rear subframe bushings and differential mounts

[Mashford]

Hey Folks -- just checking in here for advice and tips as I get the car up in the driveway to replace subframe bushings and differential mounts. (I will get to the front end later, but steering / handling up front is also loose and I can see some cracked bushing; may as well do the engine and tranny mounts later on front end, too... later).

I've been through all the threads and youtubes I can find, FWIW, on subframe bushings and differential mounts. I'm not finding Bentley's terribly helpful on details (but overall good reference).

Indicator:  The car is driving "loose" and I am getting the classic "thump" in the back drive train area when I back up or (sometimes) when engaging 1st from stopped position and/or working the clutch to move slowly in parking lots, etc. 

I put my jack lift on the differential and lowered the car onto jack stands on the side runner jack stand points (the "official" points) to get the car up and steady for work. 

On the differential mount(s):

• When I first lifted the car with lift jack on the differential, I was alarmed to see the differential shift up (kind of popped under strain of lift against it) an inch or two (!) before the whole car started lifting.  Did I damage the drive shaft / differential alignment?  Is that a sign that the differential mount is shot (loose?)?  Made me nervous.
• Is there more rubber than the rear mounting bolt of the differential that I should replace at other bolt points on the front end of the differential?  Three bolt points total, correct (I am going to check them all)?  Not finding much on this in Bentleys.
• Can I service / replace the differential mount(s) without dropping the exhaust and/or the drive shaft (presumably, if I support the differential with a jack, I don't need to worry about the shaft)?

On the subframe bushings:

• FWIW, I bought the bushing puller from Finland -- often cited here and in other DIY sites -- so I don't need to melt (!) or cut to get them out.
• Can I lower the subframe by setting car on side runner jack stand points and "dropping" the subframe from the mounting pins with enough space to use the puller on the bushings?  I think that's what I've seen in some youtubes, but not always clear how the weight of one is being used to leverage the other (e.g. raising the car to drop the subframe versus lowering the car to push back up against the pins).  Presumably, I am working with lift on cross bar to raise and push out the pins (with a piece of metal or wood blocking pin from going back into the bushing) after dropping the subframe , and then lowering back on to the side runner jack points to get to the bushings.
• Related, is it necessary (valuable) to remove the pins at all, or is that just a "nice to have"?
• Are there other jack stand points I can use so that the the downward weight of subframe is enough to lower it from the car / pins and give me access to the bushings?  I don't like putting jack stands on the side runner points, as I have damaged the sheet metal before at those points and recently paid "too much" to get the rust and sheet metal repaired.  But, if no alternatives, I have bought some plastic cushions for the jack stands that should save the runners and sheet metal, etc., at those points.
• Can I do this without dropping the exhaust (I have to fix an exhaust leak / replace gasket at manifold at some point, so could do that now, but trying to do a bunch of stuff on front end later, as mentioned)?

I know that's a lot of questions, but hopefully it's easy to respond by just typing in answers/advice bullet by bullet.

Thank you!  Making a donation now, as this forum has been and remains so valuable to me!

[Blue Shadow]

No damage, diff mount is separated and lifted. Truncated pyramid keeps mount from dropping too low.

Diff mount is all you do. Four bolts to subframe are metal to metal, 4 bolts driveshaft to diff, 4 bolts diff mount to body, one bolt diff to diff mount. Change only the mount, don’t need to mess with sf-diff check diff to ds.

Jack under diff, remove all 5 bolts, lower diff, swap mount, put it back together. 

You are already worrying about the shaft, stop it. 

You may need to melt them to ease the removal in some cases. Read Rod’s tutorial on sf bushing replacement. 

Car moves independent of subframe once released, to a degree.  Don’t know Finland tool. 

Tools used determine need to remove pins. Pressing bushings with sf off the car, leave the pins. I removed pins and it took some serious pounding with a short handled bfh. Be sure to use a sacrificial nut threaded on the pin or have replacement pins as needed. 

The area where the rear push rod is attached to the body should have enough metal to hold up the car. 

Haven’t dropped an exhaust for these bushing replacements. 

