Houston National Tour
Posted: Fri Apr 08, 2005 9:27 am
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 fstest combined time for the weekend. I plan on trmoving 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-Cal ... outing.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'll be selling my solexes, U20 aluminum flywheel, comp oil pan, U20 hot cam, and 12.5 to 1 pistons. I've also got several U20 motors, 4 and 5 speed trannies, and a bunch of other parts that need to go.
Later,
Andy
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-Cal ... outing.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'll be selling my solexes, U20 aluminum flywheel, comp oil pan, U20 hot cam, and 12.5 to 1 pistons. I've also got several U20 motors, 4 and 5 speed trannies, and a bunch of other parts that need to go.
Later,
Andy