Auto box issues

Stig1 · Jan 19, 2020

My auto gearbox in my 2000 p38 dhse changes gear funny and seems to struggle on hills . Today I've dropped the oil and refilled and added some lucas transmission fix and within 5 miles you can tell it's better just not quite right . The video dont really capture the problem at its worst some times up hill it will drop a gear or 2 and really over rev and I'm also having a issue with reverse it hasn't got the same power in reverse as forward I'm planning on changing the oil and filter again in about 250 miles and adding some more lucas transmission fix the oil that came out wasnt very good at all looked more like gravy than dx3

Henry_b · Jan 19, 2020

Knackered clutches i'd assume.

Better to have the box rebuilt..

That lucas only improves shifts.

Stig1 · Jan 19, 2020

Henry_b said:
Knackered clutches i'd assume.

Better to have the box rebuilt..

That lucas only improves shifts.

Its says it improves clutch plate friction

romanrob · Jan 19, 2020

I'm not sure I would add anything other than Dex III.... Drop the ATF out again (unless you flushed it there's still a load of the old ATF in there anyway) and then just use Dex III. The times I've read about anyone using different spec the gearbox has misbehaved until it was replaced with just Dex III. I'm guessing you levelled correctly ie engine on, and after running through all the gears ?

Stig1 · Jan 19, 2020

romanrob said:
I'm not sure I would add anything other than Dex III.... Drop the ATF out again (unless you flushed it there's still a load of the old ATF in there anyway) and then just use Dex III. The times I've read about anyone using different spec the gearbox has misbehaved until it was replaced with just Dex III. I'm guessing you levelled correctly ie engine on, and after running through all the gears ?

The gearbox was playing up before the oil change

romanrob · Jan 19, 2020

I hear you, but maybe it just wanted clean Dex III ? Now you have a mix of new DIII, your old gravy (unless you attempted a full flush) and then the transmission fix. I would try straight DIII. Assuming you don't want to go and pay for a proper transmission flush then you'll need to sacrifice a few litres of new ATF to do a couple of fills/ drains. As you said, after the last refill it's better, but not quite right...quite right could be just around the corner, by using the right spec.

jamesmartin · Jan 20, 2020

Stig1 said:
Its says it improves clutch plate friction

the friction material is paper thin once they slip they neeed replacing

Henry_b · Jan 20, 2020

Stig1 said:
Its says it improves clutch plate friction

of course it does

eventually it'll **** the bed, better to have it rebuilt..

Datatek · Jan 20, 2020

Lucas transmission fix works well, it more or less cured the flaring 2/3 shifts on mine and has kept it going for years. I now have a used HP24 box to fit which is a stronger box and a cheaper option than rebuilding. The double down shift on hills with accompanying high revs followed by an up shift seems to happen on all the diesels

Stig1 · Jan 20, 2020

Datatek said:
Lucas transmission fix works well, it more or less cured the flaring 2/3 shifts on mine and has kept it going for years. I now have a used HP24 box to fit which is a stronger box and a cheaper option than rebuilding. The double down shift on hills with accompanying high revs followed by an up shift seems to happen on all the diesels

is there a way I can check if the box is slipping I did read about pulling away in 3 and flooring it tried that and it seemed to drive the same as it would in D I found that odd sorry for all the questions I'm still finding my feet with the p38

Datatek · Jan 20, 2020

Stig1 said:
is there a way I can check if the box is slipping I did read about pulling away in 3 and flooring it tried that and it seemed to drive the same as it would in D I found that odd sorry for all the questions I'm still finding my feet with the p38

Selecting 3 simply tops the box changing up to 4th. An autobox will always pull away in 1st. On hills, I always use the gear lever to select 3rd as soon as the car starts to slow which avoids the double down shift and over revving.
You need to do at least one more change of oil, preferably two with Lucas, then see how it goes. It took a long run before mine settled down after the oil changes and Lucas Transmission Fix.
The P38 does struggle on hills, it's a 2.25 tonne vehicle with 136BHP with a strange throttle response, it can still be made to shift when you get used to it, that's another reason I manually select third on hills.

Stig1 · Jan 20, 2020

Datatek said:
Selecting 3 simply tops the box changing up to 4th. An autobox will always pull away in 1st. On hills, I always use the gear lever to select 3rd as soon as the car starts to slow which . avoids the double down shift and over revving.
You need to do at least one more change of oil, preferably two with Lucas, then see how it goes. It took a long run before mine settled down after the oil changes and Lucas Transmission Fix.
The P38 does struggle on hills, it's a 2.25 tonne vehicle with 136BHP with a strange throttle response, it can still be made to shift when you get used to it, that's another reason I manually select third on hills.

that makes sense now I'll give that a try thank you for your help yet again

Henry_b · Jan 20, 2020

Diesel gearbox more often than not has a shorter life than a petrol box..

Grrrrrr · Jan 20, 2020

Datatek said:
Selecting 3 simply tops the box changing up to 4th. An autobox will always pull away in 1st. On hills, I always use the gear lever to select 3rd as soon as the car starts to slow which avoids the double down shift and over revving.
You need to do at least one more change of oil, preferably two with Lucas, then see how it goes. It took a long run before mine settled down after the oil changes and Lucas Transmission Fix.
The P38 does struggle on hills, it's a 2.25 tonne vehicle with 136BHP with a strange throttle response, it can still be made to shift when you get used to it, that's another reason I manually select third on hills.

Thought it was locked to the chosen gear in LOW?

Datatek · Jan 20, 2020

Grrrrrr said:
Thought it was locked to the chosen gear in LOW?

Who is talking about low range?

Datatek · Jan 20, 2020

Henry_b said:
Diesel gearbox more often than not has a shorter life than a petrol box..

Because the HP22 is marginal for the torque curve of the diesel.

Henry_b · Jan 20, 2020

Datatek said:
Because the HP22 is marginal for the torque curve of the diesel.

The Hp22 has a max imput torque "listed" at 350nm the Thor 4.0 uses the same unit, and puts out around the same..
The V8's torque is much ore gradual though, unlike the "punch" of the diesel, not to mention the shifts in a diesel P38 and a Petrol are vastly different in feel

Henry_b · Jan 20, 2020

Stig1 said:
Its says it improves clutch plate friction

It won't if there is feck all left..

Grrrrrr · Jan 21, 2020

Datatek said:
Who is talking about low range?

Did he not want to know if he lock it in a gear to test the clutches?

Datatek · Jan 21, 2020

Henry_b said:
The Hp22 has a max imput torque "listed" at 350nm the Thor 4.0 uses the same unit, and puts out around the same..
The V8's torque is much ore gradual though, unlike the "punch" of the diesel, not to mention the shifts in a diesel P38 and a Petrol are vastly different in feel

That is why the diesel EDC operates a torque reduction on shifts because the HP22 is not up to it. It is also why a power box tends to knacker the box because it negates the torque reduction.

Auto box issues

Active Member

Think outside, no box required.

Active Member

Well-Known Member

Active Member

Well-Known Member

Well-Known Member

Think outside, no box required.

Well-Known Member

Active Member

Well-Known Member

Active Member

Think outside, no box required.

Technician, Bodgit & Scarper Ltd

Well-Known Member

Well-Known Member

Think outside, no box required.

Think outside, no box required.

Technician, Bodgit & Scarper Ltd

Well-Known Member

Similar threads