clunk when changing down ..?????

more than likely the shunt is just play in the driveline, unless it is a pronounced thump-clunk that shifts you out of your seat!!!!

slightlyriskyneil said:

Have a Range Rover P38 2.5 DSE late 2000 model - Did a fluid change to address delay in changing up from 2nd to 3rd and clunking between 3rd & 2nd and 2nd & 1st when changing down also replaced the filter. I had done a couple of heavy tows which pushed the car to the maximum. No play in prop shaft as far as I can see.

The transmission fluid looked dark but red and of good consistency. I refilled and the delay in changing up has gone however the clunking as she changes down remains. I decided to add some Lucas auto fix so drained out some fluid to make room and the fluid I had put in (good quality dex II) appeared to be dark and brown ... strangely not in as good condition as the old fluid I had previously drained (having done no more than a couple of hundred miles)!?!? I’m not sure where to go from here ... am I looking at a replacement torque converter or more ??

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Downshift clunks seem to be the norm and will be a little worse with Lucas in my experience, it is as Saint said just drive line slack, not the torque convertor.

slightlyriskyneil said:

I had put in (good quality dex II)

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Isn't the correct grade of ATF Dextron III not II?

I doubt it makes much difference, but it might?

MrGorsky said:

Isn't the correct grade of ATF Dextron III not II?

I doubt it makes much difference, but it might?

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Dexron IId or Dexron III

I would check the props and the rubber coupling its like a damper also have front or rear wheels up chocked and hand brake/ park off as prop could be tight not showing free play .

cheers guys will check the drive chain as advised ........ will feedback when able

checked this morning in neutral with handbrake off. No excessive movement noticed. The shafts from each end of the transfer box were tight in relation to each other. when i change between drive and reverse there is no distinctive clunk it's just when it changed down. Less so when warmed up. The transfer box was wet so am going to check fluid level. there is also a brief 'flare' in revs between 2nd & 3rd when I accelerate a little hard ??

Sticky valve block. Ratio clutches are supposed to engage and disengage synchronously. When the incoming clutch hesitates as the outgoing clutch is disengaged you will get flair changing up on acceleration and a clunk, for want of a better word, on change down.

What is a sticky valve block (where is it) and how does one cure it?

I do get a flair when accelerating and I thought TC was on the way out. I towed a heavy load and could barely pull away it was all revs and no moving. I tested this on the drive by putting the foot brake fully on and managed to rev to almost 2500 revs before the car wanted to move. I was heading towards replacing the TC but would hate to do this and retain the symptoms of flaring on up-shift and clunking on downshift .... any advice which way to go from here ?>?????

slightlyriskyneil said:

What is a sticky valve block (where is it) and how does one cure it?

I do get a flair when accelerating and I thought TC was on the way out. I towed a heavy load and could barely pull away it was all revs and no moving. I tested this on the drive by putting the foot brake fully on and managed to rev to almost 2500 revs before the car wanted to move. I was heading towards replacing the TC but would hate to do this and retain the symptoms of flaring on up-shift and clunking on downshift .... any advice which way to go from here ?>?????

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In order to change gears inside an Auto Box, there is a valve block filled with the valves that open and close to allow hydraulic pressure from the pump to actuate the clutch pistons and drive brakes inside the gear box which need to engage and disengage the clutches for each gear.

If the oil is leaving deposits and debris insode this valve block, the valves start getting stuck and not opening and closing fast enough to change gears....

As a for instance, flaring: As one clutch valve closes to release a drive clutch and a second valve opens to engage the next gear, if one of those valves gets stuck or is slow to react, it will act as if you have just put your foot on the clutch of a manual car and not taken your foot off the accelerator pedal hence the revs will rise but there will be no drive until the sticky valve has fully opened or closed....

The valve block is mounted inside the Gear Box....Lucas Transmission Fix is an oil additive that can be added to the gearbox oil and will clean up and the valve block and coat the valves and block in a nice silky smooth residue.

Can take a few hundred miles to fully clean the block, and a couple of oil flushes and refills along with the Lucas Transmission Fix additive wouldn't go a miss....people do swear by it!