ZF 8-speed issues - can you help me diagnose?
Discussion
I wonder if I may ask for some knowledgable help on what may be the cause of some shifting issues on the 8HP70 fitted to my 2012 Range Rover:
1. Main issue is a bit of minor thunk when off and straight back on the throttle say second gear. Kick down is a bit thump too.
2. If you happen to stab on the accelerator during an upshift it will 'thump' too.
3. Accelerating with fixed throttle is ok upshifting through the gears but I notice a 'flare' ( I think it's called that ) in the engine revs momentarily when it changes 2nd to 3rd.
4. Higher gears, higher speed all pretty smooth.
Car has done 120k miles so I bought a new ZF pan and 10 litres of lifeguard 8. I know that dropping the fluid only replaces around 4 litres but I wanted a complete fluid change so I did 3 consecutive fluid changes from the the pan with a drive in between each change to get it up to temp, open the thermo valves to ensure fluid in the cooler and lines was changed.
As a competent hobbyist mechanic I did this myself. However, unfortunately doing this did not change any of my symptoms.
Getting DIY advice for these transmissions is not easy so I wonder if you would be good enough to give a little advice?
Thanks in advance!
1. Main issue is a bit of minor thunk when off and straight back on the throttle say second gear. Kick down is a bit thump too.
2. If you happen to stab on the accelerator during an upshift it will 'thump' too.
3. Accelerating with fixed throttle is ok upshifting through the gears but I notice a 'flare' ( I think it's called that ) in the engine revs momentarily when it changes 2nd to 3rd.
4. Higher gears, higher speed all pretty smooth.
Car has done 120k miles so I bought a new ZF pan and 10 litres of lifeguard 8. I know that dropping the fluid only replaces around 4 litres but I wanted a complete fluid change so I did 3 consecutive fluid changes from the the pan with a drive in between each change to get it up to temp, open the thermo valves to ensure fluid in the cooler and lines was changed.
As a competent hobbyist mechanic I did this myself. However, unfortunately doing this did not change any of my symptoms.
Getting DIY advice for these transmissions is not easy so I wonder if you would be good enough to give a little advice?
Thanks in advance!
I know you’ve discounted the prop... your symptoms sound identical to a fault I had with an old RAV4 where the rear diff mount failed . This caused the rear diff to move and knock against the failed mount under certain driving conditions. It was particularly noticeable if you accelerated, let off, and then stabbed the throttle.
Appreciate there are many differences between the two vehicles but perhaps it may be worth looking into prop / diff movement.
Appreciate there are many differences between the two vehicles but perhaps it may be worth looking into prop / diff movement.
hi thanks for replies so far.
I have eliminated driveshaft / propshafts. Rear diff mount I will double check though, thanks.
However I am very sure it's the box.
As mentioned if I stab on the accelerator during an upshift I get a 'thump'
but as a comparison:
no thump if I stab the accelerator the moment - and I mean the split second - the upshift has occurred
.
I have eliminated driveshaft / propshafts. Rear diff mount I will double check though, thanks.
However I am very sure it's the box.
As mentioned if I stab on the accelerator during an upshift I get a 'thump'
but as a comparison:
no thump if I stab the accelerator the moment - and I mean the split second - the upshift has occurred
.
4x4xFar said:
stickleback123 - how would I check?
I reset them using my Gap IID Tool
.
Ah, the correct LR software (and probably the Autologic and other high end diag kit) can read the adaptation pressures for the 5 (I think it's 5..) clutches. How far positive they are can give an indication of how much the box is adapting to internal wear.I reset them using my Gap IID Tool
.
My experience is that many of the previous 6 speed boxes were often done in at 120k or so, particularly if they'd never had their fluid changed. They were never anything likes as good as new after "remanufacture" either. Not sure about the ZF8.
tgr said:
How frequently are people encountering problems with high mileage ZF8 gearboxes?
One hundred seventeen thousand miles, the gearbox has lunched itself, no reverse and only first gear. It gone in for a complete rebuild, clutches and torque converter, using ZF parts £1850+VAT. Great gearboxes never the less.
Bogracer said:
One hundred seventeen thousand miles, the gearbox has lunched itself, no reverse and only first gear. It gone in for a complete rebuild, clutches and torque converter, using ZF parts £1850+VAT.
Great gearboxes never the less.
A £2k+ rebuild after 120k not sure if call the Great myselfGreat gearboxes never the less.
My ZF8HP70 started showing a few troublesome signs at around 65k miles with not so smooth shifting when cold etc, so at 70k I got a Jaguar specialist to change the fluid and pan filter. The old fluid was cooked and stank and the filter magnets were coated in a metallic slime.
It didn't really improve much but didn't get worse either for the next 5k miles before selling.
It didn't really improve much but didn't get worse either for the next 5k miles before selling.
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