discomikey Posted December 30, 2013 Share Posted December 30, 2013 Hi all, first of all, apologies if this is in the wrong place, i just thought that as it fits all rover axles it wasnt specific as such. i thought i would add this as i couldnt seem to find any reviews for this diff barring on traction controlled vehicles where apparently they work incredibly with the system. (no connection to Mr Ashcroft at all) So i fitted my LSD a while ago and it sat in the workshop since, but the other day in order to pull my series 2 round to worrk on that i got to drive it with the LSD for the first time so first impressions. the machining quality build quality and aesthetics are all spot on. i didnt dismantle it for fear of losing a part or not rebuilding it correctly. i asked for it to come with carrier bearings pre fitted and they were Timken bearings so no worries there. fitting and setting up is just as easy as any standard differential although it would have been nice to come with a piece of paper supplying torque and backlash settings although theyre not hard to find for a standard diff, there may be some reason why the ideal is not exactly the same re backlash but i cant see why so i went with standard figures. checked it up with some blue and the R&P run nicely meshed together. unfortunately dont have any pics of the install but i used series 12/24 splines backwards for now till i can afford decent shafts. operation wise so far im very impressed, round the yard there is zero scrub, even on the gravel round the back. i can put it sideways on wet tarmac (our yard is big) and control it so much easier than i ever could with an open diff. there are no clunks as it works not tried donuts yet on the yard bit in the field it is rather fun. not to my dads amusement! i cant comment off road wise yet as i am still running it minus front halfshafts since the disk conversion but i have high hopes for it. best of all you cant even tell its there in normal use! more reviews to come as i use it more and especially when i take it off road! Quote Link to comment Share on other sites More sharing options...
robertspark Posted December 30, 2013 Share Posted December 30, 2013 Can I ask what the views are on LSD bias (LSD in front + LSD in rear, rotating in opposite directions). Seems that (and I may be wrong here) Eaton sell a front + rear LSD, and Ashcrofts + Quaife sell an LSD (not specified front or rear). There is an article here on flipping gears over to make a truetrac front a rear LSD and visa versa: http://www.discoweb.org/truetracgears/index.htm I can understand the principle of flipping the gears and why as the helical gears will either be forced outwards or inwards before friction against the carrier resists them from rotating, but does anyone have a knowledgeable view? I have both a Truetrac and an Ashcrofts (had I known Ashcrofts made their own at the time I was getting one, I would not have bought the Truetrac). I put the ashcrofts at the rear and the true trac up front on the basis that the truetrac may have less bearing surface area from the 3 pockets of helical gears, (and therefore may offer less resistance when locked / transferring torque for example when steering), and the Ashcrofts with 6 pockets may have more surface area with 6 pockets. Quote Link to comment Share on other sites More sharing options...
Disco1tdi Posted December 30, 2013 Share Posted December 30, 2013 I've only had good experiences with the Ashcroft unit. To be a pedant. Both the Ashcroft and Truetrac diffs are ATB's, not LSD's. LSD's are totally different animals, containing friction plates. (i'm ducking now, waiting to be told that they're all Limited Slip Diffs....) Quote Link to comment Share on other sites More sharing options...
robertspark Posted December 30, 2013 Share Posted December 30, 2013 Technically they are all Limited Slip Differentials as they all limit slip just by different means? http://en.wikipedia.org/wiki/Limited-slip_differential Torsen (not for LR), Ashcrofts, Quaife, and Eaton Detroit Truetracs are in fact ATB (automatic torque biasing) Limited Slip Differential Friction Plate (clutch) type LSD such as KAM (+ older GKN I think, no longer avail for some time (for STD landrover diffs), but pop up on ebay from time to time though). (GKN seem to be doing one for the 2014 Evoque through) Quote Link to comment Share on other sites More sharing options...
missingsid Posted December 31, 2013 Share Posted December 31, 2013 Torsen (not for LR)?? I am pretty sure mine is an early Torsen not a Quaife. They were available for a while then they stopped the after market sales and only went for manufactures. Quote Link to comment Share on other sites More sharing options...
Daan Posted December 31, 2013 Share Posted December 31, 2013 I have been very impressed with my truetrac in the front; the challenge boys may put their noses up to them, but they always give you an advantage when the terrain is not straight. A full locker may give more traction on a straight line (debatable), but when you go round a corner, their front diff usualy needs unlocking to allow it going round corners; the truetrac than still works. The best of both worlds would be a lockable truetrac, for the times you do go in a straight line. But that is in the vapour cabinet at the moment.... Daan Quote Link to comment Share on other sites More sharing options...
robertspark Posted December 31, 2013 Share Posted December 31, 2013 Sorry, did not think Torsen ever made them for LR ~(my ignorance). Daan -> ATB-LSD + Traction Control / fiddle brake? May aide to bias in a wheel spin / wheel in the air situation (would this not be closer to a locker and offer a more flexible solution for near all conditions - maybe not for slow rock crawling through with the ABS pulsing the wheel in the air and shock loading the driveline?? Anyone with any experience in this area?). Discomikey - > sorry did not mean to hijack your thread. Quote Link to comment Share on other sites More sharing options...
