 | Home > Maintenance & Modifications > Rear Diff failing, what advice replacing with ATB diff? |
 
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| Grenadier Member Since: 23 Jul 2014 Location: The foot of Mont Blanc... Posts: 5886   
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Evening all,
I am fairly confident that my rear diff (stock Puma 110) is on its last legs, as there is a shocking amount of slack now present. In this regard, I’m thinking of an upgrade and I have my eye on a Ashcroft ATB, as I mainly use the truck on the road, will soon have a 170bhp, and live in a region with many, many bends and hairpins which stress a standard diff. I know nothing of ATBs, so any advice as to which version should I get? And is this something I can easily fit myself without removing the axle, and also likely attempted on a driveway (although might be able to borrow a lift)? Anything else I should know or consider? Thanks in advance.  Monsieur Le Grenadier
I've not been everywhere, but it's on my list..... 2011 Puma 110DC - Corris Grey |
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12th Mar 2025 6:50pm |
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| rustandoil Member Since: 08 Sep 2012 Location: Cotswolds Posts: 808  
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The slack could easily be half shaft / drive member spline wear.... But if it is the diff swapping it is an easy job, but it is heavy!
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12th Mar 2025 7:17pm |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 678 
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my thoughts are that an atb or any other version of a limited slip diff is there to help you maintain some drive in the event of a wheel on that axle starting to loose traction....so im not sure that for normal road use you will notice any benefit by fitting one in the rear.. as for the straight swap, will that not depend on where your current slack in the diff is in crown pinion mesh , if so a bit more than just swapping diffs or the slack or some of it will still be there unless that is addressed when you change over...
im going down the same route myself mind, just for fun, but intend putting an atb in the front and a electronic locker in the back whenever I can get round to it... |
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12th Mar 2025 8:11pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20688
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I agree rear DM wear and fretting is likely, can get quite bad, and that appears as slop on the driveline, but, is not the Diff.
Ashcroft does make some good kit! TheThunderRolls🇬🇧🇺🇸
⛽️🛢️⚙️🧰💪 |
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12th Mar 2025 8:13pm |
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| BrickBox Member Since: 05 Oct 2021 Location: Wales Posts: 910  
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If it’s the original standard diff, I’d save my money and just have a new, standard one fitted. Spend the money else where, if the vehicle is just mainly road use. 2008 2.4 110 Utility Station Wagon XS.
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12th Mar 2025 8:22pm |
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| Grenadier Member Since: 23 Jul 2014 Location: The foot of Mont Blanc... Posts: 5886
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Thanks all.
My ‘test’ was to park the Def on flat ground, chock the wheels and release the handbrake. On turning the prop, there was approximately 1cm movement of the prop before I felt any engagement, and from feel I thought it was within the diff casing. Recently I have noticed a huge amount of slop when driving, (pulling away, accelerating/lifting/accelerating again, changing from reverse to 1st etc etc). I assume it is the diff because of where I think I feel the slop, the sound it makes , that ‘test’ above, and also because I have HD half shafts and HD flanges fitted. So, for those with more experience, does that sound diffy? Monsieur Le Grenadier I've not been everywhere, but it's on my list..... 2011 Puma 110DC - Corris Grey |
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12th Mar 2025 9:38pm |
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| Mo Murphy Member Since: 01 Jun 2008 Location: Letchworth Garden City, Herts Posts: 2311 
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By testing with the handbrake how do you know it's the rear diff ? Could be the transfer box or the front diff, they're all connected.
I would suggest a better method of diagnosis before spending piles of money. Mo The Land Rover 90 - Many are called, few are chosen. 50 Shades of Pennine Grey |
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12th Mar 2025 10:17pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20688
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When driving it’s not always the drivetrain, but other components too.
Such as play in rear damper bushes, trailing arms, A frame ball joint etc. Is there any leaks at all? I think there is always a little slop in the diff, but it shouldn’t be excessive. I tend to go by, if it’s kicking then you have a problem, if not then it’s fine. A frame worn ball joint and bushes makes the rear feel all over the place, it will also create a knock or loose feel on coasting, coming on or off power Loughton coasting in gear on flat ground, but so will rear damper bush wear too. Around 25mph in say 3rd gear, on and off light power, you can sort of feel any slack by lightly going on and off the power, there should be very little other than throttle and turbo spool on and off, there shouldn’t be any kind of drivetrain lag or clunk. TheThunderRolls🇬🇧🇺🇸 ⛽️🛢️⚙️🧰💪 |
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12th Mar 2025 10:31pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8201  
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1cm turn of the prop isint unusual. Not great but not unusual.
