Insanely Loose Suspension?? *Updated w/ Verdict*

Tchao · 06-01-2015, 11:36 AM

Ok so after installing my new Apex wheels with SS595 in 225/40 and 255/35 the car suddenly feels very loose. All four tires are at 40psi. Did a slalom test to scrub the new tires in a bit, and the snap-weight transfer is horrendous.

Now I know these car suffer from a loose rear subframe and wobbly multi-link, but the car didnt feel this bad before. Sort of like a swaybar got disconnected. The wheel/tires I had prior were stock AS non-runflats. Car is stock M sport. It drove like a stock car, not tight but not like a 30yo E21 either!

My question is, can a bit of upgraded grip really show how bad the stock suspension is, or did I break somtime with my slalom test? Just wanted your inputs before I put the car up in the air and take stuff appart.

Thanks,
-San

MightyMouseTech · 06-01-2015, 11:43 AM

What kind of tires previously and now?

If you went from stock runflats to Federal (?????) SS595, that's your problem. Looking at reviews, and those tires are not rated very well.

Also, 40 PSI all around is going to be too high in the front. The higher the pressure, the smaller the contact patch.

Tchao · 06-01-2015, 01:27 PM

I am very familiar with Fed 595's.
They are great for the price, one of the best grip per dollar tires out there. Of course they won't compare to PSS or RE11's but PSS won't offer 3x the grip either. I've done plenty of DE4 in 595s and they are fine for a semi grippy street tire.

I had some AS Continentals 205/50 and 225/45.....don't ask, it was the PO's choice.

I just can't imagine the 595s to be this bad!!! I ran several sets before on a differnt chassis without issues. At the very least it's a step up from the tiny AS conti's on the car.

MightyMouseTech · 06-01-2015, 01:50 PM

If all you did was change the wheels and tires, then yes, they are that bad.

Tchao · 06-01-2015, 03:46 PM

I really hope not, I've had great success with them before. I'll put the stockers back on today and do the slalom again.
I'll report back this afternoon.

Tchao · 06-01-2015, 07:21 PM

So after swapping back to the stockers, car drove fine.
Put the 595 fronts on, still fine.
Put the rears on, wobble wobble on slaloms. (stockers or Feds front independent)
The fronts grip very well, and is on alignment of what SS595's have been for me in the past. Maybe swap to HTR Z-III's....

Solo_M_Tech · 06-02-2015, 09:01 AM

Quote:

Originally Posted by Tchao

Verdict:

So after swapping back to the stockers, car drove fine.
Put the 595 fronts on, still fine.
Put the rears on, wobble wobble on slaloms. (stockers or Feds front independent)

My rear tire/wheels are causing the extreme wondering. WTF.

The fronts grip very well, and is on alignment of what SS595's have been for me in the past. Maybe swap to HTR Z-III's....

The increase in rear grip+ stock sub frame bushings+ softer sidewall+ soft spring rates+plus poor shocks+ etc etc etc. No wonder you are having rear stability issues.

3002 tii · 06-02-2015, 09:35 PM

If you ditch run flats you need firmer shocks and bushings

Tchao · 06-06-2015, 08:20 PM

Okay, so it does look like the suspension and not the tires. Switched rears for some Pirelli's and still the exact same behavior in the rear. Scary.

So AKG sub-bushes here we come. Ill do shocks when I do the coilvers.

Solo_M_Tech · 06-10-2015, 07:27 AM

RSFB are a must on these cars. you also need stiffer springs and shocks as 3002tii stated. When you increase the amount of traction the car is capable of you put more stress on the suspension and bushings and they flex, alot. I ran into the exact same issue as you, I replaced everything to get rid of it. Now the car is planted and smooth. Just need an LSD to finish everything off.

BMW135pls · 06-11-2015, 08:54 AM

Quote:

Originally Posted by ApexResistance

RSFB are a must on these cars. you also need stiffer springs and shocks as 3002tii stated. When you increase the amount of traction the car is capable of you put more stress on the suspension and bushings and they flex, alot. I ran into the exact same issue as you, I replaced everything to get rid of it. Now the car is planted and smooth. Just need an LSD to finish everything off.

I've been considering putting off my intercooler (which would complete my FBO) to put on shocks instead because of how important they are on standard rubber. My question is, are shocks enough, or would it be wise to change out struts/springs while you have everything apart? I've never really heard anyone complain about the stock struts/springs as being terribly subpar, but it would make sense to do everything all at once.

