Georgia Fiero Club Forum

All Things Fiero => Expert Tech Advice => Topic started by: GTRS Fiero on October 26, 2020, 06:50:53 pm

Title: Fiero bumpsteer explanation
Post by: GTRS Fiero on October 26, 2020, 06:50:53 pm
This explains what is it, why, and the basics of how to correct bumpsteer.
https://www.hotrod.com/articles/pontiac-fiero-rear-bumpsteer-kit/
Title: Re: Fiero bumpsteer explanation
Post by: Roger on October 26, 2020, 06:55:28 pm
Just buy an '88.
Title: Re: Fiero bumpsteer explanation
Post by: GTRS Fiero on October 26, 2020, 06:59:58 pm
Some people are very sensitive to the bumpsteer issue.  That was why I bought an '88.  Many people don't seem to notice.

The '88 does have a better ride.

It is possible to make earlier Fieros handle as well as an '88, or better.  If you're going to improve on the '88 suspension, it's probably best to start with an earlier year Fiero.
Title: Re: Fiero bumpsteer explanation
Post by: Mike_21 on October 26, 2020, 07:31:10 pm
I haven't noticed the bumpsteer issue so far but I haven't pushed the car to it's limits yet.

This winter I plan to move the tie rod attachments points and shorten the tie rods on my 85 as described in Robert Wagner's performance book. But before I do it I'm going to remove the springs from my coilovers and measure the bumpsteer through the maximum range of motion on the suspension travel. Then I can test it again once the mod is completed and have some data for comparison.

Title: Re: Fiero bumpsteer explanation
Post by: GTRS Fiero on October 26, 2020, 07:43:34 pm
If you drive your Fiero down a road, just following the speed limit, maybe 35 MPH, and the rear wheels intermittently hit bumps, the Fiero will briefly self-steer.  It corrects itself rapidly, so some people automatically make small compensatory steering adjustments.  Yes, if you push your Fiero hard through the turns, it will also self-steer, which can be disconcerting.  Depending on the banking, the rear wheels can steer in opposite directions.  Alternatively, the rear end can cause oversteer or understeer, going through turns, depending on braking or acceleration.  If you know what is happening and why, you can adjust.
Title: Re: Fiero bumpsteer explanation
Post by: Mike_21 on October 26, 2020, 08:04:27 pm
I remember the bumpsteer very well on my 1985 fiero when it was new from the dealer. With 150 miles and 1 track day on this car, I haven't noticed bumpsteer to be an issue yet but it's not quite stock.

Title: Re: Fiero bumpsteer explanation
Post by: GTRS Fiero on October 26, 2020, 08:08:51 pm
Is your Fiero ready for a cruise?
Title: Re: Fiero bumpsteer explanation
Post by: Mike_21 on October 26, 2020, 08:29:37 pm
Not yet but the break in is going well. Suspension, brakes, and the cooling system from hell are dialed in and I finally ripped out the garbage fuel injection system. Once I get the carburetor dialed in I'll be more comfortable going outside a 5 mile radius from my toolbox.
Title: Re: Fiero bumpsteer explanation
Post by: TopNotch on October 26, 2020, 09:52:38 pm
This explains what is it, why, and the basics of how to correct bumpsteer.
https://www.hotrod.com/articles/pontiac-fiero-rear-bumpsteer-kit/
It can be done without a kit. See page 78 of "High Performance Fieros". My brother used that method.
Title: Re: Fiero bumpsteer explanation
Post by: Wreck It Ralph on October 26, 2020, 10:19:01 pm
This explains what is it, why, and the basics of how to correct bumpsteer.
https://www.hotrod.com/articles/pontiac-fiero-rear-bumpsteer-kit/
It can be done without a kit. See page 78 of "High Performance Fieros". My brother used that method.

Just ordered me a copy of the book.
Title: Re: Fiero bumpsteer explanation
Post by: GTRS Fiero on January 03, 2021, 01:31:45 pm
Haven't seen you post for a bit.  Still making good progress?