[Mashford]

 Don’t know Finland tool. 

 

 

 

Thanks!  I will aim to do this without removing pins.

The puller tool I mention is here in ebay (I am not endorsing).

https://www.ebay.com/itm/334790214083

[Mashford]

Meanwhile, I have to drive about two hours (round trip) this weekend and wondering if it's ok with the rear clunk (differential mount shot) or too dangerous.  The family needs the other cars.  

Is it dangerous / risky to do so?

Thanks.

[gwb72tii]

 Don’t know Finland tool. 

 

 

Thanks!  I will aim to do this without removing pins.

The puller tool I mention is here in ebay (I am not endorsing).

https://www.ebay.com/itm/334790214083

That tool works and makes the job pretty easy, and you can buy it directly from the manufacturer. You do not need to remove the pins. You will need to  remove the diff from its mount so the entire subframe can be lowered, but then you're replacing the diff mount. Be careful to order the correct diff mount. You want the 528e diff mount for 528e's made from 1985 and up.

[Mike W.]

Meanwhile, I have to drive about two hours (round trip) this weekend and wondering if it's ok with the rear clunk (differential mount shot) or too dangerous.  The family needs the other cars.  

Is it dangerous / risky to do so?

Thanks.

No, it will be ok for a while. Do drive gently, which doesn't mean slow, just gentle shifts and especially in reverse. You could even pull or even just lower it, stick some rubber in there like fuel line between it and the body to fill that void and minimize stress and clunking, retighting it afterwards of course. It's not a fix but kind of a band aid.

When I first lifted the car with lift jack on the differential, I was alarmed to see the differential shift up (kind of popped under strain of lift against it) an inch or two (!) before the whole car started lifting.

That's why I always stick the floor jack waaaay in there so I get under the subframe, not the diff so I'm not putting any load on the diff mount. Kind of a pain, but cheap insurance.

[Mashford]

Thanks, everyone!

Does anyone have an opinion on the PowerFlex versus OEM subframe bushing replacements?

[dsmith]

I use the PF bushings. Much easier and I don’t notice any harshness.  

I remove the pins with a sacrificial nut and a sledgehammer.  I put a 4” long piece of brass pipe between the bushing and body, heat up the end of the subframe until the rubber starts to melt and jack up the subframe to push out the old bushing.  Clean up the bushing hole and good to go.  Takes about 30 minutes per side and no special tools.

[LarryM]

Subscribed.
I have subframe bushings on order from Germany and am trying to decide if this job is something I'd like to tackle, or if I've "aged out" from projects that require slinging a sledgehammer and working with fire under a car in a cramped space. Years ago I removed the subframe on my E24 and had the bushings replaced by a shop that also welded up a Dinan adjustable camber kit. I didn't even need to remove the pins. This time it's my E28 that needs bushings and if I can do it without having to remove the subframe, I might be up for this task. I had thought it was necessary to remove the diff and drop the exhaust system but it sounds like neither of those is required.

Mostly, I'm curious to see if the two bushing pins/knurled bolts really need to be removed from the car when using the above tool. If you can eliminate that step, the job probably isn't too intense. In that case I'd be up for purchasing the tool and having at it.

BTW, I've spoken with a couple of local BMW Master Techs about this and they both advised using the OEM rubber bushings vs. the poly bushings, due to the poly bushings transmitting road noise into the cabin.  

 

[Mike W.]

While everyone says how easy it is to do the subframe bushings with the tool, the sawzall method isn't all bad either. No fire, no sledge, but it is a little messy. It was one of those jobs I got myself all steeled up for, expecting a big fight, and 2 hours or so later I was almost disappointed. I was done.

It's kind of a no going back sort of thing as I at least cut out the bulk of the rubber IIRC, then I could really get in there and cut the sleeve. I think I had to make 2 cuts per side to relieve the preload, and lots of WD40 as lube. If you go this route, cut towards the inside so if you go too far it will still have strength.

