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martinsaunders06

Drops 8x6 auto box

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I've not long bought a daf drops and am just getting used to whats what etc . When the truck arrived I found that after a few days standing and only so from cold it would stand still/ not move in drive or reverse even with revs increased and this coincided with a lot of pump type gurgling/ priming noises . I found the auto box level to be low by some 10 litres or so .

I renewed the auto oil and filter and this seems to of cured these problems . The truck now drives ok but the gears seem very aggressive and harsh in the way they change gear especially when it's changing down into the lower gears and seems to almost come in with a bang or jolt ( changing down 3rd to 2nd to 1st worst).? Is this the way they are and quite normal or is there something I can do to smooth or alter this like some form of basic calibration etc , early vw cars autos of similar age reqd a basic reset done which went something like stopping in drive, switching off still in drive and turn ign on again ???. Thanks martin

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Hi, mine is very smooth, not harsh at all and I've been very suprised how smooth and quick it changes. To me it always seems to be in too low a gear compared to where I would change, but saying that it does it all ok.

I'm not sure of any reset or recal procedures, but will look through my documentation to see if anything is mentioned.

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Thanks that would be great , I did notice the kick down switch ( I'm guessing?) was adjusted up too much ( new cab) so much that the throttle pedal operated it at only half throttle when I'm thinking the kick down should work at nearly full throttle , also there is some sort of throttle position sensor on fuel pump linkage with a low and high mark which corresponds to pedal position . At idle the marker was inline with the low but no where near the high mark when operated to touch kick switch so I have adjusted kick down switch to what I think ? And now with a slight adjustment to sensor arm the the marker now is inline with high line and kick down only works at nearly full throttle . Not sure if this is near correct or will make any odds but looks more sense but can always move back if ness . ? Do you know what that throttle angle sensor does please .

Not driven yet as sump leak and split front engine mounts to do first

thanks martin

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Thanks that would be great , I did notice the kick down switch ( I'm guessing?) was adjusted up too much ( new cab) so much that the throttle pedal operated it at only half throttle when I'm thinking the kick down should work at nearly full throttle , also there is some sort of throttle position sensor on fuel pump linkage with a low and high mark which corresponds to pedal position . At idle the marker was inline with the low but no where near the high mark when operated to touch kick switch so I have adjusted kick down switch to what I think ? And now with a slight adjustment to sensor arm the the marker now is inline with high line and kick down only works at nearly full throttle . Not sure if this is near correct or will make any odds but looks more sense but can always move back if ness . ? Do you know what that throttle angle sensor does please .

Not driven yet as sump leak and split front engine mounts to do first

thanks martin

 

Dont know for sure but i think you have adjust speed limiter although it wont have altered its maximum set speed. Havnt got the drops anymore so cant check. to put your mind at rest the Drops i had did the same as yours when i first got it i filled with oil and it was erratic on gearchange but it was at the time a couple years ago when temp was droping to -12 -16 as tempretures came back up or it did longer runs it worked perfect. It could seem harsh on changes if you floored it all the time but if you didnt go to harsh it was very smooth. Also had problem with it not always getting full air pressure on i think no 3 tank. This used to cause it to slam down a gear if you were on trailing throttle and then tried to accelerate.Also make sure retarder button has not stuck on

Edited by cosrec

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These comments relate to auto boxes in general, not to your truck specificaly, but auto boxes need to know how hard the vehicle is being driven as well as how fast it is going so that they can decide which gear to be in and how aggresively to engage the next gear. There will be signals from both the input and the output shafts of the gearbox to tell it the engine and road speeds and it will find out how hard the engine is working from the throttle position and posibly from inlet manifold pressure. If either these last two are giving wrong signals the result is either too soft or too hard shifts. Modern cars use the computer to set the engine revs to exactly the speed needed for the new gear so the clutches can be engaged without any shock or sliping but older car and most truck and AFV autos do it the old fashioned way and engage them regardless so they have to adapt to the wildly varying conditions from one gear change to another. It sounds to me as if your box thinks you are driving flat out all the time.

 

Kick down is a rather seperate subject as it is to make the gearbox go into the lowest safe gear immediatly and as you say is usually engaged at almost full throttle only. This is seperate to the need to know how hard the engine is working.

 

 

Hope this helps a bit.

 

 

David

Edited by David Herbert

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Just looked at a manual, the throttle position sensor you mention is the load sensor for the gearbox. To adjust, make sure that with no throttle it lines up with the mark on the sensor labelled low. Then check at full throttle that it lines up with the high mark. At full throttle the kick down sensor should also operate.

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Not familiar in the least with these Fodens, but:

 

Do these transmissions have a lock-up facility? Many have a system whereby once the drive is smooth the torque converter goes into 'lock-up' i.e mechanical drive straight through. When the load gets excessive the converter comes out of lock-up and this seems like the box is changing down but it isn't. I had experience of an Allison CBLT4460 with this feature in a 30t dumptruck, and would be amazed if these Fodens were not similar.

 

So may not be the gear change, but the lock-up valve causing the harshness? I only mention this because the lock-up change is typically much more harsh than the smooth clutch pack gear changes.

Edited by N.O.S.

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Thanks all for this help, the up changes didn't seem to bad compared to the down changes , when slowing down off the throttle etc say slowing to a almost stop to turn right for example the last 3 gears or so really jolted you in seat as they engaged and if combined with a gentle touch of the brakes it felt really abrupt and seemed to slam in. From what I've adjusted it was definitely the case that on ( not flat out) acceleration the kick down switch was being operated regardless due to its setting which I'm hoping along with that load sensor reading being wrongly set ? Was confusing the box somewhat - Is this possible to do ?? .. Does anyone have any thoughts as to if there is a basic reset or calibration possible for this type of box or do you think it could poss improve with driving if these switches / sensors were set up wrong .

? What make/ spec of auto oil do you recommend for this ZF box?.

Thanks martin

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Use engine oil for the gearbox. 10/30 is equivalent to OMD 90. Originally the zf auto box was spected with an ATF oil, but the military respecified it to engine oil to reduce the number of oils used.

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my drops only changes up gears when its at 2000 rpm! is this normal? i have checked the throttle position valve and seems ok..

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