E46Fanatics

E46Fanatics (http://forum.e46fanatics.com/index.php)
-   Suspension & Braking Forum by BimmerWorld (http://forum.e46fanatics.com/forumdisplay.php?f=97)
-   -   So, you wanna service the rear trailing arm? Definitive Trailing Arm Guide (http://forum.e46fanatics.com/showthread.php?t=1006058)

Mango 09-18-2013 12:09 AM

So, you wanna service the rear trailing arm? Definitive Trailing Arm Guide
 
1 Attachment(s)
Definitive Trailing Arm Guide

This thread will guide you on how to properly service your rear trailing arm.

BMW has been using the rear trailing arm for decades. Its design coupled with careful suspension tuning has been one of key ingredients to BMW's dynamic driving qualities.

The BMW rear trailing arm serves for the backbone of the rear suspension/wheel/wheel bearing/brakes and is designed to provide toe-out under heavy acceleration and toe-in during heavy braking. These characteristics is to stablize the vehicle.

The rear trailing arm bushings AKA "RTAB" (as pictured in blue) helps deflect vibration and harshness while absorbing shock mid-corner which could otherwise upset the vehicle's stability.

These bushings fail quickly and often because they are high-load items and a lot of work is asked of them. Typical life expectancy is anywhere from 35,000 to 70,000 miles. The effectiveness of these parts are not an "on/off" switch and their performance degrades over time as the rubber deteriorates. You may not feel that you need new RTABs if you have slowly become used to their gradual decline in performance. Common signs of failure of the RTAB includes rear-end wandering often tmes under acceleration or braking or in more severe cases, clunking noises.

The other two components pictured are the rear trailing arm bushing and/or balljoint. These items are (as pictured in red and green). These are also serviceable items but do not wear as quickly as the rear trailing arm bushing.

Note that non-M models come with a bushing at the lower location and balljoint at the upper location.

///M3 models come with balljoints at both upper and lower locations for improved feel and control.

This dual-balljoint setup can be applied to non-M models using ///M3 parts. (Thanks to CPOSK)

Rear trailing arm bushing:

http://forum.e46fanatics.com/attachm...1&d=1379476693

http://www.turnermotorsport.com/imag..._carm_bush.jpg

Replace these at 60,000+ miles. Personally, I recommend replacing them every 20,000 miles.

M3 Rear Trailing Arm Bushing Part number (upgrade): 33326770817 (Two per vehicle)

Comments and Concerns Addressed:

Q) When should you change your Rear Trailing Arm Bushing?

A) If they are original or you don't know. If you get rear-end wandering or the rear end is unstable during acceleration or braking.

Q) But what about polyurethane?

A) I don't recommend it. On a street-driven vehicle, this bushing should be rubber. Polyurethane is not ideal for multi-axis movement and not meant for this location. I would avoid this type of bushing here.

Q) But, Mango... what about pre-load?

A) There are documented ways to do this but I've found the easiest way is to mark the position of the rear trailing arm carrier in relation to the arm after the arm is dropped. Simply re-torque the carrier after installation of the new bushing after it is aligned with the mark you made. I found on several vehicles the trailing arm bracket lined up perfectly with a line cast into the control arm. The goal is to have zero load on the bushing at rest.

Q) What tools do I need?

A) For the RTAB, the MIS RTAB tool. For the upper and lower balljoint/bushing, you need a special press for them. These can be found on Amazon and eBay such as here.

Q) What brands do you recommend, Mango?

A) I recommend Lemforder for all three locations. Personally, I am using OEM M3 parts for all three parts.

Tips:

Some people use "limiters" which are essentially plastic shims that go on either side of the rear trailing arm bushing. These spacers limit trailing arm movement within the pocket and can extend the life of the bushing.

Limiters

Before dropping the trailing arm, disconnect the brake line from the trailing arm via a 10mm bolt. This is important.

Use a large hose clamp to compress the split bushing before pressing it into the trailing arm. Press into the trailing arm on the side of the trailing arm with a beveled edge.

