🔧 BUILD Quest for improved 4th gen Fbody drivability

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I wanted to update this thread (June 2023) with a more detailed summary of the 14-year journey with my 1998 Trans Am. In my day job, I'm an automotive journalist, so I drive a lot of performance cars, and every winter when the TA is under the cover I’m tempted to buy something new after driving the latest and greatest all year, but then every spring I get back behind the wheel and regain enthusiasm to keep at it. My goal over the last couple of years was to give it as much updating as possible to build a well-rounded late-model muscle car that blurs the line between muscle car and sports car, just how the new Camaro and Mustang have evolved over the years. And to get there, I had to correct a lot of self-inflicted mistakes that ruined the car’s drivability without much gain. This is quite the write-up for an only mildly interesting car, but verboseness comes with the territory, so here we go:

I bought the car from my cousin’s husband in 2009 for $4,000 with 100,000 miles. Their priorities shifted and the car was in need a lot of maintenance; it ran poorly, had dry-rotted tires and was in barn storage so it came with a family of mice for no extra charge.

What I bought was a stock 98 Trans Am with 16-inch wheels, sleek beak hood and SLP loudmouth exhaust. I immediately added drag radials, addressed the maintenance items and went to the drag strip, hoping for high 12s, low 13s because that was my expectation after being on LS1Tech for 5 minutes. HA. Well, the fastest F-Bodies run those times in later build years with 3.23/3.42 gears, LS6 intakes and factory production tweaks to the cam/heads. In stock configuration with loudmouth exhaust, my 98 with 2.73 gears, LS1 intake and 853 heads ran anywhere between 13.6 and 14.0 seconds, which was slower than my (at-the-time) daily driver mildly modded Grand Prix GTP.

From there, I added a Yank SS3600 torque converter and rear tubular lower control arms, which knocked 8/10ths of a second off the quarter-mile time to run consistent 12.8s; sub-frame connectors also went on at this time and really helped clean up the rattles and looseness of how the car flexed over bumps.

And then I ruined the car for a few years with poor choices.

I put a lot of trust into a performance shop that picked an inappropriate cam and didn’t put the effort into tuning. The car wouldn’t start when hot, it inconsistently idled and the torque converter tuning would make the car lug and vibrate. It was really a couple of miserable years with a loud, annoying and slow car. The cam was 231/235 .617/.621 113+3 with stock heads and a really mismatched powerband for an auto car with 2.73 gears. The car also had an LS6 intake, 42-pound injectors, 1 3/4 headers, off-road Y-pipe and Magnaflow exhaust. From there, I found a new tuner who fixed all the drivability issues so it drove much nicer, and then added 3.73 gears.

I had it dyno’d a few times in this configuration. The initial shop’s dyno spit out 401 rwhp. On a Dynojet at Dean's Performance with the revised tune, numbers were 370/345 in third gear with the converter unlocked. And then I had it dyno tuned from Speed Inc where it made 380 rwhp and 355 rwtq on their Dynojet. But it I was still disappointed at the track, running a best 12.0 at 113 mph. Looking back, that initial shop’s first dyno was laughable considering the trap speed and how poorly the car drove.

During this time, I also played a lot with the exhaust, finally settling on a Kooks catted Y with true merge, versus the ugly T-merges from previous designs that created that awful hammering sound at part-throttle.

And then I decided to take a big swing at the car. Up to this point, I had been running QA1 shocks at the back with drag radials, while up front was stock shocks/springs and summer tires. I hated how the car drove with a clear imbalance between the front end’s tightness and rear end’s looseness. I also had a drag-oriented short torque arm. So off all that went and in come the final suspension setup: Koni shocks, Strano springs, Strano sway bars, UMI long torque arm, double-adjustable lower control arms, adjustable panhard bar and a few other things. Holy smokes. Besides the converter, it was probably one of the biggest changes to how the car drives. Tight, controlled, responsive. It was like driving a car 20 years newer, instead of a bucket of bolts like how it drove with the old suspension.

