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Anyone broke a front halfshaft?


twodoorgaz
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Hi everyone.

just something I’ve been thinking about today. Has anyone in the forum ever broke a front halfshaft on a Series II/III Land Rover?

 

While I haven’t (plenty of rears but never a front), I’m sure others have.

 

if you have broken one - can you remember if it went at the diff splines, the hub splines or in the UJ?

 

I'm curious to know whether the UJ portion of the front shafts is the weak point or if it (anecdotally) is actually less weak then the splines ends.

 

I fully appreciate that the only time the fronts are under load is when 4WD is engaged - at which point the front axle will only really be seeing half the torque from the engine.

Edited by twodoorgaz
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Brilliant - thanks both.

 

I've been gathering bits for years to assemble a really solid V8 SWB, every now and then I pop in and check on something else. The last things to get are the rear shafts and ATB from Ashcrofts which I'm about to order now they're back in stock. The engine is about to go for machining so I can dial-in as much power as I like but am trying to set sensible limits on torque - I'm aiming for "would Land Rover hand done it on a regular production vehicle" rather than "it'll be OK if driven sensibly". I only need a little and a standard 3.5 V8 is usually plenty for me in a SWB Series but I want a very balanced, torque-appropriate drivetrain behind it.

 

  • I have a 9.5" clutch (300TDI had the same size and 195lb-ft)
  • A suffix L stumpy 050A ratio R380 with a Milner adaptor ring and custom input shaft (allegedly good for 380NM, but known to be fitted to a 4.0V8 with 250lb ft)
  • Standard SIII transfer box with Ashcroft kit (allegedly fine behind even big American V8s so plenty for any RV8)
  • Shortened rear prop and extended solid 3.9 RR front prop (fine for everything)
  • (to buy) Ashcroft 4-pin 4.7 ATB (no idea, but can handle a lot more than I want to put through it)
  • (to buy) Ashcroft uprated 24/24 rear halfshafts (again, no idea but can handle a lot more than I want to put through them)
  • Standard front 4.7 diff (fine for 124lbft in a standard series in the rear when in 2WD, so logically should be OK for double that torque in the front axle, given torque will be broadly halved)
  • Standard 24/10 LWB front shafts - I really wasn't sure about these hence the question.
  • Heystee front swivels and 8" servo allowing me to fit a full Defender 200TDi brake system. A similar setup was used on the 180 BHP NAS110 V8s (disc/drum) as well as on pre-defender 90 V8s.

 

Going off the above comments, I'm leaning towards making a set of (dangerous) assumptions:

1) if the front shaft doesn't tend to break at the UJs then given they're broadly the same thickness as a rear, then I'd assume a similar torque capacity in the fronts as the rear. If anything, they're shorter and would flex less.

2) The rear shafts take all 124lbft in a production SWB 2.25petrol when in 2WD

3) if the fronts are no weaker than the rear then this means they'll take a vehicle producing 248lbft when split 50:50 between the two as they'd only ever 'see' 124lbft..

 

The goal was to identify the weak point in the drivetrain, which I think I have with the clutch (proven in production to 195lbft). Which is great as that's more than enough for me and I'll send the 3.5 block away knowing that even with EFI it'll barely crack 195-205lb/ft and that every drivetrain component should (in theory) be well within their design limits and if I want to push it a little then I can just fit an uprated clutch to bring the capacity of the new system up closer to 240lb/ft - leaving a nice 20% buffer for those inevitable oops moments.

Edited by twodoorgaz
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ATBs aren’t 4-pin; they don’t have cross pins at all.  They used paired scroll gears parallel to the half shafts and the side gears are regular helical gears - there are no bevel gears at all.

The idea that the diffs will only be dealing with half the torque is not really correct at all.  Off road, you could be putting all the torque through the front diff if the rear has little or no grip.  In low range, torque is more than double that of high range, too.  So, I’d be a little wary of the front diff, or more specifically, the inboard ends of the front shafts.  The diff itself was used on RRs and Defenders with big V8s, but hard use did break them.  I’m pretty sure someone made 24 spline versions of Series front shafts.

As far as I know, 88 and 109 front axles were identical except for brakes for any given timeframe. The diffs and shafts didn’t vary between wheel bases, and the 24 spline outer end was on both for the post 1980 “rationalised” axles, including Lightweights (which lost the flat hub centre covers).

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The half shafts work harden from use. If you replace every, say, thirty thousand miles, then breakages aren't likely.

But. Read my lightweight thread, convert to CVs and custom half shafts? GB engineering will make you what you want.

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Thanks all - I’ll have a good read and a weigh up.

