Hi Don,
it was a bunch of things: replacement of several bearings (including 'donut' again - turned out that previous garage had placed the wrong one and it had already cracked), spring that dampens the movement of the drive Shaft, ignition was revised, transmission flushed, some computer ajustments and an overall alignment check. May have forgotten some things, but those should be the most important

 

Hi David,

By "donut" I assume you mean a driveshaft flexible coupling (flex disc, Giubo or Jurid)?

I can't think of a spring that dampens the driveshaft. There is a center bearing - could that be what they replaced?

I'm not aware of any adjustments that can be done to the X300 computer - can you help us with the details?

Cheers,

Don

 

Hello Don,

The donut is what the garage mentions as the 'Hardy disk' on their invoice, and I think that is what you were also referring to, the driveshaft flexible coupling
The spring apparently is part of the transmission mount, not of the driveshaft, my mistake

About the computer adjustments, I honestly couldn't say. I don't go to that garage anymore since the owner treated me quite rude after a simple remark about the invoice being over 300 euro higher than his estimate without a clear explanation (the computer adjustments were not the only vague element). Told me in so many words that I shouldn't buy Jaguar if I couldn't afford it. Not going back there anymore.

Anyway, my current garage seems much more reliable and human, but not close to home. And although specialized in older Jaguar types they were just as puzzled by the vibrations as all the previous specialists. So I hope that with the replacement of the entire driveshaft the problem will finally be solved. It would be another 400 euro, but if that does the job so be it.

 

Driveshaft was replaced yesterday and.......... it didn't help at all.
Feels even a bit worse. According to garage there was in fact a slight deformation and abnormal wear of the original so it needed replacement anyway. But we're almost out of options now and I am starting to feel desperate (and broke). It is a real enigma.

Because the vibrations seem to dissappear temporarily when slightly touching the brake pedal (without actually braking) and are less when driving in 3rd manual, we're back to electronics and the transmission (2 things I thought we had covered already, but what do I know). One outside source suggested a malfunctioning convertor is the culprit...
I am waiting for a second opinion now before making another steep investment.

 

I am now at my 6th expert opinion on the matter, and the only certain thing is: noone is certain what the problem may be. Last garage I spoke had 40 yrs experience with Jaguar and they said it was a needle in a haystack. The vibrations are most likely to come from the front, but could be generated in a number of places. The vibrations could then be passed on through the lockup converter to the rest of the car. Or it may be the cause itself. Or other parts of the transmission, or... My options according to them are:

• put in a new (secondhand/rebuilt) transmission for 2000-3000 euro - that is way above budget for the car in it's current condition, and no guarantee the vibrations would definitely be gone
• only replace the lockup converter for 750-1000 euro - within range, but it may not solve anything either. So it's quite a gamble as well
• keep driving the car as it is, untill it gets worse and the cause better reveals itself - no cost (yet), but it doesn't feel comfortable either.

For now, I'm going with the last option

 

David,
I can sense your frustration, and that it may be turning to despair! As you will have gathered, there are many people in the forum who are willing and able to help, but it is extremely difficult to do so from afar, particularly when the issue concerns something as vague as a vibration. You have certainly been to a lot of trouble and expense to get the driveline checked out, and in rereading the thread, a couple of thoughts occur to me.
Are you completely sure the vibration is coming from the driveline? I find it very difficult to pinpoint certain types of noise and vibration, as they seem to be able to migrate through the body shell. These cars have been around a long time now, and there is quite a large body of accumulated experience of what goes wrong. The automatic gearbox, torque converter and propshaft seem to be pretty robust (touchwood!!) and whilst they must eventually fail, they do not appear often in the forum. On the other hand, some issues come up relatively frequently. Your comment about touching the brake pedal making the vibration disappear makes me think of the often ignored joints in the half shafts, and of a sticking brake caliper piston, both fairly common faults.

 

yeah, it could also be a sticky caliper slider.
i had that on my subaru, and it resulted in some vibrations at high speeds, but then you would probably notice that one of the rims were hotter then the others due to the brake dragging.

 

Wow David, you've been dealing with this for some time now. That's gotta be frustrating, especially after all the cost involved, not to see improvement. Sympathies!

Check those U joints and brake calipers and rotors (you might have done so already). Then, budget permitting, go for the torque converter.

While there are few reports of X305/6 converters failing or wearing out, certainly it can happen. The 4L80E is common in the US. All the GM pick-up trucks have them. There are forums on the topic where you could get informed about this possibility (again, if you haven't done so already).

It is not a small job, but limiting the work to transmission removal and torque converter inspection will keep the cost minimized. Often you can tell a ruined torque converter upon sight. In any case, maybe the shop can rebuild the converter for you to help save some money, as opposed to buying a new unit from the US.

You've come a long way, so much of the driveline has been reworked. I think there are few other possibilities remaining.

 

Thank you all for the advice and consolation. Heartwarming and badly needed

I can't do much at the moment with all the COVID19 restrictions in my area, but I will check again with my garage whether they looked at the caliper sliders and the joints in the half shafts like Countyjag mentioned. It just might be that they overlooked.
The torque converter was inspected in september (without actually removing it, just the protective cover) and seemed in good condition, as well as the plate. That's why the garage was inclined to look elsewhere for the problem.

Thanks again everyone. I'll keep you posted!

 

Hi, thanks for the input! I've learned that there are at least 5 different versions of the 4L80E and on my Jag only a specific Hydramatic version would fit. And it is quite rare I've noticed. Not to be found on the pick up market unfortunately. Best chance of finding one was in the UK or the Netherlands, but even then quite expensive including transport. I've even been looking on youtube for videos on how the 4L80E works and gets dis/reassembled. Interesting enough, but I'm not skilled nor equipped enough to even think about doing it myself.
I'm going to try and rule out the other suggested causes first. But I will look around for a shop that might take on the torque converter for a reasonable sum as a next option.

 

Check on Youtube for precision transmission in Amarillo Texas. They have tons of vids covering the 4L80E and you can also contact them for advise and information.