Rear Sway Bar Bracket Cracking Solution

[HBalzanya]

I have a 01 M5 that keeps breaking rear sway bar brackets (33552283159), always in the same place the same way. That wouldn't be a huge problem if the brackets weren't so expensive. After buying two OEM alloy brackets within 5,000 miles, I got tired of dealing with a part I know is going to break again due to a bad design.

So I called up a friend of mine who used to work in the auto manufacturing industry, sent him one of the broken brackets and asked if it could be done better. The solution he came up with was simple, make the bracket exactly the same way but make it out of something strong enough that it won't break from normal use. Instead of making brackets out of aluminum, just make them out steel. Not only are they less expensive, but they won't break under normal use because steel is many times stronger and stiffer than aluminum. Not sure why BMW didn't do this but then again, they love making things out of plastic, so this must have been one of those "things" they do.

Anyway, they've been installed on my car for 2,500 with zero issues, no special bushings or anything just OEM. Since they worked so well he decided to make a run of them to sell. Full disclosure, I got mine for free for testing them, but the rest of this is his deal.

https://www.ebay.com/itm/143830785168

20200601_130444.jpg

Steel Bracket - 03.jpg

[Twistytee]

The standard e39 sway bar brackets are made of steel vs aluminum on the M5. Not sure of the engineering rationale for putting aluminum brackets on a higher torque car like the M5, but you can use the regular brackets on the M5 bar as they’re the same dimension.

[BimmrMeUpSnotty]

They’re all aluminum on E39’s. You need to order the ones from an E38. No need to bug friends in the parts manufacturing circles....

[JimLev]

After I put the Eibach sway bars on my 540 both of my rear aluminum brackets pulled out from the top.
I bought the steel brackets that are used on the E38. That was 6 years ago, no problem.
I have broken the front steel sway brackets, they won’t stand up to years of quick sharp turns if you have the Eibach 28mm front bar and polyurethane bushings. The fix is to weld gussets on the ends of the brackets.

[Twistytee]

They’re all aluminum on E39’s. You need to order the ones from an E38. No need to bug friends in the parts manufacturing circles....

Interesting. Good to know. When I bought my rear bar from Clemster he said non-M5s used steel. Never thought to check figuring he parts out so many of them.

[claylakem6]

Another solution, BeastPower brackets. Well made. Although my Dinan bar came with an additional reinforcement piece similar to a square washer with longer bolts.



Sent from my iPad using Tapatalk

[Stillmatic718]

Interesting. Good to know. When I bought my rear bar from Clemster he said non-M5s used steel. Never thought to check figuring he parts out so many of them.

Is it installed on this 530i? I just purchased one from Clemster. SMH

[HBalzanya]

General responses:

The E38 bracket is the same as the E36/E34, it's not a special bracket nor does it fit right on an E39. The E39 has an aluminum subframe whereas the older chassis had steel subframes. The steel subframe has a hump that is raised away from the subframe for the rear sway bar tab to slot into, the E39 uses aluminum which has a slot instead of hump.

That's why the E39 piece had to be taller, it's effectively the same concept as the E36 bracket but because the subframe is a different design so is the bracket. In fact, the E36 bracket is about 6mm (1/4") shorter than the E39 which may not sound like a lot, but it shifts the way the entire brackets sits. Jamming the stock bushing into the E36 bracket deforms the bushing and puts the sway bar into bind which can cause handling/stability issues. That is unless you hack and slash the bushing up but even then, it won't ever be right and could still have the binding issue.

The Beast Power part is a fine piece but it's expensive and you had to buy them in pairs.

The point of making these was to provide a proper, cost effective fix for a known problem that has personally affect me along with many others in the 5 series community. Before this you had three options, open up your wallet for OEM which will break again, open up your wallet for Beast Power and run poly, or hack and slash your bushings to make the E36 bracket "work." Now there is a bolt on solution that is exactly the same as OEM, but it's steel so it won't break and it's significantly less expensive. Not only that, but these are made in small run by a US fabrication company. No one involved in this is getting rich by selling sway bar brackets.

