240 Rear end clunk + wandering at high speed. 240 wagon.

Not looking for help so much as creating a place to record what I found.

For a long time the rear end of my 240 has had a clunk, however when I first noticed it I tried to find it, and failed (story of this car + me, makes me wrong every time! lol). A few weeks ago I noticed the car felt wandery like it might with 15psi in the tyres, so I checked and topped them up. No better. Drove it around all weekend at speeds up to about 140kph sustained and the wander was most obvious at higher speeds, not to the point of keeping in the lane, but nearly. No steering play felt. Today under down shift or decel to accel transition noticed clunking has gotten worse, sometimes multiple clunks per event, like a small series of them. I strongly doubt the front end has gone from beautiful alignment to toe-out by itself.

Guessing several of the bushes in the arse end are flogged and need replacing, so will endeavour to investigate after some higher priority chores are out of the way.

However any tips re the wandery nature of it or the accel/decel transition clunks (either direction) are welcome!

No, didn't search, just noting the story down, for now.

Cheers.

If it's rear suspension bushing related, and it sounds like it might be, it can't be a zillion things.

it's either (7,6,3,2,4 or 5) or a combination, or ALL OF THEM!

Just crawl under there and gawk at the bushings until you figure out if which one of these blimmin' things is buggered.

Yeah, that's the thing, when I first heard it, I did dive under and stared and wiggled and found nothing. They all looked okay, or seemed to. I'm hoping now that it's worse it'll be more obvious!

Haven't gotten back under, yet, though. Lots going on, but should have a chance in the next month or two, I hope.

I'd be willing to bet it's the trailing arm bushing (#2 in the diagram above). It isn't necessarily super easy to tell that they're cacked unless you drop the trailing arm and take a peek. The torque rods (6 and 7) are the usual suspects for rear end clunkage, but they don't typically cause the car to wander. If you haven't replaced any in a while while, odds are pretty good you have more than one borked bushing.

Pro-tip: replace everything but the trailing arm bushings with polyurethane bushings. They're slightly more expensive, but they'll last waaaaaay longer than the OEM rubber ones. I put some in about 100k miles ago, and they still look brand new. Unfortunately the trailing arm bushings need to be able to twist in order to work properly, so you're kinda stuck with the rubbery stock style, unfortunately. There are spherical bearing conversions available (I have one I've been meaning to install), but they're expensive and the lead time is about a million years.

Another clunk from the rear of the car is that rear ujoint. It takes a lot of abuse.

But the wandering is bushing related for the most part. Also how are the shocks? if they are worn they contribute to the problem as well.

In order of typical failure...
1. Upper control arm bushings.
2. Main TAB bushings.
3. Front lower trailing arm bushings.
4. Panhard bar bushings.

If they have never been done, I would recommend you just replace them all.

Don't use poly bushings, they just bind and squeak.

I'll lay down 20 greenbacks to say it's not the U-joint. Last time I made a monetary bet on a car I was a teenager and I lost Not this time.

Shocks are meh, but functional. The ones in my 740 GLE 16v are way softer and don't give any drama even doing skids all day. Contribute, yeah, but a clunk and wander both require play/gaps to be an issue.

Fjergus, I'm unwilling to bet you're right, but you probably are given your comment on hard to see - would explain my inability to spot the issue. What happens if those are urethane? Excess stress on the steel parts under bump/rebound when geometry changes?

Chances are I'll go with ozzy made superpro urethane for at least most of it - comes with a special grease and I've never had issues with urethane squeaking or binding before. There are applications where it's the wrong choice, eg front upper arms of R32 skyline where a hard precision bushing is required and urethane is too soft.

quillc, which location(s) bind and squeak for you? I have in the past had a local company custom make me urethane bushings to my spec in my chosen grade of urethane. If the trailing arms need more give as Fjergus says, then I could have that done and get them to use a soft grade. But probably not worth the hassle. Super useful for obsolete cars that you *can't* get off the shelf stuff for, though.

Chances are none have ever been done, so replacing the lot in one hit does seem like a sound approach. Best I get onto the hydraulic press project that's been shelved for months, then...

FreeEMSFred said:

quillc, which location(s) bind and squeak for you? I have in the past had a local company custom make me urethane bushings to my spec in my chosen grade of urethane. If the trailing arms need more give as Fjergus says, then I could have that done and get them to use a soft grade. But probably not worth the hassle. Super useful for obsolete cars that you *can't* get off the shelf stuff for, though.

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I've just used the iPD upper control arms that have the poly bushings coupled with the TAB poly bushings (Superpro I seem to recall). Pretty sure the TAB bushings were at fault. There were several times where I would go through a dip to enter a driveway of a business. Since the car is lowered, I would go at an angle and the rear right tire (turning right) would hang in space as the bushings were so stiff that the suspension wouldn't articulate. Got stuck once that way with the one wheeled wonder just spinning away in space.

I put a set of Ben's comfort upper arms and spherical TABs and the problem went away.

I vote trailing arm bushings. Spherical is great there but comes at a price.

JW240 said:

I vote trailing arm bushings. Spherical is great there but comes at a price.

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And road noise. I made my own bushings because I couldn't see paying what Ben wants. They are nice and solid but are more noisy ( road noise) than rubber ones. However, it did not solve my wondering problem.

