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-   -   Thrust arm (http://www.bimmerfest.com/forums/showthread.php?t=480228)

lau814 08-27-2010 08:01 PM

Thrust arm
 
I want to order the thrust arm from ebay,anybody tell me how is it.
http://cgi.ebay.com/ebaymotors/NEW-B...Q5fAccessories

cn90 08-27-2010 08:49 PM

Stay away from this ebay seller "Deutsch Parts". They sell basically junks.
Want quality parts? Ask Mark @ EACTuning.com.

Lemforder or TRW brands only.

lau814 08-27-2010 08:52 PM

I want the quality like OEM.

cn90 08-27-2010 08:53 PM

Then stick to Lemforder.
Call Mark at EACTuning.com.

bluebee 08-27-2010 09:09 PM

Can someone break it to me gently ... What IS a thrust arm? What does it do?

Why do you guys replace them (how do we know if they're bad)?

I keep hearing this term but I have no clue what it is. :(

lau814 08-27-2010 09:32 PM

call Mark will cheaper than order online?

dms540i 08-27-2010 09:42 PM

Quote:

Originally Posted by bluebee (Post 5427679)
Can someone break it to me gently ... What IS a thrust arm? What does it do?

Why do you guys replace them (how do we know if they're bad)?

I keep hearing this term but I have no clue what it is. :(

I agree it's confusing jargon for what others may refer to as the control arm - see #5 in the link below. The culprit bushing is #6.

http://www.realoem.com/bmw/showparts...64&hg=31&fg=05

bluebee 08-28-2010 01:41 AM

1 Attachment(s)
http://www.bimmerfest.com/forums/att...1&d=1282984868

xraye39 08-28-2010 04:27 AM

Quote:

Originally Posted by bluebee (Post 5427679)
Can someone break it to me gently ... What IS a thrust arm? What does it do?

Why do you guys replace them (how do we know if they're bad)?

I keep hearing this term but I have no clue what it is. :(

Ahem.....using the search function for the E39(1997-2003) forums returns 585 hits for thrust arm.

Additionally Raj already has a great write up below
http://www.beisansystems.com/procedu..._procedure.htm

Fudman 08-28-2010 04:42 AM

Quote:

Originally Posted by bluebee (Post 5427679)
Why do you guys replace them (how do we know if they're bad)?
:(

Replacement is to correct a failure or as preventative maintenance when failure is imminent (e.g. after 70K miles). There are two things that fail on the thrust arm, other than the aluminum arm breaking, which can only happen on impact. The ball joints can fail (a more common occurance on the control arm) or the bushing can fail (leak). BMW uses a liquid filled bushing to maximize ride comfort. This is prone to leaking over time (after +70K miles). The recommended fix is the EACTuning solid rubber bushing, which cannot leak and fail, eliminating this failure mode. The degradation to ride quality is minimal and near-impossible to detect. Some people replace their own bushings but that is a bear of a job and it is much easier to buy replacement thrust arms with the HD bushing installed.

For the control arm, only the ball joint can fail as it already uses a solid rubber bushing.

bluebee 08-28-2010 08:17 AM

Quote:

Originally Posted by dms540i (Post 5427716)
I agree it's confusing jargon

Thanks dms540i for pointing out the control arm in the realoem diagram and the fluid-filled bushing which apparently leaks at around 75K miles.

It is confusing to me. Apparently RealOem calls the "thrust arm" a "Tension Strut" when it's on the I6 but they call it a "Traction Strut" when it's on the V8. I've also seen the abbreviations CABs & FCABs, which I duly added to the E39 glossary just now so others would benefit. Then there's the matter of the apparently similar, but different "control arm" ...

So that's at least four names I need to reconcile which seem to take the place of the "A Frame" of olden days ...
- control arm
- thrust arm
- traction strut
- tension strut

Quote:

Originally Posted by xraye39 (Post 5427933)
Raj already has a great write up

Thanks xraye. That Beisan writeup was pretty good.

At first I thought a thrust arm was the same as a control arm but the Beisan statement "The thrust arm is longer than the control arm" says otherwise.

Confusingly, Beisan calls the "thrust arm" the "upper control arm" and the "control arm" the "lower control arm" so that adds another set of somewhat confusing terms to someone who is uninitiated. Reading on, we find the "thrust arm" on the I6 is also called the "leading control arm" making the "control arm" the "trailing control arm". Much to my chagrin, on the V8, things reverse! :(

So that's now six (confusing) names for the same or similar things:
- thrust arm (longer than control arm, uses hydraulic rubber bushing)
- control arm (shorter than thrust arm, uses solid rubber bushing)
...
- upper control arm (i.e., the curved thrust arm, longer, rises higher to the frame)
- lower control arm (i.e., the straight control arm, shorter, rises lower to the frame)
...
- leading control arm (i.e., the thrust arm on the I6)
- leading control arm (i.e., the control arm on the V8)
...
- trailing control arm (i.e., the control arm on the I6)
- trailing control arm (i.e., the thrust arm on the V8)
...
- traction strut (i.e., the thrust arm on the V8)
- tension strut (i.e., the thrust arm on the I6)

Quote:

Originally Posted by Fudman (Post 5427953)
ball joints can fail (a more common occurance on the control arm) or the bushing can fail (leak)...recommended fix is the EACTuning solid rubber bushing...much easier to buy replacement thrust arms with the HD bushing installed...

