The clutches consist of alternating steel plates and clutch plates within the drums.

When "not activated", i e not compressed by fluid pressure on the pistons at the bottom of the drums, they are loose fitting.

When compressed there is supposed to be gap at the top/open end of the drum between the last steel plate and the circlip holding all plates/clutches in place.

There is a very complex ritual to measure that space for each drum. Which I could not wrap my head around.

I intended to measure that space in each drum before disassembly to get a good idea what it should be. I did not.

None of the YouTube rebuild videos I watched did this procedure, Not one and I watched a number.

What they did do was the "air test" where compressed air is blown into each relevant "orifice" for each drum to see if the clutch assemblies move into a compressed state.

That is what I did and they all moved..........in the end. In the beginning I had two drums too tightly packed.

You can see what I went thru earlier in this post but I ended up buying a complete used A drum assembly just to get additional "thin" steel plates to make packing adjustments.

Each drum has different thickness measurements for the steel plates and the clutches. Some are common and they all have same diameter except the E clutch which has much narrower
diameters.

Incidentally my kit came with a number of additional clutch plates for the E clutch.

I have quite a few "spare"parts especially the bushings so if you run into an issue with some parts I may be able to help out. Also a set of new solenoids.

I used the 2007 XKR blue top solenoids and valve body mated to my 2005 XJR TCM in the end.

I tried re flashing the XKR TCM but no joy with that.

When I had the initial failure while driving the car still drove just fine so long as I did not accelerate hard.

Also during the refill procedure the first time, after the rebuild , when going thru the gears I felt a good solid thump in my rear as gears engaged.

However by the time I finished no grip to speak of at all!!

 

Is there any manual that you would recommend.

 

https://www.scribd.com/doc/20322431/Repair-Manual
https://www.thectsc.com/images/pdf/6HP26-28_Catalog.pdf

Earlier on in this thread there are documents listed for repairing the ZF6HP26 as well.

 

Thank you

 

Jackra_1
Awesome job and write-up!
Thanks for sharing your hard work.
Mike

 

Any update?

 

There are curved wrenches for the top bolt. Called half moon or c wrenches. Get a half moon with a ratchet. Makes the top bolt bearable.

 

I had some "spare time" the other day or excess energy whatever after solving my really big hassle of a job with my Range Rover EPB issue with the help of jlrsdd.

No red flashing lights.

Saved beaucoup $$$ doing it myself even if I had used a good independent.

Would have helped enormously if I had a lift!!!!!!!

Anyway back to topic.

I looked at the new solenoids that I put in my original transmission very carefully, thinking about junking them, and I found VERY fine metal particles on the metal gauze filters of several of them. Not all.

I used the ones yhat were in the XKR unit I purchased hence these are spare.

So what happened?

Did they come from the valve body from the original transmission as a result of the hard failure?

In any case the valve body probably has particles in it for sure.

I will take that apart soon to look.

Also the rest of the rebuilt transmission may well have contamination which I am sure could be cleaned out.

I know that when refilling the rebuilt unit at one stage when going thru the gears I could feel the clutches engaging.

When finished they did not engage at all because the valves were not functioning prperly for sure I think.

Trouble is it there is way too much work to to correct the issues and re install the unit to find out......unless there is another way?

Car is running so well now. I know I am tempting fate here!

 

Hi John,
I followed your Herculean task to pull that ZF6HP26 and rebuild it.
My once daily driver 2003 XJ350 with 3.5L V8 has a problem.
Short drives O.K. but once the fluid warms up changes from ( I think ) 3 to 4 often flags an error and invokes the limp mode.
Google hits suggest worn bushes a typical cause at the car's 152,000km.
First part of solution I purchased a 2017 XF for the daily driver.
Second part is the XJ is now up on my 2 post hoist waiting for me to pull the box.
I would appreciate your experience to answer:
1) Was it hard work to separate the exhaust components and remove them ?
2) Do you really need to remove that starter bolt ?
3) Will a standard ring wrench ( spanner ? ) fit the crank to rotate the engine ?

I have the XJ350 pdf repair operation manuals, but they are often sketchy on details.
Once I have the box out on a bench I can figure out if better to rebuild myself or take it to a specialist shop.

Well, almost ready to start work.

 

Hello Richardsjags.

For me removing the exhaust components was not at all hard. However it was not that long ago when I replaced the cats with 200 cell bolt on units and also replaced the center resonator
with an X pipe.

As for that pesky bolt on the starter if I can remember it may not be necessary to remove.