Under the hood, I had Pat G from LS1Tech spec out a combo that would give stock-like drivability but with 11-second potential. It consisted of a pair of 799 heads (Z06-equivalent) pulled from a junkyard, which I had cleaned up and checked out, and an EPS cam with the following specs: 222/226 .626”/.626” 115 LSA +3, as well as a refresh of the valve train with trunion upgrade on stock rockers instead of something fancy the other shop installed. With this milder cam and upgraded heads with more compression, the car saw a giant torque increase under the curve, and power was much more usable and better matched to the auto trans. Now, I was making 390/375 to the wheels on Speed Inc’s dyno, but with a lot more power and torque under the curve and stock-like drivability.

That resulted in 11.82 @ 115 mph, and it has trapped as high as 117 mph. I consider this very impressive because it drives like it did when stock and power is accessible all over the place. Since then, I’ve installed a chrs1313 A/C ram air and have a dedicated set of C5 17-inch wheels with Hoosier drag radials to try and hit 11.50s, but my last time to the track with the setup was a bust because (as I discovered afterward) the throttle blade wasn’t going WOT thanks to the throttle cable adjustment being unclipped.

I still enjoy driving the car. I debate what to do with it (sell or keep) because I also feel a sense of stewardship to keep this car on the road looking and driving as good as I can make it. All the kids in the neighborhood turn around and give it a thumbs up when I drive past, and my kids (2 and 5 years old) call it “Dad’s Trans Am.” They pretend work on their cozy coupe (like dad’s car). I know it’s superficial, but I don’t think I’d get that kind of engagement in a CTS-V or newer car. Or maybe I would, because they could actually ride in a car that properly fit child safety seats … the debate continues.

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Bru's bird makes me want to mod my Camaro. Good thing I am fixing it up a little cosmetically currently. I lost my front right stock ground effect and am currently working at getting someone's and getting them to repaint it my color and get it shipped here overseas. Also having them ship to my parents a passenger side skirt that is also getting paint matched.
 

SHARKBITEATTACK

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Jun 15, 2008
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Bru's bird makes me want to mod my Camaro. Good thing I am fixing it up a little cosmetically currently. I lost my front right stock ground effect and am currently working at getting someone's and getting them to repaint it my color and get it shipped here overseas. Also having them ship to my parents a passenger side skirt that is also getting paint matched.
Same here. All kinds of little shit that's wrong with my TA that needs to be fixed.

Its awesome to know that 4th Gen Fbodys are still a formidable weapon (while still NA) against all this new stuff.
 
Same here. All kinds of little shit that's wrong with my TA that needs to be fixed.

Its awesome to know that 4th Gen Fbodys are still a formidable weapon (while still NA) against all this new stuff.

Ever track your TA and find what it runs stock at the 1/4th Et/mph?

I've only managed 13.1 but something is off because my mph went down a bit and I'm leaning towards tune, trans (even though it has probably 4000mi/2.5 years on it driven easily), or stall. I don't know.
 

Lead Pipe

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Track results are in. I posted in the other thread but will update here. Ran well for a baby cam and I think there's more in it. One run had a 116.5 mph trap but the Nitto 555Rs couldn't handle everything it had out of the hole. Still impressed that the tires, for their poor reputation, had a 1.61 60' in it with lowered suspension and stock-style shocks. Previous best on the old cam and stock heads was 12.00 at 113 mph. With a better tire and a chrs1313 ram air I think the car could be closer to mid 11s.

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http://www.youtube.com/watch?v=I3VCC4k_k58

I put an A/C Chris1313 on my car and have been happy with it. Some lighter wheels will help you out a lot too. You need to throw a bottle on it...
 

Bru

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I put an A/C Chris1313 on my car and have been happy with it. Some lighter wheels will help you out a lot too. You need to throw a bottle on it...

How was the install? Yeah, I want to keep A/C. It looks like some guys have picked up 2 mph with the kit. Is that what you've experienced? I'm considering lighter wheels but don't really take it to the track enough to justify the money of a full set so am considering V6 or base wheels with a slick. Or maybe scour the tech classifieds.

