mjom89 Posted December 8, 2017 Share Posted December 8, 2017 Hi All First post so please be kind... I have a DAF T244 canvas back troop carrier with a centre diff lock issue and am hoping for some help. The warning light is on the dash showing the centre diff is locked (I have learnt it is permanent four wheel drive from another post on this site here much like a Land Rover) and the air actuator did not seem to do anything. I remove the actuator from the arm on the diff and tested it while it was connected to the air supply - it moves as it should. The arm on the diff that engages the lock is solid and I believe it is in the unlocked position as I have checked another vehicle but when turning the vehicle on concrete I feel the tyres scrubbing. See the attached image with one end of the actuator removed (apologies for the poor quality). Does anyone know if this is engaged or not? Should this arm move freely and what can I do to unjam it? Any advice would be appreciated! Matthew Quote Link to comment Share on other sites More sharing options...
Wendelspanswick Posted December 8, 2017 Share Posted December 8, 2017 So I have the same truck, are you sure the diff lock is engaged and its not a faulty dash light, the buzzer sounds every 30 seconds with the diff lock engaged. Quote Link to comment Share on other sites More sharing options...
Wendelspanswick Posted December 8, 2017 Share Posted December 8, 2017 Just reread your post properly, have you tried driving it on loose ground to see if that unlocks the diff, it might be wound tight so it's not releasing. Quote Link to comment Share on other sites More sharing options...
mjom89 Posted December 8, 2017 Author Share Posted December 8, 2017 I haven’t heard a warning buzzer but then I have never heard the warning buzzer! Should it sound when you test the dash warning lights? It is driven on loose ground most of the time - only driven on a hard surface when parked up. I am not certain that it’s engaged as I’ve never driven it when it was purposely engaged. I think I am noticing odd behaviour because I am looking for it! What do you mean by wound tight? Quote Link to comment Share on other sites More sharing options...
Wendelspanswick Posted December 8, 2017 Share Posted December 8, 2017 It doesn't sound like it applies to you but if you drive with a locked diff on hard surfaces the discrepancies between the front and rear axle wheel circumferences induce a torsion effect in the running gear so everything gets wound tight. Sometimes you need to drive on a loose surface to release some of the torsion so the diff lock can release. I have a muddy track that I regularly drive along and a slightly drier but fairly steep stoney track I drive up and I'd struggle without diff lock. It's the same buzzer for the diff lock that sounds until the air pressure is up to working pressure. Quote Link to comment Share on other sites More sharing options...
Wendelspanswick Posted December 8, 2017 Share Posted December 8, 2017 Have you read the operators manual? https://www.google.co.uk/url?sa=t&source=web&rct=j&url=https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/573991/FOI2016_09103.pdf&ved=0ahUKEwjgxujJxfvXAhUBZ1AKHU4OCyoQFghGMAo&usg=AOvVaw2cDuqjEKv0EzfnjZrvLBbG Quote Link to comment Share on other sites More sharing options...
mjom89 Posted December 11, 2017 Author Share Posted December 11, 2017 Thank you for the help. I have never heard the warning buzzer despite needing to wait for the air pressure to build up so that must be faulty too! Is it on the dash console somewhere? The truck was driven on a loose surface all day on Saturday and the warning light never came off. The diff lock actuator still fails to move the lever on the diff downwards to the locked position so perhaps it is wound too tight? I currently think the diff is unlocked but the warning light is on when it shouldn't be (sensor fault?) and the diff is wound tight so it won't engage the front/rear lock. Could that be right? I have come across that document before - it is very helpful indeed and has taught me a lot!. Quote Link to comment Share on other sites More sharing options...
Wendelspanswick Posted December 11, 2017 Share Posted December 11, 2017 There are 4 square plastic blanking plugs on the dash, if you prize those out there are 4 1/4 turn screws underneath that release to allow you to lift the dash. I'd get the buzzer working as it should be an easy fix and that should enable you to work out whether the diff is locked or not. I can get under my DAF and measure the actuator rod length in both positions if that helps? Quote Link to comment Share on other sites More sharing options...
john1950 Posted December 11, 2017 Share Posted December 11, 2017 Easy test. jack one front wheel of the ground then try to rotate. If it is in 4wd it will only turn part way and will try to turn rear propshaft, If it is in 2wd it should rotate. Quote Link to comment Share on other sites More sharing options...
mjom89 Posted December 11, 2017 Author Share Posted December 11, 2017 Thanks both - I will do what @john1950 suggested first to save @Wendelspanswick climbing underneath and then report the results. I will also get that buzzer sorted too. Quote Link to comment Share on other sites More sharing options...
Wendelspanswick Posted December 11, 2017 Share Posted December 11, 2017 43 minutes ago, john1950 said: Easy test. jack one front wheel of the ground then try to rotate. If it is in 4wd it will only turn part way and will try to turn rear propshaft, If it is in 2wd it should rotate. Will that work as it's permanent 4wd? The button locks the centre diff. Quote Link to comment Share on other sites More sharing options...
john1950 Posted December 11, 2017 Share Posted December 11, 2017 It will give you an indication. A third diff proportions the drive between front and rear axles, to design specification. When the third diff is locked it gives both axles the same power. When it is unlocked front and rear axles are not positively connected so should give propshaft rotation. It may just be a small of propshaft rotation by rockingthe tyre. Does not cost anything to test. Axle stand or blocks for safety. 1 Quote Link to comment Share on other sites More sharing options...
mjom89 Posted December 14, 2017 Author Share Posted December 14, 2017 I jacked up the rear near side wheel, let the hand brake off and released the wind up. I could then move the diff lock lever manually 👍 It thanked me for it and then the alternator failed. Never mind - I needed something else to do! Thank you all for your help. Quote Link to comment Share on other sites More sharing options...
john1950 Posted December 14, 2017 Share Posted December 14, 2017 That was why I said Front, It would still be standing safely with the parking brake on. Quote Link to comment Share on other sites More sharing options...
johnwardle Posted December 14, 2017 Share Posted December 14, 2017 (edited) 8 minutes ago, john1950 said: That was why I said Front, It would still be standing safely with the parking brake on. The parking brake on a Leyland Daf T244, being air operated, works on all 4 wheels, much to the amusement of my MoT tester, yes he did try it! Edited December 14, 2017 by johnwardle Extra text added Quote Link to comment Share on other sites More sharing options...
mjom89 Posted December 14, 2017 Author Share Posted December 14, 2017 The unwind was intentional - something I had read else where that was needed to release the diff lock. It seemed to work and was done carefully! Quote Link to comment Share on other sites More sharing options...
john1950 Posted December 15, 2017 Share Posted December 15, 2017 (edited) I have learnt something new , every day is a day at school. That still means the vehicle was standing on a jack with the parking brake off. Stay safe, and be there at the end of the day with your knew found knowledge. As I have gone through working life I have known Two people killed in incidents with bottle jacks, Both experienced Mechanics. My father was trapped under a car once when a friend came into his garage and was talking to him while he was working under a car. He was leaning on the trolly jack handle and let the car down unintentionally he then ran in a panic looking for help because he did not know how to jack it up again. He always had a block or something under anything he jacked up after that. Sorry to deviate from difflocks most complicated ones I have worked on were Terbergs 8x8s Usual way to unwind, a short reverse usually one wheel revolution will suffice. Tyre pressures and tyre circumference are critical on multidrive vehicles. Edited December 15, 2017 by john1950 addition Quote Link to comment Share on other sites More sharing options...
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