ZF4HP22 and chipped DHSE

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Greenrover

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More serial lurking from since February, only chip in when I have something useful to say

Well surprise, surprise after all the fun last rear, replacing the gearbox and then the engine, the gearbox has gone up in smoke, well not literally, just lost all drive.

I have heard it said before that the ZF4HP22 stuggles to cope with the torque from a chipped diesel, or is this just internet b******s?

I understand the ZF4HP24 is a stronger box.

The ZF4HP24 is approx 15mm loger and I understang this is due to the pump being wider. Is it possible to just swap the pump for a HP22 pump and fit it or are there also electronic differences?

Thanks
 
its the larger clutch A and clutch C and free wheel that make 24 better than 22,does yours still drive in rev is oil black not too bad to fix usually
 
most likely if you remove bell housing and pump housing first clutch pack you see ,now its possible more than one but usually just one needs changing
 
Thank you again
I am away in London this weekend, so will not be able to get box out until next weekend, if it is ok I will pm you when I have it on the bench and sort out what parts I need.
Much happier rebuilding the existing box than buying another refurb!
Will have a look in Rave to see if there are any destructions for the box, otherwise google is my friend.
Thanks once again for your help.
 
Greenrover said:
More serial lurking from since February, only chip in when I have something useful to say

Well surprise, surprise after all the fun last rear, replacing the gearbox and then the engine, the gearbox has gone up in smoke, well not literally, just lost all drive.

I have heard it said before that the ZF4HP22 stuggles to cope with the torque from a chipped diesel, or is this just internet b******s?

I understand the ZF4HP24 is a stronger box.

The ZF4HP24 is approx 15mm loger and I understang this is due to the pump being wider. Is it possible to just swap the pump for a HP22 pump and fit it or are there also electronic differences?

Thanks
Click to expand...
Chipping the diesel takes it over the toque limit of the ZF4HP22 by some margin.
The ZF4HP is stronger and longer. The extra length is accomodated by a shorter spacer between the autbox and the transfer box. It should as far as I can determine be a straight swap. Electronically for the P38 it also looks the same although there may be differences in the ECU regarding change characteristics, I haven't checked the part numbers as I can't afford to do it!:)
 
Datatec said:

Chipping the diesel takes it over the toque limit of the ZF4HP22 by some margin.
Click to expand...

What are the torque limits of the gearboxes?

I chipped my 2000 auto DSE about 8 years ago. It increased the torque to 255 ft lbs at 2300 rpm, a big increase of about 33%. I haven't had any problems except for the gearbox overheating on one occasion when the cooler fan got blocked up with mud. I do a lot of towing.

I understand that the 4.0L petrol p38 uses the same ZF4HP22 gearbox and puts out 250 ft lbs of torque but at higher rpm. This is of the same order.

:confused:
 
dave4x4 said:
Datatec said:



What are the torque limits of the gearboxes?

I chipped my 2000 auto DSE about 8 years ago. It increased the torque to 255 ft lbs at 2300 rpm, a big increase of about 33%. I haven't had any problems except for the gearbox overheating on one occasion when the cooler fan got blocked up with mud. I do a lot of towing.

I understand that the 4.0L petrol p38 uses the same ZF4HP22 gearbox and puts out 250 ft lbs of torque but at higher rpm. This is of the same order.

:confused:
Click to expand...

The torque figure I have for the diesel is considerably higher than the figure you quote, I'd have to look it up again as my memory is not so good but as standard it's something like 265/280ft lbs on a box rated at 250, chipped I seem to remember the figure for mine is 313 ft lbs
 
I think we have a problem with units.

I have got a figure of 347 Nm for my chipped diesel vs 245 Nm for the standard engine.

I converted to ft lbs above - much more civilized units.

You say the box is rated at 250 ? ft lbs or Nm ?

:confused:
 
dave4x4 said:
I think we have a problem with units.

I have got a figure of 347 Nm for my chipped diesel vs 245 Nm for the standard engine.

I converted to ft lbs above - much more civilized units.

You say the box is rated at 250 ? ft lbs or Nm ?

:confused:
Click to expand...

It's been a long day, yes my figures are Newton fecking meters, my brain is calibrated in foot pounds:rolleyes:
 
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