There's a few threads about removing the front and rear subframe for various reasons but nothing about actually removing and replacing the bushings themselves. Has anyone done this? Have anyone's subframe bushings actually failed and necessitated replacement? It seems like it might not be a common issue on our cars (even though all the other rubber frequently requires replacement).

According to the repairs manuals, you need some fancy Jaguar tools to remove and replace. Is it the same process as pressing out bushings in the suspension arms?

 

Since no one has responded, I'm guessing no one has ever had to replace their subframe bushings. Has anyone ever had their subframe bolts loosen up?

For the past few months I've been getting a clunk from the front that could be described as a loud popping type noise. It only occurs on very sharp turns or when making turns over grade changes, like in and out of a driveway. You can feel it in through the pedals. Sometimes it feels like someone is tapping the floorboards and sometimes it feels like something is shifting. You never hear it while going straight, except on the deepest of potholes, which I always avoid anyway.

I've gone through everything in the front suspension that was still original and have replaced it all, including engine mounts. I've even gone through and replaced what original parts were left in the rear. I've gotten a full alignment, balancing and rotation, but the popping-clunk is still there, and in fact seems to be getting worse.

Even with the entirely new suspension setup, my front end seems loose and harsh even while going straight (but no clunks while going straight), and now I'm starting to get a steering wheel shake at high speeds.

While researching online, I came across many VW forum threads where people were complaining about pretty much the EXACT same symptoms I'm experiencing. It turns out that its a well-known issue with certain VW models that the front subframe bolts become loose over time and cause pops and clunks during tight turns and turns over grade changes.

Those subframe bolts are 'torque-to-yield', meaning they stretch during the initial installation, which is why they have to be replaced every time they're removed. At least on the VWs, it seems that they eventually lose their strength due to that stretch.

I believe I'm experiencing the same issue but I find it curious that no one else has ever mentioned this here. I couldn't possibly be the first to have this issue, could I?

My plan is to replace those four bolts one at a time without actually removing the subframe. I'm guessing that if I put the front wheels up on ramps and level out the rear with jack stands, I can then use another jack to hold up each corner of the subframe as I replace each bolt one by one.

If this doesn't solve the issue, I don't know what will. Any input would be much appreciated.

 

The bushings do not seem to fail. I have not heard of
the bolts failing. Tighten them and they should be fine.
Take a look at the hubs. The ball bearings can bind up.

 

The front hubs are only about a year old and I inspected them again recently. Nice and smooth still.

The title of your post seems to suggest you have to drop the entire subframe in order to replace the bolts, is that right? Are you suggesting it might be better to just tighten the existing ones?

 

at least check that none are loose. These bushings are not a high failure item. Never heard of the bolts being an issue.
Checking the bolts will tell you if the bolts may need replacing. I know VW/Audi uses a lot of stretch bolts. Did not know the subframe bolts on the XJ were stretch. Did not replace after dropping subframe to inspect the bushings at 10 years and 100,000 miles.

 

According to the repair manual, they require something like 100nm followed by another 270 degrees (don't quote those numbers), so it definitely seems like they're stretch bolts.

After nearly 13 years and 167k miles, I wouldn't be surprised if the bolts have begun to degrade (like the rest of the suspension since we have the worst quality roads in the nation here in "beautiful" Los Angeles). The bolts that connect the front wishbones to the straight control arms are also stretch bolts, which I recently had to replace because I found they were rusty and corroded.

I've already ordered a new set of subframe bolts and they should arrive before the end of the week, so I'll crawl under on Saturday and see what's up. I'd feel much better just outright replacing them rather than tightening up the old ones. I'm always weary of retightening old bolts...I've had way too many of them strip or snap on me.

 

I replaced 3 of the subframe bolts last night. The old ones weren't loose but they were corroded and rusty. The smaller 18mm rear bolts torqued up just fine but the giant 22mm front bolts are giving me trouble. With the amount of torque specified for those, I can't get the socket to stay firm. It slips and begins to strip the bolt head. Will try again tomorrow.

