The vibration from hell

[goondragon]

Years ago, when I first got my '90 SI, I rebuilt the front suspension. Immediately there was this twisted vibration.

It's not there all the time, which is possibly the weirdest thing about it. It starts at about 65 or so, and worsens the faster I go, but I have occasional zones of complete smoothness, which only make me crazier. The other day I noticed that if I took a light swerve at speed, then straightened back out, the vibration would cease for several seconds. What the hell...as if there was significant play in the rack, or somewhere, and the swerve forced the relevant components back into place.

I have all new parts on this monster now, and have rebuilt my rebuild a coupla times, to no avail. Right now it isn't professionally aligned. I just have it set to a straight, neutral toe-in. Professional alignments in the past haven't helped much, which seems as strange as anything else.

I have the rack travel centered relative to the turn of the steering wheel WITH THE TIE-ROD END ASSEMBLIES UNBOLTED. I mention this because with the rack in this position, the two tie-rod assemblies are not the same length; the passenger side is considerably longer than the driver side. I believe in the past that I've put it together so that the tie-rod assemblies were the same length, but that there wasn't any difference by way of the vibration.

Not long ago, I rebuilt the front of an '88 DX. Before this rebuilt, it was fine in terms of vibration, but after the rebuild, it, too, cranked up the shake.

Clearly I've done this, but what exactly is it that I've done? I used just your generic, major-autohouse parts, from AutoZone, I think. Could that be a problem? Would it help to bail the off-the-shelf stuff for something genuine Honda? You d-series superfreaks are the authorities, and every time I visit this site, I learn about a hundred new things. Anybody know what stupidity I'm visiting on my killer kids?

[Siege911]

Do you think it could be something as simple as balancing the tires? Actually on my old set of rims there was a bulge in the tire on the tread (from who knows what), and this caused the tires to vibrate/bounce a little at higher speeds... that's just my initial thoughts though.

[areskzc]

Do you think it could be something as simple as balancing the tires? Actually on my old set of rims there was a bulge in the tire on the tread (from who knows what), and this caused the tires to vibrate/bounce a little at higher speeds... that's just my initial thoughts though.

Siege you read my mind!

Well if it only happens after 65mph is a very certain sign of unbalanced wheels. Also could be a bent rim or a warped tire.
Check your car shoes before fixing its bones.

[SillyImportRacer]

Do you think it could be something as simple as balancing the tires? Actually on my old set of rims there was a bulge in the tire on the tread (from who knows what), and this caused the tires to vibrate/bounce a little at higher speeds... that's just my initial thoughts though.

My thoughts too.
I've had speed sensitive vibrations that can in @ Xmph & stopped X+20 mph. I was due for new tire & after I got them the vibation was gone.

God luck.

[goondragon]

Man, thanks to all you d-freaks for the commentary. I really appreciate the insight.

Actually, the first notion I had when all this started was that it must be a balancing problem. When I got the car, it had Toyo 205/50/R15s, riding on American Eagle rims, and it was seamless, no matter what speed. When I rebuilt the front suspension, I put H-rated Dunlops of the same size on it. But the different tires were just one of the new components; I did ball joints, tie rod ends, and Energy Suspension bushings at the same time, which, by way of troubleshooting any problems that might arise, was damn stupid of me.

Everyone's impression that it must be a balancing issue is pretty much the status quo at this point. The best mechanics I've spoken with have told me, as if it's gospel, that shaking is always centered at the wheel, as long as engine and transmission mounts have been eliminated as a cause (yeah, they have). Here's a possibility, I suppose: I put T-rated Yokohamas on it earlier in the year, and although the vibration persisted, it didn't seem as intense. Could it be that running 205/50s on these particular rims requires tires with sidewalls as hard as mommie's heart?

Hell, I'm still stumped, but I appreciate the replies. Anything more arcane than balancing?

[99EJ6T]

Everyone's impression that it must be a balancing issue is pretty much the status quo at this point. The best mechanics I've spoken with have told me, as if it's gospel, that shaking is always centered at the wheel, as long as engine and transmission mounts have been eliminated as a cause (yeah, they have). Here's a possibility, I suppose: I put T-rated Yokohamas on it earlier in the year, and although the vibration persisted, it didn't seem as intense. Could it be that running 205/50s on these particular rims requires tires with sidewalls as hard as mommie's heart?
these may be dumb questions but....
are the rotors warped?
is the steering rack installed correctly?
were the hubs disassembled, if the hubs were taken appart, were they assembled correctly? (if not ignore)

Anything more arcane than balancing? probubly not

[Dweezil]

Check for worn bushings. My `90 was doing the same thing before I put in my ES master set.

[99EJ6T]

^ looks like he already changed out the bushings

I did ball joints, tie rod ends, and Energy Suspension bushings at the same time, which, by way of troubleshooting any problems that might arise, was damn stupid of me.

[Dweezil]

Must read and not skim.... I'd check the brakes like other people are suggesting. Also did you replace the inner tierods?