Removal of rotor arm from shaft. 1981 XJ-S V12

Have read all posts regarding the removal of rotor arm, but none unfortunately give me an answer to my problem. I know for a fact that the car has sat idle for at least 14 years, and this may have some bearing on the issue at hand. I cannot remove the rotor from the shaft. It seems to be welded to the shaft, rust, corrosion of some kind? I have been able to remove the distributor body (complete with rotor arm, electronic timing rotor, etc) from the motor and have it on the work bench. Quite a deal of force has been exerted onto rotor to extricate it from the shaft, but have had no luck. Is there any way of using maybe a liquid to loosen the fitting of the rotor arm? Can anybody help me?

Worst case,. It’s plastic, break it. But before, you would have been better off leaving it in the car so the distributor is held steady while working on the rotor. Then climb ON TOP of the car. Get on the engine, and make sure you pull that rotor UP, not sideways at all. When they’re stuck, you can’t just pull them off from the side of the engine back. Get ON the engine so you’re way in there.

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Yes John. Followed your advise (Climbed on top of engine as per you scenario) for approx four sessions. In desperation removed complete distributor to place in vise get greater purchase. No joy unfortunately. Might try soaking in WD40 or some other degreaser?

Wow, have never heard of this before.

Yeah, I would flip distributor upside down and spray some PB Blaster in there (WAY better than WD40)

If that doesn’t work, since you have distributor out, I would carefully cut a line in the rotor parallel to the shaft (using dremel?). I’d only go about halfway, so you have no chance of hitting the actual distributor shaft. With a screwdriver, you should be able to pry at the cut and weaken the rotor so it slides off.

If you have this much trouble getting rotor off, I would think centrifugal advance is also in bad shape. Definitely do a dissassembly/cleaning/oiling as mentioned in Kirby’s book. You need the distributor out anyways for this.

And just like that, your centrifugal advance springs are stretched beyond recognition. If the rotor is to be replaced, I recommend twisting it hard enough to break it loose, even if that means breaking it into pieces. Easier to twist with the distributor in the car, though, because the engine will hold the shaft still. With it on the bench, it’ll be harder to hold it still without boogering up the teeth on the gear. Might wanna just drop it back into place long enough to twist that rotor off.

Hi Greg, Yes I agree. The centrifugal advance is also sized. There is no backward spring with the rotor.

When I get the rotor removed (one way or another) there will have to be work done on the centrifugal advance mechanism.

As an update. Rotor now removed. It had to be broken off. Removed the trigger board, and now the trigger wheel. Problem… STUCK. Yes removed retaining clip and washer.
Just like the rotor arm, the trigger wheel is firmly attached to the shaft. No movement whatsoever between the wheel and shaft, Have now placed the distributer completely in penetrine. Will leave for a few days and try again

There’s a keyway with a weird little clip in it that aligns that toothed wheel. Remove the clip, then try to turn the toothed wheel (carefully!). If you can get it to turn, you’ll have an easier time feeding oil into the joint to get it loose.

Hi Kirbert, I’m not there yet. It is the large trigger wheel which I cannot move. I know it has to come straight up after removing the circlip and washer. Removed same but trigger wheel won’t budge.

Oooh, this is an Opus? It’s a big plastic disc with 12 ferrite inserts you’re trying to remove? Good luck! Some have suggested tying string or wire through the holes to give you a better way to pull up on it, but I’d still bet you’ll break it trying to get it off.

Might as well go ahead and break it, then replace the ignition system with an aftermarket ignition system from FAST:

https://mossmotors.com/electronic-ignition-kit?utm_source=feed&utm_medium=free&utm_campaign=shopping&gclid=CjwKCAjw2ZaGBhBoEiwA8pfP_pvAP9w2DwQmW_T2lE-jksUNEkF_rm_jRF_ak_2QTCOmR2ZEA3SzXxoCwZgQAvD_BwE

Make sure the kit you get has that 12-slot aluminum trigger wheel shown in that photo.

Yes. Well, it seems that I foreshadowed the wire idea. I have tried long plastic zip ties to get that purchase. Still no luck. I’ll leave it in the penetrine for awhile to see if that has any effect on the wheel. I will certainly have a look at the web sites you have emailed me. Thanks.

Just curious, so is your '81 a preHE? I thought that’s when the HEs started.

Hi Greg, Still having trouble removing the trigger wheel. Yes my 81 Jag is Pre HE. Not too sure as to how to interpret the Vin number. The Australian compliance plate is dated 9/81.

Hi Kirbert, Checked out the aftermarket ignition system by FAST. Checked out the instructions which go with the unit, and there seems to be no clear correlation between the system and the instructions. Am I reading it incorrectly?

You’ll get all the instructions you need here. That system was previously known as the Allison XR700 and after that the Crane Cams XR700, and it’s been installed by scads of guys on here. A quick search of the archives will turn up enough reading material to keep you busy for a week. The short answer is the XR700 is considered a far superior ignition system to the original Opus, superior enough that you’ll notice the improvement every time you drive it.

Great. I will still persevere for a little longer with the trigger wheel etc. If I don’t do any good, then it’s a possible go with the XR700.

Hi Michael, l also have an '81. I am in Melbourne, Victoria. The '81 l have found is a bit of a mixture of HE and pre-HE. Makes life interesting at times… l have started a complete strip down/ bare metal restoration. It’s not a weekend job that’s for sure…haha. Covid and lack of work have enabled me to put a good dent in it though (no pun intended) feel welcome to PM me if need be.
Cheers. Richard Ferrie

Hi Richard, not sure how to PM you, but my purchase was only a few months ago. It doesn’t require the type of work that yours does, however been sitting in a barn, covered for 15 years. My work will be on the motor more than anything else. At the moment the distributor requires a complete overhaul. Getting it apart is proving to be a challenge. Regards Michael

Michael if you touch Richards avatar it should bring up this;


Use the blue message box to PM.

Hi Robin. Thanks for that. Michael