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Solutions for the repair of rear subframe bushing mount points for the E28?

10K views 14 replies 4 participants last post by  ramelloh 
#1 ·
It's a long title, but it's a big problem. Has anyone had any experience with repairing rust-out of the formed sheet metal underbody section that helps locate the subframe bushings. In my otherwise beautiful and mechanically sound '87 535is, this condition threatens the life of the vehicle.

My experienced BMW mechanic has never seen this condition before. We are ready to try and make a fix. Has anyone heard of a weld-in repair kit for the sheet metal bushing beds?

The solutions seems to be that we must cut out the old sheet metal section and weld in a new section. The bushing pins are still there and the heavier cross section they attach to is OK. The bushings are shot. They will come out and be replaced, possiblyalong with the old pins. We need to come up with just the underbody sheet metal for that area (both sides) or build something else that will cup the bushing accurately and securely in place.

Help, please!

Regards,

Rick Melloh
 
#3 ·
Thanks South26

Andy,

My mechanic has found a very confident body/restoration man. Two different layers of metal will be replaced in the process. It is stated that it will be much stronger than new.

It is the perfect time to replace the the tender cat-back exhaust with a new SS Ireland Engineering system, as it has to be pulled off anyway, in order to remove the sub-frame. The old system will probably fall apart coming off. It was just starting to make some nice sounds.

The 23 yr old fluid lines, fuel and brake, will be ideally accessible, so those are getting replaced as well. I am trying to imagine where all the money is coming from.

I am also having the mechanic check out the differential clutch assemblies while the subframe is on the bench. They were acting funny. I hope it was simply related to the bushing problem and the variable twist of the loose subframe. Crossed fingers.

I will pass your sheet metal offer on to the shop guys and also put your e-mail in the old 535is file.

Do you by any chance have an interior, driver's side, door post trim? Mine kept snagging on my Carhart jacket and is falling apart. It had a snag on it before I got it. I tried to repair it a couple of times. Once that vinyl comes unstretched on the substrate, there is no getting the genie back in the bottle.

Quote me a price on that trim piece, anybody, at ramelloh@sover.net.

Otherwise, all this ride needs is a little yearly paint and body work. Even the original radio/tape player still works. Front seats are still whole. Winters are hard on it here in New Hampshire, but it's a daily use vehicle on dirt, back roads, a hoot to drift in the snow and ice.

Regards,

Rick
 
#4 ·
Sorry, I do not have a good drivers side b-pillar. The best one I have the card board is cracked but the black stuff is whole. I would hate to see the bill when this is done. You also might change the diff to a lsd if it is not. Also the rear links, and dog bones and make sure the rear diff mount is good. If the rear diff mount is bad make sure to replace it with the one for the 528e it is the cheapest and the best made (makes no sense, but true)

Andy
 
#5 ·
south 26,

Thanks for getting back. The 535is comes with the LSD. I leave double tracks everywhere I go. It makes a great snow car with 120 lbs of sand in the trunk and the best and freshest snow and ice tires money can buy. I think the shifting rear subframe with busted bushing was foolinging my LSD, making it think it was turning a corner all the time. We'll see. It's the best scenario I can hope for.

I could have picked up a driveable 535is for $500 a couple of years ago, a red on black one. I wish I had. The driver's side door post trim would have had me well on my way to vindication. I didn't because of the unregistered-vehicles-on-the-lot rules in our town. I think I could have covered it up, out of sight, in our "back forty". Now, the E28s are suddenly disappearing from the Upper Valley, a rare sight. No more $500 parts cars. I keep looking.

Anyone else out there have a E28, black, driver's side door post trim in good condition?

The car went on the lift on Friday for subframe and exhaust removal. The Ireland Engineering exhaust system and fluid lines are on their way. Here we go. I'll post when it is all over. I'll try to scare up a pic or two.
 
#7 ·
I have discovered the same problem with my 1985 535i. The body shop trusted by the BMW dealership says they cannot fix it, something about the difficulty of welding double layer panels.
How did this repair turn out? Did they cut a chunk out of an undamaged vehicle and replace it for yours?
Any specifics you can provide are welcome.
 
#8 ·
Rear subframe repair results results

Hey zthreepio,

The work is done. Your prompting has inspired me to do what I said I would do, let interested parties know how things progressed.

The work is done. It was a major success. The car is now in a "perfect storm" condition; new brakes, wheels, tires, fluid lines, rear bushings and mount points, new exhaust, upgraded engine on a chip (1990 3.5 liter: zoom, zoom). It is a joy to drive.