[4DSC]

Hopefully this isn't the case on your car, but just FYI, the metal around the subframe mount where the pin goes through is prone to rusting. I didn't truly see the extent of mine until I had the subframe off, and that stalled my project for quite a bit while I looked for a welder that would be willing to come to me and repair the area. I suspect the rust issue is exacerbated if you've ignored the ripped bushings for a while and the carrier(?) occasionally comes into contact with the underside of the car, as was the case for me. If you do end up having to take the pins out, for me they were the most stuck I've ever experienced any kind of bolt. Tried everything. Drilling the center, heat, etc. eventually with much sweat I got it with a 10lbs hammer from below, which there was not much room to swing with the car just on jackstands. Wishing you the best of luck! Hopefully it's an easy 2 hour job for you

[Tiit]

Not exactly a "HOW TO", but this is how I did it. 
https://youtu.be/ADWDEOvKEmg?si=CSiQgVxIhB1Y-AMs

[LarryM]

While everyone says how easy it is to do the subframe bushings with the tool, the sawzall method isn't all bad either. No fire, no sledge, but it is a little messy. It was one of those jobs I got myself all steeled up for, expecting a big fight, and 2 hours or so later I was almost disappointed. I was done.

It's kind of a no going back sort of thing as I at least cut out the bulk of the rubber IIRC, then I could really get in there and cut the sleeve. I think I had to make 2 cuts per side to relieve the preload, and lots of WD40 as lube. If you go this route, cut towards the inside so if you go too far it will still have strength.

 

 

Mike, 
With the car on a rack or with the subframe out of the car I could see where using a sawzall would be a good option. But with it in the car and with the car on jackstands, do you have enough room to get in there from below to make an accurate cut or two without cutting into the subframe? That would be my concern. 

[Mike W.]

While everyone says how easy it is to do the subframe bushings with the tool, the sawzall method isn't all bad either. No fire, no sledge, but it is a little messy. It was one of those jobs I got myself all steeled up for, expecting a big fight, and 2 hours or so later I was almost disappointed. I was done.

It's kind of a no going back sort of thing as I at least cut out the bulk of the rubber IIRC, then I could really get in there and cut the sleeve. I think I had to make 2 cuts per side to relieve the preload, and lots of WD40 as lube. If you go this route, cut towards the inside so if you go too far it will still have strength.

 

 

Mike, 
With the car on a rack or with the subframe out of the car I could see where using a sawzall would be a good option. But with it in the car and with the car on jackstands, do you have enough room to get in there from below to make an accurate cut or two without cutting into the subframe? That would be my concern. 

A basic floorjack and jackstands is all I used. Likely jacking from the subframe in front of the diff. Emphatically not up on a lift. Longshot, very long shot, I might have had a 2x6 in somewhere to get it a little bit higher... but I don't think so. I'd like to think I'm good, and I'm not bad, but this isn't precision work here. Careful is probably the most important part. I might have used a small chisel to try to split and widen the gap to ease it's tension and removal, but it was 20 years ago, I don't remember the details. I would say slow and cautious and saw towards the inside are the most important things.

Really, I swear, I was done and thought, "Is that all there Is?" credit Peggy Lee

[Mashford]

Thanks everyone!  Great information here all around. 

Any suggestions on sourcing the differential mount?  Part number: 33171125290.  Pelican and ECS Tuning both say "indefinite" delivery time.  On ebay, they ship from Germany or Lithuania, but for over $500 ($250 for shipping?).  I am a bit stumped. 

Meanwhile, driving carefully and cringing at every clunk. 

[Mike W.]

You don't want that one, you want the one for a 528e. Much cheaper and stronger too. No it doesn't make sense. Search just to reassure yourself and confirm.

33171129784

https://www.fcpeuro.com/products/bmw-di ... gLKx_D_BwE

[Mashford]

You don't want that one, you want the one for a 528e. Much cheaper and stronger too. No it doesn't make sense. Search just to reassure yourself and confirm.

33171129784

https://www.fcpeuro.com/products/bmw-di ... gLKx_D_BwE

 

 

 

 

Thanks, Mike.  That is a relief. 

