Rear suspension refresh - essential to drop the diff?

[Salamander]

Hi!  This is Liesl, a 1976 2002 Base with 1974 Frankenparts... purchased from Craigslist.  She is running (barely) and driving (rough).  I am Sally (yes, a girl).

 

As a beginner shade tree mechanic, I chose to tackle suspension first.  With the help of Blunttech, IE, and Pelican, I have a good jump on parts.  I have read the Owner's Manual, BMW Service book, Haynes Repair Manual, 02' Restoration Guide, and BMW Workshop Manual.  I am also a voracious student/lurker of this site and am currently enrolled in the University of YouTube.

 

So... first noob question:  is it essential that I drop the differential with the rear subframe to "refresh" the suspension?  I am nervous about disconnecting the driveshaft, flex joint, and exhaust given I am currently playing at Level 1.  Thoughts, tips, and advice?

 

[rstclark]

No need to remove the diff to do suspension work. Change the springs and shocks to start. Take a look to see where all that oil is coming from. Front seal or rear cover Snug the bolts on the rear cover at least

[tech71]

14 hours ago, Salamander said:

is it essential that I drop the differential with the rear subframe to "refresh" the suspension?

No real need to drop the subframe unless you plan on changing swing arm bushings.

If you are planning on removing the subframe, for sure disconnect drive shaft and take the diff out first. Suckers heavy

Is that a rear subframe mount I see on top of your new struts?

Looks like you already have Bilsteins on rear at least, something wrong with them? Why new struts/shocks?

Edited May 29, 2023 by tech71

[bergie33]

Welcome Sally! Suspension is a great place to start. David on YouTube has a great video for suspension/subframe rehab. Have fun! 

[tech71]

Is that a hole in pass side inner CV boot?

Edited May 29, 2023 by tech71

[TobyB]

It entirely depends on what you want to 'refresh'-

 

from the pile of parts, I see a subframe bushing, and at that point,

it's so much EASIER to lower the subframe, clean it all up, change everything,

and then reinstall it.

And the diff comes down attached to the subframe.  You can leave the diff bolted to the subframe,

if you like.

 

You probably want a new guibo and driveshaft support, so that's not wasted time.

 

You probably don't have the neck muscles of an F1 driver, so that's saved pain.

 

You ought to go through the brake system on a new- to- you car, so that's not wasted time.

 

Yes, it's all 'mission creep' but that's just what we've all learned by horsing around with half measures!

 

Me, I say drive it a bunch, and see how worn out it is, and THEN drop the subframe.

It's an easy weekend job...  ok, it's not easy, but it's a weekend, tops.

If you have bushing pullers, etc, ready to go.

 

t

[Mike Self]

First of all, welcome to the 02 fraternity/sorority.  Looks like you've done your homework both WRT parts and instructions--and don't be shy about asking questions of the FAQ members.  We were all noobies once and are happy to share our combined wisdom.

 

WRT to your question:  You'll need to lower the subframe some if you're gonna replace the subframe mounts themselves.  That's a difficult job, especially if the mounting bolts are rusty/stuck.  If you find that, it's a job you just may want to farm out...

 

Replacing the diff mount can be done by simply supporting the diff on a jack, unbolting the old mount, lowering the diff a little and then installing the new mount.  

 

And yes, looks like a hole to me also.  Check and fix asap or the CV joint will soon be toast.  A quick 'n dirty temporary repair is to wrap several layers of Saran wrap around the boot and wire in place with thin wire or zip ties. 

1 hour ago, tech71 said:

Is that a hole in pass side inner CV boot?

 

I'm looking to replace the rear suspension bushings on my '73, and have been told by those who've done it that those bushings can be removed/replaced without dropping the subframe.  I made pullers/installers from thick wall plastic plumbing pipe, thick washers and 3/8" bolts when I did my front suspension and they worked just fine.  I'll be interested to see what other FAQers say about those rear suspension bushings/lowering the subframe.  

 

mike

[Georges]

I know it sounds like mission creep, but it really is easier to just replace all the rubber parts in one go (maybe two weekends if it's your first time). There is plenty of room and everything just bolts together. The only hard part I remember is pressing out old bushings and inserting new ones. I'd also stay away from polyurethane and stick with rubber unless your are planning for aggressive driving. There are some great youtube videos out there.

[Mark92131]

I see some nice new rear subframe mounts, so in order to get those installed, the subframe needs to be dropped.  This is not hard, but lots of opportunities for scope creep.  At a minimum, you need to drop the muffler, undo the rear brake lines, pull the emergency brake cables, unbolt the drive shaft from the differential, disconnect the rear shocks, unbolt the differential hanger and undo the nuts holding the subframe mounts and straps.  The whole rear subframe should drop down in one piece.  After that, it is just a matter of how deep you want to go.

 

1. New differential mounts?
2. New trailing arm bushings?
3. New rear brakes, (shoes, wheel cylinders, drums)?
4. New flex brake lines?
5. New emergency brake cables?
6. New rear axle bearings?
7. Paint or powder coat the subframe and trailing arms?
8. New spring pads?
9. New bump stops?
10. Rebuild the CV joints (disassemble, clean, new grease, new boots)?
11. Service the differential, (new rear gasket and seals, gear oil)?
12. New sway bar bushings?

If you get stuck, plenty of people here to help.  Take pictures of your progress and have fun...

 

Mark92131

 

 

 

 

[jgerock]

The suspension on these cars is the best part!  Have fun.

[jgerock]

While you are having fun, invite some friends over…

[Salamander]

Thank you all for the warm welcome and encouragement!

 

I tend to agree with those who said "You might as well..."  I don't know a lot, but it is evident the car has sat for a time and been neglected. 

 

In the spirit of learning, having fun wrenching, and to make the car safe and enjoyable, I'd like to service the car from bonnet to boot.  This is why I am choosing to replace the existing Bilsteins, etc.  The number of missing bolts, severed hoses, and stray wires in this car is staggering.

 

Unfortunately, I am sidelined today with a wicked cold.  But I am making another parts list to include servicing the CV joints and differential.  Stay tuned and thanks again!

[jgerock]

3 minutes ago, Salamander said:

Thank you all for the warm welcome and encouragement!

 

I tend to agree with those who said "You might as well..."  I don't know a lot, but it is evident the car has sat for a time and been neglected. 

 

In the spirit of learning, having fun wrenching, and to make the car safe and enjoyable, I'd like to service the car from bonnet to boot.  This is why I am choosing to replace the existing Bilsteins, etc.  The number of missing bolts, severed hoses, and stray wires in this car is staggering.

 

Unfortunately, I am sidelined today with a wicked cold.  But I am making another parts list to include servicing the CV joints and differential.  Stay tuned and thanks again!

Scope creep is a term used to describe working on anything old. It is accompanied by “while I’m in there” and “you might as well” and countless Social media frenzied folks’ comments who just love to help spend your money on car projects.

 

I applaud anyone who wants to wrench on their own project.  I learned from my next door neighbors and friends.  The FAQ crowd is here to help.

[mgben]

Lots of nice parts, I am sure you have all the tools. Trailing arm bushings are a treat. (I sent a link, in DM,).

Suspending the diff is too much work, just drop it all. 

This site is also good for how to 

cyclopticgaze - bmw 2002

WWW.CYCLOPTICGAZE.COM

 

Your old shocks look very nice, and someone here would use them.

 

[bergie33]

I don't think that is a hole in the cv boot. If you zoom in close, it looks like a hole on the wheel well in the distance behind the cv boot. Still though... While your in there...