I would check drive members first. If going for rear diff change centre, crown wheel and pinion. Yes you can do it on your driveway. Propshaft tool, impact gun, torque wrench, 17mm socket some oil and gaskets. Personally for strength I run ashcroft low pinion rear diffs, hypoid design. Cheers James 110 2010 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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12th Mar 2025 11:33pm |
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| 34064 Member Since: 12 Dec 2023 Location: South Central Posts: 225 
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I have a pegged ATB in my 110 from Nige at Xcess4x4 its an absolute work of art it makes a world of difference to traction from open diffs both on and off road. Speak to Nige if you want the best you can get. 110 Td5 Ex Utilities slowly converting into a pop top camper one day
Build thread:https://www.defender2.net/forum/post1024784.html#1024784 |
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13th Mar 2025 8:27am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17674 
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Personally I would fit an ATB without an moment's hesitation, it will make the vehicle more sure-footed on the road and is substantially stronger than a standard P38 short-nose four-gear diff. It is certainly cheaper to buy a new ATB from Ashcroft Transmissions than a new genuine four-gear diff from the Land-Rover supply chain.
It is not clear whether you are asking about buying an ATB differential and building it up into your existing pinion housing, or buying a complete built up pinion housing with an ATB already fitted (and this is largely due to that fact that people tend to call the assembly a "differential" when in fact the diff is just a part in the assembly). If you are planning to buy and fit a complete, built-up assembly (pinion carrier with differential, crownwheel and pinion assembled, set up, and ready to go) then it is a very easy job to fit it yourself, even working at ground level. You simply need to drain the axle, disconnect the rear end of the rear propshaft pull the halfshafts out an inch or two, then unbolt and remove the old assembly. Reassembly is the reverse of the process. The only potential difficulty is that the assembly is quite heavy (don't drop it on any soft parts of your anatomy). If you mean building up the assembly yourself using your existing pinion carrier, crownwheel, pinion, etc., then the job is rather more involved and requires engineering understanding and a number of special tools to set bearing preload, backlash, etc. Generally I would not recommend this unless you already know that you know how to do it. You have another option, which is to fit a long-nose diff in place of the P38 short-nose. The long nose is stronger, but you then still have the ATB vs. open diff decision, plus you need a non-standard propshaft. All things considered you my suggestion is go for the cheap strong upgrade, namely an ATB in a P38 carrier unless you are planning heavy off-road or expedition usage. |
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13th Mar 2025 11:51am |
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| Chicken Drumstick Member Since: 17 Aug 2020 Location: Near MK Posts: 860
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Clunking? How, where and when? Sounds more like an issue was replaced with a new part, rather than the ATB magically curing tbh. |
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13th Mar 2025 12:11pm |
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| Chicken Drumstick Member Since: 17 Aug 2020 Location: Near MK Posts: 860
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On road traction differences? 
Unless you are driving like Collin McRae with full bore dragster style starts, I don't believe you would notice any real difference on road, even in the wet. |
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13th Mar 2025 12:14pm |
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| Chicken Drumstick Member Since: 17 Aug 2020 Location: Near MK Posts: 860
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Like others have said. Are you really sure it is the diff? My guess would be it is unlikely and there are far more likely culprits. You can also buy a replacement diff used for cheap and just swap it over in about an hour. Likely less than £100 and maybe as little as £50. Very unlikely to buy a "worn" diff, as they don't really wear in that way. They can fail, but not any slack or clunks are likely from elsewhere. As for an ATB, they are as a cool as f***!!!
But only really serve a purpose for two types of use. 1. Off road and specifically when flexing out the suspension or on loose/slippery surfaces 2. Driving like a loon with wheel spin and power slides For "normal", even spirited road use, you will not notice it at all, nor really reap any benefits from it. If you want to buy one, just because. Then none of this matters, so go fot it. But if you need to justify the expenditure and expect a return in ability/performance for your money, then it is likely very limited unless doing the points above. The second point is also very hard to acheive, as most 4wd systems and specifically a Land Rover will tend to understeer not oversteer, even on slippery surfaces. So you could argue if you are only having one axle with a Limited Slip Diff, you'd get more on road benefit from fitting it in the front, not the rear. A centre limited slip diff would also likely pay bigger dividends on road than a rear axle one. |
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13th Mar 2025 12:23pm |
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