Member
My 2000 2.3 has been experiencing quite a rattling in the rear. The noise comes out when driving over potholes and cracks, and sounds very similar to a stack of metal plates crashing on top of each other. My best guess is the gas tank straps; they're rusty, and I'm sure missing a few foam pads.
Previously, as a short-term fix, I loosened the gas tank straps and tried to shove some new foam pads in. This helped reduce the rattle, but was not a complete fix to the problem. I also replaced the shocks and struts, and was pleased to find no evidence of RSM damage that could have created the rattle.
More recently, I began the process of dropping the subframe to get better access to the gas tank straps. But while there, also taking care of various bushings, including subframe bushings. The exhaust connections proved to be quite a challenge, but the exhaust came apart with the help of an exhaust specialist.
Thankfully, the subframe bolts were not a challenge to remove. The parking cables, however, were hellish.
e_brake_broken_off_in_body.jpg
The parking brake cables are meant to be loose enough to "pull out." Unfortunately, that means a lot of moisture can get in over the course of 20 years. Here, after some twisting, the tip of the cable broke off inside the chassis. Fortunately there's only a plastic sheath and the small-diameter cable to cut. I cut it with a small rotary tool, and that was the last thing in the way of dropping the subframe.
The subframe didn't exactly slide off the subframe pins, but some Kroil, WD40, and regular gear oil helped with that. When the subframe caught the pins, I oiled it up, raised the frame a bit, and let it slide back down. A few blows of the hammer on each side, downward, directed at the axle carrier casing around the bushings, and it dropped without much fuss.
bmw_z3_subrame_removed.jpg
Note the Harbor Freight motorcycle/atv lift. I wouldn't trust my life to HF tools, but this was really handy to stabilize the subframe. It provided a much larger, flat surface to rest everything on. The lift made this a one-person job.
At this point, the parking brake cables were still fused inside the trailing arms. They did come out later. Will share that next.
Member
Could it be the bumper weights?Originally Posted by Schreier
https://www.bimmerforums.com/forum/s...back-somewhere
BMW MOA 696, BMW CCA 1405
Member
Could it be the trunk lid struts?
Member
Very well could be. The tank straps are awfully rusty, and I've found some missing foam pieces on the floor. But I'll check the bumper weights. The wheel arch liners are off anyway, and I'd love to shed those bumper weights while I've got the chance.
Thin Air
You may have already checked, but if the sway bar mounts to the body break loose (just a couple of spot welds) the sway bar will bounce around.
2002 M Roadster, Steel Gray Metailic, Gray Nappa Leather, Black Soft Top, Steel Gray Metailic Hard Top, TC Kline Double Adj Shocks with H&R Springs, Stromung Exhaust, SSR Type C Wheels. Looking for a new home.
2022 Z4 M40i, Misano Blue Metallic, Prem Pkg, Driver Assistance Pkg
2023 X5 M50, Phytonic Blue, Black Extended Merion Leather, Driving Asst Pro Pkg, Park Asst Pkg, Exec Pkg, Climate Comfort Pkg.
Member
They are attached to the body and apparently serve a damping function:
https://www.bimmerforums.com/forum/s...2#post28788732
https://www.bimmerforums.com/forum/s...1#post21148471
I would keep mine and just tighten them:
http://www.bimmerforums.com/forum/sh...6#post28785216
Last edited by Vintage42; 12-23-2017 at 07:08 PM.
BMW MOA 696, BMW CCA 1405
Member
Hmm. Well thank you for learning me a thing about those weights. All I've heard about them is people removing them. Sounds like they are more critical than I previously thought.
Member
Other uncommon rattle causes:
1) There is a roll over stop valve on the top of the fuel tank that consists of a metal ball held in a plastic molding. Sometimes the molding breaks and the ball is a bit freer to move and causes a rattle. Diagnosed by hitting the bottom of the tank will cause it to rattle.
2) Worn CV's on the half shafts. Diagnosed by being able to move the half shaft in and out (axial travel) 10 to 15 mm when the car is sitting on the ground. Position it pushed into the diff to reduce the rattle.
3) Rubber spring perch pads have worn through or are impregnated with small stones.
1999 2.8L Z3 Roadster,
2000 3.0L Z3 Roadster,
There is only one thing more pleasurable than working on a Z3, that's driving it top down on a fine day.
Member
If the handbrake cables have any slack in them, they'll rattle; it's a tinkling kind of rattle though, not particularly loud or heavy sounding.
