How To Guide Another rear end refresh

mrscalex

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I know we have several good posts now on this from the Zedshed and @Faheem inparticular but it's a big job to tackle for most of us and I thought a few more pictures and ramblings might be useful.

I'm not going to cover the whole thing. But I'm going to try and home in on some of the detail I've not spotted myself before and maybe document a slightly different piecemeal approach. It's going to be photo light on the dismantling side (just because I only just decided to do this post) but will take a lot more as it all goes back.

The car in question is a facelift 2.2 Sport. But with the exception of the exhaust being a possibility to remove on earlier cars it should be a largely similar sequence.

So this picks up from the point where the following has already been removed. I'm not going to note these initial steps in any detail as it's relatively straight-forward compared to the rest of the procedure. These steps are not without their challenges but treat them as an iniative test for bigger stuff to come ;):
  • Spare wheel & carrier
  • Anti-roll bar
  • Calipers & carriers, brake discs.
I've gone for the approach of removing everything peicemeal. For 2 reasons:
  1. I don't want to remove the exhaust due to the infamous wasted bolts/flange issue
  2. It's quite awkward dropping the whole thing in one go, even axle beam & diff together
I don't have photos prior to dropping the beam & diff but the sequence was:
  1. Disconnect drive-shafts from diff. Air-wrench very useful here
  2. Remove the drive-shaft bolts. These can be encased in a wasted away lock-ring which welds itelf to the nut. You may not even notice it's there amongst the crud. It will need splitting away from the nut. Without doubt an air-wrench is your best friend for removing the nut itself
  3. On this car one driveshaft came out with a straight-forward tap. The other one has so far defied all attempts and is about to go to a machine shop for removal. I'll show the strip-down of the trailing arms (hubs, bearings and bushes) at a later point. I'm using swap-out trailing arms, nothing wrong with the arms on there but it speeds things up as everything is going to the blasters/powder coaters
  4. On this car I was renewing the flexbile hoses (recommended) so I just cut through these
  5. Remove the 4 trailing arm bolts - a long-job in situ. Just use what ever tools you're comfortable with and allow a couple of hours
  6. Remove the handbrake cables. On this car they were both seized in the housings at either end so I just cut through these too. Not happy about this as they were working well with no splits in the casing and it's going to cost me £50 for 2 new ones. But I'm also jiggered if I'm going to spend longer than I have to crawling around on my hands and knees under a car. Removing the cut ends is much easier with everything dismantled
  7. Remove the nuts from the propshaft where it attaches to the diff
  8. Remove the infamous 4 beam bracket bolts. I used a mixture of an irwin bolt grip and the standard 6mm hex head. But banging in a 5.5mm hex head first to clear the hole out - this is probably the best tip I can give here
  9. Cracked the main axle beam pin nuts with a breaker bar and undone so the nut was at the bottom of the pin, ie so the beam could drop without falling off
  10. Dropped the exhaust off the 3 rearmost hangers - 2 floorpan & 1 axle beam. With a wire restraint to stop it dropping down too far - important as the axle beam could put a lot of pressure on the exhaust when it's removed.
We're into the first of the photos I took now. And the decision point I took to remove the diff and then the beam as 2 seperate assemblies. I know the Zedshed do this in 1 maneouvre but they are well versed and on this occasion I was on my own with no James to help (girlfriends :().

I'd asked Father Christmas for one of these last year with gearbox and diff removal in mind. They are about £30 and to cut to the chase it worked like a dream. I didn't use the cradles.



So I jacked this up under the diff to just start taking the weight. And undid the hanger bolt. I then lowered it enough on the jack to remove the four bolts securing the diff to the beam. These sit very high and you won't get a tool in without doing this. I used a ring spanner and heavy lump hammer as the bolts are on tight.