I never realized how much torque steer I was wrestling with when the rear subframe bushings and mount points were bad. It was something I just got used to over time. If it would only have caused the tires to wear funny, I would have noticed and addressed the problem long ago, or pitched the darned money pit before I got in too deep. I hate to think of tossing a vehicle with perfect winter and summer alloy/tire sets, plus all the other goodies afore mentioned.

The body man I used did not use BMW sheet metal. He hand built what was required. My mechanic says it was good work. I inspected from below when I picked it up, but what the hell do I know? I know it tracks perfect and feels like a brand new vehicle.

I have to go now. I'll wrap this note up with a mention that I live in NH. The body guy is in VT. Ask, and I'll give his #. The cost for all the work he did was $2200. There were a lot of other things addressed. These cars are not designed for a salt environment in the long term.

I look at this vehicle as if it were an alternative for a new 5 series. What would that cost per year? Would it look as cool as my rig? I don't think so. I have a lot of wiggle room to invest on a yearly basis.

Regards,

Rick Melloh
 
#9 ·
Hey zthreepio,

The work is done. Your prompting has inspired me to do what I said I would do, let interested parties know how things progressed.

The work is done. It was a major success. The car is now in a "perfect storm" condition; new brakes, wheels, tires, fluid lines, rear bushings and mount points, new exhaust, upgraded engine on a chip (1990 3.5 liter: zoom, zoom). It is a joy to drive.

I never realized how much torque steer I was wrestling with when the rear subframe bushings and mount points were bad. It was something I just got used to over time. If it would only have caused the tires to wear funny, I would have noticed and addressed the problem long ago, or pitched the darned money pit before I got in too deep. I hate to think of tossing a vehicle with perfect winter and summer alloy/tire sets, plus all the other goodies afore mentioned.

The body man I used did not use BMW sheet metal. He hand built what was required. My mechanic says it was good work. I inspected from below when I picked it up, but what the hell do I know? I know it tracks perfect and feels like a brand new vehicle.

I have to go now. I'll wrap this note up with a mention that I live in NH. The body guy is in VT. Ask, and I'll give his #. The cost for all the work he did was $2200. There were a lot of other things addressed. These cars are not designed for a salt environment in the long term.

I look at this vehicle as if it were an alternative for a new 5 series. What would that cost per year? Would it look as cool as my rig? I don't think so. I have a lot of wiggle room to invest on a yearly basis.

Regards,

Rick Melloh
Keep up the good work. And remember, there's alot of bad habits that could cost you much more...:D
 
#10 ·
Bad habits and body work

Roger that, Catso. I have had my share of bad habits, some I don't regret, and some I do. Sometimes, doing something bad feels so good, you don't wanna be right, at least for a little while.....like pouring money into an old BMW beater. ;0)

I have a little more time today and would add that some of the cost of the body work included mending the angled face of the driver floor board, patching one of the trailing arm builds to strengthen and prevent further decay, repair of the rear wheel well arches, replacement of the driver's side, lifting hard point. This body guy, Phil Gates, was going on a rampage for this car. I finally had to say whoa, save some for next year. It was a lot of work and the ride could use more. GD money pit, but it looks cool and drives like a dream.

If anyone has a 5 series of this vintage, the above are places you need to inspect.

I still have a little moisture getting in at the back/bottom of the trunk area. I will have to chase after that. I thought the new front and rear glass would cure all those problems. Damn!

;0) r
 
#11 ·
Roger that, Catso. I have had my share of bad habits, some I don't regret, and some I do. Sometimes, doing something bad feels so good, you don't wanna be right, at least for a little while.....like pouring money into an old BMW beater. ;0)

I have a little more time today and would add that some of the cost of the body work included mending the angled face of the driver floor board, patching one of the trailing arm builds to strengthen and prevent further decay, repair of the rear wheel well arches, replacement of the driver's side, lifting hard point. This body guy, Phil Gates, was going on a rampage for this car. I finally had to say whoa, save some for next year. It was a lot of work and the ride could use more. GD money pit, but it looks cool and drives like a dream.

If anyone has a 5 series of this vintage, the above are places you need to inspect.

I still have a little moisture getting in at the back/bottom of the trunk area. I will have to chase after that. I thought the new front and rear glass would cure all those problems. Damn!

;0) r
Alot of those minor trunk leaks are from the seals around the tailights.
 
#12 ·
Leaks

Thanks for the tip, Catso. I have silicone. I'll check the gasket/seal situation out. The tail lights have always had fog in the lenses. I thought it was coming from elsewhere. I sealed a couple of tight cracks in lenses with super glue, to no avail. There is less fog now than ever before. I started with a new trunk deck gasket (not an easy or cheap thing to do, $175 for the gasket, getting the old one off was the worst part). I am sure the rear glass was leaking. You don't want to know what that cost. I always supect the ancient moon roof and drains, always. I am just grateful the moon roof works reliably.