[philly98540]

I like what you made and its the most cost effective solution. The E38 brackets are too short and require bushings to be trimmed. Not a big deal, but yours is better. Nice job.

[claylakem6]

General responses:

.....
The Beast Power part is a fine piece but it's expensive and you have to use polyurethane bushings which can make noise and/or cause binding issues.......

The BeastPower do not require poly bushings. I am using rubber nor is the information provided with brackets indicate a requirement for any specific type of bushing. Price is $119 w/ free shipping.


Sent from my iPad using Tapatalk

[JimLev]

If you use the synthetic grease that comes with the poly bushings it doesn’t squeak.
If it binds on your E39 you did something wrong.

[cnsorial]

Nice! Do you know if this would work with a Dinan rear sway bar?

Thanks!


Sent from my iPhone using Tapatalk

[JimLev]

Nice! Do you know if this would work with a Dinan rear sway bar?

The E38 clamps??

[cnsorial]

The E38 clamps??

Oh sorry, I was asking about the clamps the OP posted about. But also curious if the E38 clamps work w the Dinan bar too


Sent from my iPhone using Tapatalk

[HBalzanya]

The steel brackets are the same shape as the OEM which it appears the Dinan pieces were designed to work with, should work fine. The E38/E36 bracket could work but again, you're going to have to slice up the bushing to get the bracket to bolt on and even then, the bar may not work properly due to binding.

In general, BMW uses one sway bar bracket that fits all the sway bars for a given application. The way they make multiple different sway bars work is by changing the bushing size, the bigger the bar the bigger than hole in the bushing. These brackets will work for any bushing designed to fit OEM one.

Oh sorry, I was asking about the clamps the OP posted about. But also curious if the E38 clamps work w the Dinan bar too


Sent from my iPhone using Tapatalk

[HBalzanya]

Original posted changed to reflect that information. The reason we created these steel versions was to offer something that is a cost effective OEM+ part. Again, the Beast Power piece does the job, but it's far more expensive than this offering which is main reason we made it to begin with.

The BeastPower do not require poly bushings. I am using rubber nor is the information provided with brackets indicate a requirement for any specific type of bushing. Price is $119 w/ free shipping.


Sent from my iPad using Tapatalk

[StephenVA]

Thanks for making them and posting. I will be ordering a few sets later this week. On my M5 I have the poly bushings and the Beast Brackets. As JimLev mentioned above, they work as designed and with the synthetic grease there is ZERO noise from the bar/bushings.

[Jason5driver]

Original posted changed to reflect that information. The reason we created these steel versions was to offer something that is a cost effective OEM+ part. Again, the Beast Power piece does the job, but it's far more expensive than this offering which is main reason we made it to begin with.

Does the Ebay item listed come with the 2 brackets required ?
# 3 :
https://www.realoem.com/bmw/enUS/sho...diagId=33_0517

So, the ebay listing is for $20 .... $20 for the 2 ebay steel brackets , correct ?
Thanks,
Jason

[JimLev]

Oh sorry, I was asking about the clamps the OP posted about. But also curious if the E38 clamps work w the Dinan bar too


Sent from my iPhone using Tapatalk

Should work fine with the Dinan bar too.

- - - Updated - - -

Does the Ebay item listed come with the 2 brackets required ?
# 3 :
https://www.realoem.com/bmw/enUS/sho...diagId=33_0517

So, the ebay listing is for $20 .... $20 for the 2 ebay steel brackets , correct ?
Thanks,
Jason

Looks like it’s for one clamp.
The last line in the eBay post says.....
We recommend replacing the brackets in pairs for a worry-free set up.

[Trasportador]

My passenger side rear bracket was breaking every couple of months on my eibach rear sway. I bought the beast power brackets, got tired of the nonsense.

