850 rear strip down and rebuild

[Luis Malhou]

850 REAR STRIP DOWN

The 850 is now parked after the last Breakfast run on Sunday and the long overdue rear end is coning off.

The unflattering waddle and rear end rattles will be coming to an end. Jacked the car in the air last night and will be doing a thread on the following work.

1. Remove the complete rear end suspension.
2. Rear brake system to be removed ,
3. Remove rear bumper and all parts
4. Fuel Tank and all pipes to be removed
5. Diff and side shafts removal
6. Under carriage clean up and remove and treat any bare or damaged areas and rust treat.
7. All rear suspension bushes removal and replace (18 in total. all new OEM from BMW) already arrived
8. All suspension parts to be sandblasted and powder coated or sprayed with Poly Urethane paints
9. New fuel lines
10. Tank cleaned inside and outside, new hoses and clamps
11.. Bolts an nuts replaced or electro Nickel Plated
12. Bumper parts sandblasted and powder coated or Poly sprayed.
13. New bilsteins sports shocks installed, redo rear coils, re-temper the coils to original compression strength
14. New Brake lines
15. Diff serviced, cleaned and sprayed
16. Side shafts overhauled,
17. Re-assemble and look forward to a excellent new ride and feel!!

This going to be long job but once done, the car will be one of a few 850 that have been rebuilt from front to back and be clean!!

 

[RAArmstrong]

This is going to be awesome! Cant wait to see your progress :thumbs:

 

[herr bmw]

will be following this thread :thumbs:

 

[b3rg]

Sounds like an awesome project :thumbs:

Goodluck and please post lots of pic's :rollsmile:

 

[Bugger]

Subscribed.

 

[ChefDJ]

Can't wait to see the process and final result :bravo:

 

[MikeR]

:fencelook: lets see the breakdown pictures

 

[Rayzor]

Nice project, please dont forget to upload pics :rollsmile:

 

[Jeremy]

:bravo:

 

[The Meatman]

Hi,
i have recently completed a total refurbish of a 1995 BMW 840CI. Nothing left as old or unfixed. Stripped down to the body. Every part of under carriage sand blasted and resprayed with Hammerite and baked for 48hrs. Resprayed by BMW Auto Atlantic to original colour spec. Totally new. Looks like an M3 on steroids. A dream to drive.

 

[Luis Malhou]

I am aiming for that at the end of the day. Looking at my past threads I have gone through the car front to back as I can afford.
After this I will be left to do the leather refurb and the respray. Then she should be like new.

 

[Revv - zn]

Subscribed

 

[The Meatman]

Leather refurb.
i do not think they come much better than McCarthy Auto trimmers. they re-did my entire interior. re-touched and fixed scratches on the plastic parts etc, etc, they know car interiors, not just leather.

 

[Luis Malhou]

So 2 hours worth of work. Removed rear bumper and brackets. Wheel arch covers and all plastic components. Had to grind of some rusted bolts, new ones to replace.
Without my 1000nm torque wrench I dont think I would have got the main wheel bolt off to remove the hub. bloody tight as hell.

Discs removed and sprayed all the nuts and bolts I could find. Have loosened most of them.

Next step is taking the side shafts and diff. Then I can drop the main frame of the suspension. Its a huge stretched X shaped mounting frame with a rubber bush on each corner. Other than the trailing arms nothing else connect wheels to the car.

I have taken on quite alot of work but the benefits will be worth it.

You can see the selection of bushes, Still a few from the UK coming and 1 that BMW lost and is replacing.

Tedious job to do on your own, lots of dirt, etc coming off. I purchased some Mechanics Gloves awhile back and were worth it, following in Chris's footsteps. Also some dust googles keeps the dust out your eyes, but my best purchase was a creeper.

Hope to have all the parts out by then end of the weekend.

 

[Luis Malhou]

So Sunday saw me climb into some further stripping.

Remove hand brake cables, unplug and unroute all the wiring.
Unbolt and mark prop coupling. Some more heat shielding and covers removed.
Some major effort to loosen the 4 main bolts holding the whole suspension, diff to the car.

3 hrs later suspension is lowered on a jack.