Member
Too valuable to get rid of.
https://www.bimmerforums.com/forum/s...8#post28759648
BMW MOA 696, BMW CCA 1405
Member
I haven't had the opportunity yet to remove the bumper and inspect the weights, but here's how I dealt with the stuck parking brake / handbrake cable. It was stuck from both ends, actually -- both inside the body, and inside the trailing arms. It would not budge from either end. After much persuasion and twisting the cable to break the rusting, the body-end of the cable eventually gave, leaving the nipple stuck in the car.
e_brake_broken_off_in_body.jpg
This gave enough space to get in with a Dremel rotary tool with a cutting disc and slice through the white plastic sheath and the cable, finally allowing me to drop the rear axle. But the nipples were still fused inside the guide tubes inside the body.
bmw_z3_parking_brake_threading_m6_1_00.jpg
Fortunately, the inside of the cable is a perfect fit for a M6 x 1.00 tap. I was able to thread the inside of one nipple completely. The other nipple was not as stuck as the first, and after threading maybe 1/3 of the inside of the nipple, the nipple began to move back inside the body. I had to send the cut end of parking cable back through the body from inside the cabin, grab the cable with vice grip pliers from below the car, and basically hammer the nipple back into place. No amount of hammering would push it all the way out of the tube, but that turned out not to matter.
bmw_z3_parking_brake_removal_m6.jpg
My kit also had an M6 x 0.75 pitch tap, but 1.00 pitch bolts seem to be more commonly available, and it seemed the 0.75 pitch would be just a little bit too finicky because of how fine the threads would have to be. Besides being available at pretty much every hardware store, the M6 bolt has the advantage of a 10mm hex head. After screwing the bolt into the now-threaded nipple with a 10mm socket, I gently tapped at the head to force the nipple into the body just enough to break the rust. Then, I gripped the head with pliers to work it back out. I applied Kroil, and repeated until I could totally pull out the nipples.
bmw_z3_extracted_parking_brake_ends_m6_screws.jpg
Ta-da! Two parking brake nipples, with the M6 bolts still attached. The very tips of the nipples were not rusted, but you can see toward the base where they were rusted and corroded. But there was still the trailing arm to worry about.
bmw_z3_extracting_parking_brake_from_trailing_arm.jpg
The rear of the trailing arm offers very little room to grab onto and twist out a seized handbrake cable. After totally removing the (now-severed) inner cable, the right size of punch can be threaded through the drive flange hub to knock the cable end back out of the trailing arm. It won't mushroom inside the trailing arm, the end of the parking brake is too beefy for that. It didn't take a lot of effort, just application of a small force to the right spot.
Last edited by Schreier; 12-31-2017 at 10:31 PM.
Member
bmw_z3_rusty_parking_brake.jpg
And that's the trailing-arm end of the handbrake cable. You can see that the rust wasn't even that deep into the cable - and the rust almost exclusively from the outboard side (centerline of car) and not the inboard side (the direction of the parking brake pads and wheel).
I just thought I'd spend some time explaining all this, because I haven't read any Z3 threads where there was this much of a problem removing parking brake cables. I couldn't even find any E30 threads with this kind of issue. For what it's worth, this was not a warm-climate car before I came to own it, and spent most of its time in Virginia and Illinois far as I can tell.
Member
As I'm going to be dropping my subframe as soon as it's above at least 20 degrees, I have a question.
Would all of the parking brake trouble have been a non-issue if the cable was disconnected at the brake lever (inside the cabin)?
I don't like surprises and am trying to be prepared for any gotchas.
Also - That ATV lift seems like a damn good solution for this work. Not sure what other use I may get out of it if I buy one, but I'll try to locate a loaner somewhere.
Also(2) - Is the car only on jack stands? That pic makes it look like it's pretty high in the air.
Member
It could potentially be an issue. Even if you disconnect the cable inside the cabin at the lever, the cable's nipple can still be fused with rust at the tubes in the chassis.
The threaded end of the parking brake cable is wider than the opening in the nipple. So if the nipple breaks off in the chassis, you won't be able to pull the threaded end past the nipple.
If this does happen, however, you can pull the cable out as far as possible, which will expose some of the white plastic inner sheath. Cut through the inner sheath and the cable to sever the connection and drop the subframe. This can be done with a small rotary tool, and is much more convenient than hacking through the entire width of the parking brake cable.
Odds are, however, this won't be a problem for you. I've yet to hear of any other Z3s, or even E30s, that had cable corrosion to this extent.
