Build Numbers 13 and 15

[Racer Z]

Three years ago, in the summer of 09 my brother and I bought a 1973 Datsun 240Z to convert into a dedicated track car. Since then we've been able to race (time trial actually) it four times a year and slowly build it. We finally got tired of sharing the one car on the track and two weeks ago we bought a 1974 260Z to convert into a dedicated track car. Like most race cars, the "build" is never really finished and everything is subject to change. We jokingly put number 13 on the 73 and that stuck cause nobody else in the club (AROSC, Alfa Romeo Club of Southern California) is using it. We later decided to paint the 13 car white and orange like a billiard ball and use a real pool ball for the gear shift knob. The only other stripped "pool ball" number not being used is 15, white and maroon, so the 74 just might become the 15 car. Currently the 73 is black and the 74 is white. "Spy VS Spy", my sister in-law called it.

 

We intend on setting to two cars up very similar and eventually racing with VARA (Vintage Auto Racing Association). Since both cars will be very similar in build and they are shared equally, I don't see any need to have separate build threads. My brother's HybridZ name is beermanpete and will be contributing to this thread (I hope).

 

The 74 was driven home, but wouldn't start up later. It's in bad shape, but we didn't pay much for it. We have not done anything to it yet.

 

The 73 has been a learning experience. It's our first Datsun and our first race car. It was stock and in very good shape when we bought it. It had been garaged and un-driven for ten years. We bought it without being able to test drive it. Fresh gas and a new battery cured that. I had looked at a lot of Z's and felt really good about this one and three years later I still think I picked a good car. It was stock, never modified, no crash damage and no rust. I had test driven Z's that were in worse shape and wanted more money.

 

A few months later we took it out to the track in absolute stock form. This included the OEM style tires, dead shocks and OEM brake pads. We took turns driving and turned a 1:52 (each) at WSIR (Willow Springs International Raceway), "The Big Track". (There is more than one track at Willow Springs and the main track is referred to as the big track.) Since then we've improved our driving skills and our car. Two months ago I turned a 1:42 at the big track. Pete was in a slower run group and got held up by slower cars. I'm sure he could have matched my time if he had a clear track.

 

To quickly go over what we've done to the 13 car, not in any order:

 

• Gutted the interior.
• Rebuilt the suspension with polyurethane bushings.
• Replaced the springs with Tokico Lowering Springs.
• Replaced the shocks with Tokico Blues.
• Added a rear anti-sway bar from a 74 260Z.
• Upgraded the diffy with a Subaru STi LSD clutch type. We got our adapters from John Coffey of Beta Motorsports.
• Rebuilt the 4-speed tranny.
• Upgraded to 15x7 wheels.
• Upgraded to Falken Azenis RT-615K 205/50x15 tires. This is not a true race tire, but a high performance street tire that does well on the track.
• Removed the bumpers and other non-essentials.
• Upgraded to Porterfield Racing pads & shoes (R4).
• Relocated the battery to the rear of the car above the rear axle.
• Had the car on scales to get the corner weights. Found that it has 51% on the front axle and was within 30 pounds on the diagonals. Did not change a thing.
• We have not re-scaled the car, but I calculated that we've lightened it by about 130 pounds since.
• Removed all the wires and switches. Installed new switches in relocated locations and built our own wire harness.
• Installed roll bar, racing seat, 5-point harness and other safety items.
• Added a Spook and a BRE style spoiler. I busted the Spook at the next event.
• Replaced the alternator with a tiny motorcycle alternator. Our Dad machined a custom pulley for us.
• Wasted time arguing over small stuff.
• Put gas in the car and went racing.

 

If you want to see some of our in-car videos, my YouTube channel is 13RacerZ

 

Pete (aka beermanpete) on left, Bob (aka Racer Z) center, my 70 Ford F250 and our number 13 car on the way to Laguna Seca, December 2011.

[Racer Z]

Just a few more pictures.

 

Pete taking a driving school on The Streets of Willow.

 

Bob at Laguna Seca. If I said I was passing a Cobra would you believe me? I got passed rather quickly.

 

I missed the corkscrew at Laguna Seca.

