No 1st with zf 4hp22

[woko]

I have a td5 with a zf 4hp22 and it won't drive in 1st. It works perfectly in every other gear but no drive in 1st. If you get it rolling it will shift to 2nd and will drive perfectly up and down gears. I have swapped valve body and ecu. No difference. Done air checks on clutch packs no leaks. 1st uses a and e clutch packs which are used in other gears as well, and 2 sprag clutchs. One of the sprags are used in other gears. The only thing that is not used on other gears is j sprag clutch but i can't fault it out locks clockwise and freewheels anti clockwise. My question is has anyone had these not lock under load as i can't put the same load on it as the engine would to get it to slip.
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[Blknight.aus]

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.

[woko]

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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[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.

[woko]

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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[stevo]

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.

[alien]

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 (http://www.ashcroft-transmissions.co.uk/frequently-asked-questions/4hp22/4e-faq-s.html)


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.

[stevo]

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

[woko]

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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[stevo]

Reading your 1st heading once you get it rolling it changes through the gears fine does this include changing back into 1st? And driving in 1st?

[woko]

It will change back to 1st and lose drive

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[stevo]

How many kms on box, i would say by the checks you have done so far you would have pulled the trans filter apart? I know that a sprag clutch will set you back close to a grand as i thought mine might have failed but i stripped mine 1st and had a donor 24hpe trans out of a BMW on stand by.

The td5 is hard on the components of the trans due to the "chatter" that the motor puts through parts so if you need to source a donor trans go for one out of a petrol engine.

Not near my computer at the moment to look at other info i saved but it may be a mechanical problem usually the A clutch pack fails in these transmissions and the housing have been known to break in half.

The splines that the clutch packs engage with can get badly peened, one of mine was this can cause slow shifting as they stick etc

[woko]

I've got this box in bits on the bench at the moment. There is 300000km on the car. It got rebuilt approx 2 years ago. There is slight peening only in F clutch but this is only used in 4th and it works fine. There is marking on C' clutch piston. I would say this is from a broken diaphragm spring previously. C' is not used in 1st. Filter was clean and normal amount on magnet.
The weird thing is that it has no drive in 1st or D and the clutch packs it uses for 1st are used in other gears and they are fine. J sprag is only used in 1st Drive but in 1 D clutch engages and J sprag is not needed. Valve body, solenoids and ecu have been swapped with no difference so it cant be control.

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[stevo]

It is a tricky problem, you said you can feel it dragging when 1st selected in earlier post? If everything else checks out maybe there is a pressure drop somewhere between the solenoid and clutch pack.

The gauge shows good pressure but you can still loose pressure further down the line that gauge cannot show due to port sizes etc that can hold pressure upstream but drop it enough downstream to cause problems.

Nothing worse when pulling something apart and not finding something obvious it does get the grey matter working, the plug seals that are held in by the springs are still soft? One area for pressure drop before clutch pack, the plate gasket also there is a screen in that as well, mine had a bit of crude in it.

Good luck with it.

[woko]

It is a tricky problem, you said you can feel it dragging when 1st selected in earlier post? If everything else checks out maybe there is a pressure drop somewhere between the solenoid and clutch pack.

The gauge shows good pressure but you can still loose pressure further down the line that gauge cannot show due to port sizes etc that can hold pressure upstream but drop it enough downstream to cause problems.

Nothing worse when pulling something apart and not finding something obvious it does get the grey matter working, the plug seals that are held in by the springs are still soft? One area for pressure drop before clutch pack, the plate gasket also there is a screen in that as well, mine had a bit of crude in it.

Good luck with it.

