Lateral-g Forums - 1971 Firebird Build ("The Other Woman", a.k.a. Project "T.O.W.")

TOW and I spent the weekend in Fort Worth at the Good Guys Spring Nationals. As in the fall, I went up primarily to participate in the autocross. Due to the weather, there weren't as many people who actually came out for this event as there were in the fall, so we actually had more runs this time. That came at the cost of not being able to browse the rest of the show though...

TOW again did well until we had an unfortunate problem which hindered her the rest of the weekend. Given the final results, it wouldn't have made a big difference most likely, but probably did cost me a position or two. First, a quick summary of what all was done before this event:

Rebuilt the front half of the exhaust to improve ground clearance
Replace brake pads with Hawk HP+ front and rear
Replaced original 550/300 springs with 700/500
New gas pedal
Removed and services the rear differential (attempt to eliminate gear whine)

The big work was rebuilding the exhaust. Eric did a great job of replacing the 3" round pipes with oval pipe from the collectors to the point past the crossmember when it transitioned back to round. Now, the exhaust it just above the subframe rails, so no more smashing the pipes over speedbumps!

The springs we replaced at Jake's suggestion. I was surprised that the increase rate didn't seems to make the car 'feel' much stiffer when driving. I expected to feel every bump in the road, but that wasn't he case.

The brake pads are definitely different though! It takes a stop or two until they really want to grab, and that can surprise you at first on the street. I have adjusted now, but it took a little driving to get there. I also have adjusted the proportioning valve to even out the front/rear so that I'm not locking up the rears first.

While the car was apart, Eric pulled the 9" chunk and carried it to the local differential shop (we only appear to have 1 that is recommended). They adjusted the pinion depth in an effort to reduce the gear whine I was hearing, and they also found that the main bearings were pitting already. Wasn't too happy with that after just 1400 miles, but better to find it now than later.

We also changed all of the fluids since I was about to hit 1500 miles. Figured it was a good time for that. Redline in the engine now and differential, Mobil 1 in the transmission.

I picked up the car from Eric Wednesday night with a planned Thursday morning departure for FW. After I drove her home, when navigating a parking lot, I noticed a strange sound coming from the back. It wasn't repeatable / consistent, but definitely there. I couldn't figure out what the heck it was, so I touched base with Eric. We decided that I would stop by on my way out of town for a look...

We pulled the rear tires and found what we though was the culprit. It seems that the rear calipers were slightly rubbing against the rotors. We are both a little perplexed as to why this is happening, because when assembled, everything looks centered. But it was clearly obvious when looking at the caliper that they have been rubbing. So Eric shimmed the calipers and we put it all back together, and off I went.

The drive up was uneventful, I made good time with the 75 MPH speeds through central Texas (I may, or may not, have averaged a little better than that). TOW really likes to cruise at just over 80. The gear whine has definitely been reduces, and while not completely gone, is much more tolerable. I adapted to the brakes, and everything else just worked. I did notice that the sound of the exhaust is different now. Neither of us have a good theory as to why, but the car is less raspy now. It's a subtle change, but I like it better now for sure.

Friday was a fun day at the autocross. After 2 runs, I was about 4 seconds between the leaders. I was struggling with a bad push and front tire chatter. While walking around the 'pro' pit area, I noticed someone wearing a JRI sweatshirt, so I walked up and introduced myself. His name was JJ, and he was there working with Kyle, Stacy, Cheryl, and Brian on their setups. I described my car and what I was experiencing, and I asked him for a 'Shocks 101' lesson. He gave me that and then some! We talked for about 30m about how the shocks are affecting my car, about my spring rate combination, and what he thought would help. Interestingly, I was about to adjust my shock settings, but I was going to go the completely opposite direction from what JJ recommended. I'm glad I asked...

My next run came down by 3 seconds and landed me in 4th place in the street machine division! It was a huge difference. While I don't run JRI's at the moment, JJ was still willing to offer a lot of advice and suggestions to me. He has won me over as a customer when I'm ready to step up.

I was able to get in 2 more runs on Friday for a total of 5, and I didn't improve on my run, so I ended the day in 4th place. I was behind Terry Neuville (sp?), Kevin Miller, and this crazy little Mini Cooper 'chainsaw' that is apparently driven by a guy who (if I heard this correctly) won in his division at the SCCA Nationals last year in a different car. So I was feeling pretty good about where I was at!

Unfortunately, Saturday was a different story. I had noticed that something didn't feel quite right during my last run on Friday, but I wasn't sure what it was. Saturday morning when I started TOW up to drive to the track, she was very temperamental, not running smoothly. I thought it was just the cool weather, so I drove on. I lined up for my first run, and while it felt pretty good, the time wasn't there. Everyone seemed to be 1/2 - 1 second faster that morning that Friday, but I was 2 seconds off. At one point I felt the car buck on the course, I thought that maybe I had just hit the throttle wrong. But the day continued this way. I was never able to get close to my best Friday run, and each run was progressively worse. Once while idling in line, TOW just died. That has never happened before. So I knew something was wrong.

The rains rolled in at 1:00 as I was 3rd in line for my next run, so I only got 5 for the day. I packed my things and headed back to the hotel to wait out the downpour. When it was time for dinner I headed out (it was still raining), and that's when the real problem started showing up. I could barely drive her. When I hit 3rd gear, she was missing and stuttering. I limped back to the motel and grabbed my laptop. When I started the car, everything looked ok, so I went out for a drive again. Same thing: stutter, backfire, stumble. But the gauges looked fine?

Very long story short, I finally deduced that I must have lost the O2 sensor. So I disabled closed loop mode, and voila! TOW drove just fine. Thankfully the base tune is in reasonable shape to drive ok. I just sure wish I had figured this out before Saturday night so that I could have had a better chance to move up during the Saturday autocross runs!

I decided to hit the road early this morning to start the trek back to Austin just in case I had any trouble. TOW did great, the base tune was just fine for the drive home. I again made good time, and after a few miles felt that everything was going to be ok.

I dropped TOW off with Eric this afternoon to remove the exhaust for the ceramic coating. We have a few things to do, first of all determine if there is a wiring problem with the sensor, or if it just died. Eric pulled it this afternoon, and it looks pretty rough (carbon), but that could be the aftereffect of it dying. I'll be ordering a new one tomorrow, and perhaps a second for a future spare.

We're going to swap back the 550 springs in the front, reset the ride height of the car (lower in the front, I want to see if I can survive a lower ride height now that I have clearance), take a look and see if the caliper rubbing is gone on the rear, and a few other little things. We're working out the kinks that a build like this is bound to have. But I have to say, I sure am having fun along the way! While it was frustrating to have the sensor problem, I really enjoyed the drive and the autocross and meeting the fellow Lat-G members this weekend. Even that Weld guy was there. Somehow we made it through 2 full days without a single mention of BBQ. Imagine that... ;)