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Well 2013 is here, the Queen has had her Jubilee, we have seen some people run real fast, jump real far and shoot real good, so after all that, the year ends and a new one begins....
A bit like Range Rover Ownership - A fault gets fixed and another one begins....
The 2002-2005 L322 V8 was fitted with the ZF 5HP24 Electronicaly controlled Automatic Gearbox (Transmission to our over-waters members), this box is considered more robust than the GM unit fitted to Diesels of a similar year, but despite this, they do still have their problems....
Most common failure is the Roller Bearing between the B & C clutches falls apart shedding their rollers into the box, and this can lead to the O Ring failing between A & B Clutches:
(photos courtesy of RRPhil from Rangerovers.net)
This in turn leads to a reduction in hydraulic pressure causing the A clutch to start slipping more than normal.
The ZF Box uses a 'continuous slip' mode of about 3% controlled by the Torque Convertor Lock Up Clutch (LUC) as ZF didn't fit a torsional damper to the TQ and as such uses a slipping method to dampen driveline vibrations....
Now, if A clutch starts slipping due to reduced hydraulic pressure, the LUC will work harder to prevent slipping beyond 3%.....this then prematurely wears the LUC friction material.....and the A clutch friction material.....all this material needs to go somewhere - you guessed it, into the Gearbox Oil......
The gritty oil clogs the filter and the poor oil pump struggles to generate the required hydraulic pressure to ensure a good clamping of the drive/brake clutches...and hence more clutch slipping and this again leads to more friction material in the oil....a nasty cycle ensues.....
For the GM Box, the problem is similar only it is not caused by the A & B O Ring....but I believe it is from the valve block valves letting by on the LUC causing excessive LUC slip, and trashing the box...(I could be wrong - but I haven't read up on the GM box - Don't have Diesel model).
Why are you telling us all this Ant - you may be asking yourself??
Well, my wonderful L322 has started a bit of a vibration/judder at between 25-30 and 45-50 or there abouts....plus when it gets warm, there is a harsh downshift from 2nd to 1st at times after stop/start traffic.....
I have just been to get a GB Filter, Sump Gasket, the required Filter O Ring and 7 litres of the required ATF (Draining the sump etc should give you around 6 litres or so of fluid as the other 4-4.5 litres is left in the Torque Convertor).
I will drain some fluid out at the weekend and see what the state of it is, replace the filter etc, refill with fresh fluid and whilst I am not in any way believing this will be a magic cure, it will give me an idication of the State of the Box and take a view on the next step....
In the interim, I have borrowed the Company Defender for a few days, as the last thing I want to do is drive it too much and feck up whatever is left of the box before I can take a goosey at the fluid....
Happy New Year to you all...2013 is shaping up to be a great year!
A bit like Range Rover Ownership - A fault gets fixed and another one begins....
The 2002-2005 L322 V8 was fitted with the ZF 5HP24 Electronicaly controlled Automatic Gearbox (Transmission to our over-waters members), this box is considered more robust than the GM unit fitted to Diesels of a similar year, but despite this, they do still have their problems....
Most common failure is the Roller Bearing between the B & C clutches falls apart shedding their rollers into the box, and this can lead to the O Ring failing between A & B Clutches:
(photos courtesy of RRPhil from Rangerovers.net)
This in turn leads to a reduction in hydraulic pressure causing the A clutch to start slipping more than normal.
The ZF Box uses a 'continuous slip' mode of about 3% controlled by the Torque Convertor Lock Up Clutch (LUC) as ZF didn't fit a torsional damper to the TQ and as such uses a slipping method to dampen driveline vibrations....
Now, if A clutch starts slipping due to reduced hydraulic pressure, the LUC will work harder to prevent slipping beyond 3%.....this then prematurely wears the LUC friction material.....and the A clutch friction material.....all this material needs to go somewhere - you guessed it, into the Gearbox Oil......
The gritty oil clogs the filter and the poor oil pump struggles to generate the required hydraulic pressure to ensure a good clamping of the drive/brake clutches...and hence more clutch slipping and this again leads to more friction material in the oil....a nasty cycle ensues.....
For the GM Box, the problem is similar only it is not caused by the A & B O Ring....but I believe it is from the valve block valves letting by on the LUC causing excessive LUC slip, and trashing the box...(I could be wrong - but I haven't read up on the GM box - Don't have Diesel model).
Why are you telling us all this Ant - you may be asking yourself??
Well, my wonderful L322 has started a bit of a vibration/judder at between 25-30 and 45-50 or there abouts....plus when it gets warm, there is a harsh downshift from 2nd to 1st at times after stop/start traffic.....
I have just been to get a GB Filter, Sump Gasket, the required Filter O Ring and 7 litres of the required ATF (Draining the sump etc should give you around 6 litres or so of fluid as the other 4-4.5 litres is left in the Torque Convertor).
I will drain some fluid out at the weekend and see what the state of it is, replace the filter etc, refill with fresh fluid and whilst I am not in any way believing this will be a magic cure, it will give me an idication of the State of the Box and take a view on the next step....
In the interim, I have borrowed the Company Defender for a few days, as the last thing I want to do is drive it too much and feck up whatever is left of the box before I can take a goosey at the fluid....
Happy New Year to you all...2013 is shaping up to be a great year!
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