Torque carrier to trailing arm bushing center bolt @ 81 ft-lbs and bushing bracket to body @ 57 ft-lbs

Trailing Arm Bushing (lower and upper)

http://www.turnermotorsport.com/imag...ng_bush_lg.jpg

As mentioned above, this is a rubber mount. This can be upgraded to ///M3 balljoints.

Rubber mount part number (2 per car on non-M models): 33326771828 :thumbdwn: :thumbdwn:

http://www.4wheelsautoparts.com/imag...771828-LEM.jpg

M3 balljoint part number (2 per car on non-M models and 4 per car on M3 models): 33326775551 :thumbsup:

http://www.bavauto.com/assets/produc...3326775551.jpg

These are torqued to around 78 ft-lbs (99% sure) if someone can find the official spec, I'd appreciate it.

Tips:

Remove rotor and set caliper aside. Mark your camber position before removing your camber bolts.

An alignment is recommended when servicing any of the above items.

Evo Panda 09-18-2013 12:30 AM

Re: So, you wanna service the rear trailing arm? Definitive Trailing Arm Guide
 
Awesome write-up! Thanks!

David McMahon 09-18-2013 02:43 AM

Planning on buying this tool as the MIS tool is expensive to buy in the UK after shipping http://www.ebay.co.uk/itm/BMW-3-Seri...item3f28862c28

Megalocnus 09-18-2013 02:43 AM

Very nice Mango. Does the car feel different after replacing the trailing arm ball joints?
Did you forget or chose not to comment on the RTAB limiters?

NoGuru 09-18-2013 06:06 AM

:thumbup:

Mango 09-18-2013 10:31 AM

Quote:

Originally Posted by Megalocnus (Post 15714979)
Very nice Mango. Does the car feel different after replacing the trailing arm ball joints?
Did you forget or chose not to comment on the RTAB limiters?

Oh yeah. Limiters. Yeah I supposed I could add those. It feels slightly more direct with slightly more noise in the back. I've gotten used to it now. Basically it will feel similar to an M3 with M3 RTABs. I believe the M3 shares all other rear control arm bushings

Brad W 09-18-2013 01:33 PM

Thanks Mango. I've got the RTAB's on my list.

Quote:

"The other two components as pictured are the trailing arm balljoint and trailing arm bushing. These are also serviceable items but do not wear as quickly as the rear trailing arm bushing."
what mileage to you consider these to be completely shot? I think this is what you consider to be the Stage 3 job in your suspension write up right?

Mango 09-18-2013 01:34 PM

Quote:

Originally Posted by Brad W (Post 15715770)
Thanks Mango. I've got the RTAB's on my list.



what mileage to you consider these to be completely shot? I think this is what you consider to be the Stage 3 job in your suspension write up right?

I would say around 40,000-60,000 miles of use, they are "completely" shot for use in their intended purpose

Brad W 09-18-2013 01:46 PM

that means mine are probably shot considering I just turned 87k this morning. what are the alternatives on tools for this job? (other than paying someone else to do it). Does Harbor Freight have a cheap option? Do places rent that kit?

I've seen a variety of options for the RTAB tool, but even to buy it isn't too big a hit on the wallet. That other bushing set is a bit steep.

What other fancy tools are needed just to get to the point of using that bushing tool set?

Quote:

These require tons of labor and special tools. These are for the pickiest of picky. You'll need an E36/E46 rear axle service kit which can be found on eBay
I might be out of my league with the stage 3 suspension refresh. How compromised is the car if this one is overlooked?

doubleda 09-18-2013 06:51 PM

got this on my list
 
OK, great write up, thanks !! OK, do you have to remove the whole arm from the car to replace JUST the RTAB with the M3 part ??? I know I will need the special tool. thanks .....

doubleda 09-18-2013 06:52 PM

Also ...
 
Sorry .... what do you think of having the reinforcement plates that you weld onto the rear camber arm to strengthen them ????