 

An impact driver makes a big difference.

I suggest that you take it just to have the bolts slackened before

the head is damaged.

 

I helped our local Mazda dealer replace one rear sub frame bush on a 2002 Lincoln LS. The alloy metal inside the rubber had corroded away and that corner of the subframe was flapping against the body. Ford do not supply new bushes only a complete new sub frame for big$. The Jaguar sub frame bushes do fit and are fairly inexpensive. We pressed the old on3 out and the new one in using a 20ton press and tools we rigged to fit.

There are threads on the S-Type forum covering this stuff.

 

UPDATE.

I was able to get the last bolt out using a Gatorgrip socket. Torqued up the new one and all my clunks and noises are gone!

As an additional bonus, my brake squeal has diminished significantly. Apparently, the loose subframe was causing vibrations which agitated the harmonics in the brake system. Its not gone 100%, but I'll take anything I can get.

 

Great job! I would never have suspected the sub-frame bolts. This is another item to check.

 

I got lucky stumbling upon those VW forum threads, otherwise I never would have suspected them either! I replaced both engine mounts, checked the sway bar links, replaced the straight control arms, the wheel knuckle ball joints, the driver side banana control arm, and got an alignment...all in search of exorcising this clunk. Granted, all those items were in bad shape and thus needed to be replaced anyway, but the subframe bolts were literally my last resort.

 

Did it fix your high speed vibration?

I'm starting to experience this in my car (110k miles) and have likewise exhausted tire balancing/bushing replacement as the cause.

 

Unfortunately, no it did not. However, I realized its not really a mechanical vibration...its more that the suspension feels more attuned to the undulations in washboard road surfaces, of which my daily commute is mostly comprised. If the road is smooth, there's no vibration. It's kinda like my suspension suddenly got very sporty.

I don't know...maybe all my new suspension bits need some time to settle in or something. Maybe I got used to the old mushy wallowing suspension. For the time being, I'm just glad that there are no more rattles or noises. Maybe I'll go back and have Firestone double-check the alignment and balancing. We'll see. But for now, I'm taking a breather from repair work!

 

I had the same high speed vibration 65-75 even after redoing the front suspension and replacing the tires.I decided to replace the original hub bearings because of age and mileage-98000.The old bearings felt tight and turned smoothly but the new bearing eliminated the vibration at higher mileage so consider replacing the hubs if they are originals.

 

Thanks for the suggestion, but I replaced those about a year ago.

 

UPDATE: Well, after a single week of silence, the noise began to slowly manifest itself again, so I crawled under to recheck the bolts and while retightening one of them just a bit, it began to turn freely. So now I'm pretty sure that the captive nut within the frame has broken free of its welds. If that's the case, then this repair is now beyond my skill set. I am not happy right now.

I don't know if every nut and bolt in this car is made of swiss cheese or if I somehow have the strength of He-Man but I am scared to death of having to apply high torque to anything because everything is constantly breaking on me.

 

XJ8R, sorry to hear about the subframe nut failure, that is tough. We own the exact same car, mine is at 169,xxx and counting - ordered new back in '05. I have a clunk that I can't run down either, will check the subframe bolts on the next oil change. Good luck friend with the repair.

 

I also have an itermittant clunk. Was planning checking the subframe bolts also.
Try backing out the bolt. May tell you if it is thread related or nut is turning.
My car is driving well. The clunk only bothers me. With also new front end it is frustrating.
Tightening the top nuts on the strut reduced it. Used a six inch wrench to prevent over torquing the four bolts. I think it is my strut.

 

Thanks, guys. The noises from the front are getting worse, so I'm afraid the subframe is beginning to flop around. I don't think it's safe to drive like that. I'll try pulling the bolt out tonight. If indeed the captive nut has broken free, I don't even know where to begin.