[nixter]

Hey all, I'd like some help with deciding what suspension mods I should do. Basically I'm happy with the ride of car in terms of how it absorbs shock, I really only want to have a little less roll in the corners. Would a thicker strut brace help or do I need to get into springs and struts? As I said I don't want the ride to be any harsher. I just sold my e34 M5 which had Koni sports, H&R springs, touring rear sway bar and an RD front strut brace. The ride was maybe a little too harsh but the cornering was just so flat and beautiful. My thinking is to initially add a strut bar up front. That should reduce roll and increase rear lateral grip even if it increases understeer a little. More grip in back is welcome as I find the rear breaks free a little too easily. Could be the Toyo Proxies on there.

 

[DHoang]

I think just thicker sway bars will do it for you.
Come to think of it, I'd bet if you just replace the rear one with a thicker one, you might just like how it turns out.
that's what I did recently to a 528i that I had inadvertently changed the near neutral handling to obvious understeer when I replaced my square 17x8 235/45r17 tires & wheels to a stagger setup 245 & 275 wheel&tire.
To try to get back the old feel, I went to the thicker [edit] rear m5 sway bar, and the results are quite impressive. Got back the lighter steering wheel feel like before, in addition to taking out all the body roll, but still as plush and comfortable as before.

 

[mister2d]

Yup, start with the rear sway first. I just installed the Dinan rear sway and I can tell the difference in cornering.

 

[nixter]

Thanks for the replies guys. However won't the thicker rear sway bar reduce rear grip while increasing oversteer? I don't want that. Quite the opposite actually.

 

[Lancefitzgiben]

Buy a Dinan rear sway and install it using the middle holes, the car will be totally neutral and turn-in will be much better. I can't say how the sway alone takes out understeer because I run 275s all around.. but with 275s and the rear sway the car is more-flat and balanced incredibly well.

Remember, while too much body roll can be a bad thing, too little can hurt you as well. Roll is communication.

 

[nixter]

Understood Lance. My understanding though is that any rear roll stability gained from a rear sway bar will also reduce rear grip as the weight distributed to rear inside wheel will be reduced. I already find the rear spins too easily so that's not something I want to increase. This is why I thought a front bar would be better. It should reduce roll, increase understeer a little and increase rear grip. Am I wrong? Of course if the reason my rears break loose early is the Toyo proxies then there's no point compensating with suspension adjustments.

 

[Lancefitzgiben]

I have no experience with those tires you speak of.. and there are a ton of variables that could cause the rear end to move around. Worn tires, broken sway mount, incorrect tire pressure, low ambient temperatures, aggressive inputs etc etc.

If you are running the stock staggered wheel/tire set-up then the front bar is probably not for you. Interesting though that with their site change, Dinan has deleted that suggestion, saying that the front and rear bars should be installed as a matched pair. I don't have the front bar, nor do I plan to get one.

I can't explain the physics of it all, but the rear bar should do something for you.. there are three settings for it, the middle being the neutral, and the others for more/less oversteer.

What tire pressures are you running and what is your driving style like? Explain a circumstance where the back end goes loose on you.

 

[nixter]

Thanks Lance. I have a good understanding of how the various front rear bars are supposed to affect handling but tires and the current cold weather could definitely be contributing factors. I will do a little road testing with my specific needs in mind tonight and report back with what I feel is happening.

 

[gsfent]

Thanks Lance. I have a good understanding of how the various front rear bars are supposed to affect handling but tires and the current cold weather could definitely be contributing factors. I will do a little road testing with my specific needs in mind tonight and report back with what I feel is happening.

Your basic understanding is correct, but your orginal question was combating body roll, not oversteer. Bigger sway bars help body roll. So a front bar and a bigger rear bar (or as suggested, the Dian ADJUSTABLE rear bar) would be good for your purposes

The car is designed to have moderate understeer with the staggered wheel and tire setup. So if you are getting oversteer, I would check all my suspension components, the air pressure of my tires, and my suspesnion settings. Without knowing your settings, adding some rear camber will help rear grip.

Regards,
Jerry

 

[Lancefitzgiben]

Good response Jerry, suspension setup, and especially camber; are all too important.

- Tim

 

[Fulltone74]

You may have worn out front shocks as well, causing oversteer.

 

[M55555]

As others have mentioned, thicker sway bars to reduce body roll. It has zero impact on ride quality and does not make a ride more or less harsh.

 

[mister2d]

...Interesting though that with their site change, Dinan has deleted that suggestion, saying that the front and rear bars should be installed as a matched pair. I don't have the front bar, nor do I plan to get one.

Actually Dinan still has the disclaimer about retaining the stock front anti-roll bar if you have a staggered setup. It was always on the front roll bar description, not the rear product.

Dinan Cars - 28mm Front Anti-roll Bar

 

[Lancefitzgiben]

good catch sir, thank you for the correction.

 

[5PEEDY]

My understanding though is that any rear roll stability gained from a rear sway bar will also reduce rear grip as the weight distributed to rear inside wheel will be reduced. I already find the rear spins too easily so that's not something I want to increase. This is why I thought a front bar would be better. It should reduce roll, increase understeer a little and increase rear grip. Am I wrong? Of course if the reason my rears break loose early is the Toyo proxies then there's no point compensating with suspension adjustments.

You have a great understanding of what a sway bar does however I would not use the word stability. My driving style dictates more front bar but I have yet to get up the courage to do the install. The rear was easy; dropping the front sub frame is a larger bite to chew.

M55555 you are incorrect. With a stiffer bar the ride will be affected when going over bumps, especially single wheel bumps. This is called tyre load variation. Say two cars are going around the same corner and they hit a patch of road irregularities (bumps). Car A has 50/50% roll rate distribution and Car B has 60/40%. The section of the corner (entry, apex or exit) will also affect how the car behaves due to the sway bar and the feedback to the chassis. Car A on entry (say trail braking) with bumps will behave better than Car B due to the front taking the load transfer from braking and now fluctuation the load on the front tyres at a greater rate than Car A. The low grip points of the fluctuation for Car B are lower than Car A, so at those time Car B is not as fast.

Any good driver will tell you knowing what he's got at any given point is a good thing. Reducing that fluctuation is important.

All this being said, getting stiffer sway bars over springs is a good idea for any road car. I love how my discussion above knocks this idea. :3:

 

[5PEEDY]

Actually Dinan still has the disclaimer about retaining the stock front anti-roll bar if you have a staggered setup. It was always on the front roll bar description, not the rear product.

Dinan Cars - 28mm Front Anti-roll Bar

I don't buy it. If you driving style dictates oversteer then get a stiffer front bar. (Disclaimer: power on oversteer is different)

People telling me what suspension setting to go with, is kind of like telling me what movies I should enjoy.

Give me more front bar, I'm about to set a hot lap. :wroom:

 

[M5erchant M5arine]

Of course if the reason my rears break loose early is the Toyo proxies then there's no point compensating with suspension adjustments.

Those Toyo Proxes you speak of wouldn't by any chance be Proxes 4 UHP A/S would they? I had a set of those on a previous car and they wore out incredibly fast. Even at their best I didn't find them very sticky in the dry.

 

[Hasan Shaikh]

Have you considered coil overs?

 

[nixter]

Proxes T1R's

 

[Beasty5]

Have you considered coil overs?

+1. Coilovers + Dinan rear sways = car on rails. No kidding!

Vic