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 Post subject: FWD suspention help
PostPosted: Mon May 20, 2019 6:56 am 
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Joined: Fri Dec 02, 2016 7:52 am
Posts: 41
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


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 Post subject: Re: FWD suspention help
PostPosted: Mon May 20, 2019 8:37 am 
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Joined: Sun Jan 23, 2011 4:54 am
Posts: 2036
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?)

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Matt Blehm
Houston Region
EP 1st Gen RX7
STU Scion FR-S


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 Post subject: Re: FWD suspention help
PostPosted: Mon May 20, 2019 9:50 am 
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Joined: Mon Mar 29, 2010 6:23 am
Posts: 135
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.


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 Post subject: Re: FWD suspention help
PostPosted: Mon May 20, 2019 9:51 am 
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Joined: Fri Dec 23, 2011 6:59 am
Posts: 1367
Location: Spring Hill, FL.
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.

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Mike Ogren/Protech Racing, http://www.FWDracingguide.com http://www.ogren-engineering.com/ 352.428-8983 mogren@tampabay.rr.com


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 Post subject: Re: FWD suspention help
PostPosted: Mon May 20, 2019 10:01 am 
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Joined: Wed Jan 13, 2010 10:58 am
Posts: 1220
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?

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 Post subject: Re: FWD suspention help
PostPosted: Mon May 20, 2019 10:59 am 
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Joined: Tue Aug 20, 2002 10:01 am
Posts: 2654
Location: Belmont, CA
Also, LSD or locked front diff. That also will effect your setup and each have different requirements.

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Tim Linerud
#95 GTL VW Rabbit GTI
2014 Runoffs Sunoco Hard Charger - GTL
2016 Western Conference GTL Champion


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 Post subject: Re: FWD suspention help
PostPosted: Mon May 20, 2019 11:00 am 
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Joined: Sun Jan 23, 2011 4:54 am
Posts: 2036
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.

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Matt Blehm
Houston Region
EP 1st Gen RX7
STU Scion FR-S


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 Post subject: Re: FWD suspention help
PostPosted: Tue May 21, 2019 6:42 am 
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Joined: Fri Dec 02, 2016 7:52 am
Posts: 41
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


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 Post subject: Re: FWD suspention help
PostPosted: Tue May 21, 2019 7:18 am 
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Joined: Fri Dec 23, 2011 6:59 am
Posts: 1367
Location: Spring Hill, FL.
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.

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Mike Ogren/Protech Racing, http://www.FWDracingguide.com http://www.ogren-engineering.com/ 352.428-8983 mogren@tampabay.rr.com


Last edited by Protech Racing on Tue May 21, 2019 8:59 am, edited 1 time in total.

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 Post subject: Re: FWD suspention help
PostPosted: Tue May 21, 2019 7:33 am 
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Joined: Tue Oct 27, 2009 6:39 pm
Posts: 446
Protech Racing wrote:
@ 2110 #, 55% nose weight.

Impressive

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Chris Schaafsma


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