Thread: No 1st with zf 4hp22

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

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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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.

Originally Posted by 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.

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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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.

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?

ZF.PNG
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

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