At this point the diff is almost free to drop but needs help off the end of the propshaft. It will need to go lower until it clears the hanger bracket on the floor pan. By this time I was hearing some distressing noises as I'd forgot to remove the heatshield but the only damage was to the heatshield itself and this can be fixed. The propshaft is capable of flexing down some distance to help with this step. Once clear of the mounting bracket the diff can be wiggled backwardwas until it breaks from the propshaft. This step was a little more tricky than I expected and did need quite a bit of persuasion.

upload_2019-10-27_19-20-33.png


And can then be lowered to the floor. Being an LSD it's heavy.

upload_2019-10-27_19-28-41.png


The axle beam can be surprisingly stubborn to remove even with the diff off. Those pins are long and the bushes bind. I used a bar to lever it down a few mm at a time either side. Here it is off. And I was glad I took the piecemeal removal option. I have a swap out beam blasted/powder-coated ready to go back on.

upload_2019-10-27_19-35-2.png


And here's what it looks like with it all out.

upload_2019-10-27_19-37-18.png


I've got a few more small bits and bobs to take off. Then the rust will be treated and I'll be respraying the floor pan. It's actually a very nice car and not too much to do here (I hope). The tank straps will be swapped out but will be staying in place just for now.

Lots more pictures to follow from this point.
 

Althulas

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I like your solution to dropping it by your self. I used a jack which went ok but so could have not. I’ll be buying one of those to reinstall much better and safer than the approach I was looking at making a cradle out of wood to fit on a jack.
 

mrscalex

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I like your solution to dropping it by your self. I used a jack which went ok but so could have not. I’ll be buying one of those to reinstall much better and safer than the approach I was looking at making a cradle out of wood to fit on a jack.
I considered the jack. I've dropped a complete rear axle (with exhaust off) on a breaker before but it's very unstable.

I also looked at the wooden cradle for the diff. It's relatively simple to do I would think. It would also give more wriggle-ability to get the diff off the propshaft. But I guess I was a bit lazy and didn't want to spend 1-2 hours trying to make it when I wasn't sure how successful it would be.

It remains to be seen how clever the motorcyle jack is for getting it back but I would guess that end of things is the more tricky whatever approach you take. But it was spot-on for getting it off.
 

mrscalex

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...but so could have not
I think that's the #1 priority ultimately isn't it, ie safety. That diff is bl**dy heavy if it falls off and lands on you. Not to mention the damage to the diff that could occur. It's not for those who don't like being under cars or for the gung-ho pulling the rear end apart.
 

Althulas

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I think sitting that motorcycle jack on some rollers or a sturdy board with some casters would be a better solution. Glad you posted this it will save some ball ache with my reinstall.
 

Mazza

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I have all this to do in two months..........cant say that I am confident about it, but I will be reading up on all the threads on the forum so I have a real plan of attack. ( thanks to @ZedHead , @Davyhoogy , @Faheem @Althulas and now @mrscalex for taking the time to do write ups to help us novices.)

As time is not an issue I may try to design and build a cradle to drop the whole lot in one hit.:eek:

The first issue will be getting the car up on 4 axle stands which is something I haven't done yet.:banghead:
 

Sean d

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I found it quite easy to drop it as a whole when I did my 2.8 but luckily the exhaust splits just behind the sub frame, in fact I did it twice as the bushes where wrong because the sleeves where to long
 

mrscalex

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I think sitting that motorcycle jack on some rollers or a sturdy board with some casters would be a better solution. Glad you posted this it will save some ball ache with my reinstall.
Very good point. I shall look out for such a thing. I think Lidl/Aldi might even have had a roller-board recently.
 

Lee

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Worth pointing a few extra steps you could of taken to make things a little easier:

1) The prop has two inserts 180* to each other on the diff flange face, we use a pri-bar to break the two faces.

2) If you plan to leave the exhaust in place, remove the pins they are a 27mm spanner. This saves you having to drop the beam 4-6"

When I did the first few on my own I found a sweet spot with the jack on the diff. I did an in depth write up on my Z3M "fuel tank rattle" has alot more info.

Good effort though we have enough knowledge between us all to make this job relatively easy.
 

mrscalex

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Worth pointing a few extra steps you could of taken to make things a little easier:

1) The prop has two inserts 180* to each other on the diff flange face, we use a pri-bar to break the two faces.

2) If you plan to leave the exhaust in place, remove the pins they are a 27mm spanner. This saves you having to drop the beam 4-6"

When I did the first few on my own I found a sweet spot with the jack on the diff. I did an in depth write up on my Z3M "fuel tank rattle" has alot more info.

