 | Home > Technical > ATB (torsen) front and rear install |
 
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| tatra805 Member Since: 16 Aug 2011 Location: Dolany Posts: 436   
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No, tube sits between inner and outer bearing, and defines distance between both bearing racers.
Between flange and outer bearing are no shims. As i understand it the tube is there to equalize preload between inner and outer bearing by fixing the distance between them, i guess size of this tube is based on measuring the distance between the seat-areas of both bearings, which also has a machining tolerance. (which would mean that the tube is paired to the diff nose, and has nothing to do with setting R&P) Preload is set by tightening the pinion bolt, i found that from a certain value the preload did not go up anymore, this would then be when both bearings are fixed to the tube, this was at 130NM, which is way above the 75 to 90NM handbook value. old and new P38 pinion 
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19th Jun 2012 4:49pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17388  
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Is the stock rear P38 diff on the Puma 110 the four pinion version or the two? I presume the four, but I haven't had my rear diff out yet.
Also, can a Rover diff be fitted in its place with a modified propshaft or does the axletube differ between P38 and Rover units? I'm not sure why the P38 was fitted but assume it was cheaper than the Salisbury, more available then the (very) old ENV, and stronger than the 2-pinion Rover diff. I don't think the 4-pinion Rover diff had been designed by then. |
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19th Jun 2012 6:11pm |
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| tatra805 Member Since: 16 Aug 2011 Location: Dolany Posts: 436
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MK, yes you are right, should be possible if you can make/obtain the right size shims
Blackwolf, P38 diff because of propshaft angles i guess. It is the 4pin as found on the 4.6 V8 P38 in the rear, other engine versions had a 2 pin in the rear. Rover diffs used to have 4 pin all round, at least my discovery 1 had. If my info is right till Puma both front and rear are 4pin. Tube should be ok and compatible with the rover diff, but propshaft will give you headaches as the rover nose is a lot longer magnifying the problem with the propshaft angles rover type diff cores (and alternatives as lockers atb's etc) can be mounted in the P38 nose using the spacer ring as described earlier.  |
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19th Jun 2012 6:22pm |
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| MK Member Since: 28 Aug 2008 Location: Santiago Posts: 2416  
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Shims are not a problem and cost peanuts. Puma 110" SW
............................................................. Earth first. Other planets later |
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19th Jun 2012 6:59pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17388
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Interesting, Tatra. I thought the four-pinion Rover diff introduced c.2008 into the Puma was the first use of 4 pinions in a Rover unit, and that the 90 initially had 2-pinion diffs f&r and the 110 2 at front (Rover) and 4 at rear (P38). Puma 90 has a Rover diff at rear (as far as I know) and has a shorter prop, so prop angles shouldn't be a problem on a 110.
My '02 TD5 Disco has 2-pinion Rover diffs f&r (same as the original front diff in my '07 Puma 110); perhaps your Disco had been upgraded? |
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19th Jun 2012 10:00pm |
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| lrmaniac Member Since: 04 Feb 2010 Location: Lisboa Posts: 762  
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Hi
Did you replaced the halfshafts as well ? Or no need to? 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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20th Jun 2012 8:39am |
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| tatra805 Member Since: 16 Aug 2011 Location: Dolany Posts: 436
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First of all... Blackwolf..... you were right
traced the disco cores this morning and they are 2pin...... my mistake Lrmaniac, No need to replace halfshafts, as the torsen is transferring torque in a 60/40 or 70/30 matter this means you never transfer 100% on 1 halfshaft (as you can do with a full locker) so no fear of breaking something. |
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20th Jun 2012 9:00am |
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| tatra805 Member Since: 16 Aug 2011 Location: Dolany Posts: 436
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Here we go; made some real life videos
First of all, the screeching sound you hear but is my mudshield on the right side hub playing up (being full with mud etc etc) The hill doesn’t look as steep as it is, this is a small gravel pit. 110 is stock on 235/85 BFG AT’s and stabi-bars still in place. No video of driving up without the ATB’s. Did this before and that was only possible on the back slope in 2nd low with a lot of accelerator and higher start speed. Vid 1: 307 front slope, CDL OFF, TC OFF . First attempt typical drop of front wheel which with a full locker is a very usual moment to break a stock half shaft.
Vid 2: 307D Front, CDL OFF, TC ON
Vid 3: 308B Front slope CDL ON, TC ON
Vid 4: 307C back slope, CDL OFF, TC OFF then CDL OFF, TC ON
Vid 5: back slope TC ON, CDL ON
Not the point here how I slide down the slopes with locked brakes, this was to even out the slope a bit. Also not the point here but this is not how I normally drive, and maybe for some “stupid” or “a waste”. Made these video’s to make the differences visible. :) Admin note: this post has had its images recovered from a money grabbing photo hosting site and reinstated |
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24th Jun 2012 5:19pm |
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| lrmaniac Member Since: 04 Feb 2010 Location: Lisboa Posts: 762
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...so tatra805, two months have passed since you fitted your atb's...
still happy with them? no faults or problems? still recomend them ? I'm very very tempted by now ...saving money, almost there  ... 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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16th Aug 2012 2:59pm |
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| tatra805 Member Since: 16 Aug 2011 Location: Dolany Posts: 436
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KEEP SAVING, you won't regret it!!