[Kevyo2]

I bought a pair of these for my 2002 M5. I have bought OE brackets (when they were cheap) and they broke again. I ordered the E38 bracket and tried to install it. The leg of the hoop with the tab was too short and it was not a good solution so I bought another OE bracket (now $80) that recently broke. I had some discussion with JimLev on another post and I offered to do a write up on the E38 bracket and the OE equivalent steel bracket, here goes:
First, a little back ground on me. I was a Market Quality Engineer (title, Staff Engineer) with a Major OE for 35 years, during that time I was assigned several specialties and at least one model. I was the chassis specialist that included brakes, suspension, steering, tires, handling and NVH. I have been on many tracks like Mid-Ohio, Waterford Hills, Riverside Raceway, Buttonwillow, Willowsprings etc... And have spent a bit of time at Michelin Americas Research & Development Corporation Marc in Greenville SC. I came to be an M5 owner when back in early 2000 we were benchmarking a vehicle that was in development against competitor vehicles. We had and Audi A8, Jag XJR, E39 540, E39 M5, Cad CTS and a few others. I was able to drive all the cars on a skid pad, wet handling course, max (dry) handling course and the public roads nearby as well as use as a daily driver for as long as I could. I called home my fist night and told my wife that I found the car I wanted. I had young children at the time, one income and a free car from my employer so it was a while before I could get and M5 and it wasn’t new. It can be a bit of a PIA at times but I really love driving it.

First I would like to point out that the bracket that we are calling the E38 bracket is really a single bolt bracket that is made of steel. It was first used on the E24,28,32,34,36,46 (non M), 52 and Z3 and Z4. BMW was smart to use the same bracket for so many cars and just spec a different busing for the bar, like 13mm, 14mm and 15mm. So the ID changes for the bar diameter but the tooling for the bushing OD and the bracket can be used on a lot of vehicles; smart. The single bolt design was flawed and flexes, especially while entering driveways at an angle. I know this because I had data on end link and bracket fatigue failures for people in metro vs rural areas. The E46 M went to a two bolt bracket for two reasons, the stiffer bar caused more flex and the drivers are (supposed to be) more aggressive. The E38 bracket, being made of steel, is considerably stiffer and has a higher fatigue life over a comparable aluminum part. Comparable aluminum part means a part of the same stiffness. An aluminum bracket needs to have three times the material to be as stiff as a steel one. So if a ruler were made of steel, 1 mm thick, clamped to a table with 10” cantilevered and a weight placed on the end, it would deflect a given amount. An identical ruler made of aluminum and 3mm thick with same 10” cantilever and weight placed on the end would deflect the same amount. You can read more about this in a book by my friend, the late Carroll Smith, Engineer to Win. Note that the E38 bracket and the E39 bracket are both 3mm thick. The E39 bracket, being made out of aluminum will flex a great deal more and also will tolerate much fewer cycles both because the cycles have more stress ( it flexes more) and aluminum has poor fatigue life compared to steel. So even if the E39 bracket was 3X thicker, it would still break before the steel one. The E39 and aE38 brackets are identical except that the E39 bracket is aluminum and the tab is 5 mm longer, more on this below. No one should ever buy an OE E39 bracket again. I could speculate how this happened as I have seen this before but….
The single bolt bracket both E38 and E39, have a tab that is inserted through a hole and ends up tucked under the subframe when the bolt is tightened, it crushed the rubber bushing a given amount, and I will call this preload. It pulls the tab up tight against the subframe and keeps the bar from deflecting the rubber until a predicted load is applied. As the bar gets larger, this preload should be less because there is less rubber to compress on say a 12mm bar to a 15mm bar. The area the bushing and the bolt tab sit on I will call the deck, it is the zero point. All above it is positive and all below it is negative. The E46 subframe is 2mm thick and the E39 subframe is 4 mm thick. Note that the aluminum subrframe is thicker by 2mm. Since steel comes in even mm 2 was probably rounded up from 1.8mm. The aluminum subframe had to be thicker and this is where the problem starts.

