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Ashlocker and ARB RD56 'Tab_Lock System'™ Upgrades.
Making Land Rover Differentials more 'Reliable'.
Making Land Rover Differentials 'Stronger.'
One of the best value for money upgrades you can do for adding strength to your Differential is our 'Pegging System'. It makes for an absolutely massive strength increase. We would actually go as far as saying that a Pegged Standard CW&P is stronger than a UnPegged HD CW&P.Additional strength can added by changing to HD CW&Ps, (and maybe changing ratios too). Even small changes can pay dividends, our upgraded 'Locking Ears' giving a much stronger solid lock on the 'Adjuster Rings', maintaining and protecting the correct 'Backlash' position, as an example But, and its a 'Big But' - whatever you do, whenever you "Upgrade" your Land Rover, especially Differentials, it means you move the 'weak point'. On a Standard Differential, the No 1 weak point is the 2 Pin Differential itself. Upgrade to a 'Locker', and it moves the weak spot to Half Shafts and your CW&P. Upgrade your Half Shafts to some HD Units, add a HD CW&P, Peg it, and the weak point then moves somewhere else. Currently up to now, if you had our Ashlocker 'Ultra Build Spec' Differential, typically a 'Pegged Ashlocker', 'HD CW&P', upgraded Carrier Cap Bolts, upgraded CR80 'Locking Ears', 'Nordlock NLXs' everywhere, genuine LR Parts, upgraded CW&P Bolts, you'd reached point where until now that was pretty much it. Many drivers are running 35s tyres (I do !), some 37s, (which as I have always said are over the limit really for a LR axle - however exotic a build), but, we have numerous customers out there running 'Ultra Build Diffs' with 37s, many haven't broken them (yet). Some will, some may never, but, Off Road the strains are huge and breakages will occur. So any idea to make our Ultra Build Differentials stronger is always on our minds. The Xcess4x4 'Tab_Lock' system evolved out of our desire to make our differentials stronger through product development. It's aimed at those wanting the Ultimate Ashlocker or ARB RD56, additionally protecting their investment. Before we just say 'Taaalaaaa here it is', first some information and background, so you can both understand the idea, and see why it might just be an additional upgrade you fancy to increase the strength of your Ashlocker Differential.
'The Glass Bolt Paradox'
Even with our 'Ultra Build', a new 'Weak Point' is emerging, putting the entire Differential at risk, CW&P bolts are shearing off. Recently one unit sent in to us had all 10 x CW&P bolts sheared off. It had been well built, having what is regarded as the strongest CW&P Bolts currently out there - FTC5150, and a Grade 12.9,used in the 'Wolf' Military Spec Differentials - So, why ?, and what could we do to improve things ?.Speaking at length to a Technical Director (A Genius on Bolt Technology) with 50+ years experience and knowledge kick started my little warped brain, understanding then led to an idea forming. All this technical data,a lot of research, analytical playing about with Solidworks Stress Analyisis we began to see the basis of an Upgrade. A very clever friend, Simon Rafferty (of X-Eng fame), also gave me a interesting lesson on a Paradox, which helped clear some of the remaining mists to a solution. It's called 'The Glass Bolt Paradox'. It goes like this. Steel has a 'Tensile Strength Rating'. Differing 'Grades' of Steel, as they go higher so to does the 'Tensile Strength. Ok, that makes perfect sense. But, Glass has a higher structural tensile strength than Steel.?. So why are bolts not made therefore out of Glass ? Because they would shatter. Simples. Now think about Half-Shafts. Standard Half Shafts will twist before they snap, actually they will twist a LOT, then more, then snap cleanly. A Heavy Duty shaft will take more before it snaps, but, when it does it explodes. Now think of CW&P Bolts. A Standard Bolt is 'Grade 7' - a very Low Grade, and these will stretch quite easily when 'hard loaded'. Once they have stretched just a bit they will unwind. We have seen CW&P bolts unwind so far the bolt heads lathe into the 'Differential Casing' wall.. A 'Grade 8.8' is classed as a 'Standard Grade', used all over Land Rovers including Differentials, it's the 'Ford Escort' of bolts. Moving up we go to a 'Grade 10.9' this is classed as a 'Heavy Duty' Grade. Finally Grade 12.9 Super Heavy Duty , FTC5150 - Land Rover Wolf Differentials - Special Bolts FTC5150. One thing in common is with 10 x 3/8 UNF bolts of ANY Grade there is a problem of Bolts 'stretching' and or 'shearing' off when massively overloaded. Use a Low Grade bolt i.e. 7 or 8.8, and it will stretch, undo, or shear some or all of the Crown Wheel Bolts. Use a Super HD and it won't stretch, but, if overloaded 'Shear' clean in half, all x 10 if really given stick, and nothing in between.
Issues Limitations and Options
However, there are limitations on a Land Rover Differential, specially around the CW&P itself and the bolt fixings used. Every aftermarket LR CW&P uses 3/8 UNF Bolt threads (with a couple of rare and rather old exception such as GGS CW&P).As such we are limited to a bolt size of 3/8 UNF. Trying to drill out, Re-Tap a hardened Crown Wheel and redrill 10 x Differential Centre holes is not going to happen, and for many many reasons. Additionally and if not more importantly, we are always doing up the CW&P bolts in 'Tension', however for much of their life the bolts are actually acting in both 'Shear' and 'Tension' . To summarise - Too Hard a Grade Bolts overload them and they are likely to shear, whereas too soft a Grade bolt means they will stretch easily undo themselves and or snap. Neither are 'Good' for Differential life expectancy.
Ashlocker Upgrade 'Tab-Lock' System
Taking the Standard Ashlocker End Flange we CNC machine 10 x special Oval Slots, adding a M5 thread at the end of each cut-out. The oval CNC cut-outs have matching CNC 'Tab Locks' allowing us to put a lower Grade 10.9 3/8 x 1.1/8 UNF CR6 Grade S' Bolt. These have more flex than a 12.9, but are far stronger than a 8.8.Special Nord-Lock Delta Protect X Series Washers are used to clamp the 10x bolts into place, the Xcess4x4 Lock Tab™ lock the bolt heads into position, themselves then cleverly locked down with a M5 12.9 Grade bolt and a Nordlock M5 NLX Washer If any of the bolts now try to stretch, they can a bit, and the NLX can cope with that (see the Video), but whatever happens the bolt cannot undo. With 10 x CW Bolts in place with the 'Lock_Tabs' they are clamped in both Tension AND in Shear. The bolt centre 12 star lock ring is machined 7.5 degrees out of line, so we can turn it over to get a better fit if it doesn't line up, calculations show the worse case scenario of having to Retorque a bit more/ less to get a bolt all to line up is 3 Ft Lbs at worst. Frankly we will be lucky if our Torque wrench is that accurate !. Video showing the Ashlocker Ultra Build + 'Tab Lock' Upgrade, in a full Build. The price is £88 Exchange + VAT on either a new unit or one in for Rebuild. Labour, ie 'build costs' remain the same, you only pay for the machining and additional parts to upgrade . The 'Xcess4x4 Lock_Tab Upgrade' is available on all Ashlockers, New or Second-hand, and will be offered as a standard upgrade. Please Note we do NOT sell this as a DIY upgrade, and is only available through ourselves