Thread: No 1st with zf 4hp22

will it manually select first?

If it wont do anything until you get the vehicle rolling by means of external input then in might be one of the input sensors for the computer not outputting to let the computer know it has to engage the selector.

easy to check if it tries to operate the packs and changes the line pressure its not electronic and you're looking for the mechanical.

IF you can get it to go by manually selecting first and using low range then its the sprags slipping under load.

It makes no difference either in drive or in 1st. I can't find any info if the electronic box engages d clutch in 1st but uses the j sprag in drive like the non electronic box does. You can watch the solenoid change state, which is mv2 to engage 1st and the modulator pressure dip and come back when it engages the clutches when put into 1st. It uses mv1 and mv2 to engage 2nd which works perfectly. It's got drag there but no drive in 1st. It has had all the electronic parts and vavle body swapped with no difference. Im sure its j sprag slipping but I can't get it to slip on the bench. I just want to prove this is the problem before getting parts as this part will be expensive as it's the front of the low planetary set.

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I would have to hunt up the info but if 1st is manually selected this locks up the clutch pack and takes the load off the sprag clutch, recommended for towing a heavy load ie boat up a ramp etc.

The non electronic boxes lock the d clutch when put into 1st. D clutch is used in reverse. Reverse is working well. All the control side has been swapped with no difference. Would be great if you could find if the electronic box should engage D clutch in 1st like the non electronic. Thanks

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About to start nightshift i do have that info somewhere on the electronic boxes and what does what and when but feelly sure the clutch pack does also lock up when 1st selected, parts are getting really expensive and hard to source for these boxes.

Originally Posted by stevo

I would have to hunt up the info but if 1st is manually selected this locks up the clutch pack and takes the load off the sprag clutch, recommended for towing a heavy load ie boat up a ramp etc.

Ashcroft Transmissions


Mine broke the Sprag clutch.
Only way to drive foward was select 1st till moving then D worked ok till I stopped again.
I don't think this is the issue with this box as its doing the opposite.

Found the info yes when 1st is selected the clutch brake is applied the same one is also applied when reverse selected

Originally Posted by stevo

Found the info yes when 1st is selected the clutch brake is applied the same one is also applied when reverse selected

Thanks for that. I can't explain why it doesn't do anything different with a different valve body and has no problem with reverse. The info I have that D clutch is engaged in 1st for engine braking.

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