Hey folks,

Looking for some help with my XF.

Under changing power, it has increasingly started to have the back end sway from left to right. If I coast, everything tight. A couple of years ago, I rebuilt the whole back end to eliminate excessive sway in corners (upper and lower control arms, track rods, sway bar bushes). All is still tight and new, so I have to believe it's coming from the differential. There's no unusual play in the driveline, so I'm thinking the diff bushing has failed and I want to change it before having to swap the diff out. Only problem is the part number (C2C16377) seems to have been discontinued everywhere.
Has anyone ever encountered this wandering of the back end before and would anyone know where to find the bushing, except the obvious junk yard.

Thanks for any help and advice.

Chris.

 

Not a direct answer to your question, but I'm having trouble picturing how the diff mount could affect tracking? The diff is mounted to the subframe independent of the suspension, if my recollection is correct. Could the rear subframe itself be loose?

 

Good question, pretty sure the subframe bushes are OK. In a previous life, I worked in the factory that they're made in and Jag was my customer. The Lemforder bushes do wear out - I used to have an S-Type that did exactly that around 220,000 miles (but at the same time, I have an X350 XJR with 220,000 miles that hasn't worn out). But with that problem, you can feel the slop in the handling when you're coasting. This XF only has 120,000 miles and all is tight when I'm coasting. Hence why I blame the diff. Pretty sure one of two things is happening: Either the diff is twisting under load due to worn bushes or it's shot and I'm only getting drive to one wheel - both of which could cause an uneven distribution of load to the rear wheels, causing the sway when in a straight line when power is added/taken away. I need to get it on my lift and look for slack in the bushes. If there isn't, I guess I'm committed to a new (or used) diff. Wonder if I can mount a GoPro to watch the diff while I'm driving to see if anything moves?

To be honest, I was hoping it was the cheap option of just the bushes, but if they don't exist, I may just have to accept the latter.

Appreciate the help!

 

Is the car a 5.0L SC with the E-Diff?
Do you have the last 6 digits of your VIN?

I ask because you mention the S-Type and that car had what looks to be the same bushing but a different part number that does NOT cross over to the XF. I think when the E-diff was released those bushings changed. The E-diff uses 2 bushings a top and a bottom one. The item your looking for is a 1 piece bushing.

This is from JPART. It's the old style diff from the S-Type.



It uses a 1 piece bushing.

This is the E-diff and it has a lower and upper bushing in that spot.




Looks like Jaguar updated from the older S-Type rear diff to the newer E-diff starting with VIN - R41865 in the XF.

I think if you have an XF with the 4.2L V-8 it will have the older style with 1 bushing. Why that does not use the old S-Type bushing (C2C1780) that ALL the S-Types use I can't explain. You might take a look at that part number as from what I can see they are very similar.
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Thanks, appreciate the level of detail, I saw the same thing online. My XF has the older style. VIN is r15010, so it looks like the same diff casing as the old S-Type and X350. I'll definitely look for the S-Type part number.

 

Yes I think they should be the same but again why did Jaguar come out with another part number? I can't explain that. No supercessions are mentioned either.
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Good question on why a different part number. My best guess is that dimensionally they're identical, but they have a different durometer to cope with the slightly higher torque from that generation of the 4.2 SC engine.

 

That's the only reason I can think of too. But there is only a tiny difference in HP. Like 390 to 420HP.
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Hi All,

Thanks to those who've tried to help here.

I believe we have our culprit. After further digging, I found that the ball joint on the rear RH toe link had about 3mm of play in it. I replaced the link and the problem went away, but then confused the heck out of me. As I'd changed the link, I took the car to Belle Tire to have the alignment re-set accurately, which they did. After the car came home, the problem had resurfaced, but not quite so badly as before. It turns out that when Belle Tire adjusted the LH link, the ball joint on that side came loose too (about 2mm of play). I changed that link last night and the problem has gone again, hopefully for good. Guess I should have known better and changed both sides in the first place.
At least if anyone else experiences the same problem in the future, this thread may help with a quick root cause to the problem.

 

Don't know why, but I've been waiting for that answer to come up
Must admit I was goung to suggest it, then I had a bundle of thing to sort out and fogot to post ir
but glad you sorted it
I love the challenges these cars throw at us, and I won't be beat