Daan Posted December 31, 2013 Share Posted December 31, 2013 I know of people that have used traction controll in combination with atb diffs, and it does work. The fidlle idea, I have considered, but the whole idea would give me to many controls I think, too much multitasking while being in a dynamic situation. Quote Link to comment Share on other sites More sharing options...
reggie Posted January 1, 2014 Share Posted January 1, 2014 I'll be following this thread as I'm thinking of one of those Ashcroft LSDs for the rear axle in my RRC. I have just acquired a pair of Ashcroft 4:75 CW&P one is fully built using a wolf 4 pin for the front axle. Quote Link to comment Share on other sites More sharing options...
Team Idris Posted January 1, 2014 Share Posted January 1, 2014 Fiddle brakes seem an answer, but only when a rear wheel is completely in the air. If the wheel has 50% of weight and it slips, you would pull the handle and have 50% drag. For us, full lockers really work for punch challenge, as they like to put dead ends into courses, where turning is tight. Having all 3 diffs unlocked helps no end in these 3-point-turn situations. Limited slip works well on the front of trailers though. I've seen a KAM locker limited-slip combo in the front axel for these events For roady stuff, limited-slip all the way. I like that Cherokee jeep dana 35 with the pump thingy, but it does bang a bit. Quote Link to comment Share on other sites More sharing options...
discomikey Posted January 2, 2014 Author Share Posted January 2, 2014 i too think that full on lockers are overrated, and no doubt they do as they say on the tin but there are some situations where a fully locked diff will hinder traction. more than that, i liked the idea of fit and forget, not having to pipe up to a compressor or wire it up. theres also the significant cost benefit Quote Link to comment Share on other sites More sharing options...
Anderzander Posted January 2, 2014 Share Posted January 2, 2014 An ignoramus question if I may - the shortcoming of an LSD is often cited as the 'wheel in the air' scenario - but I presume it is unable to reduce slip in any situation where there is a wheel with no traction ? Such as a wheel spinning over a wet rock etc ? Quote Link to comment Share on other sites More sharing options...
bill van snorkle Posted January 3, 2014 Share Posted January 3, 2014 An ignoramus question if I may - the shortcoming of an LSD is often cited as the 'wheel in the air' scenario - but I presume it is unable to reduce slip in any situation where there is a wheel with no traction ? Such as a wheel spinning over a wet rock etc ? In that situation you need to simulate traction to the wheel in the air by brake modulation to transfer drive to the wheel on the ground. Fine on vehicles with auto trans like my 2.6 Isuzu Trooper, but just stalls the engine on my high geared manual trans 2.3 Trooper. Just my opinion, but if you have strong axles and absolutely positively need to get there, and have control in all situations, then selectable mechanical lockers are the only option. Quote Link to comment Share on other sites More sharing options...
discomikey Posted January 3, 2014 Author Share Posted January 3, 2014 An ignoramus question if I may - the shortcoming of an LSD is often cited as the 'wheel in the air' scenario - but I presume it is unable to reduce slip in any situation where there is a wheel with no traction ? Such as a wheel spinning over a wet rock etc ? spinning a wheel over a wet rock will always need a certain torque to overcome the (largely reduced) grip of the tyre. this torque is what the ATB uses to drive the other wheel. it does what it says on the tin really, torque biasing. like bill suggested in a wheel in the air situation there is nigh on zero resistance to that wheel spinning therefore it has no torque to bias, which is where you have to left foot brake. This is why when used with a traction control system the diff actually complements the standard system and creates a drive system which i personally believe to be far more effective than mechanical lockers in probably 90% of situations. with the added benefit of it working automatically Quote Link to comment Share on other sites More sharing options...
