Suspension and Chassis Questions about your suspension? Need chassis advice?

Subframe flexing?

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Old Jul 30, 2017 | 11:06 PM
  #1  
gulf_coast_228's Avatar
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Joined: Sep 2006
Posts: 108
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From: Biloxi, MS
Car: 1992 Firebird Trans Am GTA
Engine: LS1
Transmission: T56
Subframe flexing?

I'm hoping I can get some advice on this. For years my steering has been sloppy in my 1992 Firebird GTA. Over the course I've time I've rebuilt the front-end with a new center link, tie rod ends, idler arm, ball joints, the works. Added a wonderbar. Got a new steering box. Replaced the rag joint. All within the last couple of years. Not sure if it matters but I also swapped in an LS1 so I had to get a new K-member and A-arms too. Also replaced is the steering pump because it was leaking.

So I'm back to trying to figure out why my steering wheel feels dead on the road, and where the slop in the steering is coming from. With all the replacements and upgrades I couldn't really figure out where it was loose, so I set up my phone under my car to look up at the suspension. Looks like the pitman arm is turning when I turn the wheel. I was surprised to see the whole front of the car flexing as I turned the wheels back an forth! That seems like an excessive amount of flexing. The wheels seem to respond okay but I still can't really feel the road, like I'm just suggesting where the wheels go. In the two videos I've uploaded the camera is stationary on the ground, pointed upward at the suspension components:



What can I do to stiffen up the subframe that's flexing? I feel like just a strut tower brace won't be enough, looking at how much flexing is going on in the videos. Also in the second video I noticed there's a bolt hole with nothing going to it. I believe this was used by my old K-member but the new one for the LS1 motor mounts (from hawks motorsports) doesn't have anything that bolts in there. So I'm not sure where to go from here and could use some advice.

Thanks in advance!
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Old Jul 30, 2017 | 11:45 PM
  #2  
jharrison5's Avatar
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Joined: Nov 2009
Posts: 1,255
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From: Lincoln, NE.
Car: '87 IROC
Engine: 5.7 Vortec w/ factory TPI
Transmission: WC T-5
Axle/Gears: 3.45 Posi
Re: Subframe flexing?

I guess I'm missing something in the videos, because I'm not seeing any flex. All I see is the entire car swaying side to side going through the normal movement related to wheel alignment.
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Old Jul 31, 2017 | 12:01 AM
  #3  
gulf_coast_228's Avatar
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Joined: Sep 2006
Posts: 108
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From: Biloxi, MS
Car: 1992 Firebird Trans Am GTA
Engine: LS1
Transmission: T56
Re: Subframe flexing?

Yea maybe I'm grasping at straws here. I'm just having a hard time figuring out why the steering feels so numb.
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Old Jul 31, 2017 | 03:39 AM
  #4  
Ron U.S.M.C.'s Avatar
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Joined: Apr 2006
Posts: 4,482
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From: Northern, CA
Car: 1989 Iroc-Z Camaro
Engine: TBI,5.0
Transmission: Automatic 700R4
Axle/Gears: Eaton Posi,3.42,LPW Ultimate Cover
Re: Subframe flexing?

Install Subframe Connectors and a Steering Brace. AKA "Wonder bar".

A lot of members here suggest the Subframe Connectors as one of the first mods to do to these cars.

Makes the car handle as if on rails.
The steering brace is mainly to reinforce the spot where the steering box is mounted to the car but does have some effect on tightening up the steering in general.

I like the UMI Performance box style connectors and there Wonderbar.
Here's a link to UMI and the parts for our cars.
= http://umiperformance.com/catalog/in...=index&cPath=6
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Old Jul 31, 2017 | 05:31 AM
  #5  
//<86TA>\\'s Avatar
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Posts: 12,805
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From: Central NJ
Car: 86 Trans Am
Engine: 408 stroker sbc
Transmission: TKO600
Axle/Gears: Moser full floater m9, 3:70 trutrac
Re: Subframe flexing?

An improper alignment can cause the car to feel numb as well.
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Old Jul 31, 2017 | 07:22 AM
  #6  
QwkTrip's Avatar
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Car: '89 Firebird
Engine: 7.0L
Transmission: T56
Re: Subframe flexing?

Agree about alignment.

You didn't let them align it to stock specs, did you?
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