How to restore handling when weight added to rear?

[khoney]

I just drove my son's Mazda 3s home from California. He's added about 150 pounds of weight behind the rear seats with amps and subs. The car handles like ass now. He's on OEM shocks and springs. What would best help with the added body roll? Aftermarket RSB? I haven't checked his rear shocks, but they are the originals so I'm sure they're due for replacement (he has 105K on an '06 3s). Should he be on a different spring/shock setup with the added weight? I thought I might make some improvements since I've got his car for 7 months while he's on deployment. Let the ideas flow (as long as they're not too expensive)!

BTW, does anyone know if the OEM MS3 springs are the same as the 3s springs? I will soon have a spare set of Speed springs - don't know if they would be of any help.

 

[Sport6]

Best option would be...remove the weight haha.

Well I am pretty sure that the suspension can be swapped between the speeds and the regular 3s because a lot of aftermarket struts are actually made for the 3 and fit the speeds.

Aftermarket RSB would another good thing to tighten things up.

 

[meicalnissyen]

Best option would be...remove the weight haha.

Well I am pretty sure that the suspension can be swapped between the speeds and the regular 3s because a lot of aftermarket struts are actually made for the 3 and fit the speeds.

Aftermarket RSB would another good thing to tighten things up.

does'nt the 3 crowd fit speed springs and rsb as an upgrade?

 

[8.5MS3]

id be careful about a rsb, usually you throw that in to ease understeer. now that you have all that weight over the back your gonna be very tail happy with a rsb. i say get a set of front and rears and some konis.

 

[BigDaddyMS3]

Deployment Gear

First of all, CHEERS, what a really nice thing to do!
I would go with Koni Yellows if the car is tracked, (adjustability feature) or the Koni FSDs, (Frequency Sensitive Damping). Both are on sale for around $550 through tirerack until the end of June, but apparently on back order.
I recommend COBB or Hotchkiss sway bars, both front and rear for around $400 to compliment your Speed3 springs.
Finally a set of new tires. Dont know what your Mazda 3 wheel size is but shop tirerack.com for size, specs, reviews and price. Also check the Car and Driver tire review from July 2009. Look for a tire rebates and/or coupons in April and May, usually the best time for tire sales.
This can all be done for @ $1,500, especially if you can install the sway bars. The rear is very easy. The front is time consuming. (direct)

 

[mndsm]

Time consuming ideed. Just did the FSB... it was brutal.

 

[bluelion]

yes the speed 3 springs fit the regular 3. i sold my springs to a guy with a normal 3....the drop is VERY minimal, if any at all. but it does stiffen it up.

 

[gogogomoveit]

Your car handle stupid because the car's weight distribution was changed. Not much you can do for that economically or practically. Springs and sway bar doesnt do anything to static weight distribution.

If you are really into fixing the problem, you need a set of height adjustable coilovers to adjust the corner weight (i.e. ride height) and spring rates to adapt for the change. Again very in depth and probably unnecessary for your situation.

The best thing to do will be to lose that audio set-up.

 

[aznsebass]

150lbs of sound equipment? holy crap. i dont know what kind or how much equipment could be installed to add up to that much other than maybe stuffing 2 midgets in the back holding a speaker and an amp. lol.

would a slight height drop and tightening up the chassis help in this situation? if it were my car, id take out the equipment and try reinstalling it either under the seats or redistributing the equipment more evenly throughout the car. maybe this isnt even possible... just a thought.

 

[Mid_Life_Crisis]

Your car handle stupid because the car's weight distribution was changed.
The best thing to do will be to lose that audio set-up.

If you had the resources to replace just the rear springs with something with an appropriate rating for the new weight balance and upgrade the dampers, shifting the weight balance in a front wheel drive car a little to the rear would be an improvement. By definition these things are nose heavy. You might consider taking it to a scale and getting the front/rear weight distribution accurately. Then see if you can order coilovers with the needed spring rates for the new weight balance.

 

[khoney]

150 is probably an exaggeration - I just know the rear end sags. The body roll is significantly worse than my Speed. I would feel uncomfortable making an emergency lane change in his car.

Once I have room in the garage, I'll be able to bring it in and check things out. Gotta get rid of some furniture and two sets of OEM rims (mine and his) first.

 

[coololddude]

150lbs. would effect handling and speed no matter where you put it!!

 

[gogogomoveit]

150 is probably an exaggeration - I just know the rear end sags. The body roll is significantly worse than my Speed. I would feel uncomfortable making an emergency lane change in his car.

Once I have room in the garage, I'll be able to bring it in and check things out. Gotta get rid of some furniture and two sets of OEM rims (mine and his) first.

150lbs is 65kg. If the weight is resting on your rear axle or behind, Your rear springs should sag about 5-6mm (~1/2inch). You can search out a set of MS3 rear springs to reduce the sag and body roll, but ride quality will slightly deteriorate. the poor transient response (i.e. lane change) could also be traced to bad shocks.