Four Wheel Alignment

[JoelH]

When I got my new wheels the shop couldn't adjust my rear wheels and get them aligned. I notice a little steering wheel bounce now. I saw a kit I think at MSA and I can't find it now to help adjust this.

Can someone explain to me what this kit does, why it's needed and how difficult it is to install? If anyone has a link to it too I'd appreciate it.

I'd just like to get all the wheels aligned and know what's going on with this kit.

[sblake01]

Rear camber adjusters. I have them on my 78 280Z and my 810. http://www.thezstore.com/page/TZS/PROD/PSDC07A/23-4171

[xray]

Rear wheels are not alignable unless you have custom control arms or camber plates/adjusters. Front end alignment is basically a toe adjustment, and if other specs are out of line, then some damage may have occurred to the suspension pieces, bushings or frame.

Steering wheel bounce? Not sure what that means, but if you've driven on front tires for awhile with bad toe, a wear pattern could have been created that now causes a bounce/wobble/shimmy once the problem was corrected. What was examined on the steering system by the mechanic that could've been loosened during his eval?

[sblake01]

Yeah, that was kind of a two part question. As far as the rear kits go, they look pretty easy to install. I didn't put them on, however, my suspesnion guy did.

[Arne]

Oh boy, where to start.

First, wheel alignment has absolutely nothing to do with wheel shake or vibration. That is a wheel balance issue.

Second, the reason the shop couldn't adjust your rear alignment is that there ARE no adjustments possible. If the rear is significantly out of spec, either the car is severely lowered or something is bent. Did the shop give you the specs? If so, please post them, along with the type of springs and shocks you have on the car.

A rear alignment kit for an S30 consists of eccentric poly, nylon or delrin bushings to replace the normal bushings at the inside of the lower control arms. You really shouldn't need these on an undamaged street car at anywhere close to normal ride height. They should be used to compensate for a small amount of body shell warpage, to correct camber and/or toe on a radically lowered car, or to fine-tune the settings for track use.

[JoelH]

Here's the BEFORE measurements:

Left front .41 RF .16 Camber

LF 2.84 RF 3.54 Caster

LF -.21 RF .42 Toe

Front .22 Total Toe

Steer Ahead -.32

Left rear -.77 RR -.73 Camber

LR .74 RR -.17 Toe

Rear Total Toe .56

Thrust Angle .46

AFTER:

Left front .40 RF .26 Camber

LF 2.84 RF 3.54 Caster

LF .14 RF .14 Toe

Front .28 Total Toe

Steer Ahead 0.0

Left rear -.77 RR -.69 Camber

LR .74 RR -.15 Toe

Rear Total Toe .59

Thrust Angle .44

That's what they gave me. The wheel shimmys a little (about a half inch side to side) when I release it driving down the road. It may have been a little loose with the other tires but not as bad as now.

I went front 175/65/14 to 205/60/15.

It's not a really bad feel. Had I driven it from the beginning like this I'd just say hey it's 36 years old but it was better. If it is a balance issue I'll take it back because it really doesn't pull, just shimmy.

[jmortensen]

Your alignment looks pretty good except for the left rear toe setting. That's a lot of toe in on the LR. The only way to adjust that out is with the eccentric adjusters or custom control arms that have toe adjustability. If you replaced the 30+ year old worn out bushings with new, you could recheck again and it would probably be different and hopefully better.

Your steering wheel issue sounds like a tire issue, not an alignment issue. Rotate the tires front to back and see if it goes away. Make sure the wheels are dynamically balanced (weights on the inside and outside of the rim) and that the tires aren't mounted improperly. Sometimes tires will set the bead wrong on the rim and the tire has to be pulled off and remounted on the rim to fix. Also look for a bent rim. You could throw in checking the wheel bearings for tightness, but it doesn't sound like a wheel bearing issue to me. Sounds like the tires are either out of balance or out of round or a wheel is bent.

[John Coffey]

Offset control arm bushings allow suspension adjustments not possible with stock components. Should be considered mandatory with wider wheels and tires. Machined from high-grade aluminum and delrin. Sold in pairs. Your car must be aligned after installation of these components. For easiest adjustment, use camber wrenches shown below.

Figure 4 to 6 hours to properly track the car (thrust angle) and set the toe using the offset rear inner control arm bushings. Its a pain in the butt and I've aligned 6 cars using these bushings. They also wear out in a couple years and you get to do the whole thing over again.

[Arne]

I agree that the left rear is a problem. I also agree (having done alignments with this type of adjuster before) that correcting it with the eccentric bushings will be a PITA.

I'd be looking at finding the root cause and correcting it there, rather than a band-aid fix. Look for a tweaked lower control arm on the left rear, bad bushings, or perhaps a bent rear bushing support brace.