Solo_M_Tech · 06-11-2015, 08:55 AM

Quote:

Originally Posted by BMW135pls

I've been considering putting off my intercooler (which would complete my FBO) to put on shocks instead because of how important they are on standard rubber. My question is, are shocks enough, or would it be wise to change out struts/springs while you have everything apart? I've never really heard anyone complain about the stock struts/springs as being terribly subpar.

The Shocks alone would be a massive improvement. Springs can be had cheap, if you don't care about buying used... however unless you want to lower the car, i'd just get shocks. Just my .02 cent.

BMW135pls · 06-11-2015, 01:53 PM

Quote:

Originally Posted by ApexResistance

The Shocks alone would be a massive improvement. Springs can be had cheap, if you don't care about buying used... however unless you want to lower the car, i'd just get shocks. Just my .02 cent.

Any good springs to match up with a pair of Koni Yellows? I'd like it a bit lower, but in the name of performance. Definitely not going for looks a-la #riceburner #slammed #stanced, and I don't want to worry about scraping.

Would 2.2"F and 1.6"R lowering look like it runs on whole grain rice? Looking at the H&R Super Sports. Possibly just the standard Sports if the Super Sports would be too extreme for a daily driver. I'll also be installing the M control arm kit in the future as well.

Solo_M_Tech · 06-11-2015, 02:30 PM

Quote:

Originally Posted by BMW135pls

Quote:

Originally Posted by ApexResistance

The Shocks alone would be a massive improvement. Springs can be had cheap, if you don't care about buying used... however unless you want to lower the car, i'd just get shocks. Just my .02 cent.

Any good springs to match up with a pair of Koni Yellows? I'd like it a bit lower, but in the name of performance. Definitely not going for looks a-la #riceburner #slammed #stanced, and I don't want to worry about scraping.

Would 2.2"F and 1.6"R lowering look like it runs on whole grain rice? Looking at the H&R Super Sports. Possibly just the standard Sports if the Super Sports would be too extreme for a daily driver. I'll also be installing the M control arm kit in the future as well.

Swift Spec-R springs. That's what I would buy.

lakefront · 06-11-2015, 08:27 PM

Quote:

Originally Posted by ApexResistance

Swift Spec-R springs. That's what I would buy.

Agreed.

Tchao · 06-13-2015, 11:37 AM

What have you guys replaced rear-wise...besides subframe?

Multi-Link is new to me, coming from a TA chassis. But I forsee replacing selective bushings in the multi-link is a bad idea, or am I wrong? Will replacing a certain part remove the slop without adding stress to others/itself or would I need to replace it all?

Just browsing the normal internet venders, it would cost an assload of money to replace the entire multi-link.

Ski Killset · 06-29-2015, 01:50 PM

2.2" front is way too low. My car is on COBB springs -1.2" front and rear.