 

Our new 15 car, a 1974 Datsun 260Z.

 

Our new VTO wheels at Willow Springs.

 

The Pits at Buttonwillow as viewed from our in-car video camera.

 

My girlfriend and her new 2012 Fiat 500C Lounge. She won't let me drive it.

Edited April 19, 2012 by Racer Z

[dexter72]

74 250Z, Sweeeeet. You really didn't want to drive that Fiat did you. lol

[Racer Z]

74 250Z, Sweeeeet. You really didn't want to drive that Fiat did you. lol

 

Oops a typo that have now corrected.

 

I only want to drive the Fiat on the track, but why should that bother her? I keep telling her, "I will only go fast in the turns."

[Racer Z]

Last week we bought a 1975 280Z with a good body shell. We found that the 74 260Z has a bent frame and way toooo much rust. I don't have any real pictures of it yet. We're going to need some parts from the 260, such as the motor, so for the moment we have two race cars and a parts car.

 

For the full story of how we got it home and a cheap picture, see this thread (Post you comments there please.): Create Your Own Caption

 

The new "15 Car" is a silver 1975 280Z.

[Racer Z]

We're working on 13, doing a motor / tranny swap. The L24 has an effective track time of six years on it and is really tired. We have a used L28 that should be in good shape and a used close ratio 5-speed that should also be in good shape.

 

Nissan made two different 5-speeds (not counting the T-5). The early units have the same gear spread as the 4-speeds while the last few years have a slightly closer gear spread. Now that our driving skills are improving and we're making better lap times, we are wanting gear 3 1/2. Were hoping the this 83 5-speed will offer better gear / RPM choices on the track. It does look better on paper

 

Last week we pulled the motor and trans, this week we cleaned the engine bay and removed a few things that are I call "dead weight". While cleaning the engine bay we noticed the frame is buckled just above the cross member. Both sides look to be bent the same. We've been racing (time trials) the car for three years now and it seems to handle the same in both left and right turns. When we first got the car we had a shop check the alignment and were told, "It's in spec." We had it corner weighted while it was still stock and it was within 30 pounds on the diagonals. We don't see any reason to change it, we're just going to keep driving it. Of course I had to check "15" and it's straight and flat.

[beermanpete]

We finally have the car running again with the "new" engine and transmission. The L28 and 5-speed are working well. We have also converted the rear brakes to disk using ATE calipers taken from the rear of a 1988 300E MBZ and 300ZX rotors.

 

I drove the car in the AROSC TT at The Streets of Willowpsrings a few weeks ago. The engine seems ot be a bit stronger that the tired L24 it replaced, but it does not make power up to 5500 ~ 6000 like the L24. It seems to be done by about 5000. The 5-speed works fine but does not shift quite as precisely as the 4-speed did. I think this is mostly due to 4-speed having the MSA short throw shifter. Also, I think the 4-speed had relatively low miles compared to our new 5-speed.

 

The brakes have improved but not as much from the rear disk conversion as from using Raybestos racing pads in the front. We started out with Porterfiled R4 pads in front and regular street pads in the rear. On Saturday it was raining a bit so the brakes seemed to handle the heat ok. On Sunday it was dry and the fronts started to heat fade after about 10 or 15 minutes. We changes out the fronts to the Raybestos but the Porterfiled pads for the rear are a bit too thick to fit in so we could not try them.

 

Initially the front brakes were shaking with the new pads but it smoothed out after a few laps. I suspect the Porterfiled pads had left uneven deposits of pad material on the rotors. Once the new pads settled in they worked great and never faded. The rears with the street pads worked but did not have enough power to keep up and may have heat faded.

 

We came equipped with Genesis Technologies brake temperature paint and found the front brakes got up to about 900°C (on the edge of the rotor and pad backing) with the Raybestos pads. We did not take temperature readings with the Porterfiled pads but it was likely similar as they come out cracked and burnt looking. Cooling ducts are clearly needed. The rear brakes were about 350°C so it seems they were not working very hard compared to the front.

 

Overall I did pretty well. I placed second in Class P, getting edged out by less than 0.1 seconds by a Miata.

 

Here is an in-car video from Saturday morning before it stared to rain: