 | Home > Technical > ATB (torsen) front and rear install |
 
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17388   
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Tim, the reason I did the front first was simple. My early ('07) Puma had the 2-pinion front diff, which disintegrated and locked solid. Made steering very "interesting"! Ashcroft ATB diff was cheaper, stronger, and shorter lead time than LR diff. See link for photos. |
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17th Aug 2012 9:25pm |
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| T1G UP Member Since: 08 Dec 2009 Location: Bath Posts: 3101  
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a trutrac diff is an ATB diff. personally i'd g with another trutrac if your happy.To get an ashcroft ATB shipped over will be expensive and any warrenty isssues ( there won't be any) could cause postage issue again. |
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23rd Aug 2012 7:39am |
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| tatra805 Member Since: 16 Aug 2011 Location: Dolany Posts: 436  
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Tjhappel,
no snow driving yet, give me 4 months to report back 
With 90% road driving i do not see the need for something else than a standard diff, but just as me in the other 10% of cases its so nice to have that extra bit of traction. I have only heard positive feedback on snow so hope for the best. Anyway i am convinced the extra traction is there when you need it. Is is also not the goal to drive "dry road" speeds in those conditions. (as eg a lot of people think about winter tires) As i have beaten to death already the stabilizing influence when braking might also on snow turn out to be a major benefit. I partly agree with T1G UP about taking a truetrac in your case, as you have one in the back already you will be able to swap if it breaks. (as some report quality issues with them in actual production) In all honesty i never had a problem with mine in my disco, but that's 6 years back. But, the construction of the ashcrofts is superior to that of the truetrac and that would be a big factor for me especially as a truetrac is more expensive here. Transport costs might be not all that bad. I cannot tell you how big the difference is going to be for you as i had both front and rear done in once on both vehicles. Take into account the understeer under power for the front which you will immediately notice.(not that dramatic and a fast learning curve)  |
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23rd Aug 2012 11:10am |
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| Tjhappel Member Since: 08 Aug 2012 Location: Southern California Posts: 32  
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Thanks for the responses guys,
So neither of you think it worthwhile to get an arb locker for the front? A few of the guys I've spoken with regarding trutrac in snow have advised to not put it upfront, hypothetical; if your turning and one wheel starts to slip a bit on an icy road both wheels will lock and could "push" rather than help to turn. This isn't my opinion since I've always driven vehicles with tc/abs. One more question.... Entreq looks like they make some unbelievable equipment, however all my emails have gone unreturned. Any advice? And Tatra since your way up north do you use a snow cover on your front winglet? |
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25th Aug 2012 10:28pm |
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| tatra805 Member Since: 16 Aug 2011 Location: Dolany Posts: 436
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OK, I’m a bit confused.
First of all, an ATB does not "lock" and not "at once" it transfers TORQUE (not movement, speed or force) smoothly and only in a 60/40 balance AND this means the slipping wheel still needs to have some friction to create torque which can be transferred. (spinning on pure ice you'll have 10% of torque compared to tarmac, of which only 40% will go to the non-spinning wheel, as the spinning wheel regains traction more and more torque will transfer. This is what makes the ATB so smooth) What is your main target with the locker? Do you need this one for heavy offroading or do you want to have a benefit ‘all the time’. A full locker will - leave all as it is while normal driving, not engaged (snow or no snow) - pull you straight and take away your steering ability when switched on (not a bit, simply NO steering anymore), this makes it useless on roads and at speed. So I would rather put it in the back and use it only when offroading. (take into account the eventual need for stronger halfshafts) In the front it wont make any difference to the setup you have now and sit useless for 99% of the time An ATB in the front will - help you all the time (dry-wet-snow-….) - improve stability under braking - but also increase understeer when under power. This will of course be more noticeable when driving on slippery surfaces, especially when both front wheels are on it. BUT if you drive normally (so not trying to break speed records) on snow roads I am sure you will get a benefit from the ATB action BEFORE the understeer becomes an issue. (IF you would put your foot down in a turn on a snowy/icy road you are asking for problems, no matter which setup you have) I see your question in a lot of discussions come up as critics to the ATB. To my opinion this is only the result of people not handling the increased traction in an appropriate way. (getting used to it and driving closer and closer to the limit of the next component = tire friction, till something happens and they go over the limit) As a very simple similar example: If you put the 3.2 TDCI engine in your defender you cannot expect it to behave as with the 2.4. You will need to adapt you driving style or you’ll end up in a ditch. The same goes for the ATB. If you floor it on a slippery surface you will create a situation where BOTH front tires will not have enough friction and start spinning. This will result in massive understeer (Almost as with a full locker) and clearly more than with an open diff (logical). The benefit and reason for putting an ATB is that where the first wheel looses friction it will engage the second wheel (double friction) for more traction. So it will take longer before you loose traction. This extra area of having traction gets smaller and smaller the more slippery the surface is. (call it the benefit zone) So you will, as with any setup, run into the limits of traction/friction faster when slippery. Still it will be later than with an open diff but the effect different, an open diff will not understeer that badly when things go wrong (putting your foot off the accelerator solves this for both of course) Same goes for ESP, ETC etc, they help BEFORE reaching the limit. Once over it nothing but luck is there to save you. Anyway, purely related to snow and ice conditions I see the ATB as a safety increasing device as is 4x4 compared to 4x2. That means you can travel at same winter speeds with bigger margin. Those who think 4x4 is the tool to drive summer speeds on snow are those who prove the contrary the first time they have to break. Snow/studded tires on a 4x2 are much more efficient than a 4x4 on summer tires. (as friction becomes more important than traction on slippery surfaces) If you drive with your brains engaged you will not experience the understeer issue of an ATB on snow as you wont go near that limit. If you push it (don’t we all) you will experience this understeer issue at eg15mph faster speeds compared to an open diff, which will need a better driver to correct it, or will make a bigger impact. just my opinion |
