ZF Heavy duty upgrades

**Slunnie** · 21st February 2008, 12:07 AM

I've got a chipped intercooled TD5 that is doing some good power. The auto doesn't cope all that well with the power and needs regular fluid and adjustment despite a really good additional ATF cooler.

Just wondering if ayybody has much experience or knowledge about these modifications that are done by Ashcroft as quoted below, who does these mods in Aus (Pref Sydney) and what type of $ it is all worth to have done. The Disco get's serviced etc by Davis Performance Landy's though I have not chatted to them about it yet.

Ashcroft Transmissions

Heavy Duty ZF autoboxes
We are able to supply the ZF4HP22 with optional strength upgrades depending what you are doing with the vehicle, what gearing, what engine Etc.
Stage 1 upgrade
We can build the 4HP22 but fit the centre section of the box with the bigger 4HP24 internals which upgrades one of the weak links being the C1/C2 one way clutch, the 24 one is much stronger, Photo here. Just the centre internals are changed so the box stays the same externally. This upgrade is an additional £ 250 on top of the normal rebuilt exchange price of £ 595 or £ 645, depending if the box is hydraulic or electronic.
Stage 2 upgrade
The box can be built with both the 4HP24 internals as above but also the 24 front end as well giving you the added strength of having the larger 24 "A" clutch, also a weak point with larger engines.Photo here There are 2 fitting implications of doing this, the unit is 15mm longer and the oil cooler nipples are M18 x 1.5 thread, on the early 22"s these threads are M16 X 1.5, the later 22"s like the TD5"s are already M18. This upgrade is an additional £ 500 on top of the normal rebuilt exchange price of £ 595 or £ 645, depending if the box is hydraulic or electronic.
Torque Converter Upgrades
The ZF auto as used in the LandRover vehicles uses three different diameters of torque converter. Small. Medium and Large.Photo here
"Small" is used on the 300 Tdi, P38 diesel and the TD5 "Medium" is used on the 3.9, 4.0 and the later 4.6 P38 "Large" is used on the early 4.6 P38"s
The converter has a lock up clutch inside and the smaller one struggles to cope with a stock engine, never mind a tuned one.
When the "stage 2" ZF is being used with a V8 or 2.8 TGV you have the option of using the larger diameter 4.6 torque converter at no additional cost but on a V8 you will also need the 4.6 boss and flexplate assy to match the bigger converter. When using on the 2.8 be sure to order the conversion kit to fit the bigger 4.6 converter. This bigger converter is recommended on the big V8"s and the 2.8 as it keeps the revs and heat down.
If you have a tuned TD5 engine, in addition to the stage 1 or 2 options mentioned above we are now able to replace the "Small" diameter torque converter for the "Medium" diameter one. This gives you the benefit of the larger lock up clutch and the lower stall speed V8 torque converter which will take up drive earlier. This option is an additional £ 250.
TD5 ZF upgrades
If you are converting your TD5 Defender to auto you have a few options, I though it may be useful to give some guidance based on our experience.
Stock 90/110, fine with a stock 4HP22 Medium Tuned 90, stock ZF, uprated converter Medium Tuned 110, stage 1 ZF, uprated converter Fully Tuned 90, stage 1 ZF, uprated converter Fully Tuned 110, stage 2 ZF, uprated converter Tuned Challenge 90, stage 2 ZF, uprated converter

**George130** · 21st February 2008, 06:24 PM

Slunnie My ZF was rebuilt with heavy duty everything in 2004 by a Canberra mob for $6500. What sort of power you putting through it and what is your problems? Also what oil are you using?

**Slunnie** · 21st February 2008, 06:43 PM

G'day george.

I'm putting about 160-165kw and 520Nm through it.

There are a few problems, initially it was an overtemp problem, though this has been sorted by adding an additional ATF cooler. These days it seems to be more that the auto seems to fairly quickly fall out of adjustment in the bands or whatever it is that they adjust when the service it. The torque converter also has a heap of slip in it.

More lately, an possibly as a by product the torque converter doesn't lockup, though I haven't checked fluid levels which potentially may be the cause and it sticks in 1st when cold which is a governer prob, possibly from material breakdown.

What I'm looking for is just something that will deal with the power of the motor without needing pampering, and it seems that the 4HP24 will do the trick but its specced up for a V8 or to upgrade the internals of the TD5's 4HP22 to 24 spec's.

I'm not sure re the oil, it's just whatever Davis Landys puts in it. No doubt Repsol or something.

**George130** · 21st February 2008, 08:54 PM

My box runs transmax Z. It used to cook the dextron 3. I'm about to fit a monster cooler with the clutch pack rebuild. We are thinking that my failure is heat related from the beach run and before that the 3000rpm stall converter it had in it. My cooling fan had also failed at some point. My box is the older D1 valve body controlled unit but has had extensive upgrading.
My power output is supposed to be 250hp and 620NM or about 190Kw so quite a bit more than you are trying. I would also guess that my 130 is quite a bit heavier.
My torque converter was rebuilt by a mob in Sydney who put as much meat as possible in it. It now locks up between 2200 and 2400rpm. I can get the details of the guys who did my box in 2004 if you want.

**Pedro_The_Swift** · 21st February 2008, 09:23 PM

250 and 620 is really awesome Edd--

**Slunnie** · 21st February 2008, 09:27 PM

G'day George, that does sound interesting especially re the fluids. That was even with the 24 clutch pack in it was it? That would be great if I could get the contact details if at all possible so that I can have a chat with them etc. Thanks for this.

**Ricey** · 21st February 2008, 09:34 PM

I'm running a BD chip & find heaps of slippage/ hunting in the normal mode but once in sports mode get crisp & quick changes. Are you getting the M&S warning lights at all?

**Slunnie** · 21st February 2008, 09:39 PM

Gday Ricey,

I don't get the M&S lights. I do run in sport mode sometimes, especially when towing because it shifts before the gearbox gets loaded up, and in many repsects I think this helps to preserve it all.

**Ricey** · 21st February 2008, 09:44 PM

Hey Buddy! I agree, it preserves the workings of it all. Interesting thread & one I may need to refer back too. My TC clutches are shot & I'm getting M&S lights when loading it with torque. The box is my weak link at the moment.

**Hally** · 22nd February 2008, 07:10 AM

I destroyed the planetairy gears in my auto which has a 4.6v8 infont of it so I now run planetairy gears out BMW V12 ZF and replaced all the clutch packs with stainless steel items and put in a 30% lower first gear which is briliant for taking off I run 36"tyres and it will beat most cars off the mark while the box was out all the oil wells were drilled out to allow better cooling I have now done about 15000k's and it's two years old and It's been all hard driving this box still shifts as smooth as the day I picked it up Temp wise I can run all day in soft sand and the hottest its been 90 deg c when I got this box built the guy's(ron hill automatics QLD) told me that it was a bit of an experiment and les richmond was toying with the idea as well, he may have already been doing that for years I dont know. all up they did me abit of a deal and it cost $5000

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