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Advanced Suspension Geometry and Design

Posted by Cosworth 
MattP
Matt Pullen
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Re: Advanced Suspension Geometry and Design
February 12, 2014 06:29AM
Chris, it could be a tire pressure thing. At RMR last year on the ice on day 2 the majority of guys were running with 35-40 psi however Taisto was asking for lower around 30 if I recall and did pretty well. All of a sudden there was a flurry of pressure gauge activity.



Yes, it's a Ranger.
Xr4Ti, it is rwd and was made in Germany.
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Reamer
Jeff Reamer
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Re: Advanced Suspension Geometry and Design
February 12, 2014 10:11AM
I ran 26 psi hot at sno drift this year with no flats. I tested them against sno banks way more times then I would of liked. I started with yoko then went to blizzak with 30 psi. Dropped them to 26. Then went back to yoko ice guards with 26psi seemed the best.

I will say the 08 up subaru are not at all lacking faward bight. They make tons of traction.



First rally 2013
Rally car type AWD subaru
Total rallies as driver 6
Total rally cars built 2
Total rally cars caged 3
Total rally cars repaired from offs 4
Total years racing exp other then rally 19 yrs
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Do It Sidewayz
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Re: Advanced Suspension Geometry and Design
February 12, 2014 12:19PM
Almost definitely not a tire pressure problem. Was running between 18-20 psi which is a common thing in ice racing.

Could well have just been the tires. I will be cutting them to add some forward bite.

I think it's more to do with the oem suspension on the car. The front end is a bunch higher than the rea. I think when the car squats coming out of he corner it's unloading the front end too much, and the front tires aren't doing much but spin.



Chris
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Reamer
Jeff Reamer
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Re: Advanced Suspension Geometry and Design
February 12, 2014 12:35PM
Ive seen guys put the forester lca rear mounts on WRX to add pro dive to the front. I believe they do this for traction? I havent tried it.



First rally 2013
Rally car type AWD subaru
Total rallies as driver 6
Total rally cars built 2
Total rally cars caged 3
Total rally cars repaired from offs 4
Total years racing exp other then rally 19 yrs
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Iowa999
no-one of consequence
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Re: Advanced Suspension Geometry and Design
February 12, 2014 10:14PM
Are you talking about an Impreza with a VC LSD center?
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Do It Sidewayz
Chris Martin
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Re: Advanced Suspension Geometry and Design
February 12, 2014 11:29PM
An impreza yes, but the VC center diff was gutted and welded up!



Chris
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Paddy1337
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Re: Advanced Suspension Geometry and Design
February 17, 2014 07:44AM
Quote
Do It Sidewayz
An impreza yes, but the VC center diff was gutted and welded up!

I've been contemplating whether to weld my VC center diff as well. I know it'll be strong, but have 0 idea what affect it'll have for rally.
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czwalga
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Re: Advanced Suspension Geometry and Design
February 17, 2014 08:01AM
Quote
Reamer
I ran 26 psi hot at sno drift this year with no flats. I tested them against sno banks way more times then I would of liked. I started with yoko then went to blizzak with 30 psi. Dropped them to 26. Then went back to yoko ice guards with 26psi seemed the best.

I will say the 08 up subaru are not at all lacking faward bight. They make tons of traction.



Lucky in my opinion. I ran 28 last year and debeeded two. I ran 35 this year making sure that didn't happen again; grip seemed pretty good.
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Reamer
Jeff Reamer
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Re: Advanced Suspension Geometry and Design
February 17, 2014 09:44AM
Guess im just to slow to worry about it! Last year was a lot faster roads with a lot more chances of debeeding I thought. This year was pretty slow roads. The thaw we had a few weeks before made the roads pretty icy. The good thing was this year we had big banks to bounce off. Last year if you went off you were hitting ditches and trees. I didnt have a flat last year either at 26 psi.

Whats the advantage disadvantage of a welded or 20k center diff?



First rally 2013
Rally car type AWD subaru
Total rallies as driver 6
Total rally cars built 2
Total rally cars caged 3
Total rally cars repaired from offs 4
Total years racing exp other then rally 19 yrs
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NoCoast
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Re: Advanced Suspension Geometry and Design
February 17, 2014 11:54AM
Quote
Reamer
Whats the advantage disadvantage of a welded or 20k center diff?

I don't think I would weld for anything unless it's something like a cheap ice racer like Chris' car.