Good effort though we have enough knowledge between us all to make this job relatively easy.
Thanks. I shall have to look when I'm under the car next to see exactly what you mean.
 

mrscalex

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I cleaned up the axle beam brackets or "push rods" as BMW call them tonight. Always thought a push rod was a Ford Crossflow engine!

Ideally they would have gone to the shotblasters/powdercoaters but timings didn't allow so I pushed on by hand.

IMG_0723.jpg

IMG_0724.jpg

IMG_0725.jpg


I scraped and chipped back as best as I could then put the angle grinder/abrasive wheel over them. And finished off the bits I couldn't get to with the dremel. They'll go in the Deox bath tomorrow for a couple of days. That will return everything to clean metal and show up the remaining rust scale I've missed this time round. Then it will be scrape/chip again and back in Deox.

IMG_0728.jpg
IMG_0729.jpg
 

Jonno Bee

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It's looking good so far.Robert!
I'm progressing a similar rebuild on mine. I've replaced the allen headed bolts holding the 'push rods' to the chassis rail with some stainless steel items.I also used stainless plain washers on the diff to subframe mounting bolts. It took chuffing hours to clean and paint the crusty but very sound diff housing but was very pleasing bolting freshly painted components together with shiny washers.
I will summarise my tips for doing this job when I finish it...

Cheers,

Jonno
 

mrscalex

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It's looking good so far.Robert!
I'm progressing a similar rebuild on mine. I've replaced the allen headed bolts holding the 'push rods' to the chassis rail with some stainless steel items.I also used stainless plain washers on the diff to subframe mounting bolts. It took chuffing hours to clean and paint the crusty but very sound diff housing but was very pleasing bolting freshly painted components together with shiny washers.
I will summarise my tips for doing this job when I finish it...

Cheers,

Jonno
Good stuff :) Caution is required when substituting in stainless bolts though. Suspension nuts and bolts are nearly always grade 8 or grade 10. And stainless bolts are not usually of the required strength. The 4 bracket bolts are grade 8 I believe.
 

Jonno Bee

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Thanks for that, I'll check the spec and replace if required. Being new they are much easier to remove!

Cheers,

Jonno
 

mrscalex

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Too wet and windy to do anything today. The car is in the garage but I like working in natural light so couldn't have the door open.

I took a few pictures quickly to remind myself of next steps.

Pulling everything out reveals the cross axle beam brake pipe runs. There can be some horror stories lurking here. And it's very difficult to determine condition with everything in situ. These aren't too bad but still not great. So they will be replaced over the whole front to back run.

IMG_0737.jpg
IMG_0739.jpg
IMG_0742.jpg


These are the old sections of pipe removed from the same area on the previous car I did. These were really nasty. One of the sections gave way as I was removing it! On this car I had to replace these rear pipes in sections as the rear end was still on.

IMG_0764.jpg


Pain in the a*se handbrake cables to remove where they enter at the rear of the handbrake. These ones are really wedged in. I couldn't shift them with the rear end in situ so I cut them. I expect I'll be able to get some mole grips on now after spraying them with releasing fluid.

IMG_0748.jpg


The photo also shows the underbody paint colour. After some research I found out this is the ecoat that BMW put on as a first stage in the factory. The shell is completely submerged and flipped 360 deg in the process. Then the paint is electrically bonded. I can only find one manufacturer who attempts to replicate this - SEM with their Ez Coat product. It even comes in the popular colours used by various manufacturers. They describe this BMW colour as light green. But it's not available in the UK. So I studied some RAL charts and took a punt on something. I'm not worried if it's not an exact match but I want to get quite close at least.
 

Althulas

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A5DFE875-9FD3-4B7D-9AF3-B2E0BC2BCFCE.jpeg


@mrscalex I used RTL 7002 in satin described as olive green but comes out lighter than a drab American tank olive green as you can see from my underneath a near match. If you try a different code I will be interested in your results.
 

mrscalex

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Fab thanks. You may mean RAL 7002? I've bought a can of RAL 1000 (Green beige). If that's not close enough I shall try your colour next.

Thanks again. Like to get it right!
 
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