

Bolt the whole thing up and make sure it fits. This is where straight hole drilling comes into play. Make sure you get them as straight as possible to save you extra alignment work. If a bolt is a bit crooked not to worry, put a couple of the sacrificial nuts on the bolt and tap it into place. The proper press in studs would be a far better option here but Keith tells me so far his efforts in locating them have failed dismally.

Next you can flip the housing over and install the sewer cap. Push (read bash with a hammer) the cap on over the lip left over when the stock cover was cut off. In our case we did not have the lip left so after removing the diff and putting it away safely [so as not to get any welding flecks in it] we just ground it all dead flat then welded the cover on fully so as to prevent leaking.  Leaving the lip makes this process a little easier and is less work. The fill hole for the diff oil should be slightly below centerline of the axle housing. With the new sewer cap front cover your diff will hold a lot more oil than before.

Make sure you clean everything up nicely and install the third member using a good gasket maker like “Right Stuff”. It is easier to bolt the diff all back together off the vehicle whereas easier to bolt swivel balls etc back once the axle is on the vehicle

If  like us, you use an E Locker from a Toyota instead of an open Toyota Diff there will be additional cutting to the axle housing and the third member holes farthest to the passenger side of the housing will need to be marked with the third member as a guide, after which they will need to be tapped for the proper threads (5/16”-18) with the tap provided [he thinks of almost everything in this kit]. An alternate for those with more money than I had, is to fit an open Toyota diff combined with an ARB Air Locker instead of the E Locker.

As for the spindles, Rover axles are 1.25” whereas the Toyota 30 spline Axles are 1.285”. Whilst the bores of late model Rover spindles are larger at about 1.28” they are still just a bit too tight. In some cases to fit the axles or Toyota CV’s the spindles will need to be bored slightly, usually .005” per side or, .010” on the diameter. According to Rovertracks this should not weaken the spindle. The front spindles will need to have a bushing pressed in, in place of the needle bearing, additionally the bronze thrust bushing on the spindle will need to be removed and the steel beneath it cut off in the lathe. Rovertracks provides this service as part of their kit.

Our swivel balls also needed to be bored to 1.375” where the axle seal is. The swivel ball seal can be retained. The axle seals in both the front and rear are omitted leaving them to run as “wet” hubs.  

How does all that sound? Probably more confusing than it actually is. The biggest jobs are removing the front end and replacing it. Cutting, drilling and welding the axle housing does not take that long and as long as you follow the provided instructions is fairly simple work.

I’ll let you know how it all holds up after the Australian Outback Challenge is over and I have recovered.  

Some of the People Who helped

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Also look out for the write up in LRM magazine