Hey, all! I'm new around these parts and looking forward to fleshing out my garage, reading, participating, etc... Love the forum so far!

My post is in regards to an issue that JUST started with my 2004 XJR. It has 70K miles and I just went through the air bag/compressor saga with it (mine needed a new control module after it had been fixed, as the ride height in the rear was at it's highest and ROCK HARD).

Now, I have a new situation and I'm hoping someone with more experience/knowledge can give me their opinion.

I just started noticing a thunk type sensation, barely audible, when coming to a stop. It's immediately while/after fully stopping, with the momentum of the car's forward motion, if that makes sense how I've described it. It also happens immediately upon accelerating from a full stop. I have noticed it a few times when going over bumps, as well.

I can feel it as a slight "thunk" in the front end, driver's side. It also has a slight sound to it, like a "gnnk" sound.

It doesn't always do this, but when it does, those are the symptoms. It literally started doing this yesterday (that I noticed, anyway). As I am still reeling from the air suspension/compressor/module, I am hoping to get an idea of what to look into and maybe the cost if someone's gone through this.

I know it needs to be looked at, but I'm hoping for a few ideas. Thank you, in advance, for any and all help!

 

With this Jag you sometimes hear the petrol sloshing around in the tank when coming to a stop.

It is a plastic tank probably with no baffles but if you are sure it is coming from

the front end?

Try filling the tank right up to see if anything changes?

 

Thanks for the suggestion meirion1! I am a fan of trying the easy stuff first. I have to admit that I hadn't even considered that, but I gave it a shot anyway. Having a full tank held no difference from a half tank, though. The sound I described didn't and doesn't have a "fluid" quality to it and it is definitely coming from the front of the vehicle. I just don't know if I should be thinking bearings, bushings, tie rods, etc... nor how to begin checking them off the potential list. Thank you again meirion1 for taking the time to reply!

 

Welcome to the forum JagnHamLove.

You should stop by our New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum and introduce yourself.

Ouch! Sorry to tell you this, but the same thing happened to me, but I was able to reflash the suspension module & the problem was solved. No need for a new module...

These are the hardest things to track down...

The front suspension can make little clunking noises from;

Droplink, sway bar / anti-roll bar link bush (in the lower wishbone, common enough)
Sway bar / anti-roll bar D bush (but unlikely)
Bottom shock bush (in the lower wishbone, common enough)
Upper wishbone bushes
Big lower wishbone bushes (commonly replaced)

Or it could be something outside of the suspension, maybe an engine or gearbox mount. As you can imagine, it's very hard to diagnose over the internet!

Lots of info here on the forum about suspension in our cars.

 

at 70k miles, some or all of your suspension bushes are likely to be worn out and need replacing. Have any already been done?

 

Again, kinda hard to diagnose via internet, but it kinda sounds like one of the many many curiosities of the zf tranny/jag programming. If all the bushes looj ok, might be worth having the adaptions reset and ensure your TCU firmware is the newest available

 

The front shock bushes located in the lower wishbone wear out quite quickly. The whole weight of the car is taken by these four bushes. I had my rears done 2 years ago, but fronts are now up for renewal. My car is on 71k miles.

 

Thank you everyone for your help. I certainly wasn't expecting a diagnosis, just a heads-up on where to start and I definitely have that. To answer your question PigletJohn, none of the bushings have yet been replaced in the vehicle, front or rear. I will use the info you've all been kind enough to provide, I'll check out other forum threads and report back when it's been managed.

 

The lower bushes,C2C36866, can anyone advise if they can be pressed out on the car or does the lower arm have to come off? I have done 130k miles and have now got a slight clunk over some bumps. I am not adverse to disassembly, just want to know how hard they are too get out?

 

Looking forward to your results as I am experiencing the same thing.

 

I can't say it's impossible, but it is certainly usual to take them off.

Mine were done by my local Indie, they put in exchange arms which had been cleaned up and re-bushed by some workshop specialising in it.

It's a long time since I changed bushes myself. If you haven't got a big press, you can do it on a warm day with a freezer and a vice. Don't try to use a hammer.

