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Upgrading early 90 axles


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Hi all, I have recently got myself a 1988 Nintey with it's original engine, gearbox and axles. My intention is to turn it into an off-road capable overland vehicle, it will not be my every day vehicle - more of a toy. The trips will be about 600miles on average with some motorway use, so I need to cruise at around 70-75mph but also be able to go to 85-90mph for overtaking. Off-road parts will include rocks, wading, mud pits and snow. Not in a competition environment so it will be nice and slow!

To that effect the engine is going to be replaced by a rebuilt 200tdi and I want to upgrade the axles with HD internals and lockers to have strong and reliable driveline.

I had a look to the Ashcrofts website to see what options I have but soon got confused! From what I gathered, the front axle I have would be fitted with the stronger 23 spline CVs. The rears is drum braked Rover axle.

So my questions are:

Can the front axle be upgraded with a Locker, HD shafts and flanges?

Can the Ashcrofts locker be installed in the 10 spline diff casing?

Can the same be done to the rear drum braked axle?

Chris

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9 hours ago, hurbie said:

90 mph 👀

Ok maybe that's a bit ambitious on my part!😎

But I've been a passenger in a group in their vehicles : 90s 100s and 130, with 200tdi, 300tdi and 2.8tgv, all were doing 85mph overtaking on the plains.  Granted all were on 35" and flat out.

Anyway, my query is more related to what options I got with the standard 10 spline axles, suggestions are really appreciated.

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Once you get above about 85mph in a clean 110, they start to fish tail a bit with the vortices shedding from the rear.  A 90 would be worse.  Things like roof racks and side mounted storage or waffle boards break up the airflow a bit and might reduce those vortices, but I really don’t think exceeding 80 mph in a Defender is a good idea.

For the use you describe, you need a full locker in the back.  It sounds like an upgrade to 24 spline shafts would be prudent.  In the front, again you want the 24-23 spline shafts you already mentioned and either a full locker or an ATB. By many accounts, ATB in the front is better if you are driving difficult tracks but for deep mud and rocks, the more extreme off roading, then a full locker is probably better.

Use the existing standard final drive ratio gears.  You could think about an overdrive or a a Discovery LT230 (mutually exclusive) for the long distance driving, but the Discovery unit will affect your low speed driving significantly , and knowing the Maltese roads, hills and towns, I would recommend keeping the Defender 1.4:1 transfer gears.

@Gremlin would be a very useful contact for you, if you don’t know him already.

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12 hours ago, hurbie said:

90 mph 👀

Olga has done 170 kph on the gps speedo.  145 with a empty auto transporter trailer behind her.   

 

Indeed , the Ashcroft half shaft's will solve your 10 spline problem

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The standard upgrades would be:

Front - a 24-spline diff (upgraded if you wish) and then Ashcrofts 23-24 spline shafts to work with your existing 23-spline CVS, which are the strongest factory version. HD drive members if you wish.

Rear - 24-spline diff (again upgraded if desired) and then ashcroft shafts/drive members. I’d swap the axle for a later disc-braked one first though.

A Tdi will cruise at 70-75mph, especially with an overdrive, but you will use a lot of fuel and make a lot of noise. That’s already an overtaking speed so I’m not sure I understand the need for 85-90mph.

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29 minutes ago, Bowie69 said:

Do they have speed limits in Malta? :ph34r:

Let's not go there 🫣

1 hour ago, Retroanaconda said:

The standard upgrades would be:

Front - a 24-spline diff (upgraded if you wish) and then Ashcrofts 23-24 spline shafts to work with your existing 23-spline CVS, which are the strongest factory version. HD drive members if you wish.

Rear - 24-spline diff (again upgraded if desired) and then ashcroft shafts/drive members. I’d swap the axle for a later disc-braked one first though.

A Tdi will cruise at 70-75mph, especially with an overdrive, but you will use a lot of fuel and make a lot of noise. That’s already an overtaking speed so I’m not sure I understand the need for 85-90mph.

Forget the speed for now, it isn't really important.

I'm more after the axle upgrade options.