Thanks Fudman, this is useful to note that the wear to look for at around 75K miles (I have almost 100K miles on my I6) is the thrust arm bushing leak or the thrust arm ball joint ... both of which can be resolved with a new thrust arm with "HD" bushings.

BTW, I didn't know what "HD" stood for so I first went to the BMW glossary which said it was for "heavy duty"; but I think you mean "solid" when you say HD (based on your context).

Searching for "HD" I find nobody defines it but they reference it as the "solid" bushing (so what does the "HD" stand for then?).
- Looking at Meyle HD everthing from OEMBimmerParts
- new thrust arms with HD bushing or replacing your worn out fluid filled thrust arm bushings with HD bushings
- I go the Meyle Thrust Arms with HD bushings.
- Meyle HD Bushing Set - This set is solid rubber to increase longevity compared to the stock, fluid filled bushing

Overall, this is very confusing; but I'm starting to get a handle on it, thank to the three of you!

540 M-Sport 08-28-2010 12:01 PM

The thrust arm bushing can fail well before 70k miles. I had a difficult to diagnose "knock" noise in fast right hand sweepers from about 30k miles up to aroun 65k miles when I was told the bushings were "toast" and need replacement. New oem ones got rid of the knock noise. Starting around 65k additional miles, I started getting some minor vibration through the steering wheel on braking from freeway speeds. An inspection found only a very slight crack in the bushing on the driver's side. Hardly worth replacing, but I went ahead and replaced them (along with control arms and center/left and right tie rods) using the upgraded Lemforder complete arms from EAC Tuning that have the solid rubber thrust bushings from Meyle installed. Amazingly, no more vibration on braking...so even a very minor amount of cracking on the bushing can be a source for vibration on braking.

Just an FYI.

BTW, I am not sure how long the Meyle will truly last, as I am not aware of anyone running them way out past 75k miles to verify durability...but the cost is not that much more, and I did not notice any difference in "harshness" over oem. I am told you definitely do not want to get polyurethane bushings. Many instances of not only harshness, but issues with them failing way sooner than oem even....like less than 10 or 15k miles. One other "trick" I am told is you can use X5 bushings in place of oem, which presumably will last longer....but now that Meyle has the solid bushing, that is probably the better alternative.

xraye39 08-28-2010 12:01 PM

Quote:

Originally Posted by bluebee (Post 5428193)
Searching for "HD" I find nobody defines it but they reference it as the "solid" bushing (so what does the "HD" stand for then?).

HD means Heavy Duty.

In this case the heavy duty design is a solid rubber bushing vs. a fluid filled one. Heavy Duty simply means its tougher.

MatWiz 08-28-2010 02:04 PM

Quote:

Originally Posted by 540 M-Sport (Post 5428584)
One other "trick" I am told is you can use X5 bushings in place of oem, which presumably will last longer....but now that Meyle has the solid bushing, that is probably the better alternative.

I think that the X5 bushings as well as the M5 bushing would fit into the 540 control arm, but not into the I6 cars. 540 bushings are wider I mean, thicker.

That is IIRC. I will gladly be corrected on this one.

mw

dms540i 08-28-2010 07:41 PM

Yes I couldn't agree more with Bluebee. This jargon is confusing, but Upper control arm = 5, Lower control arm = 12 in the Real OEM diagram below.

http://www.realoem.com/bmw/showparts...64&hg=31&fg=05

bluebee 08-28-2010 10:58 PM

1 Attachment(s)
Quote:

Originally Posted by dms540i (Post 5429307)
jargon is confusing

Oh my! Your new information adds yet another name for the same parts, i.e., the realoem diagram you refer to calls what you call the "#12 lower control arm" the "#12 wishbone".

This new "wishbone" term makes it an even dozen names for the 2 "arms":
- thrust arm (longer than control arm, curved, hydraulic bushing)
- control arm (shorter than thrust arm, straight, solid rubber bushing)
...
- wishbone (i.e., the leading control arm on the V8, straight, shorter, solid bushing)
- wishbone (i.e., the trailing control arm on the I6, straight, shorter, solid bushing)
...
- traction strut (i.e., the curved thrust arm on the V8)
- tension strut (i.e., the curved thrust arm on the I6)
...
- upper control arm (i.e., the curved thrust arm, longer, rises higher to the frame)
- lower control arm (i.e., the straight control arm, shorter, rises lower to the frame)
...
- leading control arm (i.e., the curved thrust arm on the I6)
- leading control arm (i.e., the straight control arm on the V8)
...
- trailing control arm (i.e., the straight control arm on the I6)
- trailing control arm (i.e., the curved thrust arm on the V8)
...
http://www.bimmerfest.com/forums/att...1&d=1283061457

bluebee 08-28-2010 11:33 PM

1 Attachment(s)
It seems that there are at least 3 different names for each front suspension arm, with two different arms, and two models, for a total of 12 unique names (i.e., each arm has three unique names).