It's possibly the angle of the photos, but I can get a measure of it for you. There was ample room to get the subframe out.
I did have to take all of the spare tire mounting stuff out from under the car, but only to accommodate the way the ATV lift worked. Here's a big hint for that: don't saw through the emergency tire drop cable like I did. That cable screws right into the emergency wheel support. If you take a close look at where the cable connects with the emergency wheel support, it takes something like a 4mm or 5mm wrench to unscrew it.
Member
Thanks for the reply! So far, I've had no seized/rusted/terribly corroded connectors anywhere under my '98 2.8, so hopefully everything goes smoothly when it's time to drop it.
Member
The jack stands are at 13" from concrete to jacking pad.
They are the standard Harbor Freight jack stands, two notches up from zero.
Member
So, I was bored on Saturday and decided to go ahead and get started on completely dropping the subframe despite the 10 degree temps. Made pretty good progress, but one thing that I'm a bit confused about is what to do with the brakes. Are the lines to be completely disconnected? If so, where is the proper disconnect point, will I lose brake fluid, and will the brakes simply need to be bled of air when everything is back together?
Part of the confusion is that some people mention just removing the calipers, but I don't see how this alleviates the need to disconnect brake lines when the entire subframe is completely dropped.
Any insight?
Member
You need to disconnect the brake lines.
1) Block the brake peddle about a quarter to a half way down. This will block the ports in the master cylinder and stop it from draining through the open brake pipes. A piece of wood between the seat motor and the brake peddle allows you to use the forward/back action of the seat to apply the pressure.
2) Using a flare nut spanner (don't use a normal open-ender as you'll most likely round the flare nut) disconnect the brake lines at the flexible hose to solid line connection at the body/trailing arm point.
3) Cover the open ends of the pipe work so that crud does not get in. The thread is 10 mm by 1 mm pitch if you are going to use threaded blanks.
4) Bleed the brakes once the work is done and the brake lines are back together.
1999 2.8L Z3 Roadster,
2000 3.0L Z3 Roadster,
There is only one thing more pleasurable than working on a Z3, that's driving it top down on a fine day.
Member
I believe disconnecting brake lines is required on non-m. In my case, I didn't have to disconnect my brake lines (m-roadster).
Tony
Tony
"You can't sign away negligence."
Member
I think I understand now and I do have a Motive bleeder, so at least it will be put to use. I will say that I'm fairly certain once I get the RSFBs, RTABs, diff bushing, and (depending on condition) giubo and CSB all replaced, this is going to be one satisfying completion of a project. Hope the rest of the project continues to go at least semi-smoothly.
Thanks again to everyone on this site for the guidance to those of us new to these cars!
Ralph
Just be sure not to allow the brake fluid to drip drip drip out until empty--if you allow air into the ABS pump, you will have to get it towed to the dealer to have the system bled electronically.
Member
I'm way behind with updates. With the trailing arms off the car, it was time to freshen them up and give them some new rubber. I couldn't locate any tool to remove the rear trailing arm bushings (RTABs), but there were plenty of guides out there on how to accomplish this by assembling simple tools from threaded rods, pipes, washers, and hex nuts.
So that's exactly what I did. Here's the parts list for my RTAB tool:
1 x Allthread (threaded rod) 7/16" - 14x3' (7/16" dia, 14 thread, 3' length)
1 x Galvanized Nipple 3/4" x 3-1/2" Southland 567-050HN
1 x Galvanized Nipple 1/2" x 3-1/2" Southland 564-036HN
4 x Fender washer SS 1/2"
4 x GRD5 washer 7/16"
3 x Hex nut 7/16"
"Galvanized Nipple" is actually what they call short bits of pipe with threads on both ends. Some of this stuff I got from my local Lowe's, but they didn't have pipe nipples in a large enough diameter for the whole tool. For that, I had to go a block over to the Home Depot. I don't know if it's a national thing, but it seems that Home Depot has a larger selection of plumbing bits and general fasteners. Try them first.
You won't need 3 feet of threaded rod. You only need about 1.5'.
The parts were assembled like so around each bushing:
IMG_20171229_164401374_HDR.jpg
If the threaded rod is bending in the process, check to see if everything is aligned, as it should not be bending a whole lot. The old bushings in my car looked pretty good for 18-year old rubber pieces, but they were quite hard indeed.
