Would anyone have an idea as to what would be involved in swapping a newer 6HP26 from an S-Type/XJ into an early build 2004 VDP?


Would the valve bodies have to be swapped?


Seems like Hollander interchange breaks them up into 2003-early 2004, late 2004 to 2005, and 2007-2009. Somewhere I read that the markings on the case are different between 2004-2005 and the newer boxes.


Tired of the constant locking/unlocking of the converter when cold. Thinking of trying the Sonnax valve fix while renewing the four or five seals in between the valve body and the trans. But then I figure why not just do it right.

 

Sonnax kit won't fix it. The issue you are dealing with is twofold. One, those who rebuild the converters, state that the spring in over 90% of the converters rebuilt do not have the required pressure to properly apply the clutch. Slippage causes heat, which only causes the issue to continue downhill. Replacement with rebuilt (around $300 or so, but doesn't include transmission R&R) is the fix. Also, the sprag in many are damaged. Secondly, TCM programming while cold has an aggressive lock/unlock which can only be addressed by firmware. There was supposed to be a flash to minimize this affect, but is dealer only.

See here; http://kinergo.eu/news/rebuilding-of...explained.html

 

Thanks David. Is the sprag the same component that is referred to as a freewheel in the linked article?


I was aware of the flash and have heard that at best it minimizes the effect but does not prevent it. Strangely, my Jag dealer told me that they could not tell from my VIN whether this fix had been done.


Going back to the initial thought of swapping in a newer transmission and torque converter, it seems like there was a fundamental change involving the valve bodies:


Talkin? ?Bout My Gen-eration: ZF 6-Speed Differences in Generation 1 & 2 Valve Bodies - Sonnax


For completeness, here is the Sonnax valve overbore for the converter lockup circuit:


Oversized Bypass Clutch Control Valve Kit - 95740-13K - Sonnax

 

I am speaking from 1st hand experience. The Sonnax kit will not help. Another valve body will not help. New solenoids will not help. The issues resides inside the torque converter itself. Once it starts, it's damaged. Concerning flashing the ECM or TCM, if it was done, there should have been a modification sticker placed under the hood by the dealer. (and yes, a one way freewheel interference clutch is also referred to as a "sprag" clutch)

 

Thanks David for the additional info. I kind of figured that converter replacement was the way to do it right. Figuring it will take me an entire weekend to get the trans out (working slowly and carefully) and then another day to put it back in, plus the cost of fluid (already tried the Motorcraft SP and a new pan/filter), would it not be worthwhile to put a low mileage transmission in place of the 130 K mile example that is there now. Am close to finishing a complete suspension refresh on this car including freshening up the air shocks.


Thus my original question, how much interchangeability is there to the transmission itself? Looking at casting numbers on ebay last night it looked like 2004 through 2007 Jag 6HP26 all began with 1068. I also have some data on which separator plates were used in what year/application which I will post up soon. There is also some indication that 2004 through 2007 were all "M Shift" meaning manual(cable), I suppose at some point Jag switched to electronic shift (E-shift) on these 6HP26's whether on the 08-09 XJ or 09+ XF I don't know.

 

Have you tried contacting zf transmission direct maybe they could help

 

Yes, thinking of contacting ZF, they have a facility in Illinois. Not sure how open they would be as they do rebuild these 6HP26 I think - so advising on recycling yard interchangeability is not in their best interests.


Lately I've been thinking about just replacing the converter and replacing the lines which have a slight weep. A lot easier on the computing end of things - just reflash to the newer program that doesn't dither the lockup for warming up purposes as much.


There is an early and late version of the valvebody (Generation I and II per thecstc.com) but they use the same solenoids.