The tracking of my car seems to be a bit odd while under heavy acceleration or highway speeds. Hitting a bump or if the tire follows a crack in the road, it seems the front end will follow the road while the rear may wiggle a bit and then fall into place. It's like the car is flexing in the middle. I know that the bushings for the sway bars need to replaced but am unsure how big of a difference the new ones would make. Would this "wiggle" be due to potential weak frame rails? Bushings? It's hard to explain in text how it feels while driving.

Car: '73 240z

Are you drion "grooved" pavement. Mine feels like that when I'm on grooved" freeways.

Not grooved pavement. Our streets up here tend to be total sh*t from frost so there will be filled in cracks here and there which may follow the street.

Mine was really bad over roads like you discribed. I had about 1/4" toe in at the rear probably from worn bushings but I got TTT control arms that are adjustable and with 0 toe the problem is solved. Although now it likes to follow the grooved concrete a little but its way better than the random crack filler on blacktop.

My car felt "snakey" when I first got it. Rear right strut was shot.

Felt like the rear wanted to come around all the time.

I replaced all shocks & springs earlier this summer and got an alignment afterwards. This is the first year I drove the car so I'm not sure if it felt like this prior to the suspension change.

How's your steering coupler? My z drift a lot in a good roads but it all changed when i switched to MSA all ABS-plastic steering coupler. Better response to quick driving and cornering.

What are you running for tires? The symptoms you describe can easily be caused by the tires being mismatched from front to back or tire pressure being too high or low front to back. A lesson learned early in my life; The tires and suspension are the most important part of the car, if they aren't of high quality and in good repair, you are in trouble.

How's your steering coupler? My z drift a lot in a good roads but it all changed when i switched to MSA all ABS-plastic steering coupler. Better response to quick driving and cornering.

I'll have to check on this one.

What are you running for tires? The symptoms you describe can easily be caused by the tires being mismatched from front to back or tire pressure being too high or low front to back. A lesson learned early in my life; The tires and suspension are the most important part of the car, if they aren't of high quality and in good repair, you are in trouble.

Yes, tires are different sizes. Fronts are 215/65/14 Rears are 205/75/14

Tire size is not an issue persay, the problems come when you run incompatable tires (radials mixed with bias ply) or hard compounds mixed with soft compounds. Also inflate the tires per the plate on the car or owners manual, not the max psi on the tire. Keep in mind that these cars were originally designed to be outfitted with BIAS PLY tires, radials were new to the seen when the HLS30 came out. The added traction of radials can cause oversteer in hard cornering, I would suggest that if everything isn't reasonably close to aligned you could get a tracking wobble for the same reason, but I got more wobble from the bias ply tires back in the day.

When was the last time the fasteners in the rear end been check for tightness? You stated the sway-bar bushings need replacement, how are the rest of the bushings including the ones on the top of the strut towers? The sway-bar just keeps the role down in hard turns so this don't sound like the problem. However bushings on the control arms, struts, mustache bar al can cause a swerve.

When was the last time the fasteners in the rear end been check for tightness? You stated the sway-bar bushings need replacement, how are the rest of the bushings including the ones on the top of the strut towers? The sway-bar just keeps the role down in hard turns so this don't sound like the problem. However bushings on the control arms, struts, mustache bar al can cause a swerve.

All bushings are original. It's one of my projects this winter to replace them.

Are there specific fasteners you are referring to?