 | Home > Technical > ATB (torsen) front and rear install |
 
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17353   
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No, nothing whatsoever has changed about DPVs.
The definition of a DPV is contained in C&U(86) (as amended) and, provided that the Unladen Weight is under 2040kg (which it was when it left the factory), your DC is legally a DPV. This is why, anongst other benefits, you can drive it at car speed limits on the roads rather than van speed limits. VOSA issued Special Notice 5-2009 in 2009 which states - "We recently sent out a system message, allowing certain 4 x 4 pickup vehicles with a DGW over 3000kg up to and including 3500kg to be considered dual purpose vehicles for test purposes where no unladen weight data is available. Following further consultation with the Department for Transport, an amendment to the Motor Vehicles (Tests) Regulations early next year will see the removal of the dual purpose vehicle definition. You should advise your customers that once the necessary changes have been made to the regulations, scheduled for early next year, all goods vehicles over 3000kg up to and including 3500kg DGW previously accepted as dual purpose vehicles will then fall in to Class 7. " This is the source of the confusion. The intent of the original system message was to address the problem of vehicles being presented for test without any evidence of the ULW being available. If a 4x4 pick-up or Defender-type vehicle has an unladen weight under 2040kg it is a DPV and is subject to a Class IV MOT, if it has an ULW of 2040 or more, it is not a DPV and is subject to a Class VII MOT. The problem is that the MOT Test station has no way of knowing the ULW (it isn't generally included in the registration details for the vehicle towhich the station has access). The concession allowed them to assume it WAS a DPV, and although the concession hasn't actually been revoked yet, MOT Test Stations have been led to believe that it has, hence no they are defaulting to assuming that it is NOT a DPV. Note that the amendment to the Motor Vehicles (Tests) Regulations never took place. If a vehicle genuinely IS a DPV,. it should be tested as Class IV, as evidenced by the MOT Testers Manual which states that a Class 4 MOT is applicable to "Cars, including 3 wheeled vehicles more than 450kg unladen weight, Taxis, Minibuses and Ambulances up to 12 passenger seats, Goods Vehicles not exceeding 3000kg Design Gross Weight (DGW), Motor Caravans and Dual Purpose Vehicles" (source http://www.motinfo.gov.uk/htdocs/m4i00000401.htm , my emphasis). Furthermore in an email to me from DVSA dated 15/07/2015, "Rebecca" from DVSA Customer Services stated "I can confirm that a Dual Purpose Vehicle would be tested as a Class 4" There really is no doubt that a vehicle which is a DPV as defined by C&U(86) should be tested as a Class IV vehicle, irrespective of its age, tax class, type approval class, or anything else! DVSA accepts this, but the test stations are in confusion! The root cause is that the testers have no way of knowing and the owner has no way of proving that the vehicle is a DPV. |
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20th Jan 2016 10:37am |
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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971 
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From Ashcroft themselves. By default with a wheel off the ground it will spin, but if you use the brakes then it won't spin, and will force the other wheel to have more torque. |
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18th Jun 2016 10:08am |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8010  
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i still have one for sale Cheers James 110 2012 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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18th Jun 2016 7:09pm |
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| Arierep Member Since: 12 Apr 2013 Location: Portugal Posts: 258  
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Whats your experience with ATBs vs wheels in the air?
Thanks for your hint, but I'm in PT, I don't know how smooth the shipping would be. PM me please |
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18th Jun 2016 10:05pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8010
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my experience and correct use of left foot braking works well with lifted wheel.
understand locaiton, could get it brought out in Sep - out there to compete. Cheers James 110 2012 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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19th Jun 2016 11:57am |
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| Alexke Member Since: 03 Jan 2011 Location: Antwerp Posts: 113 
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I have TC and it saved me a few times, but it is kinda harsh on the drivetrain.
