Bumpsteer mod?

Atilla the Fun · Post by **Atilla the Fun** » Mon Mar 24, 2008 2:41 pm

Hello all! New to posting but have browsed here for a year. Sorry no pics yet. Last summer I got an '84 2M4, and it drove really spooky at anything above 70. I want advice on doing solid cradle mounts WITH the bumpsteer mod. Can these two be done together? If not, which is better? This is my first Fiero, I've always wanted one since around 1990, (I was 14) about when I first learned of the V8Archie V8 kit. But I want to do a TDC 3.4 with a ProCharger. This car has 42K miles, all service records, the 4.10:1 geared 4-speed stick, and at the SLC, UT Pick-N-Pull I got a '91 FWD Getrag. So, anyone have the answers? Thanks in advance.

Pyrthian · Post by **Pyrthian** » Mon Mar 24, 2008 2:57 pm

best way to reduce bumpsteer is to reduce wheel travel. stronger springs, new struts & rear sway bar.

and - also - many other rear independant suspension problems are often blamed on bumpsteer - like mainly bad rear a-arm bushings, and also bad rear balljoints, tie-rod ends & sloppy axle bearings.

FieroJimmy · Post by **FieroJimmy** » Mon Mar 24, 2008 4:49 pm

Also, if you shouldn't have any bumpsteer issues driving in a straight line if your alignment is right, unless the road is VERY bad.

If someone did an alignment on the car and set the rear toe to 0 you can have stability problems at high speeds.

High speed stability problems can also be helped by adding a hood vent. It's not generally reported to be as big a problem on the bumperpad cars as on the aero cars, but it can reduce front end lift at highway speeds.

And, like Pyrthian said, make sure the suspension is in good shape before spending big money on upgrade parts.

Atilla the Fun · Post by **Atilla the Fun** » Tue Mar 25, 2008 4:35 pm

I guess I should specify I'm installing all new poly bushings, except where the cradle attaches to the car, and as I understand it, the bumpsteer mod consists of using a die to add threads to the rear tie rods, then cutting the inner mounts off the cradle and moving them out like an inch and a half. As for toe, I don't know where it is, probably factory spec, but does anyone know of any settings better than factory? I'm mostly fishing for you guys' experiences, good or bad, not theory. I'm not new to cars, only Fieros. Again, Thank You all! -Atilla

Kohburn · Post by **Kohburn** » Wed Mar 26, 2008 8:00 am

basicly you have to move the inner tie rod pivout out about 2 inches. i am not certain of the exact measurement. so this means you need a different tie rod. the kits use heim joints for the inner pivot. pretty easy to remove the old inner mount and weld on a new clevis to hold the heim joint. heck you can even put a series of holes in it or even a slot to make it adjustable untill you find that perfect sweet spot.

Pyrthian · Post by **Pyrthian** » Wed Mar 26, 2008 10:40 am

dont worry about the bumpsteer
most people blame every rear suspension issue on bumpsteer. just not the case. as others mentioned - your problem is likely the rear toe. and factory specs are fine. being its a Fiero - it never will feel like any other car - so - cant use that as a guide. the rear will always feel funny.

The Dark Side of Will · Wed Mar 26, 2008 11:25 am

Agreed... remove the goo from the rear suspension, stiffen the springs and shocks significantly (beware of too much bar, though) and add the widest wheels/tires your budget will support to the rear. If you still feel that you have issues, THEN start playing with the geometry.

You should DEFINITELY pursue solid or urethane cradle mounts.

Kohburn · Post by **Kohburn** » Thu Mar 27, 2008 8:54 am

The Dark Side of Will wrote: You should DEFINITELY pursue solid or urethane cradle mounts.

second'

a sloppy craddle can feel similar to bumpsteer. after rebuilding the rear suspension with all poly and all new baljoints i never felt anything like bumpstearwithout going over raised diagnoal railroad tracks