Original alinement specs (Page 1/1)
hunter29 JUL 03, 07:06 PM
So I got a look at the rear FSB 87-3-8

This was to reduce rear toe to zero for improved tire wear.

So I wonder if the original spec is better for handling, or even if so it's not enough to make it worth while.

I assume the front spec change is for the same reason, but I don't know that for a fact.

Anyone look into this?
theogre JUL 03, 10:20 PM
Toe Spec in most cases has near 0 affect on handling.

+ Toe AKA Toe In is a "Pre Load" to counter the force of driving that loads the steering, control arms & their bushing, & more trying to Toe Out.

GM found the OE Spec cause Excessive Tire Wear on a Fairly Light Car & National Speed Limit @ 55 MPH

Most US States now Highways w/ Speed Limits @ 60, 65, 70 or even higher. Even in Areas where Banned because too much Traffic in or near big cities when EPA & USDOT first stated to allow 60-65 speed limits.

Is Why in my Cave page states: https://web.archive.org/web...e/fieroalignment.htm
quote
Higher highway speeds can/will effect Toe adjustment because More speed then more toe load. GM Spec was written for National Highway Speed Limit, meaning 55MPH. Now some states have 65-75MPH speed limits really means many drivers drives at 70-85. If you set any "toe out" on a machine then it will only get worse to drive. Spec says 0 ±0.1° tolerance but any −/out is bad on front of Fiero.

Rear Toe is affected by road speed and engine load. A bit of Toe Out might be a good thing but that is not covered here.

Because
● If you start w/ Any Front Toe Out or Excessive Toe In then gets way worse actually driving & That Will cause Tire Wear & Handling problems. Way worse w/ Higher Speed Limits or on Bad roads like Rutting problems from big trucks etc wearing out the Pavement. In Extreme Cases, can cause Wheel/Hub Bearing Failure Fast.
● Rear Toe the Road Loads are trying to force Toe Out but Engine Loads can try to force Toe In. And @ Cruise on a highway, HP doesn't mean crap & that's most of your driving. Even in "cities" most are not slamming the pedal very often so big motors don't matter there too.

While many "books" show wear marks on tires that point to Toe or Camber problems, often the tires never show those patterns but wear out way faster.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

hunter29 JUL 04, 07:54 AM
Understand, thanks for that explanation.
Yellow-88 JUL 05, 07:43 PM
I both agree and differ a bit from Theogre. Yes, toe setting are based on the amount of flex in the parts that control them. In an ideal system, zero flex anywhere, zero toe always, could be the goal. In the real world, rubber or poly, parts flex. Dynamic forces are constantly pushing and pulling at the chassis.

I'm convinced that the one setting that a driver "feels" the most is toe. Part of why bushings are rubber is to soften what would be "harsh" communication between car and driver. Bushings are a bit of a damper on the direct "feel" of slight unauthorized toe changes. With solid bearing at the control points, you "feel" every tiny toe change.

I'm also convinced that "feel" has a lot to do with "handling". We often confuse handling with cornering.
theogre JUL 05, 11:18 PM

quote
Originally posted by Yellow-88:
I both agree and differ a bit from Theogre. Yes, toe setting are based on the amount of flex in the parts that control them. In an ideal system, zero flex anywhere, zero toe always, could be the goal. In the real world, rubber or poly, parts flex. Dynamic forces are constantly pushing and pulling at the chassis.

I'm convinced that the one setting that a driver "feels" the most is toe. Part of why bushings are rubber is to soften what would be "harsh" communication between car and driver. Bushings are a bit of a damper on the direct "feel" of slight unauthorized toe changes. With solid bearing at the control points, you "feel" every tiny toe change.

I'm also convinced that "feel" has a lot to do with "handling". We often confuse handling with cornering.

Even w/ "solid" Pivots for control arms, wheel bearings & other "solid" parts like tie rod ends need some Toe In because all those parts "tighten up" under load while Driving. That's New Parts.

OE & "upgrade" bushing is not there just to keep the Driver happy but protect the metal parts from impact & vibration that would kill them quickly. Even w/ the bushing, Most Bolts & hardware to mount the Bushing are Class 10.9 or SAE Grade 8 or higher rated just to stay tight while driving. If those bolts get the tiny bit loose, the bushing cores & more will fail & very soon need major work & parts to fix if can be fix @ all.

If have "upgraded" a car w/ ball ends etc that eliminate the bushings & other mods & drive on the street expect legal problems when suspension breaks w/o warning & hit something or someone then get sued. Oh that assume you survive the wreck... No. they can sued your family &/or the estate to recover money from life insurance etc.

Another Fact most ignore or ignorant are Trucks that have Single Beam Front axle w/ King Pins has Zero Soft parts often still have Toe In spec for same reason because multi-link tie rod & support parts go w/ that & wheel bearings have some slop/play @ rest then go tight while driving.
jelly2m8 JUL 06, 03:17 AM
Think I posted this not long ago............

I am a certified Hunter and John Bean alignment tech I took the courses, I have had all of the free time alignment rack time any one would want....... sure many have been there..... I as much as anyone want to bash the manufacturer, but GM Factory specs really are the best overall settings. If you want a specific setting, sure non- OE will work for that application.....

If you want a comfortable daily driver with optimal tire wear, the most latest GM spec is probably where you want to be.


Tires are not cheap these days and modern tire technology is far, far better than it was, so for me, my Current Fiero handles better than what I had 30 years ago solely due to tire technology, on a GM recommended alignment.
Yellow-88 JUL 06, 12:02 PM
[/QUOTE]Even w/ "solid" Pivots for control arms, wheel bearings & other "solid" parts like tie rod ends need some Toe In because all those parts "tighten up" under load while Driving. That's New Parts.

OE & "upgrade" bushing is not there just to keep the Driver happy but protect the metal parts from impact & vibration that would kill them quickly. Even w/ the bushing, Most Bolts & hardware to mount the Bushing are Class 10.9 or SAE Grade 8 or higher rated just to stay tight while driving. If those bolts get the tiny bit loose, the bushing cores & more will fail & very soon need major work & parts to fix if can be fix @ all.

If have "upgraded" a car w/ ball ends etc that eliminate the bushings & other mods & drive on the street expect legal problems when suspension breaks w/o warning & hit something or someone then get sued. Oh that assume you survive the wreck... No. they can sued your family &/or the estate to recover money from life insurance etc.

Another Fact most ignore or ignorant are Trucks that have Single Beam Front axle w/ King Pins has Zero Soft parts often still have Toe In spec for same reason because multi-link tie rod & support parts go w/ that & wheel bearings have some slop/play @ rest then go tight while driving.[/QUOTE]

I agree. I didn't mention it but yes, compliant control point bushings help protect damage from impact loads. Anyone considering solid control points must do their homework about the design loads of the components and functions involved. As armature engineers, at least triple the highest numbers you see. Trust the laws of physics. Never guess.

On legality: People who modify chassis components must be aware that there are people who would actually pay for an investigation into the cause of an accident. And yeah ..... break a chassis part at speed and you are in big trouble even if there are no lawyers around.

And yes, rolling on the road forces tires to toe out. Tiny little clearances add up. The less compliance (new parts), the less "forced" toe out. Heavy trucks have more "parts" in there steering linkage so there are more clearances to add up. Higher speed means more "force".

As parts wear, clearances change. It's really hard to measure toe while rolling on the road, but static Toe is easy to measure so doing it often is a way to see if wear has become visible. If you see it there, there is some notable wear.

I do stand by my statement that you can feel toe, especially with low compliance control points. Yellow has solid control point bearings everywhere and I can definitely feel toe settings.