 

Snagger - with the 50:50 split I was assuming in 4x4 low with equal drive hitting both front and rear. The torque multiplication would then surely be the same as that faced by a rear axle in the same circumstances. I hadn’t appreciated that even with the transfer box effectively ‘locked’ that with spinning rears the front axle could see more than half the torque… bugger.

re: my reference to LWB front shafts, there’s not much in it but I was convinced the majority of LWB vehicles had 24 splines at the hub and 10 splines at the diff with SWB vehicles having 10 spline in each end. Until as you say the early ‘80s rationalisation when SWB vehicles gained the 24 spline hubs along with 11” front brakes. But looking at my SIIA parts catalogue, it’s the same part number - so you must be right.

regardless, I have a set of 24 spline ouers so I may as well use them.

the chap who used to make uprated fronts was SeriesTrek in the US but he’s long since stopped trading. He used common US Precision Brand 371 UJs in some sort of yoke on custom shafts, but I was never able to figure out the yoke source with a view to approaching a U.K. manufacturer. I’d buy a set tomorrow if I could get a source.

http://www.expeditionlandrover.info/frontAxleRebuild.htm

Gazzar, I’ve read your post. Currently I thing CVS and custom shafts are the only way to upgrade. I’ve looked at the kits from Design and Development too - my issue in that regard is I’ve already bought the early type of Heystee swivel housings (1x big bearing 1x small) and the D&D kit only suits the later hub style. I wouldn’t want to make my own kit.

Edited by twodoorgaz
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Ps, Gazzar - could you share contact details for GB Engineering? I’ve googled it and there’s loads but none that look right.

 

my ideal scenario would be for a pair of SeriesTrek front halfshafts but Jim hasn’t made them in 10 years. They seem to be based around a Dana 30 yoke and UJ and there’s loads of firms in the US that do uprated shafts for them. So with the right measurements and bearing/seal positions they should be able to knock up a set. CV conversion is possible but very involved DIY and very expensive off the shelf. Plus given I have 4x2/4x4 it’s a bit unnecessary for me.

Edited by twodoorgaz
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GB engineering

 

Most of my engineering for the CV conversion was the added complication from the lightweight flanges. The rest was dependent on the stage 1v8 stub axle, but if you are going heysee I think that makes it easier.

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On 1/19/2023 at 9:13 PM, twodoorgaz said:

Thanks all - I’ll have a good read and a weigh up.

 

Snagger - with the 50:50 split I was assuming in 4x4 low with equal drive hitting both front and rear. The torque multiplication would then surely be the same as that faced by a rear axle in the same circumstances. I hadn’t appreciated that even with the transfer box effectively ‘locked’ that with spinning rears the front axle could see more than half the torque… bugger.

re: my reference to LWB front shafts, there’s not much in it but I was convinced the majority of LWB vehicles had 24 splines at the hub and 10 splines at the diff with SWB vehicles having 10 spline in each end. Until as you say the early ‘80s rationalisation when SWB vehicles gained the 24 spline hubs along with 11” front brakes. But looking at my SIIA parts catalogue, it’s the same part number - so you must be right.

regardless, I have a set of 24 spline ouers so I may as well use them.

the chap who used to make uprated fronts was SeriesTrek in the US but he’s long since stopped trading. He used common US Precision Brand 371 UJs in some sort of yoke on custom shafts, but I was never able to figure out the yoke source with a view to approaching a U.K. manufacturer. I’d buy a set tomorrow if I could get a source.

http://www.expeditionlandrover.info/frontAxleRebuild.htm

Gazzar, I’ve read your post. Currently I thing CVS and custom shafts are the only way to upgrade. I’ve looked at the kits from Design and Development too - my issue in that regard is I’ve already bought the early type of Heystee swivel housings (1x big bearing 1x small) and the D&D kit only suits the later hub style. I wouldn’t want to make my own kit.

I thought the Heystee swivel housings were all the same it was just the stub axle that varied between the early and late models.

I made my own CV kit but it does require some engineering without a doubt. I also have the Heystee swivels for disc brakes but they need machining slightly to fit the Defender stub axle and CV.

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Bill van snorkel on here had 2 long shafts shortened and cut to 24 splines on the large tapered section. One would fit to the short side, for the other side he made a 24 spline extension sleeve. But the engineering involved in that is probably not dissimilar to a CV and shaft conversion. Or a welded solution maybe?

The D&D kit I would dismiss because you cannot use land rover wheels anymore. There is always mike browns conversion that uses defender outer swivels and shortened shafts.

Daan

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On 1/23/2023 at 5:39 PM, Daan said:

Bill van snorkel on here had 2 long shafts shortened and cut to 24 splines on the large tapered section. One would fit to the short side, for the other side he made a 24 spline extension sleeve. But the engineering involved in that is probably not dissimilar to a CV and shaft conversion. Or a welded solution maybe?

The D&D kit I would dismiss because you cannot use land rover wheels anymore. There is always mike browns conversion that uses defender outer swivels and shortened shafts.

Daan

DDE do those shafts. I bought those and just used a combination of standard series and defender hub components to convert to CVs and permanent 4WD.

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Thanks everyone. That's really helpful.

So - I found the OEM who made the Seriestrek front UJ halfshafts (Dutchman axles in the US). They still have the drawings and can make them, but they're a lot of money at about $1400 - there is a big demand for uprated UJ-type front halfshafts in the US for some of the smaller Dana axles, like the 40 - though these tend to be open knuckle types. A set of these would be by far the easiest route forward, though while I'm willing to spend that sort of money on a permanent fix - I'm less inclined to commit to spending that sort of money on what is fundamentally a consumable item that couldn't be quickly replaced in the event of a failure (not without swapping back to a 10 spline diff and refitting factory halfshafts). Unless there's a UK engineering company with experience of yoke-type shafts.

Daan - a custom 24 spline innered, otherwise standard-spec halfshaft has been on my mind over the past few days. I've been considering having just a pair of inner sections made and fitting standard UJs and standard 24-spline outers. That way it creates a natural weak(er) point in the easily replaceable outer shafts/UJs but protects the vulnerable diff end by upgrading to 300M or similar and 24 splines. I hadn't considered recycling a couple of spare long ends - as you say the issue is the lack of material in to recreate the long end. I don't know if the shaft and Yoke are cast/turned from one piece or if the Yoke is made separately and somehow fitted/friction welded onto the shaft. If that's the case then perhaps someone like GB could separate a factory yoke and reattach it to an upgraded 24-spline inner shaft. That would do me nicely.

I hadn't heard that the DDE kit forces you to use aftermarket wheels - is that just their Disc brake kit (bear in mind I'd be using my Heystee hubs) or the CV kit?

For reference, the DDE kit I was referring to is here: https://www.designdevelopmenteng.co.uk/shop/Series-Land-Rover-CV-Front-Axle-Conversion-Kit-p389433970

Re: the Heystee kit - just to be clear I've already bought this and it is the type designed for the earlier bearing arrangement (1 large, 1 small) which as said above I understand relates solely to the hub they supply. I can't get hold of Heystee to order a metric/later hub that would let me make use of the DDE CV kit.

Interestingly, this post on Guns'n'rovers covers much of the same issues I have and it was resolved by buying a DDE kit, less the custom stub axle, and Greg Forbyn provided an early spec stub axle that was tailored to an AEU2522 CV. I don't know how he does this, I assume its a turning operation on a factory hub. I called Greg and he's happy to supply a pair of stub axles that should work with the DDE CV kit along with my early-style hubs.

I do actually prefer the earlier style of hubs - they are more readily available in the long term and the replaceable seal lands make them serviceable. The 1982- hubs do give me some obselesence concerns.

 

My options seem to be:

1) pay the money and buy the SeriesTrek/Dutchman shafts. However this commits me to a difficult to source consumable part that might be needed in 20 years.

2) if the factory front halfshaft yokes can be seperated/machined off and reattached onto a new set of custom uprated inner shafts then this could be a really sustainable solution that would be adequate for this project (just trying to get something a little stronger than factory).

3) Convert to CVs - taking advice from the above:

           3a) I don't want to/feel capable of completely designing this myself. Though I will read through any posts from gazzar/Jon/etc to better research this.

           3b) I can't justify the £3k for the full DDE CV kit, plus I'd be nervous on having so many custom parts 

           3c)...so my leading option currently is to speak with DDE and find out how many of the parts are custom and how many could be replaced with standard/pattern parts following a milling/turning operation. Their kit                       looks amazing, but I realise that a lot of the parts are heavy duty custom made - whereas for my application even standard/pattern parts would be sufficient.  I have a lathe and access to a mill so as                                         long as I have a starting point I'll be away. But no sense in reinventing the wheel for basic shims and pins and the custom inner shafts etc.

 

 

 

 

 

Edited by twodoorgaz
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On 1/20/2023 at 6:04 PM, Gazzar said:

GB engineering

 

Most of my engineering for the CV conversion was the added complication from the lightweight flanges. The rest was dependent on the stage 1v8 stub axle, but if you are going heysee I think that makes it easier.

Thanks Gazzar.

 

They're really close to me so can swing by with a few samples and can have a chat.

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If I recall, the reason I had to use the s1v8 stub axle, rather than the defender version, was to have a decent mounting reference for the caliper bracket. If you have the heystee caliber swivel housing then you've not got that problem. That is, if I recall.

 

So can you use the defender item, standard CV joints, britpart, file down the swivel balls to suit and custom GB shafts?

Done, and, in a pinch, reversible to UJs.

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