Calling all E36 experts ... unusual rear clunk i can't figure out

[Lawrence1]

1998 E36 M3/4/5 no fold down seats so it's harder to listen in the trunk area.

so here's the story ... i have this clunking coming from the rear of the car when i go over potholes or cracks in the road.

This started happening sometime after i replaced the RTABs, or at least thats what i think as i never noticed it before but that might be because the suspension was crap when i bought the car a few months ago.

This is what i replaced so far:

1. RTABs(completely shot, the rubber center was separated from the metal on the old ones)
2. rear schoks(new BMW OE shocks, old ones were blown)
3. meyle hd rear shock mounts+reinforcement plates from(UUC kit)
4. flex disc(probably not related)
5. alignment
6. all front bushings, lots of other maintenance, etc (not related)

i checked the shock towers and they're not cracked, i checked the diff mounting points and they looked fine ... i'm ready to take it in to a shop and pay them to diagnose it as i'm out of ideas.

what say you bf.c?

[svginferno]

did you check if the sway bars are properly connected to the rear trailing arm?
also, check the brake dust shield, they should not make a sound if you hit them.

how's the guibo? gluck!

[Lawrence1]

guibo is good(replaced it already).

sway bar brackets ... never thought of those, i'll take a look and see.

any other suggestions?

[zerreissen]

Could be the rear control arm bushings/balljoints.

[Moron95M3]

my battery was loose and caused a clunking over bumps...but i would guess that's a rare, lucky problem. maybe it's ur spare tire or jack if it's loose too? hoping for an easy fix here, lol.

good luck!

[BeerHat]

Could be the rear control arm bushings/balljoints.

Jack up (and support well) the rear of the car with the tire about 3" off the ground, and have a friend stick a length of scrap 2x4 under the wheel using as a lever. Have the friend pull up and down sharply while you feel around the suspension for the clunk.

This worked for me.. my clunk was indeed the rear lower balljoints. Car is tight as a drum now.

p.s. when it comes time to do the rear balljoints, cheap 1 3/4" hole-saws are your friends!

Dan

[Lawrence1]

you got a pic of which ball joints you're refering to? would replacing the lower control arms all together take care of the balljoints or are those attached to something else?

thanks.

[BeerHat]

you got a pic of which ball joints you're refering to? would replacing the lower control arms all together take care of the balljoints or are those attached to something else?

thanks.

Them'z them. :O)

Dan

[Balthazarr]

Them'z them. :O)

Dan

OP, you'll notice the lower is different than the upper in the diagram.
The pic shows identical parts.
It's ok to use the same part in the 95's as used in the 96+.
In fact, it's considered an upgrade.

[Lawrence1]

got it ... thanks.

whats the procedure for replacing these seeing they;re in the trailing arm ... any special tools needed?

and also putting pressure on them with a large screwdriver or lever should exhibit some movement/play, correct?

[Yarberrymt]

check your front diff bolt, i just broke mine off inside the diff.

[Lawrence1]

update: i had the car on a lift today and looked at everything back there.

the ball joints had some play in them and the lower ones were torn, the lower diff bushing is worn but probably unlikely to be the cause of the clunk, subframe mounts look good, RTABs i didnt check to see if they;re centered but applying pressure to them gave no movement so i would assume they're ok(i'll take another look tomorrow). shocks look fine, RSMs look fine, shock towers are good ...

i'm going to tackle the balljoints next and will probably replace the lower control arms as well because they're cheap.

what's shocking is that i got quoted at 7.5 hrs + parts + allignment to do the rear balljoints(that comes to $900(labor) + parts) which seems like robbery to me.

[rebs]

Those ball joints are a cunt... you can get a pair for 45 bucks on ebay (4 needed), and i HIGHLY suggest just taking the whole arm to a machine shop to have the old ones pressed out and the new sets pressed in. Removing the arm isnt that bad.

[Balthazarr]

Those ball joints are a cunt... you can get a pair for 45 bucks on ebay (4 needed), and i HIGHLY suggest just taking the whole arm to a machine shop to have the old ones pressed out and the new sets pressed in. Removing the arm isnt that bad.

The fiddly part of removal is the E-brake cable, right?

[elsdragon314]

Check your exhaust mounts, sometimes if one of those has given the exhaust will hit things over bumps, or particularly through turns. Wouldn't hurt to also check the diff bolt, although normally that is related more to clunking from acceleration instead of bumps.

[BeerHat]

Those ball joints are a cunt... you can get a pair for 45 bucks on ebay (4 needed), and i HIGHLY suggest just taking the whole arm to a machine shop to have the old ones pressed out and the new sets pressed in. Removing the arm isnt that bad.

They're not too bad actually, if you're inclined. Usually the bottom ones go first, my bottoms were way toasted and I didn't need uppers.

