Ashcroft ATB on road

[BogMonster]

Correct, my Tdi is a 2006 model year, I bought it just before the Puma came out in case I didn't like the Puma. So it has the late axle fitted to all post 2002 vehicles.

Coincidentally I also bought a late Puma in case I didn't like the next version ... which proved to be a much better judgement

[Snagger]

18 hours ago, Peaklander said:

Hope you don't mind a numpty question @BogMonster, I have a 110 TDi and it has a Salisbury rear axle. Reading this interesting thread and following through to investigate further, I see that the Ashcroft ATB isn't available for this type of axle. Have you changed yours or was it always something different (Rover)?

For Salisbury axles is the only way, to go for a different brand of ATB and pay the additional money?

You can replace the axle and prop with the 2002+ type and fit the Ashcroft, but that axle has more pinion issues than the Salisbury because the pinion is so short that the bearings have a hard time keeping it straight, or you can go with a Trutrac or Quaife.  The cheapest I have seen the Trutrac is at the LR Centre at Speke, Liverpool.  The Quaife is better, but almost twice the price (around £1k inclusive, plus bearings and any labour).  I have a Salisbury axle on my 109 and will fit one of these (myself), hopefully the Quaife if possible at the time.

[Snagger]

14 hours ago, reb78 said:

I'm curious. Are there options for the Salisbury axle? 

 

Eaton Trutrac and Quaife.  Quaife is considerably better quality and has six worm gears each side (like the Ashcroft) rather than the 3 of the Eaton, who should be a lot more effective as well as more robust, but it’s 50% dearer too.  

[Ed Poore]

3 hours ago, Snagger said:

plus bearings

I vaguely seem to remember them being both difficult to source and extortionate in cost. I think when Nige and I priced up a full set of bearings for the Salisbury it wasn't far off the cost of the diff itself . I think that that might have been a case of check the condition of the existing bearings and reuse where possible.

[BogMonster]

21 hours ago, Snagger said:

You can replace the axle and prop with the 2002+ type and fit the Ashcroft, but that axle has more pinion issues than the Salisbury because the pinion is so short that the bearings have a hard time keeping it straight, or you can go with a Trutrac or Quaife.  The cheapest I have seen the Trutrac is at the LR Centre at Speke, Liverpool.  The Quaife is better, but almost twice the price (around £1k inclusive, plus bearings and any labour).  I have a Salisbury axle on my 109 and will fit one of these (myself), hopefully the Quaife if possible at the time.

...or you can order a pegged P38 diff from @Hybrid_From_Hell which solves that problem

[Snagger]

17 hours ago, Ed Poore said:

I vaguely seem to remember them being both difficult to source and extortionate in cost. I think when Nige and I priced up a full set of bearings for the Salisbury it wasn't far off the cost of the diff itself . I think that that might have been a case of check the condition of the existing bearings and reuse where possible.

About £60 for a full Timken set last time I checked with my local uk supplier.  But they’re easy to source, just not through LR franchises as they tend to support vehicles of 10 years and younger, the minimum by law.  Thanks for that, Tata.

[Peaklander]

3 hours ago, BogMonster said:

...or you can order a pegged P38 diff from @Hybrid_From_Hell which solves that problem

Ah so are you saying that one of these will fit in the Salisbury axle case along with an Ashcroft ATB?

[landroversforever]

Just now, Peaklander said:

Ah so are you saying that one of these will fit in the Salisbury axle case along with an Ashcroft ATB?

No, the pegging solves the issue of the later type, short nose, rover diff pinions moving. 

[Peaklander]

Yes, I was just checking further up the thread and realised remembered that we are of course talking about the later axle. 
 

You beat me to my edit!

Edited October 16, 2019 by Peaklander

[Chicken Drumstick]

On 10/14/2019 at 10:39 PM, reb78 said:

I'm curious. Are there options for the Salisbury axle? 

The Salisbury is basically a Dana 60 centre. Very popular with Ford, GM and Dodge. So lots of aftermarket bits. I'd probably opt for a Detroit locker over than ATB in one of those.

[deep]

The Detroit is very popular but a friend has one in his alleged 90 and it can be a vicious beast in some circumstances, as it throws the car around quite violently when it "bites" in slippery going.  Basically, it just wants to go straight, like any locker, but that is not always predictable.  I think I'd still have one though, because I don't do intense off-roading of that type.

(Edit) Just as an aside, he put the Detroit locker in the rear Salisbury (the "90" is a cut-down 110) and a Tru Trac in the front, something like twenty years ago.  As far as I know, they've proven to be very robust and durable.