So, the one for 528e will fit my '87 535is?  My dumb-googling around took me to the hard-to-get part.  It looks a lot different (more "robust"?) than the other one. Just want to be sure. 

[Blue Shadow]

Does it fit?  

Did you see where it was recommended you search to confirm that saving piles of money and using an e-bomb part is the right thing to do?  

Mike posted “Search just to reassure yourself and confirm.”  

If you are not going to take our word as gospel, you gotta at least put in some effort when told to search. That is a mye28 search. 

[Mashford]

Does it fit?  

Did you see where it was recommended you search to confirm that saving piles of money and using an e-bomb part is the right thing to do?  

Mike posted “Search just to reassure yourself and confirm.”  

If you are not going to take our word as gospel, you gotta at least put in some effort when told to search. That is a mye28 search. 

 

 

Sorry. You and Mike and others have been a great help. FWIW, I was just reading and typing fast and didn’t even register the “Search just to reassure yourself and confirm.”  I will slow down and process. 

Onwards, and thanks for monitoring. 

[peter100]

Look up home made bush press I posted this a few years back after doing mine so it may help.

Regards Peter

[Blue Shadow]

Did you get this job done?  If not, drop by and I’ll watch you do it. Recite manual torque specs if you want. 

[Mashford]

Did you get this job done?  If not, drop by and I’ll watch you do it. Recite manual torque specs if you want. 

 

 

 

 

Hey Blue — haven’t started yet. Waiting on parts and prepping driveway for better set up. Aiming for next weekend, June 14-15. I’m in southern Maryland, a bit of a schlepp from PA. 

[Blue Shadow]

Did you get this job done?  If not, drop by and I’ll watch you do it. Recite manual torque specs if you want. 

 

 

Hey Blue — haven’t started yet. Waiting on parts and prepping driveway for better set up. Aiming for next weekend, June 14-15. I’m in southern Maryland, a bit of a schlepp from PA. 

I’m only about 30 miles from MD by 95 or RT 1.  But southern MD can be a haul. 

[Chicagotrader92]

Okay, so I replaced my rear subframe bushings three months ago. No special tools. Only a jack, two jack stands, a torch, and something to wedge the bushing out... I believe I used a 34mm socket, but really anything strong and dense should work. 

1) Jack up.
2) Remove associated subframe bolts. 13mm nuts for the bracket, and a 22 mm nut for the slined bolt. 
3) Keep the 22mm bolt threaded a bit, and smash the splined bolt up with a hammer. This took me about 10 minutes on one side and an hour on the other side. Buy replacement bolts in case you destroy them. Tip: Soak the bolts from up top (beneath the rear seat) in WD40 or PB for a few days before you attempt to get them out. 
4) Okay, so now for the part no one talks about. 
- Wedge a large socket (or whatever you'd like) between the subframe bushing and the chassis. Jack up the subframe so that the weight of the rear end is now pressing into the bushing. 
- Carefully, use a torch on the subframe (around the bushing)... You will start to hear the old bushing crackle and smoke... Don't stop. After about 5 minutes, it should pop out. Open your garage door or do this outside, and you should probably even wear a mask if you are a health freak. 

The hardest part for me was getting the splined bolt out. The threads were destroyed after hammering on them for an hour. Getting the bushing out via torch and something wedged in there legit took 5-10 minutes. Getting the new bushing in takes 3 minutes. 

* Use Powerflex bushings as replacements, simply because they are so easy to pop in. 

[Mashford]

Okay, so I replaced my rear subframe bushings three months ago. No special tools. Only a jack, two jack stands, a torch, and something to wedge the bushing out... I believe I used a 34mm socket, but really anything strong and dense should work. 