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27th Aug 2012 10:47am |
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| Tjhappel Member Since: 08 Aug 2012 Location: Southern California Posts: 32
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Tatra,
Thanks for the awesome well thought out reply. I think you've convinced me to give it a try... I would probably only actually "need" a full locker once a year so getting more traction all the time makes a ton of sense. I usually drive 5-7k per year on snow/ice roads however it's either in a landcruiser or g-wagon and I guess I'm spoiled by both of them as they have the full barrage of electronic goodies to help compensate for stopping etc. unfortunately I sold them to fund owning my dream vehicle, a puma 110, but I had a ton of difficulties last year in snow compared to either of the aforementioned vehicles. No abs is like you said just different to get used to as well as having open lockers. I wasn't able to order my defender with etc/abs so I'm hoping this trutrac setup will be the next best thing or better. other thing that's hard to get used to is driving in several inches of snow the width of the defender is quite a bit narrower than mst vehicles so it was consistently "hunting" in the tracks of other vehicles before it. I really really appreciate your help in this matter, most cars built over here have electronics and the last year anyone worked on defenders was 1997... So I'm always browsing the forums for good solutions. I totally agree on the snow tires, it makes all the difference! Any other ideas you have would be greatly appreciated. Per chance do/did you experience any issues with you car in cold cold weather say anything below 0, my car would run fine, needle go up to normal operating temp whilst driving but the second the car idled the temp coming out of the heater vents gets colder and after 5 minutes the needle is at the bottom again. It took me a very long time to fix that one! I was curious if anyone else had that issue. |
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28th Aug 2012 4:36am |
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| quentin Member Since: 23 Jul 2012 Location: on tour Posts: 119  
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I put truetracs in mine front & rear, (For the argument they are the same as ATB, torsen LSD's but made by Eaton instead of Ashcroft) Agree with Tatra's comments about how awesome they make your Defender (great write up by the way)
But still you SHOULD engage center diff when you normally would - if you want to keep a nice tight transmission engage the center diff early Below pic is a screencap of the highest I can get up the ramp with Front & Rear truetrac, Traction control ON & (center diff engaged of course) The yellow line is the most it would go before I put the truetracs in. (measured at the center of the wheel)  Click image to enlarge Of course My old 90 with maxi drive front and rear would drive right to the top so dont let anyone fool you into thinking they are as good as Diff Locks in that respect. That Said, for sand driving and desert work I think the advantages of Truetracs (ATB's) outweigh the advantages of Diff Locks. ( A different matter for mountain climbing & rock crawling) |
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28th Aug 2012 5:20am |
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| tatra805 Member Since: 16 Aug 2011 Location: Dolany Posts: 436
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Quentin,
Fully agree with you on the center diff. I'll try to rephrase an explanation i got. just as info. Center diff works as a normal diff inside your transfer case. It is not designed to cope with prolonged big speed differences between front and rear axle. Also remember the physical design of the center diff is not as big/strong as an axle diff. Compared to an axle; when you turn both wheels are turning and the speed difference between left and right is a low percentage (depending on how tight the turn is). This speed difference is compensated by the movement of the satellites. It is only when spinning a wheel on an axle that the satellites will have to work hard, for a very short period of time. The unlocked center diff will work similar on tarmac and compensate for a low percentage speed difference between front axle and rear axle. (and thus avoid wind-up) In a non locked center diff driving offroad the difference between a slipping wheel on the front axle and a non slipping wheel on the back axle is 100%, massively more than during normal diff operation on paved roads. The satellites have to compensate for this and will work overtime as you will spin your wheels continuously. (wheelspin does not have to be “out of control high speed”, eg on gravel a wheel has traction but spins faster than a passive wheel rolling over the gravel) Also imagine the construction of a diff, for one rev of the axle the satellites are rotating around 4 times (if I remember correctly). A turn with a difference of 3 rpm between inner and outer wheel (outer wheel covers 7.5 meter more distance per rotation of the inner wheel) makes the satellite turn at 12 rpm. A wheelspin at 40km/h = 11.11m/s, avg wheel circ: 2.5m = 4.4 rev/sec = 266rpm axle = 1066 rpm sattelite. That is almost 100 times more than normal intended operation. On a construction without bearings you can imaging the wear. When engaging center diff lock, you not only avoid wheel spin better as both axles are driven but also take out the weaker center diff and make that the axle diffs have to cope with the speed differences when slip occurs Heavy duty center diff parts are available, eg for competition use. And just as info a lot of the first generation permanent 4WD systems from other brands are using a torsen type diff as center diff. 2cents |
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28th Aug 2012 9:16am |
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| lrmaniac Member Since: 04 Feb 2010 Location: Lisboa Posts: 762  
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being an off topic, it's not... I was considering buying ashcrofts ATB front and rear, still am...and do the mods Tatra805 did...fitting them front and rear...
