My 2008 Range Rover HSE Supercharged transmission is slipping but only under hard acceleration. It happens in every gear only if I accelerate hard. Not too hard but enough for it to down shift. Almost like it looses all forward momentum will rev as if it's in neutral. Then after letting off the accelerator at lower rpms it will drive normal again. I don't know where to start here as from what I understand the rear stator bushing is a common culprit in these transmissions but I do not believe that this is part of that symptom.

Can someone please help..

Also Rrphil I am hoping maybe you can chime in here as I have been following your advice and posts for years now.

Thank you in Advance

The rear stator bush seals the hydraulic feed circuit to the E-clutch so only affects 4th, 5th and 6th gears.

If the clutches in the transmission were slipping you would expect the speed sensors to detect this and the transmission would failsafe, storing error codes.

A sensible first step would be to check the fluid level in the transmission. You have the ZF 6HP26X transmission which uses ZF Lifeguard Fluid 6.

Click image to enlarge

First I would like to say thank you for responding in a timely manner. I was not expecting you to respond so quickly. I am star struck right now, you are like a legend!

About 2 weeks ago I did a flush and fill but noticed I only drained approx. 6 quarts. I bought 12 bottles of zf fluid from the RR dealership thinking there would be more. Also I'd like to mention that when I did, I did not have my scanner available so I could not monitor the transmission temperature. I was under the impression that it needed to be at that temp to fill properly because of some advice I read on another forum.

I am just now seeing the fill procedure on your attachment indicating 30 - 35 degrees. It is late now but tomorrow I will remove the drain plug while cold and see if any fluid comes out. Then proceed to monitor the temp to 35 and check/fill again.

Can I let you know my results tomorrow? I will respond whether it's fixed or not.

Thank you again

Thought I should also include a picture of the fluid I received. Does this look okay to you?

Click image to enlarge

Also regarding the RR storing codes I have had a code in the past for "incorrect gear ratio", but it is not there currently. It was intermittent before the fluid change but has gone away now. Problem still persists though.

Just for the avoidance of doubt, the most critical thing when setting the fluid level is that the engine is ticking over while the level is being set. If the engine is turned off, the fluid in the torque converter will immediately drain down into the sump and produce an artificially high fluid level. If you remove the filler/level plug when the engine isn’t running, you should get a litre of fluid down your arm.

LRN13754 is the Land Rover badged version of Shell ATF M-1375.4 (hence the LR part number) which was the original fluid specified for the 6HP26, since superseded by TYK500050 or Lifeguard Fluid 6. That must be a seriously old bottle of fluid in your photo.

Phil