To press in new bushings, do the reverse, as you would imagine. I did freeze the new bushings for 24 hours before the job, with the idea that they would contract and widen the tolerances a bit before pressing them in. Don't know how much that actually helped, but the new bushings went in pretty easily with the tool.
Also ground off a lot of rust using a wire brush mounted on an angle grinder, and a Dremmel with various wire brushes. Painted with Rustoleum flat black, then treated it with 3M 03584 Professional Grade Rubberized Undercoating. I was very happy with the undercoating in particular -- didn't expect anything with that durability to come out of a rattle can like that. But it's essentially asphalt spray, so go figure.
IMG_20180124_210814375.jpg
One last point of interest: if you're anything like me, you'll probably snap the white plastic bits holding the rear brake pipe to the trailing arm. It's old plastic, and as you would expect, very brittle. Fortunately, those parts actually just screw on to a threaded post that's welded to the trailing arm. I couldn't determine this from a visual inspection, and for whatever reason, thought it was more involved than that. The old part number is 34301161567, but those were discontinued, so you'll need to use 34326855500 instead.
More to come.
Member
The subframe is back in the car! Time to bring this thread up to speed. A few words on the gas tank straps, specifically.
Old gas tank straps:
old_gas_tank_straps.jpg
New gas tank straps:
new_gas_tank_straps.jpg
As you can see, the old gas tank straps were in pretty rough shape. Much of the original cushioning material was degraded and falling off. Also, the gas tank straps themselves were heavily rusted.
A few notes about gas tank straps:
- It doesn't seem that BMW offers any stock of the 16111185025 (longest) strap. It's backordered at all the usual online retailers. Your best bet is to source gas tank straps from eBay or a salvage yard, and clean them up yourself. I got a complete set on eBay, but ended up only refurbing and using that longest strap. All the others I used fresh BMW parts.
- The same 3M 03584 Rubberized Undercoating used on the trailing arms works well for the gas tank straps. That's what I used on these, after thoroughly cleaning them off with a wire brush on an angle grinder.
- Instead of the factory 16111183476 cushions, I sourced a generic 33' long x 1/4" thick x 1" wide roll of self-adhesive neoprene. It seems much easier to work with a roll of neoprene than a sheet that you have to cut exactly.
- The fuel tank straps use two plastic clips in total to hold wires in place. These parts aren't included in the Real OEM diagram, but BMW officially calls them "Wire/Cable holder" or "Tubing support". They are part 12521741316, and are meant to be single use. They don't come pre-installed on the OEM parts, either, so make sure to order two of these if you're doing this job yourself.
Member
Now for more information on refurbishing and re-installing the subframe, based on my experiences:
Differential Stuff
differential_bushing_removed.jpg
- One of those "while it's out" jobs I did was removing and installing a new differential bushing (33171090950). I removed the old bushing by drilling out the rubber portion with a series of drill bits of increasing size. Then, I cut a strip out of the metal casing with a Harbor Freight electric body saw (#65766). It's very easy to overshoot the casing and cut into the differential cover, so take your time.
- I froze the new differential bushing for 24 hours before attempting to install it, in hopes of shrinking it just slightly and providing easier installation. Before installing the bushing, I cleaned up the housing for the bushing with a few rounds of fine-grit sandpaper and eventually some polishing compound and a Dremel rotary tool with a cotton polishing wheel. I then applied Loctite C5-A copper anti-seize to the very cold bushing, before attempting the instal.
- I used the same DIY RTAB tool described earlier works great for pressing in the subframe bushing, with a simple modification: I added two "floor flanges" that increased the diameter. You can find these in the plumbing section of your local hardware store. Two 3/4" steel flanges were enough to fit over the backside of the cover and press the differential bushing into place.
- The bushing was just slightly askew when installing, causing some problems. The precise application of a hammer was useful to put it in its rightful place.
- RealOEM had listed 33111210405 as the paper gasket for the differential. This was the wrong gasket for my differential, however. Blue RTV will work just fine for this application. It worked well for my job. I re-attached the differential cover after applying the RTV, and then got the bolts finger-tight. Then I waited two hours for the RTV to cure, then torqued them down.
Subframe re-assembly
cleaned_up_subframe.jpg
- Before I cleaned up and undercoated the axle carrier, I had the Garagistic E30 Subframe Reinforcement Kit welded onto the axle carrier. I've only seen the differential mounting holes rip apart once in this forum, and this is only a 2.5L engine without forced induction, but again it was a relatively cheap, easy thing to do "while it's out."
