Re: Playing in Pueblo

[gary kaklikian <gary.kaklikian@Compaq.com>]

What a coincidence, as I just returned from a day of testing the 4000 TQ
at Pueblo. It was a dreary day in the Denver area, with snow imminent,
but in the Pueblo oasis it was sunny and in the 70's.

I loaded up the spare wheels/tires , tools, etc and picked up a friend
who is an accomplished ex-Formula Mazda racer. When we got to Pueblo
Motorsports Park, it turned out the vintage racers, FF's, FV's and some
others were practicing for this weekend's events. Our goal was to test
the new Kumho's -205/50-15's,  diagnose the damn G60 front brake
problems,and have some fun. 

After a few warmup laps, tire pressure adjustments and instruction laps
(my friend Dave showing me the proper line), we started running some
solo laps.  Dave complained the car was pushing terribly
and resisting all his turn-in efforts. Still, he was running 1:56's and
said the brake shudder/chatter through the pedal was not bad.
(Interestingly, last time we were at Pueblo with my 16" street Pirellis,
he said the handling was neutral, though there was much less grip.) I
was a few seconds slower, thought the car was pretty neutral, yet felt
terrible brake pedal shudder. Brake fade really didn't seemed that bad,
but the pedal shudder got worse as the brakes got hotter. Going into
turn 1, the long front straight helped to cool the brakes a bit and the
shudder wasn't objectionable. But by turn 3, the G60's were HOT and the
shudder was very bad.

I decided we'd try running with the center diff locked. Our earlier
laps the diff was open, and the inside rear wheel would spin exiting the
tighter turns under power. I noticed an immediate improvement with
the center diff locked, and my times gradually dropped, until by the
time we quit (prematurely), I actually turned a few 1:56's. Dave
insisted he still could not get the car to turn-in, and that tire
pressure adjustments, diff open/locked did not seem to make a difference
(Maybe he's just not accustomed to driving such a "heavy" car on the
track). Regardless, he eventually broke into the 1:53's. I was trail
braking into and powering out of the corners pretty hard (once the
center diff was locked), but Dave was still 3 seconds faster. We both
passed quite a few vintage racecars, and I was passed only once - by a
Formula Ford. 

The day came to an early end when 1)the gas gauge took a serious dive, 
and 2) we demolished a new Kumho. The left front tire, in which we were
probably running 50psi hot, was cooked - the outer third of the tread
had completely delaminated to the point where the cords were exposed!!
Maybe the car really was pushing as bad as Dave said. Yes, the track is
run clockwise and the fastest turns are right-hand ones.

So, other than the tire failure and irritating brakes, it was a pretty
successful day. Dave thought that if we reduced the understeer (already
have a good size rear swaybar) and put some "real" brakes on the car, he
could turn 1:50's or less. I thought the car was handling fine, but the
brakes were severly overheating. He agreed that when he starting using
the brakes harder, the shudder was horrific. 

We succeeded in expending 14 gallons of fuel (with octane booster) in
about 125 miles (did we do that many laps?), this on a car that actually
gets 24mpg on the highway! Dave's words, and I agree,  were, "I didn't
think this car could suck down that much gas!"

We stopped at the alignment shop on the way home for advice on the
understeer condition and the decimated front tire. The mechanic, who
aligns many SCCA cars emphasized, "Well, I keep telling you we can set
this car up for the street or the track, but not both! He said the -1
degree camber in the front was the most he could get out of the car, and
the 0 toe was about the most toe-out he would recommend for street use.
His suggestions were to 1)dial-in more toe-out for the track only !?,
and 2)replace the stock (actually UrQ) upper strut bearing and cap plate
with some type of aftermarket bushing/plate -- this to minimize front
suspension deflection and allow him to set the front camber more
negative.

As to the G60's, my feeling is that with the clamping power of the dual
master cylinder unit and the Pagid racing pads, they are simply
overtaxed. We're going to try some cooling ducts and Porterfield pads
and see what happens. If that doesn't help, it's time to look into some
4-pot calipers. 

The Kumho's stuck well, though I'm having a hard time believing the
left front tire wasn't somehow defective. The asphalt at Pueblo is
pretty abrasive and the left front takes the brunt of the load, but the
tire looked ok until my last session on the track. The other three tires
looked decent at the end of the day. Next time, I think I'll have Tire
Rack heat-cycle and shave them. I started with full tread (4/32") and
heat-cycled the tires on the highway only (they probably didn't get hot
enough).

