There are two versions of the HP24 gearbox used in the p38 an early one and a later type known as an 065 box. The number will be found on the gearbox plate.

The earlier HP24 is 15mm longer the diesel tailend housing can be fitted to bring it back to the same length overall. However the 065 is the safest bet The HP22 is shorter than the early HP24 and so there is a spacer between the auto box and the transfer box, this spacer has to be removed to fit an early HP24 or left in place for the later 065 HP24.

Ashcroft however can fit the HP24's stronger internals into the 22's casing.

TQ's only the diesel torque converter will fit into the diesel bellhousing. The 4.6 torque converters are too big Ashcroft again can fit a diesel one and reduce the stall speed to suit the derv better it reduces the revs and takes up the drive earlier which results in much more relaxed driving for the diesel.
 
update number 2.....

Had time yesterday afternoon to drop sump oil (god it's nasty stuff, haha). Refilled as per procedure. Drove around block, dumped sump oil again, still lovely and dirty as suspected. Refilled again and drove again. Worse than before now, as little drive in D. But bizarrely I swear R is making more of an effort, especially in Low mode.

Ran out of time then. Waiting on a bottle of Liquid Moly cleaner to arrive. Then will add that and run for 10mins as prescibed. Dump oil, change filter, and refill. Will then drive it a while, do final dump and refill including bottle of Lucas..and keep fingers crossed....

watch this space.....haha.
 
update number 2.....

Had time yesterday afternoon to drop sump oil (god it's nasty stuff, haha). Refilled as per procedure. Drove around block, dumped sump oil again, still lovely and dirty as suspected. Refilled again and drove again. Worse than before now, as little drive in D. But bizarrely I swear R is making more of an effort, especially in Low mode.

Ran out of time then. Waiting on a bottle of Liquid Moly cleaner to arrive. Then will add that and run for 10mins as prescibed. Dump oil, change filter, and refill. Will then drive it a while, do final dump and refill including bottle of Lucas..and keep fingers crossed....

watch this space.....haha.

paradoxically the dirty fluid has suspended clutch material in it, this allows the worn clutches to "engage" without slipping. When you flush it out and replace it with new,
you have nice new fluid but no clutch material floating around so it tends to slip..

Worn 'oot i tell ya!!

Pushing cleaners through it will likely make it worse..

And tbh this crap inside won't be doing the Valvebody any good neither.
 
Also valvebody solenoids gummed up with crap, not allowing the correct fluid pressure will cause slipping but i doubt this is your problem in this particular instance.
 
paradoxically the dirty fluid has suspended clutch material in it, this allows the worn clutches to "engage" without slipping. When you flush it out and replace it with new,
you have nice new fluid but no clutch material floating around so it tends to slip..

Worn 'oot i tell ya!!

Pushing cleaners through it will likely make it worse..

And tbh this crap inside won't be doing the Valvebody any good neither.

I'm sure you are probably right.....but I'm a stubborn bugger, haha. As Autos are new to me, and I have already bought the oil etc, I'm using it as a learning curve. Will carry on, but am prepared to have to replace box, and have already sounded out local garages for costs to drop mine out and fit a replacement.
 
I is very unusual for the reverse clutch to burn out, main forward clutch yes but not reverse clutch. But as with everything it depends on how much the box has been abused.
 
Still they should be strong enough to take a considerable amount of abuse , or the manual can anyway?

The manual is a different animal, the only thing to burn out on that is the clutch itself. Under normal circumstances the auto is robust enough to take normal use for a long time. If it has been neglected however and the valve block has become sticky, full pressure will not be applied to the clutches and they spin under load. Sadly lots of automatic boxes are neglected, that neglect leads to failure.
 
So in effect the auto boxes burn themselves out?

One thing I have been meaning to ask you, what do you consider highest speed/abuse the manual and Tbox can handle in low, how much is too much?

If neglected yes. Don't have a clue, depends what you are doing with it. If you are off roading i would suggest screaming around in low ratio full throttle would not be the way to do things.
 
Other trucks I’ve had say ‘do not exceed 5mph in diff lock’ or ‘do not exceed 15kph in low’ for example. No mention of anything with P38? No warning stickers nothing in owners manual :confused:
I have towed a large broken tractor (JX85 + huge loader/bucket and kit) in low @20mph 3miles down road with no problem years ago? If it handled that and everything in between & before then I’m guessing heavy use is normal enough for it :)
 
The manual is a different animal, the only thing to burn out on that is the clutch itself. Under normal circumstances the auto is robust enough to take normal use for a long time. If it has been neglected however and the valve block has become sticky, full pressure will not be applied to the clutches and they spin under load. Sadly lots of automatic boxes are neglected, that neglect leads to failure.
Got to agree with @wammers I had service history to say gearbox had been serviced but oil and filter had not been touched. My oil and filter were a mess, valve block U/S clutch U/S replacement gearbox was only option. Luckily local independent sorted this very very reasonably.
 
So in effect the auto boxes burn themselves out?

One thing I have been meaning to ask you, what do you consider highest speed/abuse the manual and Tbox can handle in low, how much is too much?

The gearbox is called R380 because it was supposed to take 380nm of torque. Think it is nm, answer probably in RAVE. It will take whatever the oil burner throws at it. Compared to the Defender everything else is heavy duty. If you're sat in mud spinning all day the viscous won't like it, I guess.

The weak point is that clutch mechanism. I'm going to have a serious think about mine. I'll start a new thread as I need to get my thoughts straight.
 
What mileage did it live to?
Gearbox was changed at 185000 Service sheet said filter and oil changed 175000, but it was black ,smelled very burnt not been changed in yonks. I had only done 6000 in it. I prefer to do my own oil changes as in past have caught several places out. Once wrote my name on a filter and was charged for oil and filter change, brilliant how they were able to copy it onto new? filter, boy should have heard excuses when I pointed this out. Full refund and never went to them again.
 
R380 is NM yes. Tbox I’m worried about but like you said defender can take anything thrown at it so P38 be okay.

@Rubberknees 185000 is pretty good life fit an auto box.

ive seen a lot of that. I prefer to do things myself as I’m picky with certain things. They’ll drop the majority then refill but il pull it apart and clean it all out then set everything accurately as possible. They don’t have the time for the consideration we will put into our Landys in general.
 
R380 is NM yes. Tbox I’m worried about but like you said defender can take anything thrown at it so P38 be okay.

@Rubberknees 185000 is pretty good life fit an auto box.

ive seen a lot of that. I prefer to do things myself as I’m picky with certain things. They’ll drop the majority then refill but il pull it apart and clean it all out then set everything accurately as possible. They don’t have the time for the consideration we will put into our Landys in general.

They tried to charge my step-father for new sparkplugs on his diesel. Then he realised he'd forgotten to leave the key and went to check if the car had moved - it hadn't.
 
the pressure plate on the B clutch assembly if broken will cause no reverse as i said above..

I have a feeling the HP22 i pulled, was broken beacuse the owner tended to drop it into reverse at over 10mph :confused:

Luckily a fresh box and a lecture on how not to drive an Auto seems to have elightened him..

Hopefully i don't have to do it again in te future..

The Oil was also Black as night..

If you have sludge and crap in your sump, it's almost certainly fooked, to put it lightly :eek::eek::D

Tranny fluid should be changed regularly.
 

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