Has anyone fitted a manual box to marelli v12, if so any suggestions as to locating the rear crank sensor? Also any views on the adaptor plates as opposed to a custom bell housing, box is a 265 getrag, any input appreciated

 

Can't you simply cut a little section out of the bell housing to accommodate for the sensor?

 

I know Mike from Ohio did. Made a bracket to hold the Marelli rear "sensor". His is a 90 model

 

This is Mike from Ohio.


The typical way this is done is to slice the bottom of your bell so that the die cast cover that is used with the autobox can be fitted. This cover has the mounting boss for the sensor. This is the cleanest way, maybe, to do it, but you will need to take that cover and the bell to a machine shop to get this done.


The engine and bell are such that a cover will need to be fitted, regardless.


Here's what I did: I got a cover for a pre-89 V12, and this fitted just fine. Then, I noted the angle where the sensor was placed on the die cast cover, and I took a die grinder and ground out a notch in the bell where I wanted to locate the sensor. I then used a broad file to create a flat on the bell (e.g., tangent to the outside diameter of the bell) where that notch was located, and I drilled and tapped two holes for the mounting screws. Fitted the sensor. Worked like a charm.


The thing you DO have to mind, though, is this: there is a clearance spec as regards the sensor and the flywheel tooth ring. Be sure you shim that sensor to the specs. If you do not, you will not be happy, as the car may start, but as the engine warms, the thermal expansion can move that sensor out of spec, and the engine will die (that sensor is a primary input to the Marelli ignition). It will restart when it cools down. Set the right gap, and all will be well.


-M

 

Mike, thank you very much! This is an issue that none of the 'specialists' here in the UK ever mention but obviously a marelli car wont run without it. Thanks again

 

gotta love them yanks, they do things because they dont know they cant!

so they do it anyway.

 

What bell housing are you using?


On my 90, I have a spun steel formed bell housing and simply used the existing cast aluminum half moon plate that was secured to the rear of the block with two 1/4 inch bolts.


You can't use the two straps that secure the cats to the bellhousing, but I have not needed them.

 

I used an aluminum bell, supplied by Keisler, when they still offered the conversion kit My kit was for a pre-89, and was not compatible with the Marelli cover plate that holds the sensor. Those bells had to be sliced to get this cover to fit.


I can image a steel bell being much easier to deal with, once the engine/dowel point matchup issue was dealt with.


-M

 

Are you sure? I had bought the Keisler kit and originally used the cast aluminum bell housing with the original sensor plate. I did not have any problem

 

The steel bell housing was obtained from The Driven Man. It was all set up for a direct bolt in to the 5.e Liter V-12.

 

I am quite sure that the Keisler kit I had featured an aluminum bell housing that was NOT compatible with the marelli sensor mount, die cast access cover. The kit I had was for a pre-89 XJS V12, was purchased new, and the original owner had never gotten around to install it. I bought it for my 1990. I had to change the pedal box, of course, and the bell had to be modified to suit the needs of the marelli sensor. And, it turned out that the later V12 engines had a different pilot bore in the crank face, so I had to get a pilot bearing custom made, as the supplied bearing was too large.


Anyway, at that early stage of the Keisler kits, which were based on the TR-3550 and TKO version of same, the bells were aluminum. Those fitted to 89 and later models had a section slice out from the bottom, permitting fitment of the OEM die cast access cover, to which the marelli sensor was fitted. I have pictures of all this, showing this to be the case. Those bells for earlier models did not require this modification; they fit the V12 straight up, and used the access cover (stamped steel) from the TH400 installation, directly.


What has happened subsequent to the Driven Man picking this line up (and Keisler going out of business), I don't know. I do know that the Tremec line expanded to include a 6 speed, and I am not surprised that a steel bell is now available. I would guess that it is much easier to use such a bell with the die cast access cover for the marelli sensor.


Every manufacturer does cost engineering where they can. It is not desirable, for example, to have to stock two different bells when one cleverly designed model will do.


The thing to watch for, too, is to ensure that the flywheel that is fitted for the manual box has the same number of teeth on the ring gear as the flexplate that was removed along with the TH400. The marelli ECU needs to have the same teeth count per rev, or things will not be the same.




-M

 

Have you considered cutting the slot at the bottom of the bell housing so that the sensor support plate can be used?

 

MikeBaker3:

In my case, I certainly could have cut a slotted section from the bell. The problem though, is that I did not have the precision cutting equipment nor fixturing with which to hold the bell, so that this slot could be made. I would have had to take this to a machine shop, along with the cover, and have them do it.

After looking at it, though, it occurred to me that I really did not need to have the bell machined: rather, it was very easy to notch it for the sensor and then simply drill and tap the screw holes for it. The notch was of enough depth that the sensor pointed directly at the ring gear teeth, and handily was flush to the face of the bell, too. Done.

-Mike

 

i did a T5 swap. mine isnt a V12. sorry im not much help, but the pedal box and hydraulics cant be too dissimilar. email me at ianfromcraigslist@yahoo.com if you need any technical help/info with the install.