Drivetrain Vibration Questions

[rocket dawg]

While chasing my vibration, I did a trans mount. It didnt fix my problem ( tires were my problem) but the mount was 100% shot and needed to be replaced. Fairly easy job, too. Car is a 79 and this was done about 8 years ago.

 

[G72Zed]

I have minimal balance weights on my 70 Z28 rims with no vibrations at any speeds. I still remember in ‘75 while driving in my 71 Z28 with M22 the speed I started to get vibrations at 150 mph. And that is no sh!t.

That's a pretty good mph with the tires of yesteryear, what gear was in it, 3.73's I would assume with a 26.5" tall tire, if so that's 7,100 rpm @ 150 mph, must of been a rush that's for sure.

I hit 140 mph last time out a few weeks ago, smooth as heck, but only turning 5,200 rpm in 5th, right at the start of the tq peak, so I had the rest of the power band to use, but tires are done, so that was it for me LOL. It was very smooth.

 

[COPO]

^With 3.73, I didn’t have time to look at the tach at that speed, my eyes were peeled on the 2 lane road. But at that speed my ignition shutdown and started again once I let up.

With brand new Firestone F60 Wide Ovals. Cost $67 each in 1975.

 

[BonzoHansen]

That's a pretty good mph with the tires of yesteryear, what gear was in it, 3.73's I would assume with a 26.5" tall tire, if so that's 7,100 rpm @ 150 mph, must of been a rush that's for sure.

I hit 140 mph last time out a few weeks ago, smooth as heck, but only turning 5,200 rpm in 5th, right at the start of the tq peak, so I had the rest of the power band to use, but tires are done, so that was it for me LOL. It was very smooth.

I find my car likes to start lifting at 125 or so, the front end starts feeling light

 

[biker]

I find my car likes to start lifting at 125 or so, the front end starts feeling light

Lowering the front end a bit seems to eliminate that. Short stiff springs and good shocks stop it from lifting over whoopdy-style road contours that you dont notice at lower speeds. I like to wind mine up to 150+ (briefly) once in a while. The aero at those speeds seems good, my worries now at those speeds are steering play and twitchiness, and tires. Time for a good new box. Tires are new, but not rated for those speeds.

 

[BonzoHansen]

I've got all that lol.

 

[MChamp]

tunnel visionnn is koool

 

[G72Zed]

I find my car likes to start lifting at 125 or so, the front end starts feeling light

Oh, ok, then I can see that can get a little scary Bonzo.

Lowering the front end a bit seems to eliminate that. Short stiff springs and good shocks stop it from lifting over whoopdy-style road contours that you dont notice at lower speeds. I like to wind mine up to 150+ (briefly) once in a while. The aero at those speeds seems good, my worries now at those speeds are steering play and twitchiness, and tires. Time for a good new box. Tires are new, but not rated for those speeds.

Good points biker, a pair of adjustable shocks can really help out in that area, on both ends. Double even better. I set mine on 8-12 compression and 12-13 rebound, digressive valving as well.

I've got all that lol.

How much toe change on lift vs baseline alignment settings? Added caster helps as well, as well as a good box and pump combo that pulls assist on higher rpms.

 

[mallard]

It's been YEARS since I dared take a car up to those kinds of speeds. Driving back to the city from the drag strip one Sunday in '74 I had a little "go" with a Mach 1 mustang on the highway. I had a '69 Grand Prix 428 at the time. From 60 to 100, he had me by about 1.5 car lengths, but from 100 on, I caught up and was about 3/4 car length ahead by 134 mph (this was before metric in Canada) and, like a previous posted said, the car was lifting in the front so I backed off. I've never had a car up to that kind of speed since.

 

[BonzoHansen]

Oh, ok, then I can see that can get a little scary Bonzo.




Good points biker, a pair of adjustable shocks can really help out in that area, on both ends. Double even better. I set mine on 8-12 compression and 12-13 rebound, digressive valving as well.





How much toe change on lift vs baseline alignment settings? Added caster helps as well, as well as a good box and pump combo that pulls assist on higher rpms.

6° caster, toe 0°. I have a decent 12.7:1 3rd gen ws6 16" wheel box, which is ok, better than stock.

I might be able to talk myself into upgrading from the bilsteins.

Don't get me wrong, it's not like crazy scary. But I can feel it. Adding the factory front spoiler helped a bit.

I don't really care that much lol