After having problems with this autobox from the time I bought the car, it seems that with the help of this website particularly, I've managed to bring a successful conclusion at last to the problems without having it expensively reconditioned, so here's my four penn'orth in return.
The 6HP26 autobox replaced the 5HP24 and was a brilliant design by a french gentleman, Lepetellier. It is lighter, shorter, and uses less components than it's predecessor, the 5-speed 5HP24.
His innovative design uses a conventional single planetary gearset married to a Ravigneaux double planetary gearset. There are no brake bands, only clutchpacks, a,b,c,d,e. Two clutchpacks are in use for every gear. The torque converter clutch, TCC is used in the same fashion as other modern autoboxes, i.e. it is sometimes partially "on" quite deliberately -- a method of operation I don't agree with called the 'modulated' method. I contend clutches should spend as little time as possible between "on" and "off", my reason being wear and longevity. I do understand the aims of this modulated clutch principle, being to save a little fuel, to dampen torsional vibrations, and to keep the engine turning during the fuel shut-off-overrun. Apart from the different and clever design, it uses no particularly exotic materials or components, OR EVEN ATF FLUID.
As everyone knows only too well, this autobox is surrounded by problems, all of them of ZF's own making. It's to do with policy more than engineering.

****-up #1:--
The autobox was released to the public without the software being properly tried and tested. This autobox relies ENTIRELY on software control, some of it passed to it by the engine control module, the ECM. The TCM, transmission control module, lives in the autobox and is subject to the heat of the ATF fluid. The problems have been so bad, for every car maker using it (Jaguar, BMW, Audi, Mercedes, Ford and others) it has actually spawned a website called
"the lurch.com" describing in graphic detail how this autobox bangs, jumps and lurches it's way into and out of traffic lights. Prior to this all-software control, the older boxes making their own hydraulic, non-electronic decisions seemed to give little trouble. To be even handed, these software problems seem to have been rectified. They should never have happened in the first place.
****-up #2:--
This one was simply a policy decision made by ZF; that policy was to replace the dipstick and ATF fluid filler system under the bonnet/hood with a so-called "sealed for life" idea, rapidly gaining the contempt of professional motor mechanics and engineers, and RIGHTLY SO. No one knew what on earth "sealed for life" meant, until it dawned gradually on everyone concerned that "sealed for life" really meant "sealed for the life of the warranty". In other words, rip-off. But this was only rip-off #1.
**** up #3:--
Apart from the sheer cost of having dealer software changes, expensively so in a monopoly situation by the dealers who charged absolutely top dollar for their services, insult was added to injury by the rip-off in ATF fluid costs from dealers. It has been established that proper, OEM Shell M1375.4 ATF fluid, the one specified by ZF, is no more expensive than usual. The price charged for this by dealers IS AN OBVIOUS RIP-OFF. If anything is likely to alienate valuable customers, this is it -- treating clients like fools. If one pays $50,000 and upwards for a car, we expect better than this. These are not $10,000 motors from the far east. I certainly do not buy any of the excuses that are made for these serious shortcomings.
Now to practical stuff, to help save you money. My autobox had all sorts of noisy problems. It had TCC grunting, and a vicious "cattle-grid" effect known as clutchpack shudder. This was so bad it triggered the fail-safe system into 'restricted performance' (The electronics measure the expected gear speed ratios, and if ouside set limits flag up a fault). It appeared that the ATF fluid had been in the autobox for the full 120,000mile the car had covered. All the good old boy mechanics said the same -- "change the ATF". So I did. The old fluid did not smell of burning and there were no metal particles in the pan. Immediately almost all the symptoms disappeared, and I didn't even use the proper original spec. fluid, but a reasonable alternative costing about a quarter. I was left with a slight gear3 clutchpack shudder, only at full temperature and hard acceleration. So I elected to try an additive called "Lucas Stops Slip". Some opinions on this were "I wouldn't put this thick glop in MY autobox". But as the ratio in use would be about 1:30, I ignored that. It wasn't "just thick glop" as when washing my hands with washing-up liquid after the job, there was a 'film' left which felt a bit like rosin, kinda tacky without being sticky. It said on the container that results could be expected immediately, but this wasn't so -- it seems to take several hundred miles to kinda "run-in". Now I can make the car accelerate in any gear, making that ever so quiet "whoosh". No burps, grunts or shudders. I've spent a lot less than £200, say $300, a recon. job on the autobox would have totalled £1,500, say $2,250. How long will it last? That's anyone's guess, but many of Lucas' adherants talk of exra mileages like 50,000 and more.
I know this is a long contribution, but someone, somewhere in the world could be thankful, and save money thereby. That'll do for me.
Leedsman.