Thanks for your help. I've put new plug seals in it. Different plate gasket with different valve body. Your right there is nothing worse finding nothing

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[woko]

More info about this problem. I finally got some adapters to fit manual gauges. The Box has low line pressure at idle, when at stall pressure is normal but slow to build. In reverse, pressures are normal and pressure builds quick when at stall also the reverse spec pressure is higher than forward.
Driving it, it has low pressures in all forward gears but only loses drive in 1st when the engine revs lower.
I have pulled all clutches out and pressure checked, none leak. have minor leaking from the ring seals in E & F clutches when assembled. There is a lot of leaking from the A clutch due to a 2.8mm orifice in the intermediate plate A clutch supply gallery.
This orifice seams very large, could someone confirm that this orifice is correct? Thanks.

[stevo]

Do you have a picture of this 2.8 mm hole and where it is positioned there was a mod that was recommended and envolved drilling a hole in the A clutch pack to bleed off some of the pressure.

I did not do this to mine as a lot of the BMW crowd were against this mod and I did not like it either, but my problem with this was it would only take a slight loss via a leak to drop your pressures in the forward gears also I would suspect slower engagement of the A clutch pack with more slippage till pressure built up.

Since your trans has been overhauled a few years ago it might have been done to yours?

[woko]

110944
Here it is marked in red.
Im the same as you, The A clutch is weak in these and all the pressure the better for engagement. I'm getting 50psi line pressure at idle and 150psi at stall and very slow to build to that. In the A clutch circuit it barely registers pressure at idle on my gauge. Gauge it a bit large for the job as it is a 870psi gauge. It has the metal sealing ring fitted but the seal kit came with both metal and teflon.

I have do you know where they were drilled. I have read that it was opening up a orifice in the valve body to into the clutch pack.
I can't see additional holes in the pack

[stevo]

This was the second part of the mod to drill out a port to increase oil flow into the A clutch pack circuit to make up for the loss oil oil out of the clutch pack through the bleed off hole drilled into the A pack housing.

When you did the air pressure test i take it you had to block off the hole to pressurize the A pack if so replace it or block off hole

[woko]

Yes had to block off this hole to air test. This orifice is in a core plug not into the intermediate plate housing

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[stevo]

I will have a look at my spare A clutch pack i think yours has been modified but may nt have drilled out the supply port to compensate.

I would personnal go back to the orginal set up the reason this mod was done was for the emission test method done in the states which caused a lot of A clutch failures due to leaking seals engaging the A clutch pack slightly and burning them out

[woko]

110971
Here is a better picture of this orifice i was talking about. I was talking to a another person about this and he thought that there may be a spring and ball in this orifice or in the port, This one has nothing. Do you have a spare intermediate plate that you could check for me?
The box is at my brothers place I will get him to have a look. I cant recall seeing any bleed holes on the clutch drum or piston but will get him to check.

[stevo]

Will check in the weekend the rental I moved into has stuff all lighting in the garage, the hole that is part of the mod is drilled into another part from memory it is drilled into the piston.

Might be able to look Thursday night if I get home at reasonable time leave in the dark and return in the dark.

[woko]

Will check in the weekend the rental I moved into has stuff all lighting in the garage, the hole that is part of the mod is drilled into another part from memory it is drilled into the piston.

Might be able to look Thursday night if I get home at reasonable time leave in the dark and return in the dark.

Thanks for that. Weekend will fine. I know the feeling of leave in dark return in dark, I work 12.5hr rotating roster. I found the mod, and your right, it's a 0.045" hole in the piston

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[woko]

Problem repaired. It is not a orifice, it's a air bleed and the ball is missing.
Thanks Stevo for all your help.

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[stevo]

Glad to hear you found it, most people would have given up, you will be an expert on the auto trans now

[woko]

Glad to hear you found it, most people would have given up, you will be an expert on the auto trans now
Thanks. I was over R&R of this box. Last removal took 2 of us 15 min to get out
Worst thing is that valve is not shown in parts or service manuals

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[stevo]

Yes i know it is known that ZF do not give out a lot of info on their transmissions, i got a lot of my info from months if searching forums, and used some of the info from the BMW forums on stac heights on clutch packs etc.