I was fully ready to leave the car as-is but after seeing 116.5 mph traps I've changed my mind :rofl:
 

Lead Pipe

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How was the install? Yeah, I want to keep A/C. It looks like some guys have picked up 2 mph with the kit. Is that what you've experienced? I'm considering lighter wheels but don't really take it to the track enough to justify the money of a full set so am considering V6 or base wheels with a slick. Or maybe scour the tech classifieds.

I was fully ready to leave the car as-is but after seeing 116.5 mph traps I've changed my mind :rofl:

I had speed install it since it is kinda of a pain in the ass and you need to relocate the trans cooler. I picked up about a mph but I still have 2.73 gears so I wasn't expecting much. I dropped 4/10's with the addition of the Chris1313, UDP and rear 15" street lites. I'm putting in an MS4 over the winter then I'm sure I'll be shopping for a trans and rear end.
 

Bad00ss

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Apr 15, 2006
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My car has never been that fast, and definitely not fast enough to make dealing with a lumpy cam, loud exhaust and noisy drivetrain worth it, so this year I took transforming the car into a more street-able configuration.

Tuning makes all the world of difference in streetabillity. I had a MS3 cam in my car before and the thing drove stock. A convertor or 6-speed is necessary tho. Made 411@ the wheels cam only. Daily drove the car everywhere.
 

Bad00ss

Rockford's Slow Junk
Apr 15, 2006
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That was prolly your problem right there. Speed inc. lol. It took my tuner 8-9 hours to get mine where I wanted. But the thing was no joke like a car that only had headers. drove very smooth. no drop in idle when the A/C was on. you could jam on the brakes to a stop sign and no surging it would idle smooth like stock. I can't say the same for previous cars that I let Speed inc do...
 

Bad00ss

Rockford's Slow Junk
Apr 15, 2006
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After driving TCG Tour, the next thing to go is ditch the Spohn tunnel mount torque arm, and Maganaflow catback. I'm going to get a beefier-than-stock trans-mounted torque arm to reduce the road noise and soften the ride comfort a little, as well as reduce the gear whine with aftermarket gears. The tunnel mount torque arm is like a stethoscope from the rear end to your butthole. No likely. Plus it clunks like a mother fucker.

You can buy a long trans mounted style TQ arm but do not actually mount it to the trans. With the power you make now if you hooked it hard on slicks you could potentially break the tailshaft housing on the trans. Look into a crossmember like UMI makes where the TQ arm mounts to a plate on the crossmember not the transmission itself. I have the UMI one. its a quality piece for a fair price.
 

Bru

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That was prolly your problem right there. Speed inc. lol. It took my tuner 8-9 hours to get mine where I wanted. But the thing was no joke like a car that only had headers. drove very smooth. no drop in idle when the A/C was on. you could jam on the brakes to a stop sign and no surging it would idle smooth like stock. I can't say the same for previous cars that I let Speed inc do...


Who's your current tuner?
 

Bru

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The problem I have is there's always a "new hot tuner" who can fix all your tuning problems, yet I always seem to have some tuning issues because of not enough time spent on drivability. I'm really tempted to start myself considering how mild of a setup it is and how picky I am. And it being a 98.
 

Bad00ss

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That won't be any quieter than what I have, right?

It will depend on the mount itself. The UMI crossmember I have will accept the same rubber mount that the one bolting to your transmission has. Mine is poly mount so it has some give. If your old one mounted to a crossmember in the back with no rubber mount and it was a rod end heim joint style that was basically metal on metal solid mounted, I would say this style would have more sound and vibration absorption. if it did have some sort of rubber/ poly mount back there then yes, I assume this one will be the same its just longer.
 

Bad00ss

Rockford's Slow Junk
Apr 15, 2006
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Who's your current tuner?

on the current setup I wont say. I towed it pretty far away to get the car done and numbers and info will not be released.

My old setup that was MS3 cam and Texas-speed heads and nitrous was tuned by Dan bills at FLP. Car drove amazing and I almost broke the 6-speed record for fastest SBE LS1 nitrous 6-speed. That shop is very hit or miss lately, but If Dan takes his time like he did with my car the thing will drive like stock and run amazing numbers. For heads/cam and bolt on LS1 cars with stock computer and MAF he is amazing. I felt my current setup was beyond what he was best at.
 

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