Folks,
Apologies if this is a FAQ - I did search the forums, but I'm either hopelessly blind or the answer isn't there, so here goes.

The 6HP box Mrs. X356 (V6 3.0, Petrol, MY late 2006) gave up the ghost. Now; not having the space, ramp and health being what it is, I thought to swap it with one that I fully reconditioned and rebuilt a few years ago. It's seen little use, before that lady blew a head gasket, and it sadly went to her grave, RIP. I did, however make a deal with the breaker to buy the gearbox off of him, for whatever weird reason. She was a 4.2, 2005, X350.

The question: apart from reflashing/recoding + swapping the bellhousing, are the two boxes interchangeable, or are we looking at different gear ratios too?

Many thanks in advance.

AAA.

 

Defenetly no gear ratio difference in the tranny .
if I remember well it is just amount of clutches in the tranny esp. On xjr 4.2 SC
The differential is different ratio:
-2.7 tdvi and 3.0 v6 and( maybe the 3.5 v8)dd have the shorter ratio.
-(the 3.5 na )the 4.2 na and 4.2 sc have the longer ratio

 

Much obliged for this @Petz . You mentioned the amount of the clutches in the tranny. This refurbed box came from a NA 4.2 X356. How much of a difference, if any, is the different clutch number going to make, and is it detrimental to the point I won't be able to fit it as a replacement in the 3.0 V6?

Thanks again.

 

you could basicly at least into the v6 3.0 put any of them since by hp is the second weakest and by torque the weakest of all the engines available.
2.7 v6 diesel tdvi
3.0 v6
3.6v8
4.2v8 na
4.2v8 sc

 

Search for" gearbox swapping" here on the forum x350. Have look as well in the files zf6hp26 automatic transmission.maybe even in the maitenance section
May want to get connected to j"aguar xj x350/x358 admirers owners and support group" on FB

 

Had a look in the stickies " maintenance" here in forums
number 19 is for the transmission

 

Generally speaking... those tranny can last a very long time but not 20 years and 250k miles with the same oil.
the xj6 I bought may 24 is a 2003 and it only had barely 85k m8les on it. Drve the car just around the block and tranny was lousy.
so I got myself a zf6hp26 oilchange kit and some rubberparts for inside and it helped enormously.
My xj8 4.2 na 2003 that I sold has now 230k miles and still the original tranny ( had an oilchange at 80k and one at 200k .
old oil, and llow evel of oil (mostly seeping at the electrical connector sleeve and sometimes the original pan )are mostly the reason for trouble .the torque converter rarely goes bad. The other thing is - the rear wheelspeed sensors and their reluctor rings being a major factor in input for speed ,abs dsc ,cruisecontrol and tranny
- bad ignition coils on the sparkplugs
If you would just give it a try if an oilchange can make a difference.
-first open up fillerhole right side of car and tranny 1 1/2 inch above pan short hex allen key( near exhaust )
-then by letting out about approx 4 liters through the screw in the plastic pan . And close again 5nm torque I believe.
-fill up till it drops out with zf lifeguard 6 oil , or any compatible oil
-Do the oillevel procedure you can find videos of zf on youtube.
☆ car has to be leveled up in the air.
After filling new oil close filler hole slightely , start engine with foot on the brake and keep it there , go from P to R to N to D 5432 each 10 15 seconds and back to P ( wheels should newer turn) let engine run , get below tranny open up filler hole again and continue to fill till it is dripping oil out of it. At 40-50 degrees celsuis oiltemperature dripping slightely ( not tranny) level will be correct. Close fillerhole and go for a drive . Self adjusting to new condition

 

these zf rubber parts just cost like 25€
Especially on early x350 they deteriorated because of the contac5 with the oil and could even get fissures and let the oil pressure capacity drop dramaticly

 

Just ordered 1068.298.090 to be prepared on my next tranny oil change. Thanks for sharing.

 

Many, many thanks for this. I have access to the 6HP service manual; just wanted sage advice with respect to swapping around a unit from a 4.2, into the 3.0; kindly provided and gratefully received.
I am active on that FB group. Very useful indeed.

Thanks again @Petz