e39 rear sway bar upgrade?

[Arma 134]

Was wondering if it is worth having m5 rear sway bar kit installed into my 530i msport. Many people seem to say the difference is quite noticeable, and it seems to be a fairly cheap mod. (Front m5 bars won't work on 6cyl e39s i think?).

Wonder if I'd have to have the sway bars shipped or if anyone has in stock here. But yeah, question is whether anyone has done this and whether it is / you think it is worth doing?

Edited May 20, 2013 by Arma

[BreakMyWindow 1874]

My guess is that you will upset the balance of the car without increasing the thickness of the front sway bar.

[M5V8 337]

+1

there is a possibility you might be throwing away your money & upsetting the handling. Mind you this bar will only come into effect when you are really loading up the rear under cornering.

If you have a few hundred and want to improve handling you should be looking at some quality aftermarket springs.

Something like H&R's with a small 1" drop & proper wheel alignment will do wonders.

[hybrid 1043]

Changing springs will just stiffen the ride and will require uprated rebound control from the shocks and uprated roll bars to restore the total suspension system balance.

Pretty much sticky this comment for all suspension modding and you cant go wrong.

[Arma 134]

Thanks for the feedback / information guys. Looks like I'd need to invest in several parts rather than just the rear sway bar to get the most benefit/improvement in handling.

[Arma 134]

the rear bar is an easy option with immediate benefits that will not be lost on future enhancements I would highly recommend you do it.

Thanks Ron. I hear the m5 sway bars are prone to breaking and are a weak point to the m5s. If this is true would it just be better to go with an aftermarket one, like Dinan etc.? Although i'd imagine those would probably cost a fair bit more. Then there is this kit: http://www.beastpower.com/p/bmw/eibach-fro...BE39-525-SUS-SB, or http://www.vividracing.co.nz/eibach_18mm_r..._1013841335.php just for the rear , which seem to have thicker rear bars than the m5 ones - though no idea how good those ones are.

Edited May 30, 2013 by Arma

[M5V8 337]

correct.

The rear M5 sway bar is 16.5mm and there's no reports of breakages that I have read. It's a pretty beefy bar i'd be surprised if that ever happened.

It's the rear sway bar links that apparently are prone to snapping. Although I've never snapped one myself, i've upgraded to the beastpower links for safety.

http://www.bimmerzone.com/product/BEP-E39-RSBB-RED.html

Edited May 30, 2013 by M5V8

[Allanw 1071]

The sway bar mount brackets are known to break on E39's:

They can break at either end. New ones are available easy enough, and it is possible to get stronger aftermarket ones - Beastpower apparently... not cheap though. New genuine ones are cheap anyway.

Plus, if the bracket is too strong, the mount can crack off the frame of the car

Edited May 30, 2013 by Allanw

[Arma 134]

Was having a flat tire changed in the morning and had a look under the car while it was hoisted up. The left rear sway bar link seems to have broken (can loosely slide along the sway bar now - with a little push) and the right rear link seems to be doing something weird / on its way to breaking / broken. See pics:

Rear left:

Rear right:

Are the m5 sway bars ones thicker than the stock M-Sport ones? Or does the M-sport kit come with the stock m5 sway bars 16.5mm. Since the links above are broken/breaking, I'm considering upgrading the whole bar with new links, rather than just the links/brackets - that is unless the msport kits come with the m5 ones already (didn't get a chance to measure the bar, was in a rush!).

Edited May 31, 2013 by Arma

[M5V8 337]

there you go. 1 broken bracket and the other is on it's way out too.

The bracket is the same size for all e39's. They are a standard thin alloy pressed design.

it's the bush that varies in size for the various bar sizes. If you went to a M5 bar you would need to replace the bush also.

This is basically what I did to sure up mine.

http://www.bimmerzone.com/product/BEP-E39-RSBB-KIT.html

Beastpower are thicker CNC machined brakets. Alot stronger.

Edited May 31, 2013 by M5V8

[Arma 134]

there you go. 1 broken bracket and the other is on it's way out too.

The bracket is the same size for all e39's. They are a standard thin alloy pressed design.

it's the bush that varies in size for the various bar sizes. If you went to a M5 bar you would need to replace the bush also.

This is basically what I did to sure up mine.

http://www.bimmerzone.com/product/BEP-E39-RSBB-KIT.html

Beastpower are thicker CNC machined brakets. Alot stronger.

Thanks, geez those brackets cost as much as the stock m5 sway bar .

Regarding the size, was a bit unclear - I meant to ask whether the m5 bar (16.5mm) is the same as the m sport bar (??mm)? Or does the M-sport kit still have just the 14mm sway bar? Does beastpower deliver to NZ? Might just order from there.

Found these on beastpower too, that are CNC machined:

http://www.beastpower.com/p/bmw/beastpower-rear/BP-BE39-RSBB

Though the Eibach ones are likely better.

Edited May 31, 2013 by Arma

[M5V8 337]

Thanks, geez those brackets cost as much as the stock m5 sway bar .

Regarding the size, was a bit unclear - I meant to ask whether the m5 bar (16.5mm) is the same as the m sport bar (??mm)? Or does the M-sport kit still have just the 14mm sway bar? Does beastpower deliver to NZ? Might just order from there.