Anderzander Posted January 3, 2014 Share Posted January 3, 2014 spinning a wheel over a wet rock will always need a certain torque to overcome the (largely reduced) grip of the tyre. this torque is what the ATB uses to drive the other wheel. it does what it says on the tin really, torque biasing. This helps refine my question - what amount of torque can it use ? Is it only zero resistance it can't cope with or is there a friction threshold ? Quote Link to comment Share on other sites More sharing options...
discomikey Posted January 3, 2014 Author Share Posted January 3, 2014 there is a torque ratio. from what i recall, it may be 3:1.. now i havent a clue wether that means if the spinning wheel takes 1nm of torque then it biases that torque 3x to the other wheel so would be able to put 3 nm through the wheel with grip or wether it is the other way around. wether there is a threshold or not i dont know, what i could do is jack it up set it going with someone in, and try to grab the spinning wheel. if it chucks it off the jack, then most likely there isnt a noticeable threshold. if it chucks me over then there probably is Quote Link to comment Share on other sites More sharing options...
discomikey Posted January 3, 2014 Author Share Posted January 3, 2014 it would be good if Mr Ashcroft stumbled across this thread in order to answer questions as people may have. maybe Nige or some of the more responsible adults on here may also have a working knowledge too Quote Link to comment Share on other sites More sharing options...
Mr Ian Posted January 3, 2014 Share Posted January 3, 2014 Hi you understand the principle the principle correctly, think of the diff center as a very inefficient gear set, it is not quite zero if one wheel is free as there are dished springs or belville washers between the gear sets to provide some pre load, obviously more spring tension more pre load, having said that this pre load quickly becomes insignificant compared with the torque generated by a wheel or an active TC system. Regards. Ian. Ashcroft Quote Link to comment Share on other sites More sharing options...
reggie Posted January 3, 2014 Share Posted January 3, 2014 So can it still work as good on a vehicle with no TC like my RRC? Quote Link to comment Share on other sites More sharing options...
robertspark Posted January 3, 2014 Share Posted January 3, 2014 Not the lost linguistic u-tube clip---- http://www.youtube.com/watch?v=LTXvH3T8Bsg It would appear that on a split surface (two different types) even on ice it can experience some torque bias (don't shoot the messenger) Quote Link to comment Share on other sites More sharing options...
Brian Posted January 4, 2014 Share Posted January 4, 2014 Working entirely from memory now, as I do not have any documentation or articles to hand, I do remember an article in Autocar somewhere around 1971 featuring the Torsen differential. It was developed by an engineering company in Devon, specifically for Land Rovers and the article featured an off road test of a Series IIA fitted with Torsens front and rear. It was very impressive. Sold as an aftermarket odd on, only for Land Rovers, at that time. GKN later bought up the rights and, from then on, it was only supplied as an OEM licence to manufacture. One of the Range Rovers, I think the early L322, featured a Torsen centre (or was it rear ?) diff, as standard fit for a while too. Electronic control superseded that though. Just thought this may be interesting extra info, although it is based on memory, so may possibly be inaccurate in details. Quote Link to comment Share on other sites More sharing options...
Mr Ian Posted January 4, 2014 Share Posted January 4, 2014 Hi Brian. Thera are three types of Torsen LSD, a quick Google for Torsen T1, T2, T3, will show the types. LR tried the T1 which I also evaluated and which has a higher bias ratio than the others but was prone to self destruct if used aggressively. The T2 was not tried ,as far as I am aware, but is similar in design to the Truetrac, Quaife, Ashcroft, ie cross helical gears. Regards. Ian Ashcroft Quote Link to comment Share on other sites More sharing options...
Brian Posted January 4, 2014 Share Posted January 4, 2014 Thanks Ian, it's always interesting to get more info on something I have been interested in for a time. Especially as it was the first type I had come across as an alternative to a full manually locking type. I do remember a bit of a reputation on their long term reliability, so must have been, as you say, the T1. Quote Link to comment Share on other sites More sharing options...
robertspark Posted January 4, 2014 Share Posted January 4, 2014 Thanks Ian, very informative. Question: the ratios (T1 - 5.0:1, 2.5:1, T2 1.4 to 3.0;1) is that derived from the gear tooth count or something else? Very interesting read: Torsen T1 http://www.torsen.com/products/T-1.htm Torsen T2 http://www.torsen.com/products/T-2.htm Torsen T3 http://www.torsen.com/products/T-3.htm Where do the Ashcroft ATB's sit with regards to bias ratio? I'm also interested in the LT230 ATB (next on my list ....) Quote Link to comment Share on other sites More sharing options...
Mr Ian Posted January 4, 2014 Share Posted January 4, 2014 Hi Robert. Ours fits in with the T2 operation and bias range. The reason we went for the 6 pocket design was to have max gear pockets hence high bias as opposed to the Truetrac with only 3 pockets. I will try to find an interesting mathematical analysis which was carried out to see if there was any difference in the gear rotation direction/vs friction bias. There wasn't!. Regards Ian Ashcroft Quote Link to comment Share on other sites More sharing options...
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