Like I said, CHEAP holesaws are your friend. 1 3/4" for the pusher to be exact. Fits around the boot, but catches the steel. I think I used a 2" holesaw for the receiver, just get one big enough to catch the lip of the arm, and will also take most of the joint as it's pulled through. Make sure you test fit, as not all manufactures of holesaws are 100% accurate.

1. Hit the front and back of the old balljoints with a little PB blaster, let soak for a bit while you move through the steps below.

2. Mark the alignment eccentric's positions with a sharpie so you keep things inline after surgery.

....2.5 When you undo the eccentric bolts, take caution not to destroy the eccentric nub on the trailing arm.

3. Then get yourself a length (8" or so) of threaded rod that will fit through the balljoint and both hole-saw's base holes. Get two nuts and washers for that threaded rod too. Washers need to be big enough to cover the entire top of your holesaws to distribute the force more evenly around the outer edges. I chose to cut the teeth off of my holesaws with a steel saw, you may not need to, but I'm just anal that way.

4. There is a taper that narrows toward the front of the car, which means the joint must exit and enter toward the rear. Put your 2" holesaw toward the rear of the car, put the 1 3/4" on the other. Stick your threaded rod through the whole assembly ensuring things are centered and snugged. Then tighten the assembly. It will take a little force, but will draw the joint out into the 2" holesaw.

5. Clean up the hole with a rag.

Installation is the opposite of removal, except you just switch around the holesaws, so the 2" is toward the front of the car. No lube is necessary. Just make sure things are going in straight as you tighten initially. The taper in the arm, and the chamfering on the edges of the balljoint kinda help guide it in.

Biggest pill for me was keeping the trailing arms out of the way. They're a bugger.

Dan

[rebs]

The fiddly part of removal is the E-brake cable, right?

thats pretty easy, the whole dis assembly is simple, its getting the old ball joints out thats a pain. I bent large Cclamps, broke numerous bolts/washers with the home made tools posted on this forum. Save yourself the time and headache, and have them done. Its cheaper than making various tools as well.

They're not too bad actually, if you're inclined. Usually the bottom ones go first, my bottoms were way toasted and I didn't need uppers.

Like I said, CHEAP holesaws are your friend. 1 3/4" for the pusher to be exact. Fits around the boot, but catches the steel. I think I used a 2" holesaw for the receiver, just get one big enough to catch the lip of the arm, and will also take most of the joint as it's pulled through. Make sure you test fit, as not all manufactures of holesaws are 100% accurate.

1. Hit the front and back of the old balljoints with a little PB blaster, let soak for a bit while you move through the steps below.

2. Mark the alignment eccentric's positions with a sharpie so you keep things inline after surgery.

....2.5 When you undo the eccentric bolts, take caution not to destroy the eccentric nub on the trailing arm.

3. Then get yourself a length (8" or so) of threaded rod that will fit through the balljoint and both hole-saw's base holes. Get two nuts and washers for that threaded rod too. Washers need to be big enough to cover the entire top of your holesaws to distribute the force more evenly around the outer edges. I chose to cut the teeth off of my holesaws with a steel saw, you may not need to, but I'm just anal that way.

4. There is a taper that narrows toward the front of the car, which means the joint must exit and enter toward the rear. Put your 2" holesaw toward the rear of the car, put the 1 3/4" on the other. Stick your threaded rod through the whole assembly ensuring things are centered and snugged. Then tighten the assembly. It will take a little force, but will draw the joint out into the 2" holesaw.

5. Clean up the hole with a rag.

Installation is the opposite of removal, except you just switch around the holesaws, so the 2" is toward the front of the car. No lube is necessary. Just make sure things are going in straight as you tighten initially. The taper in the arm, and the chamfering on the edges of the balljoint kinda help guide it in.

Biggest pill for me was keeping the trailing arms out of the way. They're a bugger.

Dan

I replaced every bushing/joint in the car. the removal and installation of arms/lines/etc is simple, its the pressing that boned me.

[Lawrence1]

Check your exhaust mounts, sometimes if one of those has given the exhaust will hit things over bumps, or particularly through turns. Wouldn't hurt to also check the diff bolt, although normally that is related more to clunking from acceleration instead of bumps.

exhaust mounts are all new.

didn't get a chance to get another look back there as i've been busy this past couple of days.

i removed a trailing arm before and it wasn't too bad. once the arm is out can you just press in the new bushings over the old ones(like the front LCABs)?

honestly, i was going to have these done at a shop but seeing how i was quoted an ass raping $900 in labor alone, i am seriously considering doing them on my own.

[Ron97M3]

Jack up (and support well) the rear of the car with the tire about 3" off the ground, and have a friend stick a length of scrap 2x4 under the wheel using as a lever. Have the friend pull up and down sharply while you feel around the suspension for the clunk. This worked for me.. my clunk was indeed the rear lower balljoints. Car is tight as a drum now.
p.s. when it comes time to do the rear balljoints, cheap 1 3/4" hole-saws are your friends! Dan

Nice practical technique! I love it.