06-01-2015, 11:36 AM	#1
Tchao Boost Addict 344 Rep 349 Posts Drives: E30, E82, F30, F87 Join Date: Feb 2015 Location: Charleston iTrader: (0)	Insanely Loose Suspension?? Updated w/ Verdict Ok so after installing my new Apex wheels with SS595 in 225/40 and 255/35 the car suddenly feels very loose. All four tires are at 40psi. Did a slalom test to scrub the new tires in a bit, and the snap-weight transfer is horrendous. Now I know these car suffer from a loose rear subframe and wobbly multi-link, but the car didnt feel this bad before. Sort of like a swaybar got disconnected. The wheel/tires I had prior were stock AS non-runflats. Car is stock M sport. It drove like a stock car, not tight but not like a 30yo E21 either! My question is, can a bit of upgraded grip really show how bad the stock suspension is, or did I break somtime with my slalom test? Just wanted your inputs before I put the car up in the air and take stuff appart. Thanks, -San Last edited by Tchao; 06-01-2015 at 07:22 PM..
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06-01-2015, 11:43 AM	#2
MightyMouseTech Major General 4338 Rep 6,196 Posts Drives: 13 135i 6MT LeMans Blue MSport Join Date: Feb 2013 Location: Ottawa, Canada iTrader: (0)	What kind of tires previously and now? If you went from stock runflats to Federal (?????) SS595, that's your problem. Looking at reviews, and those tires are not rated very well. Also, 40 PSI all around is going to be too high in the front. The higher the pressure, the smaller the contact patch. Last edited by MightyMouseTech; 06-01-2015 at 11:54 AM..
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06-01-2015, 01:27 PM	#3
Tchao Boost Addict 344 Rep 349 Posts Drives: E30, E82, F30, F87 Join Date: Feb 2015 Location: Charleston iTrader: (0)	I am very familiar with Fed 595's. They are great for the price, one of the best grip per dollar tires out there. Of course they won't compare to PSS or RE11's but PSS won't offer 3x the grip either. I've done plenty of DE4 in 595s and they are fine for a semi grippy street tire. I had some AS Continentals 205/50 and 225/45.....don't ask, it was the PO's choice. I just can't imagine the 595s to be this bad!!! I ran several sets before on a differnt chassis without issues. At the very least it's a step up from the tiny AS conti's on the car.
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06-01-2015, 01:50 PM	#4
MightyMouseTech Major General 4338 Rep 6,196 Posts Drives: 13 135i 6MT LeMans Blue MSport Join Date: Feb 2013 Location: Ottawa, Canada iTrader: (0)	If all you did was change the wheels and tires, then yes, they are that bad.
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06-01-2015, 03:46 PM	#5
Tchao Boost Addict 344 Rep 349 Posts Drives: E30, E82, F30, F87 Join Date: Feb 2015 Location: Charleston iTrader: (0)	I really hope not, I've had great success with them before. I'll put the stockers back on today and do the slalom again. I'll report back this afternoon.
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06-01-2015, 07:21 PM	#6
Tchao Boost Addict 344 Rep 349 Posts Drives: E30, E82, F30, F87 Join Date: Feb 2015 Location: Charleston iTrader: (0)	So after swapping back to the stockers, car drove fine. Put the 595 fronts on, still fine. Put the rears on, wobble wobble on slaloms. (stockers or Feds front independent) The fronts grip very well, and is on alignment of what SS595's have been for me in the past. Maybe swap to HTR Z-III's.... Last edited by Tchao; 06-13-2015 at 11:38 AM..
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06-02-2015, 09:35 PM	#8
3002 tii Lieutenant General 2304 Rep 12,570 Posts Drives: Z4 M, X5, GX460 Join Date: Apr 2008 Location: CT iTrader: (99) Garage List F15 X5 xDrive35i [8.75] E86 Z4 M [10.00] F10 550i (Retired) [9.17] F25 X3 xDrive35i (R ... [9.43] E82 135is (Retired) [9.50] E85 Z4 M (Retired) [9.41] E90 328i xDrive (Re ... [9.25] E86 Z4 3.0si (Retired) [9.07]	If you ditch run flats you need firmer shocks and bushings __________________ Follow for latest mods
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06-06-2015, 08:20 PM	#9
Tchao Boost Addict 344 Rep 349 Posts Drives: E30, E82, F30, F87 Join Date: Feb 2015 Location: Charleston iTrader: (0)	Okay, so it does look like the suspension and not the tires. Switched rears for some Pirelli's and still the exact same behavior in the rear. Scary. So AKG sub-bushes here we come. Ill do shocks when I do the coilvers.
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06-10-2015, 07:27 AM	#10
Solo_M_Tech Brigadier General 1688 Rep 3,141 Posts Drives: 2014 M5 6MT Join Date: Nov 2013 Location: Massachusetts iTrader: (7) Garage List 2014 BMW M5 [0.00]	RSFB are a must on these cars. you also need stiffer springs and shocks as 3002tii stated. When you increase the amount of traction the car is capable of you put more stress on the suspension and bushings and they flex, alot. I ran into the exact same issue as you, I replaced everything to get rid of it. Now the car is planted and smooth. Just need an LSD to finish everything off. __________________ 2014 M5 6MT
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06-13-2015, 11:37 AM	#16
Tchao Boost Addict 344 Rep 349 Posts Drives: E30, E82, F30, F87 Join Date: Feb 2015 Location: Charleston iTrader: (0)	What have you guys replaced rear-wise...besides subframe? Multi-Link is new to me, coming from a TA chassis. But I forsee replacing selective bushings in the multi-link is a bad idea, or am I wrong? Will replacing a certain part remove the slop without adding stress to others/itself or would I need to replace it all? Just browsing the normal internet venders, it would cost an assload of money to replace the entire multi-link.
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06-29-2015, 01:50 PM	#17
Ski Killset Second Lieutenant 25 Rep 293 Posts Drives: 08 AW 135i Join Date: Mar 2014 Location: Portland, Or iTrader: (0)	2.2" front is way too low. My car is on COBB springs -1.2" front and rear. Attached Images
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