Replacing Rear Subframe Bushes... Procedure.

[e34.535i.sport]

REAR SUBFRAME BUSH REPLACEMENT
Thought i'd bang this one out while i can still remember how! This is intended for the first timer (like myself at the time), hopefully it'll be of some use.

Ok, the Rear Subframe Bushes are prone to fatigue on the e34 so if you own one you're going to need to replace them sooner or later... (Hopefully later).

Failure Symptoms: More than likely a knocking noise from the rear end when driving over rough surfaces, and particularly when taking off from lights or stopping suddenly. You might experience a slight delay during take off from the lights as well? Possibly a looser rear end in the corners too... Visual inspection is possible to an extent.

Benefits of Replacement: No noises from the rear end and a tighter feeling at the back, with no hesitation on take off!


TOOLS
I use the bare minimum tools when i do any DIY jobs... It would probably be much easier with air tools, a ramp, 1/2" ratchet etc but i like a challenge. The bare minimum for this job-

+ Ratchet and Various sockets (13mm and 22mm i think).
+ Breaker Bar.
+ 2 Jacks.
+ Sawzall or at least Jigsaw (not easy with this though... )
+ Mole-Grips (Pliers)
+ Big Hammer (Lump Hammer)
+ WD40.
+ A Freezer.
+ Washing up Liquid
+ Elbow Grease
+ BIG BRASS B*LLOCKS!

Optional but advisable - Heat Gun (about £20).

PARTS
The first thing you want to do is get some good quality parts. Personally i went with Main Dealer parts but they're expensive (About £25 each), so you may want to go elsewhere. I have one spare by the way which i bought from BMW and can't return it as its been too long... if someone needs it get in touch.

I hear good things about the Powerflex bushes but you would have to do a bit of research into those yourself if you want to go down that road. I'm sure there will be some threads here for you, do a search. I went with the standard ones as they give a softer ride than the powerflex apparently, which is what i prefer (personal choice). Always best to do both sides at the same time. I'd also get a new subframe bolt/nut, and four of the 13mm bolts that hold on the subframe plate. Have a look at this:

http://www.realoem.com/bmw/diagrams/o/k/9.png

PREPARATION.
Now, this job is not one to rush into as i found out the hard way. My first attempt took me a week - literally. I know it's pitiful. However, i learnt some valuable lessons and i'll pass them onto you so you don't have to suffer like i did.

A few days before you plan to do the job take off the rear seat bottom... (pull up sharply on both sides and remove the seat). No need to remove the top part. Now have a look on each side - move the rubber padding around to reveal the small hole where, if you look down it, you'll see the head of the subframe bolt. Spray this liberally with WD40 (both sides of course). Put the seat back on and forget about it. I'd have a look around where the bush is situated (near the front end of the rear wheel arch under the car...) Familiarise yourself with the area.

The night before you're going to do the job put the new bushes you bought in the freezer... yes the freezer. Long story short this shrinks them slightly to help with inserting them later! MAKE SURE YOU DO THIS, or you will regret it.

STARTING THE JOB.
Take the rear seat bottom off again and pull it out of the car out the way. Now jack one side up, remove the wheel and support with an axel stand. I normally leave the jack there too just incase. Now get under the car and you will see a plate with two 13mm bolts holding it on one end, and a big nut (22mm i think) holding it on the other end. This nut attaches to the bolt you WD40'd the other day. Remove the two 13mm bolts (with care as mine were a bit fragile). Now support the trailing arm with a trolley jack and remove the big 22mm nut. I used BIG breaker bar for this as it was on tight. You may need to go to town on it, but you'll get it off. Now you will need to use some elbow grease along with the big hammer and knock the bolt up through the car into where the rear seat is. This may be hard, but the WD40 should have helped. Now clean the plate off and spray it with some rubber based undercarriage protector if you have any. Mine was getting surface rust i thought it best to spray it.

CUT THROUGH THE BUSH.
BMW themselves use a special puller tool to remove the bush, but its really expensive to buy so the next best way is to cut it out. A sawzall would be best - example:

http://tbn0.google.com/images?q=tbn:...ilw6523_21.jpg

I only had a Jigsaw, so i made do with that - example:

http://tbn0.google.com/images?q=tbn:.../75109-275.jpg

However, doing this on the drive meant i had little ground clearence, making the Jigsaw a viable choice. The next part is obvious, you need to cut the bush out. The best way is to cut in a straight vertical line right through the rubber inner and metal outer casing. If you do the bush should lose its structural integrity and you should be able to pull it out with the Moley's. Cutting it out is a scary thing to do so wear eye protection and gloves or whatever. You need to observe the following things if you are going to do this job successfully and relatively quickly:

1). Don't fanny around with the saw - you need to go to town on it and make sure you go all the way through the bush. If you don't and you are too cautious you'll be there all day. Just go for it. (Still try not to cut into the subframe!)