The issue back then was that separating the tranny from the engine was a huge effort and I felt for sure then that it was the bolt in question that held everything together.
If yours separates easily without undoing that bolt you may be lucky?

I believe one person stated that it was NOT necessary to remove that bolt and he is a recognized expert on here.

A good spanner or socket will fit no problem however for me I had to tilt the engine to get a socket in past supports in front of that space.

I think I removed spark plugs to make it easier to turn over the engine.

I replced the tranny cooler lines as mine were leaking quite badly. That was quite the pita!

Good luck.

 

Hi John,
Thanks for reply, much appreciated.
1) The exhaust is off. Very impressed with the slip joint design to separate components, much easier than exhausts on other cars I have dealt with.
2) The fluid is drained. You can see I fitted a steel pan and new fluid only 6 months ago on the off chance it would fix my problem.
Got to say the original ZF plastic pan and fancy fasteners does not endear ZF to those who keep cars going for many years of life.
3) All the plugs are out. I have sockets up to about 36mm, any idea what I need for the crank ?
A quick looks says it aint going to be real easy to get a socket and bar into that space, but I guess it must be doable.

I am in a much better position than you were with the car up on a hoist. Also the car has always been garaged at home and under cover at work, and in any event the Australian climate is mostly benign towards keeping rust at bay. The underside of the car is pretty clean so it was quite easy for me to see that the starter mounting flange is about 3" from the tranny mounting flange on the engine. You would not expect a bolt thru that 3" of engine casting. The starter is mounted on a studs.
I can understand your frustration and surmising that could be a starte bolt holding you up.
On that note there is a Utube video of a guy in Austria totally rebuilding a beaten up looking S type. ( Why would you bother ? ).
Point is he was on his back under the car and could just pry a small gap at the bottom of the tranny but still could not get it off even with all bolts removed.
So he stuck small shims half way up the flange, then rebolted the bottom edge whch tended to lever the top end to open up a gap.
That way he worked a gap all around and separated the thing. He found a couple of dowels were just so tight.

I will get my step son to give me a hand to drop the box. Since I bought a 2017 XF to replace the XJ350 I have promised the car to him once fixed. It is up to him to decide to keep or sell.
I am kind of regretting this since I think the XJ350 is a more comfortable drive and if no major headaches occur it would last me another 10 years.

Nice and clean, easier to work on

Same again

Starter has stud at low end

 

The "shim method" sounds good if you have a problem loosening the tranny from the engine.

My car is extemely clean with little to no rust as I do not drive it in wet weather as a rule and keep it garaged.

Never the less two dowels were somewhat rusty and that was the issue for me in separating the parts.

I envy you having a lift!

When you get the valve block check the valve's mesh filters for metal fragments.

Did you find any metal shavings when you did the fluid and pan change before?

Good luck.

 

This is a great thread I have stumbled across. I am currently overhauling my E53 beemer box. I see clutch pack thickness issues earlier. While the large friction plates come in two thicknesses, some packs have thicker steels also, they are not all the same. The thicker steels go with the thicker frictions. Did you mix them up maybe or fit them in the wrong position? You should not have to mix thick and thin steels at all. I am using Raybestos frictions.

Rule #1 with all my trans overhauls (I am also doing a GM 5L40E at the same time) is to get the torque converter overhauled any time the trans is out of the car. For example, the 5L40E would only drive whan cold, once the oil was hot, no drive. Cause=failed converter. Did you get the converter in your ZF box overhauled when you did the box? I can see no mention of this happening, but may have missed it? In my GM case, the owner kept driving till it said enough, non-magnetic glitter all through the box and cooler, hence the overhaul.
Cannot recommend a TC overhaul strongly enough when the box is being taken apart.

The ZF box had oil service 18 months ago, and when doing now, was much darker than expected, so TC overhaul was first cab off the rank.
My ZF overhaul manual has lovely photos, but reads like it is written in Swahili when you look at the clutch pack clearance adjustments.
I have an ATSG Ford 6R80 manual (license built ZF6HP26 with a couple of mechatronic valve differences) which documents that clutch pack measurements much differently, and is easy to follow without all the BS and special ZF tooling. ATSG themselves recommend this as a reference for the ZF box as well.
were the solenoids replaced at the same time? I am putting in a Transgo shift kit and some Sonnax bits to cure the mechatronic issues these have (doenshift from 2nd to 1st is like getting rear ended).
And finally, did you replace all the bushes in the drivetrain at overhaul? These are critical to prevent 3rd gear codes, among other things. I think your initial code was for a 3rd gear fault was it not?
Just a thought.