Question for Ashcroft re ZF 4HP22

[Philip A]

I have a 92 Range Rover 3.9 to which I have fiitted, a unichip, modded heads, and "Thor" inlet manifold which results in about 50% more "tractive effort" at about 2000RPM. The car has done 115KKms and the auto is flawless in operation. Filter changed at approx 100K.

I have also topped off the ZF with Castrol transmax Z synthetic fluid at the last change. Volume is about 4 litres or 50%.

I notice on the highway when climbing hills on wide throttle openings that I get a rise of about 400RPM (1800 to 2200RPM indicated) when the car dips below 85Kmh and the converter unlocks. At about 20% slip this seems a lot to me. It appears to me much more slip than prior to the mods. Of course its useful as the car then accelerates , but it tends to then hunt in and out of the lockup.

Does the thinner transmax Z cause this or is it just a byproduct of the greater engine power and torque converter stall point? should I change out the Transmax Z for normal Dextron 111?
Any advice appreciated.
regards Philip A

[RaginRover]

Phil,

I have read here and elsewhere that the 4hp22s work best with dextron II - which is factory spec and I haven't been able to find a supplier here in brisbane yet.

Read this thread I started on aussie frogs (aussie french cars) the pug 505 V6 has the 4hp22 in it and Alan S on that forum had some interesting things to say .....

http://www.aussiefrogs.com/forum/showth ... ht=zf4hp22

Hope that helps mate

Tom

Another point worthy of note is to be 100% certain the correct fluids are being used.
Without going back to the long winded threads on autos and fluids that I had a while back, it's absolutely amazing how many people, professionals included, continue to use incompatable ATF in transmissions and equally amazing how many supposedly in the know can't be convinced of the problem even while they're standing knee deep in blown up transmissions.
Cits regularly blow autos at 120 K klms as apparently do certain model Beemers with the same box in them, yet Saabs don't and it was reported that Saab mechanics openly state the difference as being the fluid used. When the characteristics of the fluids are compared, it's not hard to understand why and even though I'm no auto fan or expert, I can pick a box with incorrect fluid within 100 metres of driving it. I was reminded of this by Edge's comment about boxes on Beemers blowing when being tested at a certain rev range. Wrong fluid that has friction enhancers which work at optimum levels at certain temps in some transmissions I could see causing problems and every ZF20 BX transmission I have seen with incorrect graded fluid in has dumped nice black fluid out within a few thousand klms due to internal friction damage.
Before you start down the rebuild road, I'd suggest taking a look at the type of ATF that's in it and checking to see what exactly did the manufacturer recommend and trying a change over to that.
For the record, Dex2 and Dex3 are two completely different fluids and not interchangeable as many would have you believe.
My guess is, (without tryng to sound like I have a constant phobia about this) is that if your car is of the same vintage as the 505 that it should have either Dex2 or possibly even TQF as the recommended fluid. If Dex3 has been run in it, (based on the myth that Dex3 is the updated version of Dex2; it isn't) there will be a tendency to hang on in gear, change prematurely with a thump and generally feel as though the engine is constantly under load.
A change to the correct fluid will show a marked improvement which if changed on another 2 or 3 occasions in the near future will correct itself to the point where you'll feel the rebuild is unnecessary.


Alan S

[Philip A]

Geez, you worried me a bit there so I went to Google.
I found the ZF approved lubricants site and Castrol Transmax Z is a ZF approved lubricant for ZF 4HP22. Whew.
Regards philip A

[RaginRover]

Need to change my fluid next weekend might try the transmax Z in it and see how it goes, I would love to find some dex2 and try it

Tom

[Loanrangie]

Interesting read, i wonder if the t/flite box is affected as much by atf type used ?

[Philip A]

To clarify , I am not now worried about any adverse effects on the transmission, but my question relates to whether the thinner Transmax means that the torque converter slips more, or whether the extra slippage is entirely due to pushing far more torque through it.
Its no BIG deal but the car would probably use more fuel with 20% slippage.
Its like an extra gear!

Regards Philip A

[ashtrans]

To clarify , I am not now worried about any adverse effects on the transmission, but my question relates to whether the thinner Transmax means that the torque converter slips more, or whether the extra slippage is entirely due to pushing far more torque through it.
Its no BIG deal but the car would probably use more fuel with 20% slippage.
Its like an extra gear!

Regards Philip A

Hi Phillip,

I am not aware of the oils differing much in viscosity so I would think it's down to the increased torque,

I may well me wrong as I am not familier with the Transmax !

[RaginRover]

To clarify , I am not now worried about any adverse effects on the transmission, but my question relates to whether the thinner Transmax means that the torque converter slips more, or whether the extra slippage is entirely due to pushing far more torque through it.
Its no BIG deal but the car would probably use more fuel with 20% slippage.
Its like an extra gear!

Regards Philip A

Hi Phillip,

I am not aware of the oils differing much in viscosity so I would think it's down to the increased torque,

I may well me wrong as I am not familier with the Transmax !

What fluid do you recommend for the zf4HP22 gbox out of interest

Thanks
Tom