Discovery 2Automatic ZFhp422 box woes

steveeasy · Jan 19, 2021

Hi,
I recently found a good solid TD5 with no forward gears for sale. did some reading and believed the A clutch needed replacing. I ordered new discs and shims and wobbly ones for the outside. Fitted them, box put back in and it seamed fine. The next day though it seams like it lost its grip, slipping. Checked oil level and cant get anymore in while running it at the 40 degrees. Id like to check the oil pump pressure in the box, does anyone know how to hook up a gauge to a ZFhp422 box?. Like to fix it if I can or at least understand what is not working correctly. my thoughts are the pump is not creating enough pressure to work the piston in the A clutch enough to lock the clutch disks?. I nothing nothing about these just trying to figure it out.
Thanks in advance.
Steveeasy

backinblack · Jan 19, 2021

I'm not a gearbox expert but I thought it had a torque convertor so only a lockup clutch at around 60mph.
Feel free to put me right cos I do seriously like to know these things, yes I am sad like that

jamesmartin · Jan 19, 2021

did you check/renew clutch piston seals,where the old discs black and friction mateial stripping off

steveeasy · Jan 19, 2021

The clutch disks had no material left on them. I decided not to touch the piston to stand a chance for it to work. it did well but for less than half hour.found nothing in the sump.

backinblack said:
I'm not a gearbox expert but I thought it had a torque convertor so only a lockup clutch at around 60mph.
Feel free to put me right cos I do seriously like to know these things, yes I am sad like that

Hey ive no idea how it works. learning as I go. I originally assumed the torq converter provided pressurised oil to the A clutch piston and everything else. then I came to the conclusion the oil pump between the bell housing and the A clutch provide this. but im only guessing quite frankly. By the time ive taken the box out a few times I might get a better idea if I last that long.
Steveeasy

backinblack · Jan 19, 2021

you're not having much luck are you, a broken disco and a broken L322.

steveeasy · Jan 19, 2021

backinblack said:
you're not having much luck are you, a broken disco and a broken L322.

No im not at the moment. the L322 is my partners, she really likes it and to be fair its been really reliable. It been quite a challenge replacing the subframes. The Discovery, ive always had one and they have been fab. gave up last year and got a transit, then found this rust free one. thought id try fixing the box, looking forward to working out how it works, eventually!!.Im used to YBW forums but Landyzone is much more fun.

thanks for your help.
Steveeasy

Shimsteriom · Jan 19, 2021

steveeasy said:
and to be fair its been really reliable.

Now that's something which you don't hear very often when Land Rovers are being discussed.

backinblack · Jan 19, 2021

steveeasy said:
to be fair its been really reliable

Say that quietly, if s/he hears you you're in trouble. Famous last words and all that

backinblack · Jan 19, 2021

Shimsteriom said:
Now that's something which you don't hear very often when Land Rovers are being discussed.

And a rust free Disco

jamesmartin · Jan 19, 2021

steveeasy said:
The clutch disks had no material left on them. I decided not to touch the piston to stand a chance for it to work. it did well but for less than half hour.found nothing in the sump.

Hey ive no idea how it works. learning as I go. I originally assumed the torq converter provided pressurised oil to the A clutch piston and everything else. then I came to the conclusion the oil pump between the bell housing and the A clutch provide this. but im only guessing quite frankly. By the time ive taken the box out a few times I might get a better idea if I last that long.
Steveeasy

you need to know clutch piston can hold pressure and theres more than one clutch involved,though clutch A is a common fault

backinblack · Jan 19, 2021

steveeasy said:
looking forward to working out how it works

I couldn't get my head round torque converters until I discovered youtube. Still confused.

steveeasy · Jan 19, 2021

jamesmartin said:
you need to know clutch piston can hold pressure and theres more than one clutch involved,though clutch A is a common fault

From what id read, the ZFhp422 box had a fault where the A clutch wore out as it was engaged more than it should be. I wrongly assumed everything else would hopefully be ok. So its coming out again, Before this happens id like to check the internal pumps pressure and it might be better to understand what the pump actually does.
Steveeasy

Burt123 · Jan 20, 2021

Hi,
I take it you are not just talking about the normal torque converter slip where it stalls at around 3000rpm?

Discovery 2Automatic ZFhp422 box woes

steveeasy

Active Member

backinblack

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jamesmartin

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steveeasy

Active Member

backinblack

Well-Known Member

steveeasy

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Shimsteriom

Master Procrastinator

backinblack

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backinblack

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jamesmartin

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backinblack

Well-Known Member

steveeasy

Active Member

Burt123

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