[urq] Tire pressure for ice racing ?

[John Cody Forbes]

I've seen (Mark Besso and Bob D'amato on a 4kq rally/hillclimb car) electric 
door actuators from a junkyard used as diff lock solenoids. They put buttons 
on the steering wheel so the diffs could be unlocked quickly and easily 
without taking your hands off the wheel. Seems like the way to go to me!

-Cody Forbes

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From: <qshipq at aol.com>
Sent: Friday, February 12, 2010 3:20 PM
To: <larichard at plguide.com>; <laraa at sympatico.ca>; <vittorio at mybares.com>
Cc: <urq at audifans.com>; <quattro at audifans.com>
Subject: Re: [urq] Tire pressure for ice racing ?

>
>
> L-A
> If you are looking to 'win' a competition, then the rear diff should be 
> locked, as coming out of a turn apex it will give you more traction.  I 
> won FTD in the 42 car SCCA Ice Rallycross at Steamboat in 97 using this 
> technique on a borrowed 5ktq with Blizzacks (somewhere in the archives I 
> did a turn by turn breakdown).  Basically, if you have a tight turn, just 
> before the turn unlock the rear diff, and blip the throttle (unlocks rear 
> diff), then at the apex, lock the rear again, and repeat.  Center always 
> locked.
>
> In my old 83 urq, I rigged up two late style electropneumatic rear diff 
> switches to run the center and rear diffs.  The key is to have as much 
> reserve vacuum (I added a vw eggcrate style vacuum accumulator tank) as 
> possible, so that the diffs can lock and unlock when under boost.
>
> All that said, for Steamboat, I just lock the rear all the time.  The 
> trick there is to come up hot to all tight turns in a straight line, brake 
> hard, then take the turn slow.  Or, if wanting to dance, you can just 
> leave the rear locked, and go at it, like you can see me driving the track 
> mars-urq in front of fellow urq lister Nate E in a 90q
> http://www.youtube.com/watch?v=KfxjwHWuTzA
>
> With a lot of sheer ice, the rear diff locked will always yield better 
> control IMO/E.  If the cones are tight, it's not as easy, but good 
> directional placement can be had by just a quick dump of the clutch (quick 
> in/out to disengage the driveline, helps oversteer).
>
> WRT 3000rpm, the technique I use is to keep the engine at 3000> all the 
> time.  If there is a snow hook-up section, I'll run close to redline, 
> which once traction is gained, keeps the car spooled up enough to not bog. 
> I used this same technique in a 90q20v at the 6900ft track, which worked 
> just as well.
>
>
> IMO/E 2 the Rsi and the WS50/60 are transparent in tractive ability (newer 
> the better) for dedicated ice tires.  IMU, the Hakka Rsi is discontinued 
> in favor of the Hakka R.  The Hakka R takes a step down in sheer ice for a 
> step up in mixed ice/snow and ultimate snow traction.  BTW, just before 
> Steamboat this year, we tied the center diff locked all the time, and I 
> ran a new line from the IM to a ck valve to the diff knob, using the 
> climate control vacuum canister as an accumulator, and the knob then only 
> operated the rear diff.  Worked immediately and without fail for 4 days.
>
> HTH and my .02
>
> Scott J
> 84 Urq
> 83 urq ice track car
>
>
> -----Original Message-----
> From: Louis-Alain Richard <larichard at plguide.com>
> To: qshipq at aol.com; laraa at sympatico.ca; vittorio at mybares.com
> Cc: urq at audifans.com; quattro at audifans.com
> Sent: Fri, Feb 12, 2010 12:32 pm
> Subject: RE: [urq] Tire pressure for ice racing ?
>
>
> Scott, why "good luck " ? You think I'll need some ? :-)
>
>
>
> Never popped a tire, but I never ran lower than 26 yet. I'll bring the two 
> sets
>
> next time, just in case I pop a tire. These are difficult to replace on 
> the rim
>
> when temps are around 0F and there is no air supply close... Brady can
>
> confirm...
>
>
>
> About the rear diff, when locked it makes the rear end very nervous under 
> power
>
> but as you say, tight corners are a nightmare if you missed your approach. 
> She
>
> just goes straight. And with that stock engine, 7:1 compression ratio, 
> there is
>
> NO torque below 3000 rpm. I must play with the revs and the clutch to make 
> the
>
> rear end slip in some slow corners.
>
>
>
> So no one think that the Michelin will be any good ?
>
>
>
> Louis-Alain
>
>
>
>
>
>
>
> -----Message d'origine-----
>
>
>
> At Steamboat Springs Ice track with the urq, we run between 24 and 26psi 
> with
>
> WS50 Blizzacks.  For the urq on ice, the best pressure will be lower, 
> generally
>
> 24-28psi.  I run to the low end of that using innertubes, but it really 
> depends
>
> on the tire size, a 205 on a fuch 15x7 will tend to pop it's bead when
>
> encoutering a snow patch at 25psi (btdt), but a 205 on a 6in rim or a 215 
> on a 7
>
> should be fine.
>
>
>
> The studded/bolted/spiked  tire will always have the advantage on an Ice 
> track.
>
> At Steamboat, none of these are allowed, but usually in Ice racing 
> competition,
>
> non-studded ice tires are in a separate competition category.  I also 
> suggest
>
> that you run the center locked always.  I also run the rear locked, but 
> can be a
>
> handful in a tight competition course.
>
>
>
> HTH and good luck
>
>
>
> Scott J
>
> 84 Urq
>
> 83 Urq ice track car
>
>
>
>
>
>
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>
>
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