Here are some frequently asked questions regarding the 4HP22 automatic gearbox.
My Autobox is now only able to select reverse. Why?
Your A clutch (forward drive) has failed and you will require a replacment autobox.
I have just fitted a rebuilt ZF gearbox but the gear shifting speeds is nothing like it used to be. I have to rev the engine really hard to make it change up. Why?
Check the setting of the kick down cable, if it is too tight the gearbox will think you have more throttle applied than is the case. Check and adjust the gearbox accordingly. As a guide the looser the cable, the earlier it will shift, visa versa the tighter the cable, the later it will shift.
What oil should I use in my Auto ZFHP22?
We recommend you use AFT Dextron 2/3.
What is the oil capacity of the ZF 4HP22 ?
Oil change approx 5 Litres
Dry fill approx 9 Litres
I have just fitted a reconditioned ZF autobox. I have filled the box with the correct amount of oil but have no drive at all, forward or reverse. Why?
The first thing to do is to remove the oil cooler pipe from the bottom of the gearbox (put a container under the open end to catch the oil) and start the engine. You should get a good flow of oil. If not the pump has been broken during installation and will need replacing/rebuilding. The torque convertor must be fitted to the gearbox, located correctly on the pump and locked into position before the gearbox is offered to the engine, otherwise damage will occur to the pump, resulting in no oil flow and subsequent to other parts of the autobox.
When I start my Automatic Range Rover in the mornings it takes a while to engage drive, it has not always done this. This has become worse in the cold weather. Why?
It sounds like you need to change the filter! In the cold weather, i.e when the oil is cold and more viscous, if the filter is partially blocked it will take some time for the pump to draw oil through it. Once the oil becomes warm it flows more freely and can pass through the filter more easily. Hence the problem only occurs when the oil is cold. To remedy this problem your filter needs to be changed. This should be done sooner rather later to reduce the possibility of damage to the autobox, by the clutches ‘slipping’ during this slow engagement.
I have a 4sp ZF, when I select “D” the vehicle won’t move, when I select “1″ the vehicle moves off. I can then select “D” and continue to drive normally. If I stop I have to start in first again. Why?
A sprag clutch has “inverted” and will need replacing. No further damage will occur if you continue to drive but you will need to select “1″ every time to start moving. A rebuild is required to correct this.
I have a 4 speed ZF Auto and it sticks in first gear in the morning or when cold and is reluctant to change up from 1st gear. Once the gearbox has warmed up it shifts normally. Why?
The governor valve is sticking, which can be caused by contamination. i.e. clutch plates or other parts disintegrating. The fine debris finds its way past the filter and tends to accumulate in the governor, causing it to stick. A temporary solution is to remove and clean the governor. The problem will often recur as debris from damaged parts continues to build up in the governor. If the problem continues after cleaning the governor then it may be necessary it replace your Autobox.
We have noticed many customers reporting this fault starting a few days after an oil and filter change and after researching this using our experience and the expertise of others in the trade we have come to the conclusion that as ATF oil is a detergent type oil, when the oil is changed this will dislodge and stir up settled debris in the autobox which in turn jams the governor valve. In light of this although it sounds controversial it is debateable if changing the oil and filter is a good idea, some say if the box it going to fail it will fail if the oil is good or bad and their advice is leave it alone. I am still undecided but the truth is I get a lot of calls from customers thinking they are looking after the autobox by servicing it and a few days later this fault occurs.
I have a range rover classic with V8 and ZF autobox and I want to remove the V8 and Fit a 300 TDi,
There are 3 ways to do this,
1) fit the whole stock 300 disco auto setup complete, this is the easiest option.
2) get the 300 auto backplate, flexplate, starter ring gear, converter and bellhousing and fit these to the V8 ZF, be careful not to break the pump.
3) contact www.mdengineering.co.uk and buy a adapter fit to fit the V8 ZF to the 300, this allows you to use the bigger V8 converter which is desirable over the smaller 300 one.
The above frequently asked questions are courtesy of Ashcroft Transmissions.