Jeremy

volvo? said:

And road noise. I made my own bushings because I couldn't see paying what Ben wants. They are nice and solid but are more noisy ( road noise) than rubber ones. However, it did not solve my wondering problem.

Jeremy

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Yes. I made my own version too. With rubber in the front of the trailing arms it's quite subtle though.

Had my WOF man thoroughly check the rear end this time and he found the clunk! JW240 and Fjergus were on the money, rear trailing arm bushings completely flogged. Pretty hard to see laying on the concrete with the car on the ground, but with the car in the air and a pry bar, he went over each one and both rear trailings were foxored. I will get a full set of urethane when funds allow and get them installed when time allows, likely within the next 5 months before the next WOF. Thanks for all input! Will update with pics once I get around to doing anything about it.

FreeEMSFred said:

Had my WOF man thoroughly check the rear end this time and he found the clunk! JW240 and Fjergus were on the money, rear trailing arm bushings completely flogged. Pretty hard to see laying on the concrete with the car on the ground, but with the car in the air and a pry bar, he went over each one and both rear trailings were foxored. I will get a full set of urethane when funds allow and get them installed when time allows, likely within the next 5 months before the next WOF. Thanks for all input! Will update with pics once I get around to doing anything about it.

Click to expand...

Kaplehenke spherical bearings are far better than poly if you can afford them, I would go back to rubber if not, that part needs to twist a little to work correctly.

Rubber or spherical Fred. I ran rubber in the front of the lower arms. Lasted and absorbed enough. BIG spherical bearings for upper arms spread the load out for quiet suspension and it will last.

Spherical won't pass a WOF here without a cert, sadly. Not quite ready to cert the car for all the planned but not yet done mods, yet. Stuff comes in different grades. Will have a think/look and let you know what I go ahead with. It doesn't tend to see much articulation so having them a bit stiffer shouldn't cause me many real world problems and it should track dead on again. We'll see. Can always put rubber back in later if I'm unhappy, right?

PS, I feel like someone that isn't me silently edited my post. Do I have to start saving copies of all posts or can said somebody please leave an edit history and reason next time? :-/

I tried the superpro poly trailing arm bushings.. The inside wheel would lift off the ground in hard cornering and they wouldn't come out in one piece so I couldn't resell them to someone else.

Bump from the not dead yet:

Going to bring the car in today and decide what to order, but chances are I'll do the whole lot and at least mostly respect Fjergus' advice:

Pro-tip: replace everything but the trailing arm bushings with polyurethane bushings. <SNIP> Unfortunately the trailing arm bushings need to be able to twist in order to work properly, so you're kinda stuck with the rubbery stock style, unfortunately.

Click to expand...

Final question, do the front trailing arm bushes need to be rubber too, or just the big rear ones? I imagine urethane in the front would be okay. Thoughts? Probably order this weekend, or early next. Due for inspection in 3-4 weeks, then xmas, then needs to be legal living on the street with no chance of a WOF over summer break here.

Thanks to everyone who contributed to this thread thus far

The later rubber bushings for the front of the lower trailing arms don't move much and are firm enough. Oh.... .gov headaches for spherical pivots. Can't be too safe!

So I jacked up the front left way in the air and climbed under to see what it did to the arms, and *all* four of them twist relative to the diff/body as they must to allow the rotation required. However none of them twist more than about maybe 10 degrees or so total including both ends as they can't given full compression on one side and full droop on the other vs the track.

The difference between the upper and lower is the width of the bushings. Narrower bushings will be more easily squished by the car's movements. The rear lower one is the widest and most substantial and would take a lot of force to twist that much.

I'll get an order in for rubber rear lowers, urethane uppers, and will see how I feel about lower fronts while ordering. They are wider than the uppers, so could probably do with being rubber TBH.

Off topic warning:

Re spherical: It's not that you can't have them, it's just that it exceeds the "free mods" limits (brakes and suspension are partly "don't touch" exceptions for springs, shocks, sway bars, bushings, rotors, pads, etc. If you change to a 16v head you have to certify the car as it's a *different* design. It also exceeds the 20% more power threshold. Spherical also crosses the line. About 400usd gets a whole car full of all sorts of tastefully/legally done mods certified. For really extreme stuff like a full cage you need a motorsport log book, and a couple of events a year to drive it on the street, but with that, you can do almost anything. Even without that you could put 1000hp in a 60s Mini if you wanted, and cert it, and drive it on the street I think the laws here are pretty fair for the most part. Many parts of Europe you can't do anything at all, and same applies to Cali re emissions equipment and some other states. Ditto NSW Aussie where BOVs are illegal. We have it pretty good Also, I have 15 cars, 7 currently legal, and the cost to achieve 7 legal cars is about 1400nzd/1000usd / year, less than you'd pay to have one legal car in most of Europe

Went urethane with the front, and checked my 240 sedan, and checked local pricing, and ordered OEM rears for the wagon, and SuperPro urethane *everything* else back there for both cars. Rear bushes in the sedan looked like new, probably done by the PO I guess. Good test of the new tax laws, will be hitting NZ with 420usd on the box, which is about 660nzd and as of today, not subject to border tax! New limit is 1k nzd. But high-volume companies like Amazon and Ebay are already charging 15% for our government as of this morning (but weren't just after midnight last night! cheeky). Might be time for a set of Eiker wheels after this change