- Knowing that the subframe reinforcements add about 3mm of thickness to the differential mounting points, I decided to go with slightly longer differential mounting bolts. The stock bolts, BMW part 07119911694, are class 10.9, M12 bolts with 1.5 pitch and 25mm length. I found that Fastenal had the same bolt with a length of 30mm, SKU 11113402, so I went with those instead. I'm not sure if it makes much of a difference, but it wasn't much of a sacrifice, either.
- Trailing arms did not go back in very smoothly. I read that they need to be inserted at a specific angle, but I couldn't for the life of me find that angle. So I slightly tapped open the mounting points on the axle carrier with a hammer. It was just enough to get the trailing arms in with a little effort.
- The wrong subframe bushings are installed in my axle carrier in the above photo. If a subframe bushing is advertised for both Z3 and E30, it is undoubtedly the wrong subframe bushing. The Z3 subframe bushing must accommodate the hex on the subframe bolt to the body. Therefore, it needs a recessed area on the top, in order to mate flush with the washer/stopper on the bottom of the car body. The absence of this recessed area is a dead giveaway that it is the wrong bushing.
Subframe installation
ie_subframe_bushings.jpg
- The above photo is the correct (Ireland Engineering) subframe bushing fully flush with the stopper on the car body. Installing this subframe with bushing was much harder than I anticipated. If both halves are the bushings are installed in the axle carrier before it is offered to the car, it is highly likely that the bottom part of the bushing will bind on the subframe bolt, and be pushed out of the axle carrier. And dropping the subframe at all would cause the top half of the subframe bushing to bind on the subframe bolt. This was a frustrating situation.
- The solution I found was this: at first, only install the top half of the subframe bushing into the axle carrier. Push the subframe up to the car with a floor jack, or preferably, a motorcycle/ATV lift (I used Harbor Freight's #61632 lift). Use another floor jack to press the axle carrier and bushing all the way to the top (using an impact socket for additional clearance if necessary). Then, when the axle carrier is in the correct position, use a rubber mallet and impact socket to hammer the bottom half of the subframe bushing in place. Alignment becomes much less of an issue this way.
- Aligning the axle was the only other major issue I came across. I just couldn't get the drive axle aligned to the differential. It turned out to be much easier to just remove the axle at the transmission, as it's only three bolts, and there's longer bolts more clearance to work with from the transmission side of things. Plus, by removing just another three bolts, I was able to replace the drive shaft flex disk / Guibo (26111227410). This actually ended up curing much of the "clunk" in gear-shifting that I was experiencing, as well.
Other reassembly stuff
- Dawn dish soap (clear, unscented) was very helpful in putting new sway bar links on the sway bar. But only just to get the links onto the nipples. Some friction was actually needed to twist the links down to the correct position, and at a point, the dish soap was just causing the link to retreat back off the sway bar.
- I found that same Harbor Freight motorcycle lift to be extremely helpful in re-installing the muffler and exhaust system. It was easy to place the muffler on the lift, raise it to the appropriate height, and re-attach it to the exhaust manifold and the exhaust hangers.
So did it work?
It certainly improved the car! The rear is much more compliant, and wanders less on cornering. The overall ride is stiffer, but handles bumps and potholes even better. It's certainly an improvement, and everything done needed to be done anyway. And it did actually stop a lot of the rattle, but I can tell none of these fixed the primary source of the rattling. The rear weights are the next things I'll be looking at.
Member
An update
The car handles better than it ever has under my care, with new shocks in the front, and new shocks and bushings in the rear. But the rattle is persisting, and seems louder than ever.
I took off the rear bumper and inspected the bumper weights. The rubber was in good condition, still quite springy, and very minimal observable rust on and around the weights. I took the weights off to see if it would stop the rattle, but it didn't.
Thinking the tools in the trunk may be the source, I removed those as well. That didn't solve it, either.
Even with the frustration, I know I'm making progress on a list of possible sources, methodically inspecting them and crossing them off one by one. But I'm kind of at the end of my list now, and don't really know what to inspect next.
The car at least has been made quiet enough that I am now starting to hear that the rattle may be from the front, instead. The front shocks and shock mounts are new. To reiterate, the rattle doesn't happen on turning, braking, or accelerating. It only happens on bumps at low speed, and only occurs with vertical movement of the suspension, and specifically when the tire hits the pavement right after dropping into a pothole, or with some other similar sharp change in the height of the ground.
Thanks so far guys, I appreciate your advice!
Last edited by Schreier; 04-25-2018 at 04:19 PM.
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