I place the E38 and E39 brackets on a piece of aluminum tooling plate. I drilled and taped 8 X 1.25 holes 45mm from the edge and 45 mm on center. I bolted both of them down to the deck, now you can start to see why the E38 bracket is not a good choice. I have already done this with an OE bracket and the replacement steel bracket; they are exactly the same. So you will notice that the tab is larger on the E39 bracket (25mm vs. 20mm), and it still is not large enough to make it stable. Could it be that they broke a few E 39 aluminum brackets during development? The gap at the top of the hump is from the material pulling during forming, it is the same amount for both brackets so the gap would be one half that amount to a straight edge. The E39 replacement bracket is nice part indeed.
Photo1.png
The next pictures show the difference in the tab length, it is 5mm. There is a picture that the caliper shows 6mm but that is because the straight edge is being pushed away from the tab by the radius by 1mm. Also note that the E39 tab sits -2mm (that is 2mm below deck) and the E39 sit 3mm above deck (the thickness of the tab). That tells us that the E39 bracket has 2mm of preload (-2 +4) and the E38 bracket has 5 mm of preload (3 + 2) on a stock E46. Now the E38 bracket on the E39 would be (3 + 4) for 7mm of preload. That is not to mention the 5mm of hoop that was pulled below deck. As you might think, the bushing is not happy, nor is the bracket after being stressed that far. That is why it takes a longer bolt to pull it down and yield the bracket tabs. This is where I stopped and looked for something better.

photo 2.png

photo 3.jpgphoto 4.png

[BimmrMeUpSnotty]

I have the E38 brackets and an M5 swaybar, never had any problems, just had the bend the tab accordingly, no big deal. But nice work with your bracket though! I may have missed it, was there a link posted for these brackets? Sorry, been skipping around too much.

[JimLev]

If your using the rear OE M5 soft rubber bushings they will compress fine using either the aluminum or the E38 steel bracket.
The Eibach bar which is thicker than the M5 bar, which comes with polyurethane bushings, you'll need to trim the bushing which is a 1 min job.
I haven't pulled out a rear bracket since I put in the steel bracket.
I didn't take a side by side of the E39 and E38 brackets, from what I remember they were physically the same.

Eibach_3.JPG

[Kevyo2]

I made a fixture because it was too difficult to show this on the vehicle. I machined a piece of 2 X 1/4 bar down to 5mm thick and milled a slot for the tab and a hole for the bolt. This is now the same as the subrframe on the E39. I machined a piece of hex stock down to 15mm round on my lathe, the same as the bar on an M5. Now I can easily install both brackets and show the difference and effects. I can also measure rotational torque using a pound/inch torque wrench. Now I have a real A to B comparison. I can only attach 5 photos so it will be on the next post.

Attachment 679041

This is the E39 steel bracket installed on the fixture. Without a bushing it sits flat and square and you can install the bolt by hand. With the bushing installed you need to use a wrench for about the last 3 mm to preload the busing. Notice that the tab is fully contacting the fixture and there is no residual stress.
Attachment 679043Attachment 679044Attachment 679045

This is the E38 bracket installed on the fixture. Note that tightening the bolt caused the bracket to deform and take a set. This is called plastic deformation or a bent part. When I removed the bracket from the fixture, it now sat at zero on the deck (I will attach the photo on the next post). I had to use vise grips to get the bolt started with a bushing installed. The bolt tab is no longer at 90 degrees to the hoop. Notice the locating tab not flat to the fixture and also the bracket is not sitting square because the length of the hoop was pulled into the slot. The bushing is also not looking too good. When I bolted the bracket in with the bushing and rod, the way it would be done on the car, the bushing really was very deformed and the residual stress went up a lot.

Attachment 679046

[f355spider]

I have the Eibach anti-roll bars on my 540. The factory aluminum E39 sway bar bracket/clamps work fine with the Eibach poly bushings. I bought E38 brackets, after seeing Jim's post over a year ago, and no way to get them to fit without trimming the bushings, which I was unwilling to do. After both oem E39 brackets broke, I went with the Beastpower, which fit perfectly.

I wish these new steel replacements were available when I needed them, they look like a great solution and awesome for everyone to have a reasonably priced fix.