Another busy harvest and could of done without a little calibration problem towards the end. Had a snatchy clutch pedal on our 2011 MF6480 dyna6 Sisu tier3, trying to calibrate it was a no-no, it would try to drive off as you released the shuttle lever instead of starting to clibrate. An error code came up for the clutch pedal switch- unlike the 6499 we have with 3 switches, this 6480 has the later all in one switch pack, changing this and calibrating it ( With engine stopped, ign on, press clutch down & up again, press the difflock switch and hold until CP comes up in the RH screen, press clutch down to bottom, wait for the bleep and back up slowly to the top, screen should go back to normal, ign off)

Now we could get into calibration but she would just sit there with 1 & 4 flashing and no sign of doing anything. After confirmation with a laptop that the new clutch switch was ok and calibrated it was diagnosed that the dyna6 part of the transmission was unable to calibrate because the gears kept turning while the 'puter was looking for the shaft speed to hit zero. Likely fault was a broken beville washer in the forward or reverse clutch packs. Although the clutch pedal was a bit sharp and gear changes a bit scruffy it was still driveable, or it was for a while but after a few days it started to play about and eventually it was deemed as having to be sorted.

Here we are, first time into a red'un! Feeling a bit strange working on something quite different to a basildon product. The Dyna6 bit is in the front of the gearbox so its easier to roll the front away with the front section still bolted to the engine although on this model it has a bracing frame under the rear axle/gearbox that has to be dropped down, this entails loosing the pickup hitch off and letting it hang on two bolts at the back near the PTO, this then allows the frame to drop and the flange where I'd split the gearbox would pass the two upturned brackets on the frame- you can't alter the two sections as there is the PTO drive shaft sticking through both halves so it has to roll apart

Here with the fuel tank off and the battery box also off there are a couple of legs/props to hold the cab up as the brackets on the gearbox have to come off

The green bit in the back section of the gearbox is the mechanical bit with the 4 ranges worked by hydraulic servos to operate the synchro gear shifts

Here we are rolled apart. The book advises unbolting the aircon condensor, compressor and all the pipework so you can hang it on the cab- sod that, recovered the gas and undid the hoses between the cab & engine- would be changing the filter/dryer anyway. a lot easier IMO. The driveshaft, guard and hoses to the front axle all come off- the oval bearing & its housing were badly worn and the bearing further back was noisy as well so they were changed

Heres lifting the Dyna6 section out, the book doesn't explain its easier to put the 2 lifting points in a certain position to allow/make it tip over one way to aid the lump lower down to clear as its lifted out. I know now! The shiny bit hung out the bottom like a prolapse is the forward/reverse clutch unit

Here the unit has been unbolted off the bottom and stripped down, using a home made tool you compress the pack of beville washers that push the clutch piston back, remove the clip and release. the toll is long so as to fit over the shaft when we do the same process on the other clutch

Heres the broken washer, just the one is all it required. They come in a set of 6 per clutch

There you are, thats the Fwd & Rev bits apart

Here is the further section that didn't need taking apart to cure the main problem but being in this deep it made sense to replace the clutch pack orings while we were there and also nail a persistent oil leak we had been monitoring for a couple of years, not much but there was a steady drip-drip from the bellhousing of transmission oil which if the spring hadn't of made us go in we would of eventually to sort the leak. It turned out to be the large, thin oring between these two flanges, the new oring went in together with some locktite flange sealer!

Here is the Dyna6 unit going back in easily because I now understand the need to make it tip over a little by putting the lifting bolts in the right places!! Note the 4 'stands' AKA 4 lengths of M14 studding to stand the housing on and allow the shaft to hang out the bottom as you rebuild it.

While we were there I changed the damper plate in the middle of the flywheel as there were hairline cracks on the plates either side of the damper springs, everything went back together and eventually the two halves were reunited, everything fitted, filled or topped up and then run up and tested, while calibrating it was possible to see the intermediate gear doing its stuff but it didn't want to sense the low speeds/stopping very well especially when she got really hot and the transmission would abort the calibration process which would then throw up an error code for the intermediate gear speed sensor, checking the wiring for this as its on the rear section showed a lot of oil in the switches guts that was leaking out of the gearbox so a new sensor was fitted and then calibration resumed, it had worked before but still didn't quite seem right, this time on the Matrix screen it was possible to see the intermediate gear come down to zero often and calibration moved on quickly now.

After the second calibration the clutch jumpiness had disappeared, the pedal again felt much better and a good test drive confirmed all was well. Quite an interesting job but being a busy time there were a lot of interruptions that didn't help with progress but it wasn't a bad job really