 

Well done Leedsman.
KBO mate.

 

I've preached and preached about the importance of changing the fluid/filter in this and the 5HP24 too, and I've proven time and again it doesn't take lifeguard 5 or 6 at $80/litre either. Just a simple $8/qt Mobil 1 or Castrol mult-vehicle ATF @ 5/qt.

Then, I've watched so many of these boxes head to their early deaths, but for simple fluid and filter changes because so many people bought into a "marketing scheme", a part of which is the very expensive "exclusive, single-sourced" fluid (yeah, right!).

An ulterior motive of "Seal for Life" (which many miss) is auto manufacturer compliance with "Green initiatives", some of which are or will be imposed by governments. Seal for life simply means - It's maintenance free (save the planet from wasted oil changes) - drive it until it breaks and we'll replace the entire box with a new one....at your cost, of course, after warranty. BTW - the chances the box will last 50,000 miles (the warranty period) is very high, then declines dramatically after that (on the owner's nickel).

But then, manufacturers would like to create "incentive" to "encourage" average owners to just trade in every four years for another new one and skip the incredibly high cost of unit replacements when they begin to fail.

Well, now I'm ready for a little nap!

 

Hear hear, Stevetech. One comment I would make about the so-called "Greens" is this.
I understand they would want to eliminate waste (such as gearbox, engine oil etc.), and this is very laudable, no doubt. But the Greens generally speaking, don't have enough imagination to see where their policies are leading. Quite properly, Stevetech pointed out that many owners will decide to junk their cars when faced by a ruined autobox, getting best price they can and BUY A NEW ONE! Cannot the so-called Greens see that an enormous amount of energy and resources are taken from the environment to do just that, build a new car, when the old car was perfectly serviceable apart from being the victim of marketing strategies? There is even an expression for this -- "planned obsolescence". That expression is from the 1960s, YES, the 1960s! Haven't we woken up yet after all this time?
The uncomfortable and unpleasant fact is that the so-called Greens are not "green" at all. They are being conned by big business just like the rest of us.
The Greens see electric cars as being the great saviour of the automotive industry, saviour from pollution by CO2 that is. Same story again -- you have to charge the batteries from somewhere, always the public electricity supply. So you shift the input of pollution from the car to the power station, which uses polluting coal, gas or oil.
Ok, some will come back with the HYDROGEN FUEL CELL as a source of major amounts of electrical power. Same story again! Where do you get your hydrogen from to power the fuel cell? By using vast amounts of electricity from power stations, that's where! On top of that, the hydrogen has to be compressed, delivered to fuel stations, which have to be built (using resources fuelled by -- guess what? -- the fossils AGAIN!).
I could go on ad infinitum, ad nauseam, and most people will switch-off, getting bored. So I will say finally the REAL practical way to cut pollution by CO2 is to build and use cars which are far lighter, with highly efficient diesel engines which approach 100mpg. in use. This target IS NOT IMPOSSIBLE.
Leedsman.

 

I've become convinced it is impossible to fight a marketing plan. Just today, there is yet another post about the 5HP24 being sealed for life....and the conclusion was - sit around and wait for it to explode....

The master marketing strategy is really quite brilliant and a WIN/WIN/LOSE.

The factory (not just Jaguar either) issues a "policy" statement - The field will no longer do repairs below the unit level, this includes maintenance items like transmission or differential fluid changes. If unit failure is diagnosed, the field tech is trained to remove and replace the unit.

WINNER - The factory - Lots of money saved on sub-unit parts distribution worldwide, only whole units are distributed. Field tech training is far less and much simpler, just follow the computer aided diagnosis and replace the unit when it says so.