So the front axle I should keep, my intention is to put a locker and HD shafts, my question is this: can I install the locker (diff) instead of the 10 spline diff and keep the same diff housing?

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1 hour ago, Bowie69 said:

Yes.

Just got a reply from Ashcroft, I can use the 10 spline casing as long as it's metric casing.

As for HD shafts they have for  both drum braked rear axle and early front axle with AEU2522 CV joints.

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Can't really see a Tdi sustaining 85-90mph on 35" tyres. EGT's would be through the roof, even in a cold climate.

I'd say you'd want to re-rear for 35's too.

 

As for upgrading, yes you can, when I looked last it was all fairly clear on the Ashcroft site, you just need to know what you have and read all the info, probably easier to read on a proper PC over a phone though.

What sort of off roading do you do in Malta? Is it rock crawling, if so, a re-gear would be even more of a must IMO, else you'll be slipping the clitch.

I'd be tempted to look at the Ashcroft ATB's over lockers, but depends on use and expectations.

Bear in mind, I think most upgraded diff centres use the 24 spline shaft. Ashcroft allows you to upgrade a 10 spline setup to make use of the diff centres. But you are then running a custom setup, so should something break, you won't be able to fix with stock parts. You'd need a spare of the custom shaft.

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I doubt you’d break one of the Ashcroft shafts without everything else having been upgraded first.  I can’t see anyone needing to keep spares of those.  
 

I’m all for ATBs for mild to moderate (tracks and savanna) off road and all-weather on road use, but the deep mud and rocks mentioned in the first post suggest full selectable lockers would be in order in this case. ATBs would be huge improvements over open diffs, but this sounds like it is going to be hanging wheels in the air and spinning in the clag, and full lockers will give significantly better performance there.  It’ll cost more in cash and in time to fit, but I don’t see the point in spending half the amount to get a compromised result on what is stated to be a toy rather than daily vehicle.

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46 minutes ago, Chicken Drumstick said:

Can't really see a Tdi sustaining 85-90mph on 35" tyres. EGT's would be through the roof, even in a cold climate.

I'd say you'd want to re-rear for 35's too.

 

As for upgrading, yes you can, when I looked last it was all fairly clear on the Ashcroft site, you just need to know what you have and read all the info, probably easier to read on a proper PC over a phone though.

What sort of off roading do you do in Malta? Is it rock crawling, if so, a re-gear would be even more of a must IMO, else you'll be slipping the clitch.

I'd be tempted to look at the Ashcroft ATB's over lockers, but depends on use and expectations.

Bear in mind, I think most upgraded diff centres use the 24 spline shaft. Ashcroft allows you to upgrade a 10 spline setup to make use of the diff centres. But you are then running a custom setup, so should something break, you won't be able to fix with stock parts. You'd need a spare of the custom shaft.

Maybe I did not explain myself, 85-90mph was not meant as a cruising speed, only for overtaking "slower" traffic on a motorway. Anyway, its not really important, as long as I can drive at a sustained speed of around 70mph at a reasonable eng rpm I will be happy!

As for offroad, it will hardly get any serious offroad use in Malta, it will mostly be in Sicily. Being out of the country where I'll be doing a lot of miles plus mud/rocks/snow I'd rather have something more reliable than standard. That is my reasoning.

If I understood correctly if I take a metric 10 spline diff case (not the axle), remove the diff centre and install an ashcroft locker, I will automatically get 24 splines at the diff. I can then use the HD shafts and flanges.

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1 hour ago, muzaz said:

 

If I understood correctly if I take a metric 10 spline diff case (not the axle), remove the diff centre and install an ashcroft locker, I will automatically get 24 splines at the diff. I can then use the HD shafts and flanges.

Correct.

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17 hours ago, muzaz said:

Maybe I did not explain myself, 85-90mph was not meant as a cruising speed, only for overtaking "slower" traffic on a motorway. Anyway, its not really important, as long as I can drive at a sustained speed of around 70mph at a reasonable eng rpm I will be happy!

As for offroad, it will hardly get any serious offroad use in Malta, it will mostly be in Sicily. Being out of the country where I'll be doing a lot of miles plus mud/rocks/snow I'd rather have something more reliable than standard. That is my reasoning.