Grant Hughes
http://rally.build
Denver, CO
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Reamer
Jeff Reamer
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Re: Advanced Suspension Geometry and Design
February 25, 2014 12:11PM
After watching O sollivans crash at 100 acre. I believe he expierened the same issue I have with the 08 rear susp set up. There has to be a way to make these cars more stable in these situations. Any thoughts?

I was starting to think maybe the wing on the vermont cars may help this situation? How fast you think you have to be going for a wing to do anything what so ever?



First rally 2013
Rally car type AWD subaru
Total rallies as driver 6
Total rally cars built 2
Total rally cars caged 3
Total rally cars repaired from offs 4
Total years racing exp other then rally 19 yrs
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Cosworth
Paulinho Ferreira
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Re: Advanced Suspension Geometry and Design
February 25, 2014 01:11PM
Not a suspension issue. The brakes were cold, and that's what sneaked up on him. He was fast in 5th, went hard of the brakes and I'm sure they're running 2 different friction materials front/rear, and as usual the idea of putting a lower friction rear means it will have a lower operating temp = having bite a lower temps too. So what happened was the front brakes had no bite and the rears had enough to destabilize the car. Its a very common thing to happen if you're not careful.
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Reamer
Jeff Reamer
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Re: Advanced Suspension Geometry and Design
February 25, 2014 05:28PM
Im running 461 xp12 carbo tech pads front and rear with a tilton pedal box and 06 wrx reds front and rear. On day 2 of lspr i wrecked the rear calipers from the wheel scrapers not working well enough to keep the dirt out. I wore the top of the caliper into the pass threw port of the caliper lost all rear brakes. This did not change the issue im having.

His deal does look like possibly a brake issue. But the cars in general 08 up have some sort of issue in the rear of the car. It looks like Vermont has it sorted out in the shocks of SP cars but they told me over 3k for just rear coil overs. Not sure what O sullivan has for rear shocks?



First rally 2013
Rally car type AWD subaru
Total rallies as driver 6
Total rally cars built 2
Total rally cars caged 3
Total rally cars repaired from offs 4
Total years racing exp other then rally 19 yrs
Like 31motorsports on FB!
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Reamer
Jeff Reamer
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Re: Advanced Suspension Geometry and Design
March 21, 2014 10:02AM
I had a chance yesterday to check some bump steer on the rear susp. Not sure if this is my issue but it was going the wrong direction. My car was towing out 1/4" at full droop and towing in 1/8" full compression. This is per side so from 7" ride height to full compression it was towing in 1/4".

Every thing ive read says you want zero to a little tow out to make the driver feel more stable on entry.

Heres a article I found seems like a pretty good read

Bump Steer…it isn’t just Front suspension, it can be rear.



First rally 2013
Rally car type AWD subaru
Total rallies as driver 6
Total rally cars built 2
Total rally cars caged 3
Total rally cars repaired from offs 4
Total years racing exp other then rally 19 yrs
Like 31motorsports on FB!
Check out 31motor sales on ebay for used Subaru parts
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john vanlandingham
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Re: Advanced Suspension Geometry and Design
March 21, 2014 12:28PM
Quote
Reamer


Every thing ive read says you want zero to a little tow out to make the driver feel more stable on entry.

A LOT of what I have read ONLY IN AMERICA, and primarily from practitioners of the most useless glorified wank-off branch of motorsport where guys obsess about minute, pointless trivialities, and I am of course referring to amateur auto-cross and SCCA A-M "Improved Touring" say toe OUT.

Nowhere else anywhere do I see people blabbering incessantly about toe-out.
ONLY (well 99%) in the most amateur of amateur "sports" with the biggest wankers in all the world (as far as I can tell)..

Logically it makes no sense. Think of vectors...direction of force Car goes this way -------->
Force goes this way <------------ look at a RIGHT control arm in rubber from above represented by this 7I forward is ^ so force goes V , rubber moves and the arm goes into this 7 wheel goes from this I to this /

It naturally is going to toe OUT some... so set it IN at static unladen height and iit will move OUTWARD....do we need to set it OUT to begin with? No.



Besides another reason to discount the 99% of drivel written HERE, 90% written by girly-men auto-crossers is WE are not driving around in a parking lot at 20-35 mph.

Find RALLY-SPECIFIC information.....

Note: only time the suspension is at full droop is when the wheel are in the air...toe is pretty unimportant then, as is camber..

Worry about the toe and camber when stuff is in "the average position"---where it is 90% of the time. basically from static unladen ride height and maybe 5 inches UP....



John Vanlandingham
Sleezattle, WA, USA

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