WINNER - The dealer network - virtually no parts department to maintain and invest in. Tech training is less expensive, repairs are much more efficient, but for the waiting for units on order.

WINNER - The first owner/buyer - He/she is offered an almost maintenance free product, the last maintenance frontier being oil changes and most factories offer that free too for the life of the warranty. The factory incurs the cost of the units replaced during warranty, but that number is pretty low.

LOSER - The second, nth, or out of warranty owner - essentially, all of us as we incur the exorbitent cost of "unit replacement" after the factory and dealers no longer support it.

Remember - the dealer network must continue to recite current remove/replace policy as that is the factory's edict, and is why most if not all dealers will tell you they cannot change the trans fluid or replace the filter...its sealed for "life".

 

A brilliant and incisive expose of marketing strategy by Stevetech there. That IS how it works.
So what will people do when these facts dawn on them eventually? What would I do is the question?
I have (say) £8G. to spend on a car. Do I buy a second-hand quality car with no warranty, (originally costing around £50G) or do I buy a new car with 5 years warranty at £8G. from the far east as they are cheaper and not at all bad? For me, the balance would be tipped toward the cheap new car. If everyone is driven to the same conclusion as me, then it would become impossible to sell a second hand quality car that is out of warranty. That quality car costs £10G per annum ALONE in depreciation. About £200 per week. Considering the oncoming world financial climate, quality car makers are foolhardy (in my opinion) in following this policy of severe planned obsolescence. The results are already showing -- who owns Jaguar now? It has had to be sold off, got shot of, TWICE/TWO TIMES.
I have personally experienced the effects of severe planned obsolescence in the domestic electronics world, where in the 1970s and 1980s the Japanese flooded the world market with fairly cheap tvs, radios, cassette recorders etc. that by and large DIDN'T GO WRONG. This was a new twist, because items made in Britain certainly DID go wrong, and often. I was employed in the industry to fix these, making a comfortable salary for hard work. But then it twisted again, the Japanese farmed out their manufacture to cheaper countries nearby, making it possible for people to simply "junk" their cheap items when faulty and buy new. A spin-off result for the Japanese was a severe financial problem for their country, which is still there today, after all this time. Those of you who follow such matters will know exactly what I mean.
My experience with my Jaguar, and it would apply the same to others, BMW, Mercedes, Audi etc., would preclude me from buying another second hand Jaguar. It revolves around my experience with the ZF autobox. Yes, it's very nice to drive a Jaguar, BMW, Audi etc., BUT, and there is a very BIG but now -- the planned obsolescence inherent in the car becomes a disincentive to buy. The pleasure in driving my Jag. has been negatively balanced by these matters. And now I'm wondering what other nasty little surprizes are going to pop out of the woodwork?
To end on an upswing, thank heavens for websites like this one, where the resourceful can get round the problems, expose the problems, expose the rationale behind the strategies of the manufacturers, and keep our quality cars on the road. As long as it lasts...
Leedsman.

 

I fully agree that MobilOne or Castrol's Multi-Import ATF should do the job, and I'll probably find out when I decide to change our factory fluid because right now I plan to go with the Castrol product....

But the remaining question is this: For cars driven under normal operating conditions (a 50/50 mix of highway/city driving, no towing, no racing, and no dirt or gravel roads), just when do you change the fluid? 50,000 miles? 60,000 miles? None of the above?

 

The guys on the spear point of this subject seem to have setteled on approx 50,000 miles.
Got to be carefull here, as those with "Select Edition" cars don't want to get caught with the wrong color fluid if the trans fails under warranty. Your dealer might want to contest your coverage.

 

Yes, very true. If you've paid for the extra warranty, let it fail and let them R and R.

 

Great info Leedsman - I have just aquired a 2004 S Type 2.7D auto and although there are no gearbox probs at present, I am thinking of doing a fluid change soon (74K on the clock).

