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Discussion Starter #1
I have a question for you chassis gurus. What would you trust more on a stock nova subframe; ball joint grease zerks or holes in the subframe? Right now, the driver's side grease zerk shows to be 1/4" forward from a reference hole on the subframe than does the passenger side grease zerk. The reason I ask is that I am trying to establish a chassis centerline. Would it be best to build off of a chassis centerline that is perpendicular to a line drawn between the two grease zerks or build off of a chassis centerline that is actually the exact center of the subframe? If I opt for the ladder, my wheelbase will be off from driver's side to passenger's side (according to the current location of the grease zerks) by 1/4". I understand that control arms move and get bent. Thanks in advance for your help.
 

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Chassis centerline is exactly that, a centerline of the chassis not the suspension components that move.
You can use the ball joint zerks to figure out a centerpoint, then a centerpoint at the rear of the car. Make a centerline from those 2 and go from there.
 

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Never use any part of the front suspension as a referance. Use the pick up points on the chassis and the pinch welds on the rockers. If they match go from there.
 

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Discussion Starter #4
Thank you for the replies. Ive dropped some more plumb bobs and the subframe seems to be square. For some reason, the grease zerks are showing that the control arms are out of alignment with the rest of the subframe. Is this a bent control arm?
 

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Not always they will move the control arms around to get the front end to align correctly, thats why we never us them for anything. On a chassis car you can if it was build on a jig table becouse you start with the centerline.
 

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The control arms are in rubber bushings and the uppers are adjustable for front end alighnment. Use the frame itself.
 

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I always open the doors on the car and make sure the rockers are level front to back and side to side...then i drop plumb bobs at front/outer most part of rocker and the rear/outer most part of rocker...mark it on the floor then use that to find chassis center line.
 

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I always open the doors on the car and make sure the rockers are level front to back and side to side...then i drop plumb bobs at front/outer most part of rocker and the rear/outer most part of rocker...mark it on the floor then use that to find chassis center line.
That is the best way I have found. Then if things seem weird front to back you can usually get a pretty good gauge from the door openings on each side, but they are not always 100% true. It's kinda like remodling an old house when building a previously older daily driver, nothings square and easy, you just have to work with it.
 

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I always open the doors on the car and make sure the rockers are level front to back and side to side...then i drop plumb bobs at front/outer most part of rocker and the rear/outer most part of rocker...mark it on the floor then use that to find chassis center line.

Every time I see a car go down the track sideways I wonder what the builder was thinking about when they attached all the parts.....LOL.
 

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If the Grease zerts and the Chassis both dont come out square something is bent. (Unless it has a set back wheel base for the rollout.) which the stock frame wont have. That's what should be fixed first.

Build off the center line, but the control arms should also line up with it. If bushings are worn they should be replaced when doing the car, having a worn bushing in a car your doing and building around it and then let it go out the door is just asking for issues to deal with down the road.
 

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Isn't there holes/measuring points on all subframes to go off of?
I mean I used these to install my ladder bars diff seem to be in the
Chassis squire can you astablish center point from them?
Not sure I understand the rocker idea as some meet head changed mine
They really don't look even
 

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Some holes you can and some you can't. Cross measure for being symmetrical, with a tram gauge, before using.

I have found Nova's to be consistently off in the section behind the front spring mount of the rear spring. Not all, but most. They also have rear spring location pin problems. This is the biggest cause of a Dog track in them.

The problem of front control arms being off, on these mid sized GM cars is often times a bent front sub frame. If ever replacing a bent control arm, pull the spindle to proper position before replacing and you will save a lot of grief. Use that bent arm up if you have to, or you may not get a new one on again.
 

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The factory subframes suck period, i have revamped a bunch of them, they will wear you out....pretty much everything is adjustable on the car including the factory subframes. The rocker panels are most likely the most accurate thats were i always start....





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Discussion Starter #16
Man, that is some nice fab work. I am really just trying to square the subframe to the car as best as I can. Trying to get the diff mounted in relation to the subframe. I am not concerned with the location of the body (as much). I don't think I have found one square part of the car yet. Thanks for the help everyone.
 
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