Indeed a couple of months later already I'm in for about 5000kms now and did not have one moment where i doubted the decision. It's hard comparing of course as you cant switch them off but on all the loose surface we've seen in the alps and home on known tracks i am still surprised how fluent they work and how much difference they make. No defenders here to compare also. One case was a nissan pickup on simex copies we were following on a nice steep wet forrest track. All of a sudden he was standing and struggling where we still had big reserves (on AT's that is + the nissan has an LSD in the back). He had to drive back in reverse while we could even park ourselves next to the track and then restart the drive up. TC is 90% less active, that is a good indicator. We had a very hard storm on the austrian highway driving to Croatia and the reassurance the diffs give you on roads with standing water is frightening. I cannot say they are 100% neutral. You do notice the increase in turning circle when accelerating, certainly if things get tight and you drive a bit sporty (hairpins eg). BUT i must say that this is easy to correct with driving style and not something that outweighs the continues benefit of having them. (and 100% caused by the front diff) Still the biggest surprise about them is how they keep the 110 straight when braking. Oh, and i surprised already a couple of sporty small hatchbacks on our mountain roads. You can floor the 110 it will keep acceleration in each hairpin so you're sticking to their back window with screaming inside tires and if hot enough a viscous fan roaring engine. 
I know these are all non standard situations, but that means to me the diffs are working a lot of times, unnoticed and you really have to push them to make it obvious they are there. One thing as a warning. Traction is the thing we are looking for and i see now very good that the AT is the limiting factor offroad (and not an open diff as many times before, we really get much further much easier) while it is the AT which is keeping us behave good on asphalt. I am sure that if you press on with MT's on pavement you'll see much increased tire wear and even will have to keep an eye out in the wet when turning and driving with a heavy foot. This is not a bad thing about the diffs but as you have more traction you can put down easier and earlier you will discover the limits of the next thing in line faster than you expect (as the diffs work unnoticed). IOW you will start driving faster everywhere without noticing and then reach the 'holding' limit of the tires, which in case of an MT is much lower on tarmac compared to an AT. If you can restrict yourself and keep the same driving style (and speeds) you wont notice. But i found out restricting myself proves to be impossible 
If i remember correctly you are also pulling with your defender. Only for that purpose the diffs are justifiable. Both in positive traction as in braking they really made a difference with the horsebox behind. For your caravanning trips it will be heaven. I had a friend over who's driving a TR DCPU (so TD5) It was funny to see how he was anticipating with slipping the clutch while you can so easily let the clutch and antistall start your traction and BEFORE the TC kills your power.(esp with the trailer on wet surfaces and inclines it is a big difference) So, am i satisfied? .... Yes Sir! |
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16th Aug 2012 3:58pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17388
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FWIW I have now had my Ashcroft ATB in the front axle for 9 months (15k miles) and have been very pleased with it. I did have some issues with a small oil leak from the pinion flange oil seal, but Ashcroft have been extremely good sorting this out. I think the occasional problem like this is inevitable, and I certainly can't fault the after-sales service I have received. Performance-wise it has been excellent, and and it really makes a difference off road (I do not have TC/ABS). It has no discernable bad manners on the road.
One thing I have noticed is that the HD pinion and crownwheel set is significantly noisier than the standard OE set, with a pronounced whine under conditions of very light power at speed. I don't think this is a fault, rather it is a characteristic of the different number of teeth causing differenet resonances. It doesn't bother me at all but if I was fitting an ATB into a mainly-road-going SW I would probably fit one with a standard crownwheel and pinion, not the HD version. Most HD sets are fitted to comp vehicles where noise isn't a prime consideration, and failures of the standard pinion and crownwheel are rare (I opted for the HD version because I wanted the strongest diff it was feasible to fit). I will deffo be fitting one in the back axle when the old national debt is back under control and SWMBO says I can (or I think I can get away with it without her finding out)! For the record, my diff was a complete assembled ATB unit from Ashcroft with the HD crownwheel and pinion and standard ratio. |
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16th Aug 2012 4:05pm |
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| Tim_NZ Member Since: 05 May 2008 Location: Australia Posts: 177 
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Blackwolf any particular reason you fitted the ATB to the front axle first? I only ask as I have on on the way and intend to fit it to the rear first.
Cheers, Tim |
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17th Aug 2012 1:08pm |
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| tatra805 Member Since: 16 Aug 2011 Location: Dolany Posts: 436
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Tim,
you bring up a very good question to which i never got a 100% answer. Why put it in the back?? or is that a legacy from the time vehicles were 2wd with a solid back axle(s) and the only option for extra traction was putting it there??? and once front wheel drive came the available lockers (full lockers) were not a good thing to put in the front as you loose steering ability. If i had to put one only, i would consider putting it in the front as it are those wheels that loose traction first, be it because they enter the obstacle first or due to weight distribution driving uphill or the fact that they have 2 tasks (traction and steering) i don't care but i am really thinking the ATB would be more value in the front. but maybe i am completely wrong in my thinking, which wouldn't be a first 
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17th Aug 2012 8:10pm |
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| T1G UP Member Since: 08 Dec 2009 Location: Bath Posts: 3101  
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i think you'll find the front diff broke so he upgraded the diff to a ATB as there cheaper than a LR item and stronger and better |
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17th Aug 2012 9:18pm |
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