1) Jack up.
2) Remove associated subframe bolts. 13mm nuts for the bracket, and a 22 mm nut for the slined bolt. 
3) Keep the 22mm bolt threaded a bit, and smash the splined bolt up with a hammer. This took me about 10 minutes on one side and an hour on the other side. Buy replacement bolts in case you destroy them. Tip: Soak the bolts from up top (beneath the rear seat) in WD40 or PB for a few days before you attempt to get them out. 
4) Okay, so now for the part no one talks about. 
- Wedge a large socket (or whatever you'd like) between the subframe bushing and the chassis. Jack up the subframe so that the weight of the rear end is now pressing into the bushing. 
- Carefully, use a torch on the subframe (around the bushing)... You will start to hear the old bushing crackle and smoke... Don't stop. After about 5 minutes, it should pop out. Open your garage door or do this outside, and you should probably even wear a mask if you are a health freak. 

The hardest part for me was getting the splined bolt out. The threads were destroyed after hammering on them for an hour. Getting the bushing out via torch and something wedged in there legit took 5-10 minutes. Getting the new bushing in takes 3 minutes. 

* Use Powerflex bushings as replacements, simply because they are so easy to pop in. 

 

 

 

 

Thanks, Chicago -- I've got the parts.  Got the OEM bushings. Now I am working on the right set up in my driveway.  We've been inundated wit rain.
 

[Chicagotrader92]

Thanks, Chicago -- I've got the parts.  Got the OEM bushings. Now I am working on the right set up in my driveway.  We've been inundated wit rain.
  

https://youtu.be/kxl7K7f62WQ?si=67wtXK3d-uKy7Y7J&t=334

I believe this is where I got the idea from, and it truly did work. 

[LarryM]

There's one thing about this job that I don't quite understand.
After you unbolt and lower the subframe, what is the reason for having to remove the two long splined bolts? Is it simply because without removing them, you don't have enough clearance between the subframe and the bottom of the car to R&R the bushings? 

I've tried ordering a pair of the splined bolts from several sources but have been told they're on some type of back order from BMW. I'd like to have replacements in case I bugger them up in the process of removing them.

However, I came across a creative method of getting them out that involves drilling and tapping into the heads of the bolts, then using a simple fabricated puller to extract them. Has anybody tried this?
https://www.forum5.co.uk/topic/47-rear- ... placement/

[Chicagotrader92]

There's one thing about this job that I don't quite understand.
After you unbolt and lower the subframe, what is the reason for having to remove the two long splined bolts? Is it simply because without removing them, you don't have enough clearance between the subframe and the bottom of the car to R&R the bushings? 

Bolt: https://www.fcpeuro.com/products/bmw-pin-33323628167
Nut: https://www.fcpeuro.com/products/bmw-se ... 7129922745

- I believe that's the reason. There's only so much room for the subframe to drop before it rests/hits the driveshaft. The Powerflex bushing is two pieces, so one has to go through the top. I've heard the OEM bushing is much harder to get in. 

* That's a good worst-case scenario for a stuck bolt, but I don't think most have to worry about that. 

[Mashford]

There's one thing about this job that I don't quite understand.
After you unbolt and lower the subframe, what is the reason for having to remove the two long splined bolts? Is it simply because without removing them, you don't have enough clearance between the subframe and the bottom of the car to R&R the bushings? 

I've tried ordering a pair of the splined bolts from several sources but have been told they're on some type of back order from BMW. I'd like to have replacements in case I bugger them up in the process of removing them.

However, I came across a creative method of getting them out that involves drilling and tapping into the heads of the bolts, then using a simple fabricated puller to extract them. Has anybody tried this?
https://www.forum5.co.uk/topic/47-rear- ... placement/

 

 

Hey LarryM -- I believe from watching the youtube videos and reading this and other threads that if you detach the differential (with support from below) and lower the subframe you can get enough clearance to remove the bushings with one of the methods or tools being tossed around... without removing the pins.

That's what I am going to try to do.

Several also say that while your doing the subframe bushings, you might as well do the differential mount (assuming it's old).  I can tell my differential mount is shot, as the rear end is thumping when I shift.

[Blue Shadow]

I have had three of us beat the ever loving crap outta those splined pins without any damage at all using the small BFH. The key is protecting the pin end with a nut threaded on so that the beating is taken by the nut, which got beat to hell, and not the pin. Easy to find a replacement nut. Used on lots of suspension pieces.  Probably have a spare somewhere.