Found these on beastpower too, that are CNC machined:

http://www.beastpower.com/p/bmw/beastpower-rear/BP-BE39-RSBB

Though the Eibach ones are likely better.

I believe the 16.5mm bar was only fitted to the M5 which is what it's a popular swap.

Yours should be either 14 or 15mm best to check you particular car tho

http://bmwfans.info/parts/catalog/E39/Seda...tabilizer_rear/

[Arma 134]

Yeah I think mine is the 14mm (I don't think I have the M Sport II Suspension - which is 15mm, just the regular M sport suspension). Talked to BM Workshop if they have any parts in stock. They don't but they said they'll contact BMW regarding part compatibility and get back to me. Not sure if it is sold as a kit or whether the sway bar, rubbert mounts, links / brackets would need to be ordered as separate parts.

I think this is the one of interest: http://bmwfans.info/parts/catalog/E39/Seda...tabilizer_rear/

Can always change the brackets later on to stronger ones - but I think being a new part it should last me a while.

Edited May 31, 2013 by Arma

[M5V8 337]

you'd probably be better PM'in Ray from Hellbm he's a sponsor on this forum.

I'd say he would have a better price on a second hand bar. It's not like you really need a new rear sway bar. Anyone old 16.5mm one will do.

Then you just need to replace the bushes. I have some new(ish) brackets if you want 'em.

Edited May 31, 2013 by M5V8

[Arma 134]

you'd probably be better PM'in Ray from Hellbm he's a sponsor on this forum.

I'd say he would have a better price on a second hand bar. It's not like you really need a new rear sway bar. Anyone old 16.5mm one will do.

Then you just need to replace the bushes. I have some new(ish) brackets if you want 'em.

Yup. Went to BM Workshop cause I was at repco (which is right next to the Grey Lynn BM Workshop ) so went in to find out how much new parts would cost. Probably will give Ray a pm regarding the parts. Would probably be a good idea to get new brackets though wouldn't it (seeing as they can break).

[Arma 134]

BM Workshop quoted $550 (or something close) + GST for all the parts (new) required - bar, rubber mounts, brackets, not sure about bushes. Seems a bit more expensive than what I've seen elsewhere.

[Allanw 1071]

Originally, your car had S705A M sports suspension II, which has the 15mm rear bar. Same as mine. I see no reason why it would have been changed previously.

[Arma 134]

Originally, your car had S705A M sports suspension II, which has the 15mm rear bar. Same as mine. I see no reason why it would have been changed previously.

Ah I had no idea. Thought the M Sports suspension II only came for 2002-2003 e39s. Yeah in that case I'd have the 15mm. Gonna make some calls to see what options I have to getting the 16.5mm bar and parts.

[M5V8 337]

i guess the question now is, is upgrading from 15 to 16.5mm worth the $$ & hassle ?

[Allanw 1071]

i guess the question now is, is upgrading from 15 to 16.5mm worth the $$ & hassle ?

Especially if it starts working properly, after the brackets are repaired

[Arma 134]

Think the best option for now would be to get some new brackets. Ray suggested sticking with the same sway bar as well. Only decision to make is whether to get the normal BMW ones again (new) or some stronger aftermarket ones . Would there be much difference in driving experience (around turns and what not) once new brackets are put in place of the broken ones?

Edited June 4, 2013 by Arma

[M5V8 337]

well currently your rear bar wouldn't be working very well, if at all.

I'd tend to agree, get yours fixed then see if it doesn't meet your requirements.

I've changed sway bars for racecars for about a 1.5mm change because they were getting too much understeer. But we are talking a racecar & on the limit handling, chasing lap times. That was a cheap fix comparatively.

I doubt you will really feel this on a road car, but it depends how you drive it I guess.

[Arma 134]

well currently your rear bar wouldn't be working very well, if at all.

I'd tend to agree, get yours fixed then see if it doesn't meet your requirements.

I've changed sway bars for racecars for about a 1.5mm change because they were getting too much understeer. But we are talking a racecar & on the limit handling, chasing lap times. That was a cheap fix comparatively.

I doubt you will really feel this on a road car, but it depends how you drive it I guess.

Cool, thanks Darren. Probably will take it in somewhere just to make sure it is only the links/rubber mounts I would need then decide on whether to get the original or after market ones.

[Arma 134]

Replaced the brackets for the sway bar. Replaced both brackets (1 was missing anyway, disappeared after breaking off): 1 bracket ordered new (by Glenn) and 1 used (from Brent). Also got a pair of new links from Brent and had those fitted in by Brock at Botany Motorworx. Apparently disconnecting the link was a tad bit annoying since the axle was in the way.

Took it for a drive afterwards and can definitely feel an improvement during cornering. Body roll reduced a lot so no more hugging the door cards during left turns etc. Car feels a lot more flat during faster turns (took a drive around Whitford road between Howick and Beachlands). I'm sure it would improve a fair bit with thicker sway bars but I think this is good enough for me, for now.

Pics:

While the parts were being fitted, noticed this donut thing (what's it called? Is it the prop-shaft coupling thing) starting to split/crack/damage (apparently common):

That would need replacing during next service advised by Glenn.

[M5V8 337]

good outcome.

way to pull together & help a brother out BMsport!