From what I understand, there is a difference between the 84 front suspension vs the 85-87 front suspension. I also hear they are interchangeable, and the later design is better. So....what is different about them, and what advantage is there to updating?

The reason I ask....I need new ball joints on the front of the convertible (84 SC). I intend to grab a new set of A-arms, sandblast and powdercoat them, throw in poly bushings and new ball joints, and then just swap them in. Figured the car will have less down time this way. Obviously, this would be the ideal time to upgrade the front end.

quote Originally posted by CowsPatoot: From what I understand, there is a difference between the 84 front suspension vs the 85-87 front suspension. I also hear they are interchangeable, and the later design is better. So....what is different about them, and what advantage is there to updating? The reason I ask....I need new ball joints on the front of the convertible (84 SC). I intend to grab a new set of A-arms, sandblast and powdercoat them, throw in poly bushings and new ball joints, and then just swap them in. Figured the car will have less down time this way. Obviously, this would be the ideal time to upgrade the front end.

Can you use an 88 Front end? IF you want you can take yours back and use it. I will just tears mine off the car to upgrade and restore.

------------------

****************************************

88 Formula CJB Arrived Finally. #689 of 1252
Time to start Working TONY!
There are Two kinds of Fiero's : Notchies and Donors!
Click here for My 88 t-Top Build

Upgrading to an 88 front end would be a major project...not something I am prepared to do.

quote Originally posted by CowsPatoot: Upgrading to an 88 front end would be a major project...not something I am prepared to do.

Plus you want the 88 for your car right.

------------------

****************************************

88 Formula CJB Arrived Finally. #689 of 1252
Time to start Working TONY!
There are Two kinds of Fiero's : Notchies and Donors!
Click here for My 88 t-Top Build

From Gary Witzenburg's book:

"To elaborate on the 1985 suspension improvements, Pontiac increased jounce travel and redesigned the Fiero's front control arms to cut the car's turning circle by a good 18 inches."

My understanding is that only the lower control arms are different.

quote Originally posted by Bloozberry: From Gary Witzenburg's book: "To elaborate on the 1985 suspension improvements, Pontiac increased jounce travel and redesigned the Fiero's front control arms to cut the car's turning circle by a good 18 inches." My understanding is that only the lower control arms are different.

That seems to match what I remember. But here is what is bothering me about that...
We will assume the only difference is the lower control arms. We know that the inner mounting points are the same...and we can assume that the positioning of the ball joint is the same. If all the joints are in the same location, how are we changing the geometry? If we aren't changing the geometry, how are we changing anything?

I replaced my 84 control arms with a set from an 85-87 car, work fine.

Before:



After:

quote Originally posted by CowsPatoot: If all the joints are in the same location, how are we changing the geometry? If we aren't changing the geometry, how are we changing anything?

The steering stops are welded onto the lower control arms so if they modified them that would account for the reduction in turning radius. Getting more jounce travel could mean a simple shortening of the bump stops. I'm only speculating though.

quote Originally posted by Bloozberry: The steering stops are welded onto the lower control arms so if they modified them that would account for the reduction in turning radius. Getting more jounce travel could mean a simple shortening of the bump stops. I'm only speculating though.

So we are extending the limits of travel, but not actually changing the geometry...so I wouldn't see a difference in the way the car drives under normal circumstances.

quote Originally posted by Bloozberry: The steering stops are welded onto the lower control arms so if they modified them that would account for the reduction in turning radius.

That's it exactly. When looking at an '84 and an "85-'87 LCA, the difference is quite obvious with the steering stops. The bottom of the shocks also mount a little differently on the LCA, but it's the steering stops that are the only critical difference.

quote Originally posted by Bloozberry: Getting more jounce travel could mean a simple shortening of the bump stops. I'm only speculating though.

I don't know if the metal cones or rubber bumpers (comprising the bump stops) are any different between '84 and '85-'87 (I suspect they're the same), but the rubber donuts sitting on top of the '85-'87 coil springs weren't used in '84. That might account for the extra "jounce" in '85-'87.

quote Originally posted by Bloozberry: My understanding is that only the lower control arms are different.

Now I don't want to throw a monkey wrench into this whole discussion, but I swear I've read at PFF that there were perhaps two or three slightly different UCA used from '84-'87.

[This message has been edited by Patrick (edited 03-09-2013).]

quote Originally posted by Patrick: That's it exactly. When looking at an '84 and an "85-'87 LCA, the difference is quite obvious with the steering stops. The bottom of the shocks mount a little differently, but it's the steering stops that are the only critical difference.