Above you see the three unique names for each of the V8 front suspension arms; below I created a picture with the three unique names for the I6.

Let me know if I made any mistakes as this is confusing at best.

http://www.bimmerfest.com/forums/att...1&d=1283063576

bluebee 08-29-2010 12:34 AM

1 Attachment(s)
Actually, there are FOUR different names for each front suspension arm.

Below is a summary for the E39 I6 (which is what I have).

Let me know if I made any mistakes trying to summarize the fundamentals.

http://www.bimmerfest.com/forums/att...1&d=1283067251

bluebee 08-29-2010 12:53 AM

1 Attachment(s)
Since many of you have the V8, I figured I'd correct those figures also with the FOUR terms for each front suspension arm.

In the future, when people ask about these parts, we can refer them to one of these two diagrams (depending on their vehicle engine).

Again, if I made any mistakes summarizing, please set me straight.

http://www.bimmerfest.com/forums/att...1&d=1283068367

bluebee 08-29-2010 01:05 AM

For the record, I updated the BMW E39 glossary with the following summary:

E39 I6 front suspension arms:
- Thrust arm (common name) = tension strut (BMW name) = leading control arm = upper control arm
- Control arm (common name) = wishbone (BMW name) = trailing control arm = lower control arm

E39 V8 front suspension arms:
- Thrust arm (common name) = traction strut (BMW name) = trailing control arm = upper control arm
- Control arm (common name) = wishbone (BMW name) = leading control arm = lower control arm

Note: Let's not even think of calling these things "rods" as that adds yet another set!

anomal 08-29-2010 06:47 PM

Glad you guys got the terminology straight. It really is comical that we have 4 names for the same thing...

+1 On EAC's thrust arms.

I was told that my front end could not be aligned due to my thrust arms. I ordered Lemforders w/ solid bushings pre-installed by EAC. Taking my time, I had both installed in less than an hour. My front end felt much better. I have a firm Bilstein/H&R setup. Solid bushings might be noticeable with stock suspension, but not mine.

Mark@EAC 08-30-2010 09:14 AM

http://www.eactuning.com/e39-thrust-...ngs-p-453.html

Thanks for the recommendations guys. We sell a lot of these arms and we believe these are the best solution available for the thrust arm bushings. I've installed them on a couple e39s personally and they really improve the ride and overall handling of the car. They take a lot of slop out of the front suspension and cure the braking shimmies that can come from worn out stock bushings. It's one of those "this is how it should have been all along" things.

cn90 08-30-2010 09:19 AM

1+,

I did a complete front suspension overhaul in Sept. 2009. It is now one year later, the thrust arm with Lemforder + HD bushing from EACTuning rocks.
The car rides smooth like silk even at 100 mph (I don't encourage speeding but I found an empty stretch of highway in the middle of Iowa with no cops and was trying to push the car to the limit ha!).

Yes, get the thrust arm with Lemforder + HD bushing from EACTuning.

bluebee 08-30-2010 10:40 AM

1 Attachment(s)
Quote:

Originally Posted by Mark@EACTuning (Post 5432213)

Hi Mark,
I can't access that site ... here's the message:
http://www.http.com//www.eactuning.c...ngs-p-453.html

Unable to connect. Firefox can't establish a connection to the server at domains.googlesyndication.com.

I have all sorts of anti-spyware stuff so I'm sure it's just me (my browser) blocking it but why do you need "googlesyndication" anyway?

If I modify the link you provided to "http://www.eactuning.com/e39-thrust-arms-with-hd-bushings-p-453.html", it works just fine.

Anyway, I wanted to confirm what little I know of thrust arms.

Is this the general recommendation (for a 2002 I6)?
0. If you notice braking-related shimmy (or if you just want to perform preventive maintenance) ...
1. Drive up on ramps (the cn90 way, not the bluebee way!) and look at the bushings at the end of the stock thrust arms
2. If you see leaks or cracks, then get on the phone with you
3. The recommendation, I think (correct me if I'm wrong), is NOT to buy the OEM bushing itself, nor to buy the HD (aka solid) bushing itself, but to buy the entire (Lemforder or TRW?) thrust arm with the (Meyle?) HD bushing already installed by you wonderful guys.

Q: Is that the correct procedure (or is there more that I missed either in the debug steps or the items to purchase)?

PS: Your web page says "loose" when I think you mean "lose" ... :)
PSS: Your web page says "thrust arm, tension strut" but that's only for the I6. It would be "thrust arm, traction strut" for the V8 ... right?


http://www.bimmerfest.com/forums/att...1&d=1283190010

Mark@EAC 08-30-2010 11:22 AM

sorry corrected my link above. Had an extra http:// on there. I will see that the grammar on the item page is corrected too.

We do not get wrapped up in the tension control reverse noodle linkage terminology. You can call the arms whatever you want. They are thrust arms, whether for V8 or I6. All you need to do is select the appropriate arms for your car from the drop down box. We have made it simpler than falling off a log for you.


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