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Ripping underside mid/back apart, what all should I do?

Posted by Earendil 
A number of things have recently conspired to convince me it's time to take the underside of my car apart for the first time.

1. I know my CV joints are bust. A mechanic warned me of this 18 months ago, it's about time to fix them.
2. Suspicious clunking noise and loud "squeeky" noise coming from back end of car while going slow (especially in reverse), I'm hoping it's the CV joints, but I'm having a hard time diagnosing the U-Joint and drive shaft from where it is. Taking it all apart may help here.
3. I know the exit seal on my transmission is leaking. This annoys me.
4. Recent "golf ball in the muffler" experience tells me something is wrong. Dropping the exhaust may help me diagnose the CAT/Muffler and see what's up.
5. My shift stick has always had about 3 inches of play in it side to side while in gear. Apparently fixing this is a 2 dollar part, but requires(at least to make it easy) dropping the exhaust and drive shaft (or transmission? I forget off hand).

In any case, it looks like I'll be putting my car up on jack stands, and spending as much time on my back as I can before I get sick of it, run out of the correct tools, or break something smiling smiley

Outside of giving tips and advice along the way, what else might I replace while I have all of this apart. I'm thinking things similar to seals, bushings, other $5 parts that require $200 worth of labor to get to. I'll probably replace the drive shaft bearings (name?) while I'm under there as well. Anything else?

Note: I'm less concerned about things relating directly to the wheel, such as wheel bearings, but more with things that require dropping the exhaust/drive shaft. All comments are of course welcome though :-)
Cheers!

-----------------------------------------------------------------------------------
1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

rear subframe bushings?


The drive shaft u joints are not replaceable unless you take the thing down to a rebuilder and have them custom fit new ones in and that is fairly spendy. You can get a new one from BMW but that is even more spendy. When you start messing with the drive-line itself it can become costly. I have no idea why BMW engineers designed it this way as they had to know these things would eventually wear out. I guess hindsight is always 20/20!



Edited 1 time(s). Last edit at 06/20/2009 11:46AM by wodcutr.
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Earendil

Outside of giving tips and advice along the way, what else might I replace while I have all of this apart. I'm thinking things similar to seals, bushings, other $5 parts that require $200 worth of labor to get to. I'll probably replace the drive shaft bearings (name?) while I'm under there as well. Anything else?

It's probably a good idea to replace the rear transmission mounts, especially if the rear trans seal has been leaking all over them. How does your guibo look? If it's all cracked up I would replace it too while I was under there. You'll have to remove it to get to the rear seal anyway, so make sure you get a new one if you see any cracks.

John
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daniel
rear subframe bushings?

Humm... I don't think I know where/what those are. Unsurprisingly it's not in the glossary of the Bentley. How might I visual inspect them?

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wodcutr
The drive shaft u joints are not replaceable unless you take the thing down to a rebuilder and have them custom fit new ones in and that is fairly spendy. You can get a new one from BMW but that is even more spendy. When you start messing with the drive-line itself it can become costly. I have no idea why BMW engineers designed it this way as they had to know these things would eventually wear out. I guess hindsight is always 20/20!

damn...
I was looking for U-Joints last night and after reading around, I was a bit afraid they weren't going to be replaceable.
So what do you do, drive it until it fails? how exactly does it "fail"? Drop the drive shaft on the exhaust? Anyone have any ideas of how bad is too bad to drive it?
A rebuilt drive shaft is $819 from pelican. Perhaps if the U-Joint was engineered to outlast the majority of the car, they didn't think it would be a problem. They didn't see guys like us coming, did they? grinning smiley


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John Yust
It's probably a good idea to replace the rear transmission mounts, especially if the rear trans seal has been leaking all over them. How does your guibo look? If it's all cracked up I would replace it too while I was under there. You'll have to remove it to get to the rear seal anyway, so make sure you get a new one if you see any cracks.
John

The rear transmission mounts were replaced earlier this spring, so they are still pretty good, if not experiencing a shorter life span due to the oil.
The Guibo is certainly something to look at, thanks for that advice.

Anyone know if there is a replaceable seal between the drive shaft and the diff? I'm not having problems with it, but hey, why not?

Another question, when pulling the drive shaft from the tranny, does the tranny oil spill out? I need to know whether I need to be draining it and buying more to replace it.

-----------------------------------------------------------------------------------
1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles




Edited 1 time(s). Last edit at 06/20/2009 04:22PM by Earendil.
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Earendil
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daniel
rear subframe bushings?

Humm... I don't think I know where/what those are. Unsurprisingly it's not in the glossary of the Bentley. How might I visual inspect them?

they are directly in front of the rear wheels, one on each side, and if they haven't been replaced on your car they are probably totally shot.

[e30world.com]


If your u-joints are toast, take the driveline down to a good shop and have them look at it. I had a shop install replacable u-joints in mine and then had it rebalanced and all and it was around $500. That was 5 years ago so it could be more now, but it is worth looking into. The car was down for two weeks, but hey it was cheaper than the other options.
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daniel
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Earendil
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daniel
rear subframe bushings?

Humm... I don't think I know where/what those are. Unsurprisingly it's not in the glossary of the Bentley. How might I visual inspect them?

they are directly in front of the rear wheels, one on each side, and if they haven't been replaced on your car they are probably totally shot.

[e30world.com]

Hi All,

Are there other symptoms for worn out rear sub-frame bushings? Like thumping noises when driving over street paving irregualritues? I've asked the mechs to check the suspension several times and they say it is fine. I don't know if they checked these bushings.

Cheers, Kelly
sdp
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Earendil

Another question, when pulling the drive shaft from the tranny, does the tranny oil spill out? I need to know whether I need to be draining it and buying more to replace it.

The driveshaft and transmission ares separated at the Guibo bushing and you will not be removing anything from the transmission, so don't worry about that.
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sdp
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Earendil

Another question, when pulling the drive shaft from the tranny, does the tranny oil spill out? I need to know whether I need to be draining it and buying more to replace it.

The driveshaft and transmission ares separated at the Guibo bushing and you will not be removing anything from the transmission, so don't worry about that.

I realized my question wasn't quite clear, unless maybe you read between the lines.
I'm going to replace the rear seal on the transmission. Does getting to this rear seal (wwhich presumably is sealing something) open up the transmission to losing oil?

Thanks smiling smiley

-----------------------------------------------------------------------------------
1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

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Earendil

I realized my question wasn't quite clear, unless maybe you read between the lines.
I'm going to replace the rear seal on the transmission. Does getting to this rear seal (wwhich presumably is sealing something) open up the transmission to losing oil?

Thanks smiling smiley

No. A few drops will probably leak out, but the oil level is below the seal.

With that said, it's always a good idea to have a drain pan handy in case somebody overfilled the transmission, but most likely you'll only see a few drops drip out when you pull the seal.

I guess it's also possible you could have the front of the car so high that the oil would reach the seal, but it's still not that big of a deal. Just check the level and top it up if needed after you replace the seal.

John

Edit - I thought of something else after I posted this. How long has it been since you changed the transmission oil? If it's been more than 30,000 miles, or you've never done it since you got the car, this might be the time to do it.



Edited 1 time(s). Last edit at 06/23/2009 08:47PM by John Yust.
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