Anyone have a pic of the two side by side? I know I have seen a pic, but wasn't able to find one when I searched.

quote Originally posted by Patrick: I don't know if the metal cones or rubber bumpers (comprising the bump stops) are any different between '84 and '85-'87 (I suspect they're the same), but the rubber donuts sitting on top of the '85-'87 coil springs weren't used in '84. That might account for the extra "jounce" in '85-'87.

Interesting. I assume I wouldn't be able to add the rubber donuts without switching to 85-87 springs or I would be changing the ride height, right? The car has the 84 WS6 springs right now and I like the current balance....so I wasn't really looking to change the springs.

quote Originally posted by Patrick: Now I don't want to throw a monkey wrench into this whole discussion, but I swear I've read at PFF that there were perhaps two or three slightly different UCA used from '84-'87.

Great...one more thing to watch for. Looks like I will be using the control arms from an 86 SE that came with the F41 and Y99 suspension codes (F41=Suspension, heavy duty, front and rear....Y99=Special Rally suspension package).

quote Originally posted by CowsPatoot: Interesting. I assume I wouldn't be able to add the rubber donuts without switching to 85-87 springs or I would be changing the ride height, right? The car has the 84 WS6 springs right now and I like the current balance....so I wasn't really looking to change the springs.

Yeah, don't bother adding the rubber donuts if you like the ride height where it is. No real need for them that I've noticed.

Upper control arms on 84, 85, 86 and 87’s are all the same. The lower control arms are the same on 85, 86 and 87’s but different on 84’s.

I recall the 84 front lower arm is made up of more peices welded together to make the A-arm



Fierosound posted pictures of the two
https://www.fiero.nl/forum/A...120111-2-110639.html

Thank you, x-thumpr-x....that thread answers most of my questions. When I do this project, I will measure the ride height before and after to answer that question. Might as well measure the turning radius as well.

quote Originally posted by Patrick: Now I don't want to throw a monkey wrench into this whole discussion, but I swear I've read at PFF that there were perhaps two or three slightly different UCA used from '84-'87.

quote Originally posted by firejo24: Upper control arms on 84, 85, 86 and 87’s are all the same.

I knew I had read otherwise, so I found the post...

quote Originally posted by bnevets27 Here: CONTROL ARM, UPPER The upper control arm is unique to the Fiero. If parts are interchanged from other Fieros, note that beginning in 1986 GM provided a revised design with 1.6 degrees more positive camber. This arm was listed as a replacement for '84-85 Fieros (in the event replacement was required due to damage). Later in 1986 GM reverted to the earlier design. To minimize confusion, we are listing the part numbers for all years so it can be easily determined which control arms are used in each car. From here: http://www.fierosails.com/Steering.html I'm curious if any one has measured the two different arms to determine the lengths. I'm sure I have the longer arms (1.6 version) but would like to confirm.

[This message has been edited by Patrick (edited 03-10-2013).]

Ahhh....very interesting, Patrick. Perhaps this could explain why some people seem to have issues with camber alignment when rebuilding their front end. I will be pulling my 86 parts out of the box this evening to tear them apart for the rebuild. I will check part numbers when I do.


Anyone know anything about the castor angles on the front end? I noticed that the alignment specs are the same for 84-86, but.... I ask because this car seems to be quite twitchy in the straights. I hear similar complaints from other 84 owners, and wondered if the 84s may have had less castor from the factory. What is the proper way to measure castor? Ball joint to ball joint?

Yes... ball joint to ball joint looking from the side view. To change the caster the non-88 Fieros use different thickness spacers between the inside edge of the two bushings and the mounting tube on the crossmember where the pivot bolt slides through. The total thickness of spacers must equal 12mm but you can move the upper control arm forward or rearward on the pivot bolt by moving the spacers. I believe the stock cars came with one 6mm spacer on each side while service packs had a 9mm and a 3mm spacer in them. The thinner the spacers between the forward bushing and the mounting tube, the greater your caster since you effectively move the upper ball joint further aft in relation to the lower ball joint, increasing the angle between them in the side view.

quote Originally posted by bnevets27 Here: CONTROL ARM, UPPER The upper control arm is unique to the Fiero. If parts are interchanged from other Fieros, note that beginning in 1986 GM provided a revised design with 1.6 degrees more positive camber. This arm was listed as a replacement for '84-85 Fieros (in the event replacement was required due to damage). Later in 1986 GM reverted to the earlier design. To minimize confusion, we are listing the part numbers for all years so it can be easily determined which control arms are used in each car. From here: http://www.fierosails.com/Steering.html

So....anyone have a way for me to determine which Upper Control Arm I have? It came from a late 86. If it is this alleged "1.6" version, I will have to find a different one to use. I thought I would find a part number stamped on it...but of course GM wasn't that generous (or I am blind).