Edited October 16, 2019 by deep

[Gazzar]

If you fit a true trac in a Salisbury, I presume you don't need to peg the diff? Plus it's already 24 spline etc., so fairly tough.

[landroversforever]

I think I’m right in saying that the only bit of a Salisbury that’s stronger than a normal rover is the centre of the diff. 

[BogMonster]

2 hours ago, deep said:

The Detroit is very popular but a friend has one in his alleged 90 and it can be a vicious beast in some circumstances, as it throws the car around quite violently when it "bites" in slippery going.  Basically, it just wants to go straight, like any locker, but that is not always predictable.  I think I'd still have one though, because I don't do intense off-roading of that type.

(Edit) Just as an aside, he put the Detroit locker in the rear Salisbury (the "90" is a cut-down 110) and a Tru Trac in the front, something like twenty years ago.  As far as I know, they've proven to be very robust and durable.

It's hearsay, but once upon a time there was a chap here with a Detroit in the back of a Discovery Tdi, and I was told that he took it out because it had a very nasty habit of making the vehicle go straight on when you got to a corner on a gravel road. Most of the roads here are gravel outside the town.

[Snagger]

9 hours ago, Gazzar said:

If you fit a true trac in a Salisbury, I presume you don't need to peg the diff? Plus it's already 24 spline etc., so fairly tough.

It’s a chunky pinion, but more than that, the bearings are quite well spaced to give it axial stability, as opposed to the P38/Wolf diff which has a very short pinion with closer bearings.  I couldn’t venture an opinion on how useful pegging a Salisbury is, but I’ve never heard of it being done, so it probably is never needed.  Nige would know more, but I don’t think he works on Salisburys, presumably because of the inconvenience of how they fit in the axle (same assumption for Ashcroft not touching them).  But their gears are substantially bigger than the Rover types, so should be a fair bit stronger too.  

The downside of the Salisbury (apart from the method of shimming the side bearings and setting backlash) is the size of the casing and its ground clearance compared to the smaller Rover units.  I have read comments and seen a handful of photos of axle cases broken at where the tubes enter the cast diff housing, but how overloaded or abused they were wasn’t mentioned and I’ve read many-fold more comments or questions about bent Rover axles, including the late 110s (which is why the MoD had them so heavily reinforced for the TUMs).

 

 

 

[Gazzar]

I've never played with a Salisbury, what's the process for shimming the bearings like? I can read the manual, but that doesn't give you the feel of the job.

[landroversforever]

37 minutes ago, Gazzar said:

I've never played with a Salisbury, what's the process for shimming the bearings like? I can read the manual, but that doesn't give you the feel of the job.

It's years since I worked on a Salisbury, but if I remember correctly it doesn't have the adjusters to shift the centre left/right like the Rover type ones. I'd imagine the shims are to do that movement, combined with the case spreader to actually get it back in.

[Gazzar]

I've read Nick's post on seeing them up, and whilst laborious, it doesn't look impossible.  

My Salisbury axle casing is quite rotten, and after 20 years fighting the rot, I think it might be time to concede defeat. I've a spare axle, but I'd rather check it over before fitting it.

[Gazzar]

And, if I'm doing that, I'll fit a true trac.

[Chicken Drumstick]

12 hours ago, BogMonster said:

It's hearsay, but once upon a time there was a chap here with a Detroit in the back of a Discovery Tdi, and I was told that he took it out because it had a very nasty habit of making the vehicle go straight on when you got to a corner on a gravel road. Most of the roads here are gravel outside the town.

The Detroit locker is in a way misnamed. It is really an automatic unlocker. i.e. it is locked, just as per any other locking diff. But under certain conditions will unlock to allow different wheel speeds on the axle. However for this to occur you probably need traction greater than that of gravel. I'm also inclined to suggest that a RWD vehicle, such as a Series or most American pickups/4x4's would work better in such a situation, as instead of understeer on gravel, you end up with both rear wheels spinning and the ability to drive in a powerslide drift. With the AWD setup of a Discovery/Defender it'll be pushing some of that power to the front and likely to induce far more understeer, as it'll be a lot harder to get the back to step out (not impossible, but will need a more aggressive driving style with a flick of the steering, rather than just pushing the loud pedal).

I'm also inclined to suggest a Detroit probably works better on heavier and longer wheel base vehicles, than it would on a shorter wheelbase lighter vehicle. A Discovery is sort of middling length wheel to short. Although this is only a hunch, I don't have any data to back up this thought.