Which fluid did you use and did you change the filter?





regards Yorkie

 

Yorkie72, the absolutely correct ATF fluid (if a 6HP26 autobox) Shell M1375.4 is available at a reasonable price on british E-bay, just use search. It is FULL SYNTHETIC and should do for 50,000mile driven conservatively. Arduous use such as towing heavy loads like a caravan, or high-pressure/speed driving, change at 30,000mile. Make sure you go to a garage that does the "full-flush", ie. gets all the old fluid out, including the fluid in the torque converter. Otherwise, Mobil-1 full synthetic meeting Dexron 6 spec. seems to be a reasonable alternative. For the 5HP24 autobox, search on here, there is much material about ATF fluid for those.
The pan must be changed to change the filter (all plastic) and they aren't expensive, mine was under £20.
In an autobox, full synthetic ATF fluid is better because of the superior heat performance, the box running some 20degree cooler with synthetic. Heat performance is #1 importance according to the boffins.
Leedsman.

 

Hi Leedsman

Thanks for the response. I have checked e-bay out and the cheapest Shell M1375.4 is £89.75 for 5L which is still pretty expensive. Also the cheapest pan/filter I can find is £77 which is being sold by a LR dealer for the Disco3 which I think uses the same box.

I have checked with 3 local gearbox specialists and none offer the full flush system that you mentioned and have quoted £200 - £340 for doing an oil/filter change using the correct filter and fluid. They all say the pan/filter is £100 from Jaguar.

Since we are not far apart do you have a recommended garage to do this?



regards

Yorkie

 

Yorkie, the fluid won't be rock bottom price as it's high spec. and full synthetic, but it's a lot cheaper than from Jag., BMW etc.
See KEVIN TAYLOR at Croft Autos: Unit 7, Calder Wharf Mills, Dewsbury WF13-3JW:
01924 462000: www.croftautos.co.uk
He specializes in Jags., the place is littered with them. Mine bill was £82:40 but I supplied the fluid. I tipped the boys £20 who did the job. I understand they supply fluid meeting Dexron III for that job, and have had no problems.
Mention me, Fred from Leeds, to Kevin Taylor by all means!
Leedsman.

 

Thanks Leedsman, will give Kevin Taylor a try.

regards

Yorkie

 

I think I really messed up my zf6hp26 I didn't know u had to add more fluild with the engine running. I drianed It i don't know how much I got out, I pumped 3qt of fluild in until it over flowed cold. I plugged it started car shifted threw gears seamed fine turned off car took plug back out and toped off. Pluged it and went on merry way driving.ran smooth as silk for 3 days this morning it started shifting funny slipping a tiny bit between 3and 4th didn't think much of it. On the way home I stopped on incline at light and heard Avery quite low whine. When I got home I read the right way to fill it. Needless to say I'm have chest pins over this NO MORE DRIVING CARI will put the right aamount of fluild in the right way tomorrow. My ques didn't I fry my transmission it now whines u can only hear it faintly under the car with it running. If I fill it right will it be ok I drove 100 to 150 with maybe 2 to 3 qtz low. No fauilt codes nothing just the whining it still dries good just shifts harder and.25 rpm spikes between gears when cold like a small slip.

 

2005Splat -- The theory behind refilling an autobox is as follows :--

The ATF fluid contains a "viscosity improver". This additive stops the ATF fluid thinning too much when it's very hot (up to 120*C). It works by the molecules in the additive "unwinding" at high temps. When it unwinds, the additive expands considerably, leading to an expansion in the amount of fluid in the autobox, also of course lifting the LEVEL of the fluid too. Giving, naturally, symptoms of OVERFILLING when hot. Full synthetic fluid (PAO type) uses a lot less viscosity improver as full synth. thins a lot less when hot.

So.....Follow the manufacturer's instructions as to how to refill after draining, such instructions being on this very website. Basically, this entails getting the ATF level right at around half-temperature, so the expansion is accommodated.

This is where you cocked-up. If the box hasn't been leaking, collecting all the old fluid carefully and MEASURING it to see how much has come out, THEN replacing with new fluid the exact SAME amount, should do the job right and quickly. Because you can't get all the old fluid out (about a litre stays in the torque converter) when it's a DIY job, you can only get 8 to 9 litres in. A little DIY trick is to leave the box draining overnight, as this get a bit more out. In the US, there are garages who have the total flush system with a special and expensive machine which gets ALL the old fluid out via the cooler lines. This also gets what old fluid there is left in the cooler as well. I haven't come across one of these machines in Britain yet.
Leedsman.