If I understood correctly if I take a metric 10 spline diff case (not the axle), remove the diff centre and install an ashcroft locker, I will automatically get 24 splines at the diff. I can then use the HD shafts and flanges.

Taking this aside, you just need an up and running vehicle - no point upgrading diffs etc for this.

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6 hours ago, rusty_wingnut said:

Taking this aside, you just need an up and running vehicle - no point upgrading diffs etc for this.

Not sure I got you, why not? At the least I may save myself a couple of winching sessions. 

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  • 2 weeks later...

Look like I will need to upgrade sooner than I thought.

The other day while parking on reversing I felt a clonk and a judder, didn't think much of it at the time. Next morning it would not drive off! Slid underneath and noted the front propshaft spinning. Put it in difflock and I could drive it however although I could not hear any grinding noises the steering was locking up at certain angles.

I suspect the front diff is gone.

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Yep, sounds like a broken CV joint to me too, but I’d not 100% rule out the diff.

Jack up the front end and try to pull the wheels from lock to lock, feeling and listening for anomalies.  Spinning the wheel over by hand with a bit of steering input should cause a click-click-click from a bad CV.

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On 4/25/2023 at 7:34 AM, rusty_wingnut said:

Taking this aside, you just need an up and running vehicle - no point upgrading diffs etc for this.

This ^^^

Remember that your truck is 35 years old and is likely well worn. Reliability isn't always about upgrading stuff, but having equipment in well maintained and serviceable condition. With this thought you would be well advised to examine to entire drive train and replace anything that is past its best, from the engine down to the wheel bearings and hub seals, but not overlooking things like the cooling system as well.
After this I always recommend the 'drive to arrive' approach, not just in terms of road safety but mechanical sympathy too. Landrovers require a lot of effort to drive at a sustained motorway speed. My V8 110 can exceed 85mph if I want it to, but it's a bit of a hair raising experience. Cruising at 60-70 however is very notably more relaxed for the driver and less likely to break the vehicle, not to mention the reduced fuel consumption. If you want to burn up the motorway a German barge would be a far better tool for the job :) 

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5 hours ago, mickeyw said:

This ^^^

Remember that your truck is 35 years old and is likely well worn. Reliability isn't always about upgrading stuff, but having equipment in well maintained and serviceable condition. With this thought you would be well advised to examine to entire drive train and replace anything that is past its best, from the engine down to the wheel bearings and hub seals, but not overlooking things like the cooling system as well.
After this I always recommend the 'drive to arrive' approach, not just in terms of road safety but mechanical sympathy too. Landrovers require a lot of effort to drive at a sustained motorway speed. My V8 110 can exceed 85mph if I want it to, but it's a bit of a hair raising experience. Cruising at 60-70 however is very notably more relaxed for the driver and less likely to break the vehicle, not to mention the reduced fuel consumption. If you want to burn up the motorway a German barge would be a far better tool for the job :) 

That's my aim, I'm upgrading the axles for this reason, as you said it's 35 years old and the maintenance is schedule is dubious. I'm not after speed, I want to be able to cruise at a decent motorway speed without fear the drivetrain might blow up. Case in point what just happened, the diff or CV joint let go. Will be included in the list from Ashcroft.

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On 5/5/2023 at 8:53 AM, Bowie69 said:

Steering locking up will be a CV normally, not the diff.

Spot on, Bowie.

Took both swivel housings apart. Found both of them bone dry and if they were once serviced they had oil not grease. The driver side was good, no wear or play in the cv joint, took the cage and balls apart - no significant wear marks. Swivel ball is good with no pitting at all.

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The passenger side is another story! The cv joint disintegrated inside the hub. Pieces of the cage and balls got wedged between the swivel housing and swivel ball, scoring the ball and probably the reason why the steering got stuck. It also has some severe pitting on the chrome. The top railko bearing and pin is rusted and worn, the bottom bearing damaged. Half shafts are both good.

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At this point I'm not sure if I'd be better off finding a good used axle rather than repairing it as the parts cost is not going to be cheap!

 

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