#1  
Old 09-14-2024, 06:37 PM
DanC's Avatar
DanC DanC is offline
Chief Ponti-yacker
 
Join Date: Dec 1999
Location: Crestview, Florida 32536
Posts: 545
Question Upper and Lower A Arm Interchange? 1978 Firebird

I'm looking at rebuilding my front end (1978 Firebird) and found no vendors that sell new stamped A arm assemblies. But there are replacement stamped units for every other GM body cars. I can buy the bushings and joints but I would rather just replace the whole assy if possible and preferably TRW.

Then when searching eBay for Firebird parts there are a couple vendors advertising A arms for '80-'96 Caprice, amongst other applications, and the header description says "(also fits 1978 Firebird)"

Does anyone here know of this, or any other, interchange? Or perhaps have a Mitchell Manual and be willing to look it up?

Thanks for any help!

__________________
------------------------------
1968 Firebird Convertable - my original HS car!
1978 Firebird Esprit "survior"
1930 Ford Model A Coupe .. (original)
1994 Buick .."TowMaster" ...woody wagon
  #2  
Old 09-14-2024, 08:55 PM
bhill86's Avatar
bhill86 bhill86 is offline
Chief Ponti-yacker
 
Join Date: Jul 2021
Location: NW Ohio
Posts: 600
Default

See if this helps you at all
Attached Thumbnails
Click image for larger version

Name:	IMG_6467.jpg
Views:	74
Size:	123.9 KB
ID:	639957  

__________________
1977 Trans Am 400/4speed (swap)

Brian
  #3  
Old 09-16-2024, 05:43 PM
DanC's Avatar
DanC DanC is offline
Chief Ponti-yacker
 
Join Date: Dec 1999
Location: Crestview, Florida 32536
Posts: 545
Default

Quote:
Originally Posted by bhill86 View Post
See if this helps you at all
Hey Brian yes, that helped. Thanks!

From what you shared, I found that no available assembly is compatible. So much for a quick n easy remove/replace on this one!

DanC

__________________
------------------------------
1968 Firebird Convertable - my original HS car!
1978 Firebird Esprit "survior"
1930 Ford Model A Coupe .. (original)
1994 Buick .."TowMaster" ...woody wagon
  #4  
Old 09-16-2024, 08:30 PM
Sirrotica's Avatar
Sirrotica Sirrotica is offline
Ultimate Warrior
 
Join Date: Jan 2005
Location: Catawba Ohio
Posts: 7,317
Default

According to this article, any 70-81 F body will interchange as long as you have the cross shaft with the assembly. Unless you're going for show points for correctness other parts will interchange.

https://www.lever-family-racing.com/...ypes-of-uppers.

Below they then list other body styles that will also interchange such as A,X, etc.

Year One lists a complete assembly for sale.

https://www.yearone.com/Product/1967-81-camaro/4487nrlh

I hope this is helpful.

__________________
Brad Yost
1973 T/A (SOLD)
2005 GTO
1984 Grand Prix

100% Pontiacs in my driveway!!! What's in your driveway?

If you don't take some of the RACETRACK home with you, Ya got cheated


Last edited by Sirrotica; 09-16-2024 at 08:54 PM.
  #5  
Old 09-16-2024, 08:42 PM
rolling money pits's Avatar
rolling money pits rolling money pits is offline
Ultimate Warrior
 
Join Date: Jan 2005
Posts: 1,617
Default

I’d love to know the difference between the A arms. Only suspension change, that I’m aware of, was the change in outer wheel bearing size in 77 or 78.

For giggles I looked at UMI and Global West, they both have 1 part covering 70/81 F and 80/96 B body cars. I understand what those arms are intended to do, but they still need to physically fit the different year
chassis.

__________________
costs too much
  #6  
Old 09-16-2024, 09:22 PM
Sirrotica's Avatar
Sirrotica Sirrotica is offline
Ultimate Warrior
 
Join Date: Jan 2005
Location: Catawba Ohio
Posts: 7,317
Default

The cross shaft and bushings changed from what I can tell. The arm is the same geometry, just the holes that the bushings mount in is changed and the cross shaft is slightly different in length.

I had steel bushings made for my 73 T/A back in the late 70s, the OEM bushings were tack welded to the control arm. Near as I can remember the later ones were press fit.

I'm fairly certain the ball joints remain the same also.

The outer wheel bearing and spindle increased in diameter from 78 to 79.

__________________
Brad Yost
1973 T/A (SOLD)
2005 GTO
1984 Grand Prix

100% Pontiacs in my driveway!!! What's in your driveway?

If you don't take some of the RACETRACK home with you, Ya got cheated

  #7  
Old 09-17-2024, 03:34 PM
Skip Fix's Avatar
Skip Fix Skip Fix is offline
Ultimate Warrior
 
Join Date: Dec 1999
Location: Katy,TX USA
Posts: 20,892
Default

Cross shafts form early to later models. I know my 81 took different upper bushings than my 78.

__________________
Skip Fix
1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever!
1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand
1965 GTO 4 barrel 3 speed project
2004 GTO Pulse Red stock motor computer tune 13.43@103.4-sold
1964 Impala SS 409/470ci 600 HP stroker project
1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs
1964 Corvette Coupe 327 4 speed
  #8  
Old 09-22-2024, 04:26 PM
DanC's Avatar
DanC DanC is offline
Chief Ponti-yacker
 
Join Date: Dec 1999
Location: Crestview, Florida 32536
Posts: 545
Thumbs up

Quote:
Originally Posted by Sirrotica View Post

I hope this is helpful.
Thank you for your reply with that interesting and informative article from Lever Family Racing!

And the link to Year One, unfortunately the upper arms are discontinued.

DanC

__________________
------------------------------
1968 Firebird Convertable - my original HS car!
1978 Firebird Esprit "survior"
1930 Ford Model A Coupe .. (original)
1994 Buick .."TowMaster" ...woody wagon
  #9  
Old 09-22-2024, 04:48 PM
DanC's Avatar
DanC DanC is offline
Chief Ponti-yacker
 
Join Date: Dec 1999
Location: Crestview, Florida 32536
Posts: 545
Default

Quote:
Originally Posted by rolling money pits View Post
For giggles I looked at UMI and Global West, they both have 1 part covering 70/81 F and 80/96 B body cars. I understand what those arms are intended to do, but they still need to physically fit the different year
chassis.
Thank you for your reply, after reading I checked out UMI and GW too. I saw where UMI covered both those and I agree that they still would need to physically fit if their listing is correct. Interesting though, in the description it states 70-81 F and 80-96 B, but when clicking the "fitment" tab it lists only 70-81 Firebird and Camaro. Then when going to the B body section it does not even show any control arms!

Looking at GW, it has Firebird uppers p/n CTA-71A and Impala as CTA-18A. The lowers were CTA-71L for Firebird and CTA-17L for Standard Impala / CTA-15L Police/Taxi (which is probably a larger ball joint). So unlike UMI, GW is saying they are different, perhaps not interchangeable, somehow!

Perhaps I just need to be "a problem customer" and order a B body upper A arm from a local parts house and physically see if/what the difference is compared to the Firebird.

__________________
------------------------------
1968 Firebird Convertable - my original HS car!
1978 Firebird Esprit "survior"
1930 Ford Model A Coupe .. (original)
1994 Buick .."TowMaster" ...woody wagon
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 11:11 PM.

 

About Us

The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.

 




Copyright © 2017