Zf transmission. Aj6 & aj16

(Caspar Bucknall) #1

My Zf is kerput and am weighing up the options for its repair/replacement. The revs climb and the car crawls forwards. Reverse is fine. This leads me to believe that the A clutch needs replacing?
I’ve found a Zf4hp22 mated to an aj16 engine on eBay. Does anyone know if the transmission mount on the engine is the same on the aj6 and aj16? Or alternatively perhaps I can keep the bell housing from my old one and bolt it to the new trans? Any help would be much appreciated :slight_smile:

(Veekay) #2

You may want to let everyone know what model year you are working on.

(Caspar Bucknall) #3

My car is an xjs 3.6 1990 automatic.

(PeterCrespin) #4

Yes the bolt patterns are the same but 90 was the transition year to the 4L which used an electronic box that requires a transmission control module.

(Caspar Bucknall) #5

So in theory I can get a zf transmission from an aj16 xjs, put the bellhousing from my aj6 onto it, and then I’ll need a transmission ECU for it to work?

(equiprx) #6

It’s unlikely that any automatic transmission has a bell housing separate from the gearbox. Perhaps I’m missing something?

(Caspar Bucknall) #7

Exploded gearbox image attached. Bell housing is separate. So from this I presume I can use the Zf4hp22 from an aj16 jaguar and use my existing bell housing?

(1994 XJS 4.0 (AJ6)) #8

As well as the ECU you will also need to check out additional speed and engine sensors to feed that ECU that might not be present on the 3.6.

For example, don’t the 4.0L models have a twin track, 6-wire TPS that feed signals on throttle position to the electronic gearbox separately? Given the way the Jaguar engineers tend to work there will likely be others.

(Wayne Canter) #9

Is the bolt pattern where the bell housing mates to the main body of the transmission the same on both transmissions. Is the depth of the bell housing the same on both transmissions, do the torque converters from the 2 transmissions both have the same bolt pattern. You may have more to consider then just the bell housing.

(equiprx) #10

Well I’m gobsmacked!
Thanks for clearing up that misconception I had.

(PeterCrespin) #11

It’s correct for manuals. Pre 90 Getrag 265 had a detachable bell and that 5-speed could be used in classic Jags with a small adapter. The post 1990 Getrag 290 has an integral bell and can only be fitted by a large adapter ring at the bell front face.

(equiprx) #12

No wonder I’m confused, I thought the conversation was for an automatic.
I need to get used to going back to the first post before I comment.
Sorry for the mix up.

(John Quilter) #13

In my humble opinion you would be better off simply getting your existing gearbox rebuilt by a competent shop. The unforeseen issues that could arise from trying to fit a gearbox from a different year or model Jaguar could be substantial and expensive. These are not simple cars and complexity results in ever less interchangeably of parts from year to year unless it is a relatively minor part. .

(Caspar Bucknall) #14

Exactly my thoughts, thanks everyone for clearing some things up for me.

I’m going down the Getrag 265 manual conversion route with this project now.


(PeterCrespin) #15

I have the small adapter you need to put the 265 on a Jag bell. I also have a new master cylinder/reservoir for such a conversion and a lightened AJ flywheel and new clutch kit. Private email if interested.