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

frame twisted? umi sfc

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Old Jun 25, 2014 | 07:44 PM
  #1  
RedneckNo4's Avatar
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From: ATX
Car: Trans am
Engine: 78 350
Transmission: T56
Axle/Gears: 9 bolt 3.27
frame twisted? umi sfc

I bought a set of UMI weld in SFC's last year. I'm attempting to install them but at least on the drivers side its not lining up?

in the back its about an inch away from the pinch weld and in the front its jammed against it. I had to use a jack to get it into position. It doesn't seem right that its at an angle, does that mean my car may be twisted?

i have it level with ramps under the front tires and jacks under the axle in the back.
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Old Jun 27, 2014 | 09:32 AM
  #2  
92camaro350's Avatar
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Re: frame twisted? umi sfc

Are your pinch welds straight? I know the previous owner of my car tried jacking it up on the pinch welds and bent them and I had to bend them back to get my jegster sfc to fit. Pictures would help
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Old Jun 27, 2014 | 09:53 AM
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Base91's Avatar
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From: Georgetown TX
Car: Base 91 'bird
Engine: 3.1 v6
Transmission: 4L60
Axle/Gears: 9-bolt 3.27 & PBR
Re: frame twisted? umi sfc

You need to put the frame on the stands not wheels or axle. Make sure the front stands and the rear stands are level. If the frame isn't naturally sitting on all 4 stands probably means it's twisted. If it is then put weights where they need to be to get the frame down on the stands then weld in the SFCs. Should keep the frame straight.
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Old Jun 27, 2014 | 10:58 AM
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92camaro350's Avatar
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Re: frame twisted? umi sfc

I was always under the impression that the vehicles weight needed to be on the suspension when installing sfc's. Thats what I did anyway.
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Old Jun 27, 2014 | 11:16 AM
  #5  
RedneckNo4's Avatar
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From: ATX
Car: Trans am
Engine: 78 350
Transmission: T56
Axle/Gears: 9 bolt 3.27
Re: frame twisted? umi sfc

the pinch weld was a little bent but i straightened it out. the SFC's are straight and the pinch weld appears to be straight. on closer inspection there seems to be what looks like impact damage to the floor over the pinch weld but no where else? I'm wondering if that corner of the car was slightly crushed in? I'll post a picture later today.

The instructions also said the weight of the car must be on the wheels and not the frame?
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Old Jun 27, 2014 | 11:24 AM
  #6  
Base91's Avatar
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From: Georgetown TX
Car: Base 91 'bird
Engine: 3.1 v6
Transmission: 4L60
Axle/Gears: 9-bolt 3.27 & PBR
Re: frame twisted? umi sfc

When the car is sitting on it's wheels there is no guarantee the frame is not twisted. Springs can sag. The ground may not be level. Once the SFCs are welded in place any twist is locked in. Twisted + SFC may be better than no SFC but straight + SFC is best.
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Old Jun 27, 2014 | 12:57 PM
  #7  
92camaro350's Avatar
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Re: frame twisted? umi sfc

I disagree, you want to preload the chassis correctly by having normal pressure on the suspension, just as it would be when the car is driving down the road. The chassis is going to flex differently if the static load point is anywhere but where it normally is when the car is being held up by its own suspension. When placing jack stands under the frame somewhere you are relying on the fact that all of the points that the jack stands are holding up the car at are supposed to be the same exact distance away from level ground.

Also if the ground isnt level and you are putting the jack stands under the frame, that is only going to make it worse than if the suspension was holding up the car.
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Old Jun 27, 2014 | 01:47 PM
  #8  
Base91's Avatar
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From: Georgetown TX
Car: Base 91 'bird
Engine: 3.1 v6
Transmission: 4L60
Axle/Gears: 9-bolt 3.27 & PBR
Re: frame twisted? umi sfc

I made the point that the stands have to be level side to side even if you have to shim them. Also implicit is the same frame parts sit on the stands side to side. The point is to make sure the frame is square before you lock it in place with the SFCs. Otherwise you'd need to compensate for any twist.
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Old Jun 27, 2014 | 05:44 PM
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Re: frame twisted? umi sfc

I disagree with all of the above.

When putting on SFCs, you want the chassis ABSOLUTELY PERFECTLY UNQUESTIONABLY STRAIGHT. All this "loaded" crap is just that, CRAP.

I had mine installed at a race car shop, on a jig. They pulled my car STRAIGHT on the jig and welded em on. Remarkably, the car is STRAIGHT to this day, over 25 yrs later.
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Old Jun 27, 2014 | 06:19 PM
  #10  
RedneckNo4's Avatar
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From: ATX
Car: Trans am
Engine: 78 350
Transmission: T56
Axle/Gears: 9 bolt 3.27
Re: frame twisted? umi sfc

I may need something like that. I bolted the passenger side connector on, It seems to fit straight but since it doesn't have the welded arm i have nothing for reference and cannot be sure.

Here is the area, the red circle is where the SFC starts hitting if i hold it straight. it also seems to be hitting somewhere in the back but i'm not sure where exactly.
Attached Thumbnails frame twisted? umi sfc-dscn0111.jpg   frame twisted? umi sfc-dscn0115b.jpg   frame twisted? umi sfc-dscn0116.jpg  
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Old Jun 27, 2014 | 06:33 PM
  #11  
Base91's Avatar
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From: Georgetown TX
Car: Base 91 'bird
Engine: 3.1 v6
Transmission: 4L60
Axle/Gears: 9-bolt 3.27 & PBR
Re: frame twisted? umi sfc

Straight is what I said. But most people don't have jigs so the next best thing is to get the frame sitting straight on stands (not suspension) and if necessary weight corners to get any twist out before welding in the SFCs.
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