 

Agreed. I just did this job, and I found a nice little 12-ton press at Harbor Freight for $80 with a coupon. See my post on "front end rattle". I have a feeling this will be a good investment.

 

I have a nuber of clunks and rattles, front and rear, and instability as well. None of my bushings really look torn but all are dry rotted. I hate doing bushings. I don't want to do it again down the road. Are there any aftermarket or even high performance solutions? I'm new to Jaguars and can't find that aftermarket gold mine. Is there really just nothing out there or am I not looking in the right places?

 

I have never understood why this Jag wears bushes so easily,mind you I have

never had the problem myself otherwise I would have sawn the old one in half

to see what was at fault.

Polybushes may be the answer that you are searching for and I believe that

Cambo has fitted some to his XJR with satisfactory results.

If you replace both sides at the same time I do not see why you cannot do it

stepwise.

I am guessing that the suspension will be a bit stiffer but the ride is so soft

would you notice the difference?

 

Wow my ears were burning

Yes I fitted some Polybushes to my X350, the bushes from the 02 onwards S-Type are a direct fit. But I did not change them all to Poly.

The S-Type kit #153 from polybush.co.uk includes the following

Front, Top Wishbone, Front & Rear Bushes, 1 partset of 4 (i put these in)
Rear, Lower Wishbone, Inner Front Bush, 1 partset of 2 (i put these in)
Rear, Lower Wishbone, Inner Rear Bush, 1 partset of 2
Rear, Lower Wishbone, Outer, 1 partset of 2
Rear, Upper Wishbone, Front, 1 partset of 2 (i put these in)
Rear, Upper Wishbone , Rear, 1 partset of 2
Rear, Shock Absorber Bush, 1 partset of 2

I have the rest of the kit sitting in my garage, as the rest of the original bushes are spherical joints, I was talked out of putting them in by the chassis specialist that did the work on my car. We only replaced the plain rubber bushes with Poly.

Why?

Well from a performance point of view;

Plain bushes = OK
Poly bushes = Better
Spherical Joints = Best

From a longevity point of view, the Poly bushes are the way to go, you will probably never have to replace them again.

But for a track-driven vehicle, just replacing the plain bushes with Poly and leaving the spherical joints like we did is better.

I was really surprised when he explained it to me, I always thought Poly was the ultimate solution. And for longevity it still is, but i'm looking for performance.

If we specifically look at the lower shock bushes, you can get Poly for the rears, but the fronts are not listed.

As far as I can tell from the parts catalogue the lower shock bushes (factory fitted spherical joint) are not the same front & rear. They have different part numbers.

Spherical joints are fantastic until they wear out, when you get a metallic knocking sound from them. Sounds familar?

FYI a number of the other bushes are originally made by ZF Lemförder, and you can buy them from ZF, here they are referenced to the Jag part numbers.

C2C26267, C2C26851, C2C36029, C2C4471, = 29783 01, Control Arm Bush, Front Axle, Lower, Left and right, Front, inner (the big one)
C2C4437 = 29784 01, Control Arm Bush, Front Axle, Lower, Left and right, Centre, inner
C2C4438 = 29785 01, Control Arm Bush, Front Axle, Lower, Left and right, Centre, Outer
C2C12119, C2C18350 & C2C36866 = 35353 01, "Damper Bush" Control Arm Bush, Front Axle, Lower, Left and right, Centre

There is only one bush from the front suspension that cannot be sourced in the aftermarket



But from what I can tell, it lasts a long time anyhow...

If anyone is interested in the leftovers from my Polybush kit drop me a PM

Cheers!

 

does it seem noisier?

 

I haven't noticed any squeaking or creaking from the bushes if thats what your asking. The ride in my XJR is quite firm, being lowered, sport shocks, on 20" wheels, and now with the Polybushes, well you hear bumps on the road a lot more than a standard car on 18's...

 

Cambo351

any clue where to get the poly bushes in the US?

thanks

Ryejag

 

Maybe its not the suspention. Crush tubes in front may be loose. TSB
JTB00002