Since you know about what speed the problem happens let’s try a few things?

You can use the J-gate to hold the transmission in gear. Try to get the car to make the sound with the transmission in D and then slow down and get the transmission into 3rd gear. Take it back up to 50mph or where ever you got it to act up. Then repeat this process for 4th and 5th gear. Let us know if anything changes.

If it continues to make the same noise I would lean towards the rear control arm but your symptoms don't really point to that?

Finally and just be careful with the shifter when you do this! Get up to speed and get the car to make the noise and then shift to N. Any changes? If the rear control arm is at fault you should be getting the same thing regardless of what gear the transmission is in.

It still sounds more like a TQ problem to me.
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Could I just chime in here? In N, what should happen if the TC was OK?

 

Not really sure just trying to get other symptoms so I can give a better guess. Right now my money is on a failing TQ clutch but still can't be sure.

Now we have a possible bad rear control arm and I don't know how that could cause any of this but it might?

My idea of shifting to N is to remove as much transmission effects as possible.
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I see. I'm tagging along on this thread and have tried the N idea already. It didn't seem to make any difference, but it's hard to find a smooth enough road of any length to discount the surface as a contributing factor. My Sports suspension doesn't help either.

We'll see how the OP get's on.

 

bump.

 

Have you considered changing to TC yourself? If so, what all is involved? Does the transmission have to be reflashed when the TC is replaced? I have no idea what a Jaguar dealer would charge and besides that the nearest dealer is about 90 miles away.

 

Changing the TC is a BIG job and without the proper conditions to work in, not worth doing yourself.
Just so you know, Mikey has bumped you a post, just above^^

 

If I shift to lower gear the surging seems to go away.

 

I don't have that much experience with Jags, but I am familiar with the rumbling you describe. I have always called it "washboarding" because it feels like you are driving on a wash board. It makes a low rumbling sound accompanied by a vibration or surging feeling. It usually happens at about 45 mph and disappears with you accelerate or decelerate.


Every time I have seen this problem, it was caused by bad universal joints (u-joint) on the drive shaft. I do not even know if the Jag has a traditional u-joint, but it may have something that causes a similar condition.


The u-joints are a cross shape with a cap in each of the ends. The caps rotate on small needle bearings. Once some of these needle bearings fail, it creates just enough slack in the system to allow a harmonic vibration to be established under specific conditions. The shaft must be rotating at a specific speed with a specific pressure on the shaft. Since the drive shaft couples directly to the rear end, the specific rotation speed of the shaft translates to a specific vehicle speed - usually about 45 mph. When the vehicle speed changes, the "washboarding" disappears. When you accelerate or decelerate, the pressure on the shaft changes, and the "washboarding" disappears.


I suspect that the Jag has something similar to u-joints on the shafts between the rear end and each of the rear wheels. I would start looking there. If these are the problem, you can usually feel very subtle amounts of "slack" in the u-joints when you rock them back and forth by hand. Don't forget to look for u-joints on the primary drive shaft, but I do not expect that the Jag will have any there because the transmission and the rear end are in fixed positions relative the each other.


Also, do not assume that the rumbling sound will be localized to the rear of the vehicle just because the u-joints are in the rear. The rumbling from "washboarding" will resonate throughout the vehicle, and usually it will not be isolated to a specific location. The associated vibration will also seem to be throughout the vehicle. You will feel this vibration in your butt rather than in your hands. That is why it is often mistaken for surging.


This is just a thought. I hope it helps.

 

Ah, a good suggestion. From my experience on other vehicles, even though I've never had the washboarding, I've noticed another symptom with bad U-joints: a metallic clang, almost like a ringing, at start and stop. A driveshaft almost sounds like a bell at times with sloppy U-joints.

It's very easy to diagnose worn U-joints. Put the car on jackstands, with the transmission in neutral and the parking brake off. Place the pad of a finger so it bridges the gap between the two halves of each U-joint. Rotate one side back and forth slightly. If the U-joint is worn, your finger will feel the relative motion.

While you're under there, rotate the driveshaft completely and look to see if there is any wobble in the middle, indicating a bent driveshaft. I think the S-type main driveshaft is well protected, but it's still worth checking.

 

I usually notice the ringing sound after the damage to the u-joint has become very significant. The washboarding can occur long before the ringing. Most cars have so many other vibrations and ride so rough that the average owner does not notice the washboarding at first. With a vehicle like a Jag it will be much more evident much earlier. This is probably especially true for the new owner of a used Jag that is actually looking for problems.


Jim

 

I just had a reason to crawl under my S-type, so I took a long look at the drive shaft and the axel shafts. No u-joints. However, your problem still sounds just like washboarding caused by bad u-joints on other vehicles.


I would take a long hard look at the couplings on the driveshaft. They are pretty beefy, so I suspect a failure in this area is pretty rare. Look for any play in the connections. Even the slightest fault can cause washboarding. I would eliminate every other possibility before I replaced the torque converter.


Jim

 

We're on the same page

https://www.jaguarforums.com/forum/s...09/#post874668

on a parallel thread from the same poster on the same problem. Possibly the two should be merged or one closed.

These cars have joints that are closer to a CV in design rather than a traditional u-joints so they are still highly suspect.

 

I just had my drive shaft replaced on my 2002. it has 85000 miles on it.
I had one shop tell me it was a bad rear wheel bearing. he had me thinking the same thing but before I tore it apart I took it to a guy who specializes in jag repairs. it took him a couple days to come up with a direction to go. he could feel it when he drove it, he could feel it when it was on the lift, telling me the whole rear end was vibrating but no obvious culprit.
since it was on the lift I asked him to check the drive shaft. it ended up being both the carrier bearing and the only u joint on the shaft. between the both of them they produced a sound that was similar to the sound of helicopter blades beating the air and only above 50 mph.

 

Was it expensive to fix?
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for him to find the problem & fix it,it was $1300.00. more than I thought it would cost. his price for the drive shaft was $975.00 im sure that's with his markup. if I had to do it again ( which im sure I wont) I would have done it myself. what the killer of it is, the carrier bearing and u joint are us serviceable so once they go bad the whole shootin mach needs replaced.
once I got the quote I did call a local drive line shop that I have used in the past. he told me the same as my mechanic, unrebiuldable

 

At 45 with cruise car surges. When I move the shifter in the J gate to 4th gear it does not surge.

 

That is a clue?

Everything after the transmission turns the same speed regardless of what gear the transmission is in. So I think you have found that the problem is in the transmission/Engine area. If it was after that the symptom would not change with different gears.

Still suspecting the TQ with what you have posted.

Here is the drive shaft and we do have a flexible rubber disc at each end also called a Giubo. Be sure and note the position of the bolts,nuts and washers if you take the drive shaft out. Jaguar uses the hardware to help balance the shaft and you can create a vibration but putting them in a different spot. Sometimes they are dabbed with different colors of paint to help identify them.





I forgot to add that the TQ does not lock up in fourth so driving in fourth gear takes the TQ clutch out of the loop.
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Is just fourth that it doesn't lock up in? If you drive around in fourth, you shouldn't experience the surge or washboarding at 40-50mph then?

 

Very good info. It sounds like the most expensive scenario to repair. Now if I can just get someone to replace the torque converter. Is it most likely just the converter or does something else cause it to go out?