ZF Box

[Bob Heritage]

Question for Russ,

On my 4speed ZF box I have been playing with the kickdown adjustment but can't seem to get it right. It goes through the first 3 gears very quickly and is sluggish on acceleration. On the fluid level side when cold it is about 1 1/2" up the dipstick and after a run when the engine is hot it is bone dry. Now do you think that I need to add more fluid? or what will happen if I overfill the box. I always thought the fluid was higher when hot, but not in this case. Clive Tate says that the fluid should be just visible on the dipstick- but hot or cold? When hot and cruising say on motorway it behaves perfectly.

Cheers-Bob

[KOY 23]

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Bob.

I think tightening up your kickdown cable will delay the changes. Your comments have made me play with mine, I have tightened it and it is now very responsive. If you go too far it hangs on too long and thumps into next gear.

Re the fluid level. I cannot get any sensible reading. For example the car has been standing in the garage for days with engine off. Dip the box, nothing on stick. Redip, level may be at top of stick or halfway. looks like the dipstick seal is holding a vacuum in the box. Tried checking with engine running after moving selector through all the gears, again no consistent level.

John.

[GDPR]

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Ok guys - you were obviously waiting for an answer from me....

This is all from distant memory, but there may be something ALL you ZF owners need to know - even if it isn't in your Stag.....

I gather that Clive has played with the dipstick to make it come out on the correct side...... I have no idea what dipstick he uses but I will try to pump him for info when I see him to clear this up, but in my mind if you do a pan change and refill with the correct amount, then that's your own personal level, but here's what should happen...

Rule of thumb for ZF boxes.....Fluid checking when hot:

The engine and transmission must be hot (so drive the car for 20 minutes or so)

The car must be parked on level ground with the handbrake on.

The engine must be running.

Start in P, then cycle through all the gears, ending up in P.

Then check the fluid . Reinsert the dipstick with the notches toward the rear to avoid jamming it in the tube.

Checking Level When Fluid Is Cold. I've found that when I have the ATF level correct (based on a warmed up transmission and the proper dipstick scale for the temperature), there is also a way to reliably confirm proper fluid level when the engine is stone cold and not running....e.g., after you've let the car sit overnight. On the dipstick, above the plastic part that has the two temperature-specific scales, there is a little rectangular notch on the metal portion. Assuming the fluid level is correct, and the car is stone cold and you haven't started the engine yet, if you withdraw the dipstick and wipe it off and then reinsert it, then upon withdrawing it for this second time the fluid level should be on that notch. This does NOT work if you just withdraw the dipstick and look at it -- you MUST withdraw it, wipe it off, and then reinsert it before withdrawing again to read the level.

There is something of an oddity with some ZF boxes that you must take note of:

Unless you know that your model of gearbox does not suffer from this fault, or that a bleed-down mod has been carried out - NEVER REV YOUR ENGINE WITH THE CAR IN NEUTRAL OR PARK AFTER IT HAS BEEN IN GEAR. This can easily and very comprehensively blow the front clutch in your gearbox to bits, and give you a hefty repair bill.

There is an anomoly on some boxes that keeps pressure in the front clutch after N or P is selected from a driving condition and if you rev the engine you will wreck the clutch pack. If you want to rev it at a standstill, turn off your engine for 30 seconds or so and allow the pressure to bleed off first.

Never let the fluid stay in your ZF for more than 20k miles..... you'll regret it.....fluid is cheap, your gearbox isn't.......

That's enough from me tonight..........

Russ:dude:

[KOY 23]

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Hello Russ.

Many thanks for that. I can now get a consistent cold reading which is 5mm below top of plasic moulding.

Attached is a photo of my stick. I cannot see the notch you are referring to.

John

[Kevin Garrod]

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As far as I can see the dipstick supplied by Clive with my gearbox is identical to the ZF box that I purchased some time ago that came from an XJ6. Clive has simply extended the tube sideways so that the dipstick comes up on the same side as it would for a BW box.

I know that I have the correct amount of fluid in mine, just the wrong type.

Russ, when you see Clive perhaps you will ask him about this bleed down mod that you mentioned? We all need to know!

[KOY 23]

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I have asked Clive, he said that he had never heard of the problem. A Google search will detail many cases, usually in USA when emissions checking BMW's with early versions of 4HP22.

John

[Bob Heritage]

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Top Man Russ

Gives me something else to look at.
I phoned Clive today after I put it on the Forum regarding the kickdown as well, he says : On the kickdown cable when the throttle is fully open, there is a 'spring' that is operated inside the box (you can feel this if you give the cable an extra tug) this spring is ideally in position just before the throttle is fully open. On the fluid level from cold he said to start the engine to put the fluid back into the torque converter, run through all the gears and the fluid should just be visible on the end of the dipstick, likewise when the engine is hot. The dipstick is moved to the offside to give an original appearance under the bonnet. So according to Clive the markings on the dipstick are meaningless.
I have put 8 lts in mine but the dipstick is dry, so probably need a bit more.What happens if the gearbox is overfilled Russ?

Bob

[GDPR]

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Simple Bob - it may start to foam up in the box, then it'll try to chuck it out the breather or if it can't, or the breather's blocked up the filler tube or out of a seal.....

Messy

Russ:dude:

[Bob Heritage]

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I've added about another 3/4 litre fluid to the box and can now get a reading on the dipstick. Another thing that Clive said regarding the kickdown was that the adaptor that is supplied to go on the end of the kickdown cable must be in an upright position, but if this is in place then the spring part can not be at the top of the full throttle position because it pulls the adaptor down from upright.:shock:

Bob