Now further stripping can occur of all the arms, remove the diff and the side shafts which I can see is going to be a pain as the cap screws are all rusted, so I think Its best to cut them off and replace with new ones in any event.

Removing the side shafts from the hubs I think will prove to be interesting just looking at it.

 

[JayDrft]

Hi Luis,

Good going on the tear-down....

My advice, for the rusted and tight bolts....invest in a pneumatic impact wrench, its going to make your life a lot easier than grinding bolts and extracting them later....I learnt this over 2 weekends ago...

Hope the advice helps.

Keep on keeping on!!!:thumbs:

 

[Luis Malhou]

Thanks Jaydrift,

The big bolts are all loosened, those I can handle, all a impact wrench delivers is brut strength, That I have!. The cap screws on the side shafts are the big issue.
1. The holes are rusted and with a cap skrew socket they round off the holes and then your are f$%#

I have learnt, cut the heads off and I have a special tool to grab the remainder bolt shaft once the side shaft has been removed. It simplifies everything. Done it this way a few times on a few cars, cant understand why BMW keeps using cap type when either a torque or std hexagonal bolt will do.

I replace the bolts with torque type bolts afterwards.

Next is the fuel tank and all its pipes. Then will do a major cleanup of the underside.

 

[Luis Malhou]

So been some time since I posted progress on the 850 rear end rebuild.

So all the good came out and its been a time to clean, scrub, swear, paint and fix and replace all that I can.

Not often you strip a car down like this so its a good time to do EVERYTHING once and it will be ok for another 30years..(I hope)

So once the fuel tank cam out I cleaned it inside and out, replaced all the clamps and rubber hoses with new hoses, soft and fresh. All the gunge inside the tank was washed out and pipes blown clean with air to make sure they are free of any dirt.
New sponge pads fitted, this where it rubs against the steel body of the car and where I found most of the rust. Also caused because BMW used sponge between the tank and the body, any water gets soaked up by the sponge and results in rusting.

Anyway I climbed in uderneath with scraper and various wire brush tools to remove the surface rust, luckily no where was there holes or severe rust.

All the areas were treated with 3 coats of Dinotrol rust converter and epoxy. The the whole undercarriage received 2 coats of rubberizing spray just for added peace of mind.

The bushes were removed from the various arms then the bits were cleaned with wire brushes, electric drill with various attachments then degreased and sprayed with some coats of Plascon Epoxy black. The areas where the bushes need to be pressed in were hone with the same tool we use to clean the cylinder heads and the new bushes pressed in. This after the bushes were left in the freezer to add some shrinkage to their size.

The side shafts have been completly stripped down, some of the parts are being nickel-plated and then I will rebuild them with new grease etc. The boots will still in good nick so they will be re-used. They are soft and with no cracks so they will last a long time still.

The diff has been stripped, new gaskets, o-rings and oil seals going back in. The diff was quiet so I will not be doing bearings. Rear cover also sprayed and new nickel plated bolts finish off the diff.

The rest of the suspension was totally stripped down and brackets etc, arms all been sent for powder coating in gloss black. The springs and anti-roll bar a nice racing red!

The large X-Box framed suspension unit and rear bumper bracket were sent for sandblasting and then to be galvanized to make sure they never rust again.

I remove the old fuel lines and I bent up some new ones form 10mm alu tubing and a handy R99 pipe bender.

The biggest pain has been one of the stub axles which has Stubbornly refused to budge out the carrier. I bought a 10t press from a lady in PTA for R1000 to allow me to press and replace bearing, bushes and so forth on my own. 10T wouldnt move this shaft.

Sent it to a friend of mine and his 20t press also failed, so off to his son in law's Heavy Eng place this morning where his 250t press eventually succeeded in pushing the shaft out at 80T!!

Hoping to start assembling by weekend to have it ready for Angela's picnic.

So far time spent on this rear build around 90hrs and another probably around another 20hrs before I am done.

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[RAArmstrong]

Good going Luis :thumbs:

Can't believe it took 80T of force to get those shafts to budge! :shocked:

 

[Luis Malhou]

My Newest toy in Tools