2). Use your guile and pick the best place to saw through. Is there anywhere on the bush that is thinner and comfortable for you to work on? Don't just start mauling it all over the place. Pick a place and stick with it.

PULL IT OUT.
After cutting through the bush you should be able to bend some of the bottom lip around hopefully and pull it out with the moley's. Keep at it, you'll get it out.

GET THE NEW ONE IN
Now the old one is out, make sure the inside of the hole where the bush goes is clean and smooth.

Now what i did was get the heat gun and heat up the subframe - until it was warm, i didn't melt it or anything so just judge for yourself how hot you want it. Heat makes metal expand so its easier to get the new one in you see. This step may not be absolutely necessary but it all helps.

Then i sprinted inside and got the new bush out of the freezer and slapped some washing up liquid on it - which there are mixed views about, some say use it other say don't. Do some research and make your own mind up - i personally had a nightmare on my first attempt without it and got a bush stuck halfway. I will always use some lubricant from now on. Anyway place the bush under the subframe hole and make sure it is orientated correctly (you can tell as there is a ridge down the new part and some small bumps inside the hole - line them up. Now you need to jack up underneath the bush until it pops into place! Be careful as you may lift the car off the stand if you go too fast! Just take your time, jack up a little and give it a few seconds to settle down. Just see how it goes and use your judgement.

YOU'VE DONE IT! Put the big bolt through the hole inside the car and check it all lines up. If it doesn't, make it. Now just put the plate on, tighten the two 13mm bolts (just torque them sensibly), put the wheel on and lower the car. Now torque up the big nut (somewhere around 140nm i think but please correct me if wrong).

Now get over the other side and do it again!

Afterwards:It felt so much better being able to drive the car without the radio on volume level 14 to drown out the knocking! Definitely a worthwhile job. No more lurch when booting it from the lights either, which improved the drive for me. Overall a great job to do if you do it right, if you do it wrong you'll be sorry you were ever born!

I'll try and throw some pictures in at some point. Any other info or tips most welcome, i'm only a rookie! . Again, this is only the way i did it with some measley cheap tools and no ramps etc. Others may do it differently and be just as successful! Anyway, good luck!

[cybereclipse]

great write-up!!!
pictures would help though

[e34.535i.sport]

Cheers man i'll get on it tomorrow hopefully... and Welcome back!

[cybereclipse]

hehe thanks

[E34 530]

Nice write-up! I cringe and shutter thinking about the day when these things go.

[e34.535i.sport]

Nice write-up! I cringe and shutter thinking about the day when these things go.

I don't blame you, it is a bit of a P.I.T.A job. They're the best ones though ha ha ha!

[Brandon J]

Nice job. You did a great job of outlining the job with the tools someone may have around. I have found the best and least dangerous way is to rent the subframe bushing tool. Works very well and well worth it. Helps to split the cost too if you have one or 2 other e34s around. Remember to keep the tool lubed while cranking. The picture below shows the bad bushing sets we did in one weekend. I think one or two pairs were missing from the pic.

[E34 530]

Nice job. You did a great job of outlining the job with the tools someone may have around. I have found the best and least dangerous way is to rent the subframe bushing tool. Works very well and well worth it. Helps to split the cost too if you have one or 2 other e34s around. Remember to keep the tool lubed while cranking. The picture below shows the bad bushing sets we did in one weekend. I think one or two pairs were missing from the pic.

damn wish I lived around you guys.

[e34.535i.sport]

Nice job. You did a great job of outlining the job with the tools someone may have around. I have found the best and least dangerous way is to rent the subframe bushing tool. Works very well and well worth it. Helps to split the cost too if you have one or 2 other e34s around. Remember to keep the tool lubed while cranking. The picture below shows the bad bushing sets we did in one weekend. I think one or two pairs were missing from the pic.

Thanks Brandon. I'm not sure where i'd rent one of those pullers where i am but i bet its a peice of cake when you do have one! Man you get a lot of those in, i'm hoping mine last a good few years now!

[Barney Paull-Edwards]

Bloody good write up, well done. I`me sure it has been written up in the past but no matter, every bit helps someone, a thread detailing the dimensions of the BMW tool to pull/push the bush would be good if somebody has it. Oh, and dont forget to use bruno`s delrins with bushes, brilliant(no comission!).