[Snagger]

4 hours ago, landroversforever said:

It's years since I worked on a Salisbury, but if I remember correctly it doesn't have the adjusters to shift the centre left/right like the Rover type ones. I'd imagine the shims are to do that movement, combined with the case spreader to actually get it back in.

Yep, that’s basically it, though the spreader is just advantageous rather than mandatory.  The difficult bit is that the shims sit between bearing inner races and diff centre, so changing them requires removal of the bearings.  

The correct set up procedure, starting with a stripped case, is to put the centre with bearings but no shims into the housing and then check for end float to find the total shim pack thickness, then remove the centre, set up the pinion in a way not that different to Rover diffs, then refit the centre (still without shims) and measure the backlash rotation angle.  There is a relationship between that angle and the thickness of shims to be added to one side of the carrier, so you add that thickness on that side and the remainder of the total endfloat to the other side, refit the bearings and reassemble, and the final checks should then be within tolerance.  It’s not as hit and miss as you’d imagine.

 

[landroversforever]

2 minutes ago, Snagger said:

Yep, that’s basically it, though the spreader is just advantageous rather than mandatory.  The difficult bit is that the shims sit between bearing inner races and diff centre, so changing them requires removal of the bearings.  

The correct set up procedure, starting with a stripped case, is to put the centre with bearings but no shims into the housing and then check for end float to find the total shim pack thickness, then remove the centre, set up the pinion in a way not that different to Rover diffs, then refit the centre (still without shims) and measure the backlash rotation angle.  There is a relationship between that angle and the thickness of shims to be added to one side of the carrier, so you add that thickness on that side and the remainder of the total endfloat to the other side, refit the bearings and reassemble, and the final checks should then be within tolerance.  It’s not as hit and miss as you’d imagine.

 

Yeah that all rings a bell, and we didn't use a spreader either (It was my year 10 school work experience at Frogs Island 4x4)

[Snagger]

4 hours ago, Gazzar said:

I've read Nick's post on seeing them up, and whilst laborious, it doesn't look impossible.  

My Salisbury axle casing is quite rotten, and after 20 years fighting the rot, I think it might be time to concede defeat. I've a spare axle, but I'd rather check it over before fitting it.

The manufacturing tolerance variances with Salisbury axles are almost exclusively in the casing, not the pinion or centre, but in reality they’re all pretty close.  You can swap pinions and centres, even changing gear ratios (remember that 4.71:ratio units have the crown flange in a different position to 4.1 and higher geared units to allow for their smaller pinion head diameter) using the same pinion bearings shims in that axle tube and retaining the existing shims on the centre.

I was quite wary of that advice and expected to go through the whole setup process until I tried it myself, installing my 109’s 4.71 pinion and centre into the 110 axle I transferred to the vehicle.  I even reused the 110’s original crush tube and everything came out spot on - the mesh amount and contact pattern were perfect.

[BogMonster]

10 hours ago, Chicken Drumstick said:

The Detroit locker is in a way misnamed. It is really an automatic unlocker. i.e. it is locked, just as per any other locking diff. But under certain conditions will unlock to allow different wheel speeds on the axle. However for this to occur you probably need traction greater than that of gravel. I'm also inclined to suggest that a RWD vehicle, such as a Series or most American pickups/4x4's would work better in such a situation, as instead of understeer on gravel, you end up with both rear wheels spinning and the ability to drive in a powerslide drift. With the AWD setup of a Discovery/Defender it'll be pushing some of that power to the front and likely to induce far more understeer, as it'll be a lot harder to get the back to step out (not impossible, but will need a more aggressive driving style with a flick of the steering, rather than just pushing the loud pedal).

I'm also inclined to suggest a Detroit probably works better on heavier and longer wheel base vehicles, than it would on a shorter wheelbase lighter vehicle. A Discovery is sort of middling length wheel to short. Although this is only a hunch, I don't have any data to back up this thought.

Yes I agree with all that.

The other reason I wouldn't have one is that in mechanical terms it's just a bloody bodge up. "We welded the axle up but then remember that occasionally it needs to go around corners, so added a freewheel bit as an afterthought".

[Nonimouse]

As an aside, I had a Quaife in the front axle of my old RRC and a TrueTrac in the rear. It was a good set up.

The only issue I had was, when driving fast in the RR, there is a technique taught in defensive drive techniques (with Disco/RRC/Defender/series/100 series) of using the lift of the inside front wheel to 'spin off' the power to a point where the vehicle settles back on to all four wheels. This allows a 'slingshot' out of tight bends etc.With LSD's etc this gets quite interesting and can involve the smell of adrenaline filling the vehicle