Brad W 09-18-2013 07:07 PM

I've lightly glanced at DIY's for the RTAB's, you don't have to remove the whole arm from what I can tell.
http://forum.e46fanatics.com/showthread.php?t=678004

Mango 09-18-2013 07:11 PM

Quote:

Originally Posted by Brad W (Post 15715811)
that means mine are probably shot considering I just turned 87k this morning. what are the alternatives on tools for this job? (other than paying someone else to do it). Does Harbor Freight have a cheap option? Do places rent that kit?

I've seen a variety of options for the RTAB tool, but even to buy it isn't too big a hit on the wallet. That other bushing set is a bit steep.

What other fancy tools are needed just to get to the point of using that bushing tool set?



I might be out of my league with the stage 3 suspension refresh. How compromised is the car if this one is overlooked?

No good or cheap alternatives. Some people have gotten by making their own tools. I tried. Snapped the tool twice. You need solid blunt precision machined tools for this job.

Quote:

Originally Posted by doubleda (Post 15716631)
OK, great write up, thanks !! OK, do you have to remove the whole arm from the car to replace JUST the RTAB with the M3 part ??? I know I will need the special tool. thanks .....

You don't need to remove the trailing arm to replace the bushing, no. As long as you use the correct tool.

Quote:

Originally Posted by doubleda (Post 15716634)
Sorry .... what do you think of having the reinforcement plates that you weld onto the rear camber arm to strengthen them ????

Fine for track use. But for street use there is an increased risk as you could overload your subframe/chassis causing permanent damage from a simple curb strike. The stock arm is designed to deflect under impact.

Quote:

Originally Posted by Brad W (Post 15716662)
I've lightly glanced at DIY's for the RTAB's, you don't have to remove the whole arm from what I can tell.
http://forum.e46fanatics.com/showthread.php?t=678004

Correct

BigDRick323 09-18-2013 10:48 PM

Re: So, you wanna service the rear trailing arm? Definitive Trailing Arm Guide
 
I am getting ready to do this on my sedan, thinking of going to the m3 setup, anything else i should do?

Sent from my LG-MS870 using BimmerApp mobile app

Mango 09-18-2013 11:45 PM

Hmmm... well I'd do the double balljoint upgrade as well but that's going to require more tools.

Hogan773 09-18-2013 11:51 PM

Even though people sometimes poke fun at Mango, I will say that he is a wealth of information and this writeup is a great example. Nice job

ClaytonL 09-19-2013 12:17 AM

Re: So, you wanna service the rear trailing arm? Definitive Trailing Arm Guide
 
Quote:

Originally Posted by Mango (Post 15717160)
Hmmm... well I'd do the double balljoint upgrade as well but that's going to require more tools.

I want to do this so bad!!!!!
I just dont want to go through another alignment. Ive pissed all my shops off around here with how picky I am.

Sent from BimmerApp mobile app

Mango 09-19-2013 02:29 AM

Quote:

Originally Posted by ClaytonL (Post 15717202)
I want to do this so bad!!!!!
I just dont want to go through another alignment. Ive pissed all my shops off around here with how picky I am.

Sent from BimmerApp mobile app

If your trailing arm bushing (lower) is in good condition, you can get by with the M3 balljoint upgrade without an alignment.

Mr Podman 09-19-2013 05:45 AM

Try to add methods for determining excessive wear and a DIY replacement procedure complete with lot's of pictures.

In it's current form, it's an incomplete piece, low on critical information with too much editorial. For example, I really don't care if you want to change yours ever 20,000 miles. I'd rather you explain the criteria for deciding when to change them out, with inspection procedures and example pictures. That information is completely missing.

Also, you might want to mention your recommendation for performing an alignment early in your post rather than sneaking it in on the last line of your post. It's a key consideration when deciding whether to tackle these tasks DIY vs. paying a shop to do it. Include web links to the very best additional DIY resources that exist.

sunsetcoast 09-19-2013 08:52 AM

Quote:

Originally Posted by Mr Podman (Post 15717434)
In it's current form, it's an incomplete piece...with too much editorial.

+1. For example, what is the reason to choose the balljoint type bushing from the M3 vs the standard one?


All times are GMT -5. The time now is 11:29 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
(c) 1999 - 2011 performanceIX Inc - privacy policy - terms of use