This didn't show up the first time I posted. Sorry if it double posts later.
I got whipped pretty good at the Houston National Tour by Scott
McQueen and his 500 horse Cosmo powered Bugeye. I had been struggling
with wheelspin earlier in the season. I shimmed the LSD and got it too
tight. During the first day of the tour Scott beat me by five
seconds. The rear axle was just like a spool. The car would not
turn. It pushed really badly and then the rear would snap around. My
times were beaten by 29 real cars on the first day. I drained the gear
oil and replaced it with non-limited slip oil hoping that the LSD
would start slipping a little. I also firmed up the rebound to max on
the rear shocks. The second day of the tour Scott only beat me by two
seconds. There was a noticable improvement in understeer but it was
still not perfect. My times were only bettered by 9 real cars on the
second day. I ended up with the 12th fastest combined time at the end
of day two compared to real cars with fenders. That isn't too bad. I
estimated a three second improvement on the second day due to the
adjustments that I made. If I was three seconds faster on the first
day then I would have only been beaten by 1 car on the first day and
would have had the second fastest combined time for the weekend. I
plan on removing one of the two shims from the LSD this Saturday. I
hope this will make a happy medium between wheelspin and understeer.
I weighed the car at the national tour and was suprised that it was
1730 pounds. I had been weighing parts as I took them off and
weighing new parts as they went on. I had estimated a weight of
1650. I also had a weight bias to the front and my cross weights were
off. I plan on moving the radiator to the rear which should make a 100
pound differential (50 off the front and 50 to the rear). I think I
can shim my motor mounts to get the motor 1/4 inch closer to the
passenger side. That might help a little with the cross
weights. Placement of the radiator and fuel cell can make up the
difference on the cross weights.
My electric water pump blew a seal prior to the race so I was
thrashing about trying to make the mechanical pump work. I was having
problems with the belt hitting the water neck. Does Michael sell a
smaller diameter water pump pulley that gives more clearance? I ended
up with about 1/4" clearance with my current setup. It was a little
too close for comfort so I put a stainless steel hose clamp around the
water neck. I figured the belt would have a harder time rubbing
through the hose clamp than it would the thin aluminum water neck. It
didn't appear to have rubbed at all.
I plan to buy some Wilwood dynalite brake calipers to replace the heavy stock
ones.
http://www.wilwood.com/Products/001-Calipers/019-FDL/mouting.gif
The stock ones are about 10 pounds without the crossover tubes or
pads. The Wilwood calipers are three pounds and will save a lot of
unsprung weight. I will have to fabricate a hanger. The roadster
calipers have a 3" center to center mounting. Most aftermarket brakes
have 3.50" or 5.25". I'm going to get the 5.25" calipers and then make
an adaptor that bolts onto the stock mounting points. I have a 280Z
master cylinder that is 7/8" diameter. I think it will work OK with
the 4-piston 1.62" bore calipers. The roadster calipers are two piston
2-1/8". I'm not sure what the bore size is on the 280Z that the 7/8"
master cylinder goes with. I will have to turn down the rotor diameter
a little more. These calipers should fit inside the 13" wheels a
little better and allow me to remove some wheel spacers. The smaller
diameter rotor and less wheel spacer will save some unsprung weight
and some rotational weight.
Another weight loss plan is to replace the factory KA24DE flywheel
with an aluminum one. I just need to sell some parts to gather enough
money.
I've got for sale.
U20 hot cam with no identifying markings.
U20 aluminum flywheel.
Old style PHH44 solexes with buggered up idle air adjustment screws.
Comp oil pan.
Jahns 12.5 to 1 pistons.
All these parts are installed on a good running U20. I'll separate or sell
complete.
I also have several other U20's, SU's, 5 speeds, 4 speeds, and other
big piles of parts.
68 SRL - a good candudate for restoration (roller no drive train)
68 SPL - Tetanus mostly worthless as a road car but good for racing or parts.
(roller
no drive train)
Make me an offer,
Andy
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