Information in the thread is confusing, sometimes contradictory.
According to the above thread, the 1984 lower control arms are: - stronger (or weaker??) - have a larger turning radius - have a higher spring seat (car sits higher)
Question. Will putting 86 front lower control arms on an 84 decrease the turning radius and lower car? (and by how much - 1/2 inch?) ...and which are stronger??
I've only seen 84 and 88 LCAs up close but seeing as there are two different opinions on which is stronger, an 84 LCA or 85-87 LCAs, I am inclined to think that the 84s are stronger. I've never heard of any wide spread complaints about the strength of the 84 LCA (and the fact that Pontiac sold 125,000 Fiero's in 84), I think it was probably a decision by the GM bean counters to lower the unit cost of the unit by reducing the sheet thickness of the Steel thus increasing profitability even more.
If you have a bend/etc arm, replace both LCA to be sure. either all 84 or all 85-87 LCA.
------------------ 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)
If you have a bend/etc arm, replace both LCA to be sure. either all 84 or all 85-87 LCA.
My Indy's front end still feels weird when steering at highway speeds - feels mushy, like driving with under-inflated tires. Alignments don't seem to be able to solve the problem. Everything is new - I'm using Rodney's lowering ball joints, MOOG problem-solvers upper ball joints, Addco sway bar with urethane bushings/endlinks etc.
Only thing left to try is replace the original OEM rubber bushings (they look OK but who knows) as I suspect that is the cause of my problems. I'm planning to replace all the front control arm bushings with new MOOG bushings (see below).
From MOOG: Moog bushings are designed to reduce vibration and absorb noise. Advanced thermoplastic bushings absorb vibration and noise and deliver better handling and longer life, while providing the performance of urethane without the “squeak” normally associated with it. They are not affected by oils, alkalines, ozone or hydrocarbons; can withstand extreme weather conditions; can carry substantial loads; and will not discolor or crack with age.
Pictures guys. Still trying to decide if I'd be better off using the 87 lower control arms while I'm at it??
I have the control arms from my 84 out. The Black one is the 84, the "needs paint" one is the 87.
The underside of the two of them. The 84 control arm is made up of 11 pieces all welded together. The one arm is almost enclosed. You are looking at the 87's two main pieces welded together, each with a bushing at the end. The edges are rolled.
The 84 looks stronger in the area for the rear bushing. It's a metal tube that the metal sleeved bushing is pressed into, while the 87 has the open arm there.
The 87 is 3 main stamped pieces. Two control arms pieces are welded together with the spring base/shock bracket rivetted to them, with one additional piece for the shock support welded in - a total of 4 pieces vs 11 for the 84. The steel seems slightly thicker.
The 84's spring base is part of the main stamping, it appears raised. Maybe the higher spring base is why all the 84's have that "4x4 look" on the front?? I installed 1" lowering ball joints AND cut 87 GT springs to lower the Indy.
It does appear that on the 87, the spring sits lower on the control arm when viewed relative to the ball joint. The steel stamping for the spring base is twice as heavy as the 84.
At the same time, the 84 control arm seems to have a "flatter" profile when looking from the front bushing to the ball joint. The things are pretty damn complex and I haven't figured out how to properly measure them to compare, but I would say the 87 looks like a stronger design.
[This message has been edited by fierosound (edited 08-09-2010).]
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05:17 PM
fierosound Member
Posts: 15147 From: Calgary, Canada Registered: Nov 1999
Image 2... Maybe stronger in 84... Maybe. 87 is use by GM, Ford, etc, in production car and it works just fine.
quote
Originally posted by TONY_C:
I think it was probably a decision by the GM bean counters to lower the unit cost of the unit by reducing the sheet thickness of the Steel thus increasing profitability even more.
84 is use for First Version... Lots of weld and parts. Weld can be a weak area if stress, bad weld from factory, etc... IE GM didn't have time to make "second" stamp version.
Yes, 85-87 is use for lower cost but keep strength. Less part/weld... Stamping can be better that allot of welds, Less stress risers, etc...
Handling? Again... I can't see any thing from image. You have to measure it. If anything, Something small is likely.
Your call... If you think something is bent, Rust, etc, then replace them. LCA has most weigh and stress so you don't want iffy arms. Otherwise 6 of one, half dozen the other...
------------------ 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)
I got the calipers out and measured. On the 87, the spring base plate is clearly double the thickness. The other stamped parts look to be about the same thickness or slightly heavier. The channels are deeper as well, and are shaped differently with rolled edges (shaped like U) instead of bent edges (shaped like L) on the bottom. I think the 87's appear to have more stiffness designed into them to prevent flexing and I think I will use them instead - I doubt GM would "go backward" in improvements.
Reminds me of the differences between the 84 decklid hinge and the ones on my 87. Many welded bits on the 84's that break, heavier more sturdy design on the later ones. See here: https://www.fiero.nl/forum/A...100421-2-098803.html
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12:41 AM
daveg Member
Posts: 193 From: Barrie, Ontario, Canada Registered: May 2004
Changes were made from 1984 to 1985 to improve handling "In addition the 1985 front suspension lower control arm has been redesigned to provide 0.5 inches more travel"
1986 " the change to 15 inch wheels and tires is mostly a styling consideration, the rest of the Fiero is virtually as you know it"
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