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Sorry folks, been bust with work.

The replacement unit has not arrived yet but just to confirm, it is the later -065 suffix ZF4HP24 gearbox fitted with the standard diesel torque converter and bellhousing. It should be a stronger bolt in upgrade. I am not expecting any performance advantage, just a potentially longer lasting gearbox. As it was the same price as a standard gearbox it makes sense to fit the stronger option.

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if i was you i would be ringing and checking that it is a standard 3 bolt convertor and not the 22 . IMHO you are better to go for the other if that is the case .

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It is definitely the three bolt diesel converter.

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ok so you will not need to remap then , but my next question is why are you not doing the upgrade , it's highly recommended as it makes a big difference to it running of the vehicle.

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Which upgrade? The uprated torque converter (if they are still available) or the engine remapping?

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the gear box you have has a small torque convertor in it as well as a small pump, ( the piece that the torque converter fits into) this is the part that failed in your box . this item can be replaced with the torque converter and pump from a hp22 box ,( the hp24 converter is physically to big and will not fit the small bell housing in the diesel gear box so you can only use the hp22 pump and converter . to do this you have to drill an access hole in the bell housing to be able to do up the bolts on the flex plate. (this is all explained on the Ashcroft site ) . as for the parts being available, they are only hp22 parts and are readily available. as i stated in my first comment you can fit a hp22 box and converter with the original diesel bell housing . all that is required is a different boss and bolts that bolt onto the engine crank and a 4 bolt flex plate that Ashcroft supply . when you stated that you was going to get a bigger clutch pack from the 24 box i assumed you was doing the mod with the bigger torque converter as well as this give you the strongest box you can fit to the diesel which is a hp24 box with a hp22 oil pump and converter as the parts are interchangeable from one box to the other . the bigger torque converter is a highly recommended modification for those that replace the box for the reason you are doing it .
PS ring Ashcroft and ask the questions as they can do it for you ,and maybe explain it in more detail .
PS if you do this you have to remap the engine or it doesn't work properly. if you put the small one back in then you don't need to remap
at the end of the day it will give you a better drivable vehicle IMHO.
this mod is a common mod for the disco diesel gearbox and i assume that box is the same as your box .
well that's my 2 cents worth , i hope i have helped in some way .

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It depends whether you are talking Disco 1 or Disco 2. The Disco 1 uses the non-electronic 4HP22 the same as used on the Classic, the Disco 2 uses the electronic 4HP22EH on the diesel and 4.0 litre petrol and the 4HP24EH in the 4.6 as used in the P38. The 24 can handle more torque than the 22 so using your original torque converter and bell housing on a gearbox with stronger internals makes perfect sense, particularly if the engine is to be modified in any way (or you spend half your life dragging 2 or 3 tonnes behind it like I do). I can't see there would be any point using a larger torque converter on a 4HP22. What are you trying to achieve?

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to strengthen the internals of the box is a good thing Richard , but that is not the failed component . the pump and converter are the items that failed and this is where the strengthening needs to be and i thought he was doing this but he is only doing the clutch pack as that was recommended i think . so this will be a strait swap and no mapping required . keeping it simple.
PS if this was me i would be considering the mod , costs etc, read the comments on the Ashcroft site about the mods that you can do to the box. the strongest box to fit to a diesel is a hp24 box with a hp22 torque convertor as the bell housing is too small to fit the bigger hp24 convertor .people that have done this say that it should have been done by the factory as it make them better vehicle all round .

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I have done a bit of delving and surprise, Ashcrofts now do a conversion kit to allow the v8 bellhousing/torque converter to be fitted to either the M51 diesel or M57 diesel.

M57 to ZF conversion kit

If money were no object, that is the way to go. If you stick with the diesel bellhousing, the diesel torque converter is the only one that fits.
When they fitted my HP24 box, I bought an uprated diesel torque converter from them. It was the only option at the time. The v8 bellhousing is a better option, omho. Stick with the diesel gearbox ECU and get the engine chipped.
I also see Ashcrofts now do viscous couplings as well. They never used to.

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Is the oil pump in the gearbox or the bell housing?
I have ordered a full ZF4HP24 gearbox but with the diesel bell housing and torque converter fitted.

The uprated diesel torque converters are no longer available from them.

Conversion kit is interesting, though obviously meant for the M57. But is out of stock.

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Smiler wrote:

Is the oil pump in the gearbox or the bell housing?

Gearbox, bellhousing is just a big lump of cast metal bolted to the gearbox at one end, the engine at the other and big enough for the torque converter to fit inside.

I have ordered a full ZF4HP24 gearbox but with the diesel bell housing and torque converter fitted.

So you'll have the 4HP24 pump too as well as the stronger internals.

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Good. A modified torque converter would be nice to finish it off but Ashcroft said they no longer do them for the p38 diesel.

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Happy to confirm that a late -065 suffix ZF4HP24 autobox fitted with the diesel Torque Converter and bell-housing does indeed bolt straight in! Just waiting for a drum of transmission fluid to arrive to see if it actually works!

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Do you have the gearbox dipstick/filler tube on the diesel or have you got to pump it in from underneath? Mine took 10.5 litres to bring it up to smack on the maximum mark on the dipstick.

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The old box had the dipstick, the new one doesn't. Oil arrived yesterday so now all topped up and back in action. Only done about 5 miles so far but all seems to be working well. Other than the change in revs the gear changes are unnoticeable.

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What is the difference in revs at changes now? My old gearbox was always reluctant to drop down a gear when I'd have expected it to and when driving normally would change up at what I always thought was too low. The new one now changes up at slightly higher revs and will drop down a gear when you expect it to. My fuel consumption seems to have improved slightly too, maybe because the engine is staying in the power band more rather than slogging at too low revs.

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Early days yet, I have been driving it lightly to make sure it is happy before getting back into the saddle properly. I will let you know.