We in Colorado are pretty fortunate to have the Pueblo track available
"for rent" to individuals during the weekdays.  It's a pretty laid-back
place, though  when I went in August, there were some ex-Indy light cars
testing there. It was a pretty harrowing experiencing watching them blow
by me on the front straight and disappear rapidly!

Gary Kaklikian
86 4kcstq
86 5kcstq

<

Lawson, Dave wrote:
> 
> On very short notice I was invited to join another ur-q owner and
> a quad-cam ford mustang cobra for an open track day at peublo
> motorsport park. It sounded like a great mental health day and a
> good reason to burn up some old R1's. The 2 ur-q's were loaded
> into the trailer and we headed south.
> 
> It was a gorgeous fall day with the temperature about 85 F.
> We were the only ones there, 3 cars, 4 drivers, and a 2.2 mile
> 10 turn road coarse. The mustang was setup for SCCA T2
> competition, the ur-q's were street/daily drivers and setup
> as follows, 1983 models, single knock MC engines, K26 turbos. I
> was running about 12psi boost and the red ur-q was running 15 psi
> boost. The red ur-q has a 2 piece EM which has been ceramic
> coated inside and out, down pipe coated too. My ur-q has
> eibach/bilstein/delrin bushings and the 3.89 final drive,
> the red ur-q has h&r/bilstein and stock bushings and
> 4.11 final drive. Both had G60 brakes, I was running stock sway
> bars and the red ur-q has a larger rear bar. I was running old
> BFG R1's on the 15x8 wheels and the red ur-q had R1's on 16x8
> S4 wheels.
> 
> Neither myself or my friend had driven this track before. The
> mustang driver has raced there in SCCA and PCA events. Our
> instructor/mentor for the day has logged lots of track time here
> over the past 10 years. He is a quattro fanatic, has a 91 200 TQ
> Avant and is building a new SCCA ITB coupe GT. He used to
> run pro rally back in the late 70's and early 80's. I hadn't been
> on a pavement track in a few years but it all started to come back
> after a few laps. My friend in the ur-q and I worked our times
> down to 2:02 and the mustang was running about 1:53. The ur-q's
> were very evenly matched, even with the difference in gearing.
> I was seeing 105 at the end of the front straight and the G60's
> did a good job of hauling the car down to ~65 for turn 1. The
> ur-q's performed great even though the temps were on the high
> side. I was seeing the coolant close to 250F, the oil temp on
> the LED bargraph was 140-150C and my EGT was 1400F.
> After a few sessions I down loaded the ECU codes and I got
> a 2141, I left my diagnostic notes at home and couldn't remember
> what it was and made a few phone calls. Turns out it is an error
> for max retard of timing due to knock. I swapped in another ECU
> with a chip with less aggressive (stock) timing and went out again.
> I still got a 2141. I ran the rest of the day with a lighter foot and
> somewhat short shifting. My ur-q ended the day by blowing off
> the vacuum line from some sort of damper for the fuel system.
> I shoved it back on so the car would idle and we loaded it back
> into the trailer for the drive home.
> 
> Some observations. My car had very neutral handling at the limit
> with just a hint of understeer. I have been tracking my ur-q on and
> off for the past 8 years and I have never experienced any handling
> traits like Dave E mentions for cars with the "old" style suspension.
> I will keep looking. The G60 brakes worked great with, dare I admit,
> stock Audi pads and crossdrilled rotors. 5 year old hardened track
> tires are way better than any street tire, the car had tons of grip
> and not a peep from the tires. Driver experience plays a big role.
> I feel I was doing fine, but our guide went out in an ur-q and I was
> chasing him, he lost me after 3/4 of a lap. I wasn't willing to commit
> that much to keep up with him. He was running close to the
> mustang times with a 100 hp deficit. I need to follow through with
> my plans for installing a larger oil cooler and radiator. The red ur-q
> has more body roll than my ur-q. The ceramic coatings on the red
> ur-q lower underhood temps.
> 
> Now it's time to get the ur-q ready for steamboat, we're expecting
> snow tomorrow, off with the track tires and on with the haka nrw's.
> -
> Dave Lawson
> 
>