1985 535i giant clunking

[wesleyc]

so the other day i was driving my car and it would squeak from behind me to the driver side when i let off the gas, in 2 days of driving that squeak has turned into a giant clunk till i was barely driving 20 it was scaring me so much. all tires where up to torque, my first guess, nothing really seams loose and the noise only happens when driving

[02Pilot]

Something's shifting when the engine load is removed. Look at the guibo, driveshaft, halfshafts (both ends), rear subframe mounts, and other rear suspension. Lots of possibilities here. A careful visual inspection is your first step. Do not drive if the noise is that severe - several of the items mentioned above could lead to a very unsafe condition.

[bmwdirtracer]

+1!!! DO NOT DRIVE THE CAR! Have it flatbedded to a good Euro specialist shop.

Please understand this is quite likely a disaster waiting to happen!

When something is making a noise like you're describing, something very heavy is very loose, and IT WILL COME APART VIOLENTLY.

Imagine a wheel falling off. Better yet, imagine the whole rear suspension and drive falling off your car. Or maybe it'll just be the driveshaft coming loose, which will only destroy the gearbox and shifter, probably won't flip the car on the roof, but it's possible. The tow bill's maybe a hundred bucks, your choice.

[wesleyc]

ok well i suppose its not giant like your thinking, maybe giant was a bad word, but im assuming its the subframe bushings since its in the rear, anyone know of a way i can check this, i wont be driving the car other than maybe 20 km to get to the shop i can work on it at.

[02Pilot]

Don't assume anything. Any loud noise of the sort you describe can easily escalate into any number of dangerous situations quite unexpectedly. A 20km tow can't cost that much.

It could be subframe bushings, or it could be the floor area where they mount; I had an E28 that I had to retire because the floorpan rusted out above the rear subframe mounts. It could also be the diff mount, a CV joint, or a number of other things. Get underneath it and do a careful visual inspection before proceeding.

[bmwdirtracer]

I have seen a fellow racer's E28 M5, with the rear subframe and one trailing arm flailing back and forth several inches. First the trailing arm's mounting eye broke it's welds, then the excessive unauthorized movement began ripping the subframe mountings out of the body. This happened within a mile of the first indication of a problem. The car was carefully loaded on a flatbed.

I would not drive the car until I checked everything - VERY carefully.

[wesleyc]

so i did a visual inspection and everything seams to have good mounting eyes and the only visual problem i see is both dog bones i think there called dont have the rubber bushing parts but the steal is intact and they move up and down about 1/8 inch either way on both sides

[bmwdirtracer]

The dogbones (rear pitman arms) are not the cause of your noise. So, when you pryed on every suspension mounting point with a 3 foot prybar, did anything move? Did the diff or subframe mountings move when you raised the car? Are the diff-to-subframe bolts tight? What do the bushings at the front of each trailing arm look like? Guibo? Center support? U-joint? Shock mounts, top and bottom?

Really, I'm not trying to make money for a tow truck driver, I'm trying to save you crashing the car, is all. You have to absolutely identify the cause of the issue before you can dismiss is.

[wesleyc]

ok so i jacked up both sides of the car and pryed on everything witha crow bar and nothing seemed to move, im really thinking its the subframe bushings, and if it is would it be safe to drive and when i either drive it to the shop or get it towed whats the best way to replace them without buying 400 dollar tools

sso yes it is the subframe bushing 100% sure now, this is the driver side under the rear seat, i guess i just hammer down the piece that drive really slow and then when i get to the shop i fix up the hole right and change both bushings

[bmwdirtracer]

Oh, Dear, God.

I'm really not sure how to tell you this, because you've been trying really hard to ignore what 2 pro techs have been telling you: but one more damned time, and that's all:

DON'T DRIVE THE CAR !!!

The rear suspension and wheeels are no longer attached to the body, except through gravity. You can't "hammer down the piece". If you want "the piece" down, just jack the car up; it'll fall out. It's not that the bushing is necessarily dead, (although it likely is): The bodyshell of the car is ripped and or rusted away.

A quick look at my racecar shows a part actually missing from your picture - and it's not a part you can buy, or that even has a part number, because it's an integral part of the welded bodyshell - a reinforcement "hump".