Cars, ya gotta love 'em.

;0) r
 
#13 ·
I mentioned your write-up to the BMW certified body shop. They simply refused the work because there was no "BMW approved fix." They also said any attempt by them would well exceed $2200. Honestly, I think they have my best interests in mind from their perspective: a 25 year old car rolls into their shop, it needs a full body repaint and some rust repair beyond the subframe, 240k on the odometer, and there are various yet undefined fluid leaks. It does not look like a worthy candidate for restoration considering its less than collectible status.

Nevertheless, I intend to drive this car as long as is feasible, and as long as it's safe.

I intend to find an independent body shop that's a bit more adventurous. For now, since I need new subframe bushings anyway, I'll replace them with polyurethane versions. The thinking is that the stiffer bushings will not allow as much deflection and twisting of the subframe bushing pins. It will hopefully resist the advance of the deterioration at the mount points. Add a rear strut brace and maybe the whole rear end will be tight enough to drive as-is for awhile. It'll give me time to determine if I want to spend thousands on the body repair, or search for a donor with a good chassis.

I'm guessing your body man never took any pictures of the work in progress, but I'd love to see them if he did.
 
#14 ·
I mentioned your write-up to the BMW certified body shop. They simply refused the work because there was no "BMW approved fix." They also said any attempt by them would well exceed $2200. Honestly, I think they have my best interests in mind from their perspective: a 25 year old car rolls into their shop, it needs a full body repaint and some rust repair beyond the subframe, 240k on the odometer, and there are various yet undefined fluid leaks. It does not look like a worthy candidate for restoration considering its less than collectible status.

Nevertheless, I intend to drive this car as long as is feasible, and as long as it's safe.

I intend to find an independent body shop that's a bit more adventurous. For now, since I need new subframe bushings anyway, I'll replace them with polyurethane versions. The thinking is that the stiffer bushings will not allow as much deflection and twisting of the subframe bushing pins. It will hopefully resist the advance of the deterioration at the mount points. Add a rear strut brace and maybe the whole rear end will be tight enough to drive as-is for awhile. It'll give me time to determine if I want to spend thousands on the body repair, or search for a donor with a good chassis.

I'm guessing your body man never took any pictures of the work in progress, but I'd love to see them if he did.
Not to throw a monkey wrench into your project, but I have the opposite opinion. I'd stick with stock or maybe Meyle. Just my opinion.
 
#15 ·
to zthreepio and catso

Sorry, no pics to my knowledge. I was far away from the body shop and too busy working, earning the coin to pay for the work. I tend to give a lot of trust to my mechanic and selected body man. Everything is done on a cost-plus basis. These old cars are booby traps, waiting to spring.

Here are some things I do know. My mechanic, dropped the old exhaust, broke down the old subframe, installed all the new bushings and new hand made SS fluid lines and put the subframe back on the vehicle in a solid enough state to self-transport it to the body shop. It was easy for the body man to re-disassemble the subframe and begin the work.

There was a lot more work done than just the bushing mount points. The body man was taking a run at a full restoration when my mechanic warned me and we put the brakes on at $2200. For that, I got a lot: a patch on a weak spot on the subframe hollow-body section (good call), exhaust hanger hardpoint rebuild, R&L rear wheel well arch repair, LF jack hard point rebuild, repair to the sloped floor of the driver side footwell in addition to the two layer bushing mount point fix on both sides. There may have been a few more little details done as well. The man was thorough and critical.

The vehicle could go back tomorrow and eat up another $2200, easy.

The BMW was able to self transport back to the mechanic's shop for the new SS exhaust and the some other minor mechanical repairs that were on order. By the time it was all over, there was a $4200 invoice in my hand.

Cars, you gotta love 'em.

Regarding bushings, my mechanic shys away from the harder polyurethane aftermarket bushings. He warns me they are more expensive and make the ride more harsh. The '87 535is is already a very firm ride, when everything is in order. I don't want it to ride like a truck. It's a luxury touring sedan.

We all know that frequent front end bushing replacement is normal on this vehicle, especially if one deals with rough gravel roads, washboard and potholes. The good thing is that the bushing rebuild is a relatively inexpensive and quick procedure, when done by an experienced mechanic using original spec parts. Every 20 to 30 thousand miles it has to be done, just like tires and brake jobs.

I am suspicious of some of the aftermarket "upgrades". Are they really improvements?
Stay away from the colorful aftermarket "high performance" plug wire set for this vehicle.
It looks pretty, that's all it is. My mechanic smirks at the wires and shakes his head at me. That hurts. It IS pretty. Mine are red. I'm still saving the old wires.
 
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