RobV8Defender

Active Member

• Mar 26, 2017

• #1

Hi All,

Question for all you Disco / Range Rover owners.

My 90 has a Disco 3.9 V8 and HP422 gearbox - as found I believe on Disco and Range Rover Mk1.

Could you tell me at what speed you change into top gear - on my setup it doesn't get into top until 50mph which seems a bit high.

Any thoughts / advice would be welcome

 

norseman

Well-Known Member

• Mar 27, 2017

• #2

I've no experience of slush boxes in Defenders but can offer the following-
Is it a factory-fitment, in which case the change speeds will have been pre-set.
If retrofitted from another vehicle who knows what the settings may be. I've had RRC's, which you correctly state also use the ZF4HP22, that have shifted into overdrive top at 50, 52 or at 40 mph, dependant on the model year. It is possible to alter the shift speed but it's a specialist job.

 

RobV8Defender

Active Member

• Mar 27, 2017

• #3

Thanks Norseman - so it is entirely possible that the gearbox is working as intended - albeit working correctly for a different vehicle

The gearbox came of a Mk2 Discovery, so all settings have been inherited.

 

cooltide

sheep fancier

• Mar 27, 2017

• #4

It should be in 4th long before that but torque converter locks up at 50-52mph.
This can be mistaken for a 5th gear

 

RobV8Defender

Active Member

• Mar 27, 2017

• #5

Thanks Cooltide, I'll do a more careful job of counting the gears and look out for that. For sure you could be right - I'll report back.

 

norseman

Well-Known Member

• Mar 28, 2017

• #6

cooltide said:

It should be in 4th long before that but torque converter locks up at 50-52mph.
This can be mistaken for a 5th gear

Click to expand...

Having owned four Classics with this 'box I was under the impression that the shift to fourth & TC lock-up occurred at the same time, but I will bow to those who possess greater knowledge. My current RRC makes that change at 40mph which suits me fine, after all I can always use the shift to hang on to third until the car reaches a higher speed, but for country lanes 40 is ideal for economy.

 

cooltide

sheep fancier

• Mar 28, 2017

• #7

norseman said:

Having owned four Classics with this 'box I was under the impression that the shift to fourth & TC lock-up occurred at the same time, but I will bow to those who possess greater knowledge. My current RRC makes that change at 40mph which suits me fine, after all I can always use the shift to hang on to third until the car reaches a higher speed, but for country lanes 40 is ideal for economy.

Click to expand...

The disco 2 will lock in 3rd at 40 if 3rd is selected, and 50 if drive selected. Nice little feature which i only discovered about a year into ownership

 

discool

Well-Known Member

• Mar 28, 2017

• #8

According to LR, the 3.9 disco auto:
"A three element torque converter delivers the power to a four speed epicyclic transmission. First, second and third gears are reduction ratios but fourth is an overdrive gear for high speed cruising. A direct drive clutch, integral with the torque converter operates to engage fourth gear."
So for my disco the speedo shows that's around 53mph, although with full throttle acceleration beyond the 52mph, direct drive doesn't engage until easing off the throttle.