From what I see, the necessary repair will begin with removing the entire rear subframe assembly, with suspension, differential, trailing arms, etc.

Then you're going to need a really good automotive welding guy to either fabricate a new, reinforced panel, exactly in the right place, 3 dimensionally, and on perfect angle - or you're going to need to cut a sizeable chunk out of the bodyshell of an unrusted donor 528e, and splice and weld it and reinforce it into your bodyshell, with the services of that same good automotive welder/fabricator.

Keep in mind that the other side needs to be reinforced, too, even if it's not torn out yet. It will have been severely weakened by the movement of the torn driver's side.

[wesleyc]

heres a pic of the other side, im thinking the 535i and the 528e have diffrent bushing mounts, i dont see much missing.

oh i and i got the car flat bedded to the shop like you said, but the parts dont come in till wensday

[g00dwagen]

Wesley,

Could you request a Moderator to delete your redundant threads? Thanks.

[bmwdirtracer]

Very interesting, wesley. I see that actually there is a significant difference in this area between your bodyshell and mine.

Interesting, because my car races as an '85 535i; but the bodyshell is actually that of an '82 528e. My car has not 1 but 2 shaped reinforcement plates for this area, on both sides. It looks like yours has a single reinforcement plate of some sort, wider in overall area than either of my two factory plates. One of my shaped plates is about six inches in diameter, the second about 8x7. Both plates overlap the vertical structures within a few inches of the subframe mounting. Both of these are absolutely factory items, and my roll cage structure overlaps them, for strength to that crucial point. My guess would be that the factory actually changed bodyshell reinforcement to this point between 82 and 85. Look carefully to see whether you have one or two layers of steel, where the bushing used to mount.

A decent fabricator will be able to add some reinforcement to the area, without much trouble. I very highly recommend adding this same reinforcement to both sides, even if the other one's not ripped, yet. The metal is equally weak by now, I promise.

This old bodyshell is very light: but very thin, in truth. (The E34 is 5 times stiffer). You now need to add a bit of structure which wasn't formerly there - because you have to distribute the load. If an inexperienced guy just welds a non-overlapping piece of sheetmetal in there, it'll rip out in a month, or the first big bump. Because of the failure, you must absolutely reinforce the area beyond the present rip. And you need to do both sides. I am not overreacting - this is very nearly a mathematical equation (I just don't know the exact math)

[wesleyc]

sorry to bug you again but if at all possible could you maybe make a little sketch in microsoft paint of what you have in mind? we have the previous owner of the car to help us now aswell (owner and mechanic of multiple bmw's) and apperantly he has already changed the subframe mount's so theres one PITA gone =D

or a picture of your car would help

[bmwdirtracer]

I'm computer challenged, and can't make a picture jump from my phone to my computer - and I damned sure can't draw with a mouse, sorry. My racecar's mounting is pretty much concealed by the rollcage mounting on top of it, anyway, the picture would confuse your issue.

Here's what you do: First, remove the subframe, and everything bolted to it, so that you have an empty subframe - which weighs about 15 pounds, as I recall. Car's likely best accessible for the fabrication work if it's about two and a half feet above the ground, and level.

When you unbolt the subframe, you're going to be left holding a piece of round sheetmetal with a nut welded to it. It may be two layers of sheetmetal. Whatever you have, you're going to clamp, spotweld, or otherwise carefully attach -in EXACTLY the correct orientation. Then you're going to weld in new steel, which overlaps (and in fact JUST MIGHT entirely replace) your round piece of sheetmetal, and overlaps and extends out a couple or five inches PAST the ripped hole. Preferably, this will intersect with one or more vertical structures, too. You'll carefully shape, bend and cut this piece into a form resembling your stock bodywork, and stich-weld it around the perimeter.

But all the above is wasted words: because an experienced automotive fabricator/welder already knows what to do.

This goes beyond the realm of even a very fine mechanic - because mechanic's don't do fabrication of structural body panels. Neither do most paint and body guys.

On the other hand, someone who builds rollcages or good roadracing cars, etc., could quickly figure out and create the part you need.

Even on a little island, I know just who to see. I worked there for a few years, a shop called "Custom Metal Creations", not an automotive shop, but a damned fine metal fabricator. Assuming you don't live way back in the woods, there's going to be someone who can handle the job.