If i had the budget and need and would drive a lot offroad I would go with: ARB in the rear and torsen in the front. if you do 30% offroad would go for Torsen front and rear with TC in the event your wheel is up in the air. Discovery 4 SDV6 Landmark F31 320dA Msport xDrive LR Defender 90SW TD4 Stornoway grey 320d E46 E70 X5 3.0d Sold! FFRR TD6 - Sold |
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19th Jun 2016 5:12pm |
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| diduan Member Since: 13 Oct 2016 Location: Central Balkan Posts: 260 
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I have an Ashcroft center ATB differential and brake tested it today on rollers with diff lock ON. They have a special setting for 4x4 vehicles that drives both rollers in opposite directions, so no torque is transferred to the center diff. I didn't trust the machine so i put the diff lock just as a precaution, but everything was fine. Defender 110 SW MY2011 2.4tdci decat, no EGR
Jeep Wrangler YJ 1990 4.0. Front 78' Dana 60, Rear CUCV 14 bolt |
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13th Apr 2017 8:02pm |
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| ROBBONTHEROCK Member Since: 23 Jun 2014 Location: Aberdeenshire Posts: 637  
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Hi All,
I have been withering for a while on going ATB on my truck. But have just ordered a new clutch and upgraded hydraulics from Ian at IBS (clutch fix organic, new input shaft adapter etc etc). While the g/box and t/box is out, I am wondering if this is my moment of opportunity to upgrade the centre diff to an ATB type. Ian mentioned that this is a weak spot on the Puma and contributes a large amount to the backlash in the system. Any thoughts on this? If i do the centre diff, should I recon the t/box (gaskets bearings etc) or just upgrade the diff to the ATB type, i.e. minimal work Car has done 75k, has drive train slop which is noticeable when changing gears. I can't do a clutch change on my back, so this is deaf a garage job, but F & R diffs i can do no sweat on my drive, so am leaving that for a future project. Welcome thoughts on the matter. Cheers Andy |
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21st Apr 2017 4:26pm |
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| MK Member Since: 28 Aug 2008 Location: Santiago Posts: 2413  
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Most of the backlash comes from worn halfshaft/flange splines.
As for the Tbox, some come out of factory with quite loose shims inside the central diff. Those fiber-like shims come in different thickness and they can be easily sourced and replaced. cheers Puma 110" SW ............................................................. Earth first. Other planets later |
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21st Apr 2017 6:11pm |
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| ROBBONTHEROCK Member Since: 23 Jun 2014 Location: Aberdeenshire Posts: 637
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Half shafts and flanges was replaced <3000miles ago (Feb 2017).
Pretty sure its slop in the drive train, could be the input shaft adapter, but is it worth doing adapter and putting in a ATB. i know its a step change in cost, but if its a long term vehicle...... 
Cheers Andy |
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21st Apr 2017 7:56pm |
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| diduan Member Since: 13 Oct 2016 Location: Central Balkan Posts: 260
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I had an gearbox output shaft failure (well known one on pumas) and while doing work down there i decided to upgrade the center diff to ashcorofts atb. Compared to other modifications, i think center ATB diff is a cheap one. Defender 110 SW MY2011 2.4tdci decat, no EGR
Jeep Wrangler YJ 1990 4.0. Front 78' Dana 60, Rear CUCV 14 bolt |
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22nd Apr 2017 6:05am |
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| ROBBONTHEROCK Member Since: 23 Jun 2014 Location: Aberdeenshire Posts: 637
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Hi,
Did it reduce the drive train slop much? Cheers Andy |
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22nd Apr 2017 8:36am |
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| diduan Member Since: 13 Oct 2016 Location: Central Balkan Posts: 260
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I didn't notice any difference regarding drivetrain slop. Are you sure that the slop is comming from the diff? Could it be rather from the splines of the output shaft? Defender 110 SW MY2011 2.4tdci decat, no EGR
Jeep Wrangler YJ 1990 4.0. Front 78' Dana 60, Rear CUCV 14 bolt |
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22nd Apr 2017 11:43am |
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| ROBBONTHEROCK Member Since: 23 Jun 2014 Location: Aberdeenshire Posts: 637
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If i'm honest I think the slop is coming from a combination of places:-
T/box Adapter; T/box Centre Diff; Front Diff; Rear Diff; Half shaft and flanges; I've replaced the rear half shafts and flanges this year already, and LSD diffs are a long term plan, so the backlash there should be improved. I have a new clutch coming along with all the parts to replace the t/box adaptor. I wonder if the workshop manual gives any angular values for drive train backlash......... I could measure the centre box backlash, with the diff in the locked position, then with the hand brake off I should be able to see what the backlash is between the front and rear props. I might have to disconnect the props though.... Cheers Andy |
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22nd Apr 2017 12:01pm |
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