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FWD suspention help
http://prodracing.com/viewtopic.php?f=7&t=19077
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Author:  itbmazda [ Mon May 20, 2019 6:56 am ]
Post subject:  FWD suspention help

I am running a FWD car in FP. The car does not turn well. It pushes then the back starts to come around.
Details:
Koni adjustable shocks two click up from soft
Front Springs 600
Rear Springs 1000
Front Bar 21 mm
Rear 19 mm

Any help appreciated
Dave Reiter
FP Mazda 626

Author:  Matt93SE [ Mon May 20, 2019 8:37 am ]
Post subject:  Re: FWD suspention help

Tires? pressures? alignment settings? how's the tire wear look?
Driving technique? (what are you doing with the pedals and steering when it starts to come around?)

Author:  Bob Clark [ Mon May 20, 2019 9:50 am ]
Post subject:  Re: FWD suspention help

Front steer or rear steer? Try disconnecting the front bar for a session and see how that goes.
Aligment specs?
In general.. That means the big picture a FWD would be a soft front, stiff rear.

Author:  Protech Racing [ Mon May 20, 2019 9:51 am ]
Post subject:  Re: FWD suspention help

My book could help you out.
Lots of things in play. Wheel rate , tire and tire pressures, Front sway bar? diff style .

For starters, the wheel rate should be close to even front to rear. Balance the car with rear bar and pressures .
1000# springs seems about 100% high but not knowing the motion ratio, I have no idea. Lots of flex with that much spring.

Author:  Jason@SportsCar [ Mon May 20, 2019 10:01 am ]
Post subject:  Re: FWD suspention help

itbmazda wrote:
I am running a FWD car in FP. The car does not turn well. It pushes then the back starts to come around.
Details:
Koni adjustable shocks two click up from soft
Front Springs 600
Rear Springs 1000
Front Bar 21 mm
Rear 19 mm

Any help appreciated
Dave Reiter
FP Mazda 626


First thing I would verify is front travel. Are you hitting the front bump stops on corner entry/braking?

Author:  racer_tim [ Mon May 20, 2019 10:59 am ]
Post subject:  Re: FWD suspention help

Also, LSD or locked front diff. That also will effect your setup and each have different requirements.

Author:  Matt93SE [ Mon May 20, 2019 11:00 am ]
Post subject:  Re: FWD suspention help

Jason@SportsCar wrote:
itbmazda wrote:
I am running a FWD car in FP. The car does not turn well. It pushes then the back starts to come around.
Details:
Koni adjustable shocks two click up from soft
Front Springs 600
Rear Springs 1000
Front Bar 21 mm
Rear 19 mm

Any help appreciated
Dave Reiter
FP Mazda 626


First thing I would verify is front travel. Are you hitting the front bump stops on corner entry/braking?

Same for rear travel if you're taking a significant amount of weight off the back and then the springs suddenly run out of travel. with spring rates that high in the rear, it's possible that you're suddenly taking all the weight off the inside corner and it upsets the rest of the chassis.

Author:  itbmazda [ Tue May 21, 2019 6:42 am ]
Post subject:  Re: FWD suspention help

Alignment:
Front -3.0 deg
Rear -1.0 deg.
It is a rear steer
Tire pressure hot 32psi font
Tire pressure hot 30 psi rear
Hoosier S75
Not hitting bump stops
total car weight with driver 2305 lbs

Author:  Protech Racing [ Tue May 21, 2019 7:18 am ]
Post subject:  Re: FWD suspention help

Those pressure are a little low for targets . You may be simply getting on the edges. That would explain the rear stupid loose after turn in. My rear targets are a lot higher 36+, while my nose runs well at 35. @ 2110 #, 65% nose weight.

Crayon the tire edges and retest. Up the pressure until the edges are 15* cooler then the middle , reset the camber to optimal, retest. You will get to the happy point of camber/pressure/temps eventually.

Many fast FWD dont use a front bar . Modify the roll stiffness with spring rate. The bar unloads the inner tire , leading to loss power application. Kinda like not running a rear bar on RWD.
Welded or some sort of locking diff will make the best lateral grip., esp in conjunction with no front bar.

Author:  chois [ Tue May 21, 2019 7:33 am ]
Post subject:  Re: FWD suspention help

Protech Racing wrote:
@ 2110 #, 55% nose weight.

Impressive

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