Now, I have the possibility of buying a Detroit TrueTrac, used, 1 year warranty left, for 300€... It belonged to a guy on a portuguese forum that bought it, but it was not enough for his needs so he bought an ARB...He says that he didn't do more than 3500km...I think it's a good deal, what do you think? If I buy it now, and the ashcroft later, do I fit this one first in the front or rear?  thanks Regards
Joao '10 Land Rover Defender 110 CC '08 BMW F800GS '64 SIIA Forward Control '69 SIIA 109 ZA CKD _____________________________________________ You have the right to remain silent. Anything you say will be misquoted, then used against you. |
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10th Dec 2012 4:50pm |
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| quentin Member Since: 23 Jul 2012 Location: on tour Posts: 119
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Be aware unlike the Ashcroft ATB , that the Eaton (Detroit) TrueTrac are different for front or rear, so if its rear one it will only work properly in the rear and vice versa. Ive had mine in for 30.000 klm & still good as new |
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10th Dec 2012 9:55pm |
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| lrmaniac Member Since: 04 Feb 2010 Location: Lisboa Posts: 762
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Thanks...The guy selling told me this afternoon that it's for the front diff!
So for a little more than half the price (new it costs 550€ here), having one year warranty left it should be a good deal!? Regards Joao '10 Land Rover Defender 110 CC '08 BMW F800GS '64 SIIA Forward Control '69 SIIA 109 ZA CKD _____________________________________________ You have the right to remain silent. Anything you say will be misquoted, then used against you. |
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10th Dec 2012 10:56pm |
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| tatra805 Member Since: 16 Aug 2011 Location: Dolany Posts: 436
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Is it a good deal?
Yes, from money side. Warrantee? Installed in second vehicle/other owner? Etc no idea and a couple of things I found on the net about people having to send in the broken diff and then get a no-warrantee closed case type answer. (Ship to USA will cost you also) But of course you have more chance it won’t break and you’ll never need the warrantee. My personal view? I rather have 2 identical new units, - which are interchangeable (if needed) - new, so no unknown history - full warrantee - Close by direct contact with the manufacterer (From my contacts with ashcroft I am sure they would see a claim in their interest finding out what went wrong) - Better construction But I do understand that 300euro is attractive. In any case, you won't regret it. Been driving on snow and ice for the past week and 
BTW: if i remember correctly the only difference between front and back truetrac is the preset initial tension on the gears which is lower for the front (so it takes a bit longer before they engage. which is just temporary thing that equalizes over time. (= back version becomes as loose as the front version) I guess they did it to reduce the torque-steer thing and make it more customer friendly for the new user. |
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11th Dec 2012 10:04am |
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| achuakh Member Since: 12 Apr 2012 Location: Singapore Posts: 158  
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I've fitted the Ashcroft ATB as well to both front and rear just about a month ago.
I'm happy. Worth it? Yes! I was thinking of only installing one in the rear as i had a worn diff in the rear, but then again, it's best to do both together. So you don't have to waste time and money to have it fitted and you do save a lil on the shipping, considering where in the world I am. The truck is : more eager to steer straight. more stable when you run thru large "ponding of waters" as what the govt in my country describes a flood as. has more grip on soft sand and i've no noticable wheel spin even when i push the loud pedal. (no TC so i don't know if TC will kick in) more likely to over steer when changing gears at faster speeds. I can't justify myself why i need an air locker when i'm on the road over 90% of the time. So this would be the next best bet for your money. consider it doesn't cost really very much over a new diff from Land Rover. From the land of the most expensive land rover defenders on planet earth. At �125k for a XS 110 csw and you get to own it only for 10yrs! Please find me a good reason to stay on this island. |
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14th Dec 2012 8:12am |
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| Phoenix90 Member Since: 04 Mar 2012 Location: Cornwall Posts: 377 
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Just ordered a diff from Ashcroft with a Ashcroft ATB built in
look forward to fitting it now.
Thanks to all of those that have given advice so far especially blackwolf
Let you know how I get on. |
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17th Dec 2012 6:10pm |
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