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Discussion Starter #1
i was reading a thread in the suspension section. and dude was having all kinds of issues. w alignment of his subframe with the car. do i have to worry about this. i have removed my subframe for welding, blasting, and painting. i dont see how i would though. im using poly bushings. that have shoulders that fit into the bodymount holes. which are tight. and heck the bolts well. theres no adjustments there either. everything clamps the subframe to the body tight as can be. i dont see how it could ever move when all the bolts are tight. if it could i would think something else being wrong... is there something i dont know here?
 

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Yes there is something you do not know, the subframe has a lot of adjustability front to rear, side to side and every angle in between.
I just installed mine and if your body is not tweaked the install is pretty easy.

After trying to clean the sub frame of my 77 on the car I realized it was a lot harder to get it done and looking good then if the frame was removed. It has been a procedure I have been avoiding for a year thinking it would be too much of a pain to get it back in correctly. Because the car had been undercoated and the coating was not easily removed there was no choice but to pull it out.
Prior to removing the sub frame I wanted to make sure that when going back together the alignment procedure wasn’t going to cause me to pull out the little bit hair that remains on my head.

After doing a little research the task did not seem overly difficult or complicated. I did all the measuring and pin fitting prior to removing the sub frame.

There are 2 holes on the sub frame, one on each side at the firewall mount next to the body mount. Above them in the body are 2 more holes, drivers side is round, passenger side is elongated. The following procedure will work great as long as the car has not been wrecked or twisted out of shape. I used 5/8” bolts 6" long as my pin gauges (the threaded portion of the bolt is not to be used as part of the gauge), 5/8” round stock will also work well. Take one bolt and slide it through the hole of the sub frame on the driver’s side and push up until it goes into the body alignment hole and make sure it is straight not on an angle. The round hole in the body on the driver’s side centers the sub frame front to rear and side to side with the body. Although you now have the drivers side aligned front to rear and side to side the frame can rotate around the pin. The oval or elongated hole on the passenger side is the centering point for the rotational axis. When the both pins pin are in the alignment holes the sub frame will be aligned with the body.

If the pins will not fit into the alignment holes the sub frame has shifted. This can be due to the bushings worn to the point of allowing it to move, previous damage necessitating a body alignment being performed or it having been removed and not re-installed properly. I would recommend when possible that all measurements in the GM service manual or Fisher Body manual be verified prior to removing the sub frame.

Do not use the any part of the car that is not solid to take measurements. Taking measurements from drums, rotors, axle housings, etc will give false readings. These components are mounted in pliable bushings and are not solid fixed points.
Using strings and weights as plum bobs hanging from the points shown in the manuals I took measurements from the 4 points indicated on the rear frame rails and 6 points on the sub frame then compared to the measurements listed in the Fisher body manual. The first check was to see if the sub frame was square, then a check of the body rear frame rails was performed. Next was a check of the sub frame to body alignment. If all the dimensions are within tolerances then nothing is bent or twisted, if the measurements are off then at some point the car has been tweaked and the front and rear will need to be brought into proper alignment by moving the sub frame to get the measurements within specs.

MY car was still within specifications so when going back together it will be a simple process of using the pins in the alignment holes.

Here are some photos of it going back in with the QA1 coil over system installed.











 

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Discussion Starter #3
ok

ok thanx i completly understand what your tellin me sounds simple i have had the subframe out three times and always go'es in and out very easily never any resistance i feel like im in good shape
 

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If youve had it in and out 3 times, then id say youve got it down. Thanks Phillip for the heads up on the measurements. I didnt even think about that. I hope those dimensions are in my Haynes Repair Manual.


I had some issues when I removed my sub frame for the first time. First, I jacked up the rear and got it leveled on stands on the axle. Then I jacked up the front............then KAAAABOOOOMMM!....The mounts under the chassis snapped out because the weight got shifted towards the middle as I jacked up the front while the rear was lifted. The frame pads were rusted to crap. There is enough meat left for me to shim something up, but what a lesson.


The brand new distributor got cracked as the engine see sawed inwards. No biggie, because I replaced the internal parts in a new housing. The shaft is good. Oh yea, a windshield wiper hose broke off. I was lucky the tranny and driveshaft bent at the yoke joint nicely and didnt snap...Im still weary on the condition of the car. The "bolt" pads that thread the body mount bolts in the #2 location are coming off in one spot. I plan on getting an arc welder from Harbor Freights soon anyways....
 

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I feel really lucky. My 77 is free of rust, dents and bondo. It did need a complete drive train and interior. It will also need painted but that will have to wait.

I used the motor mounts to hold the car up while it was moved in and out of the shop. It was also a good balancing point for the install of the sub frame back into the car.

I would advise putting anti sieze on the body bolts, it will help stop them from rusting to the nuts.
 

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I have complete factory sub frame measurements on a diagram and will try to post it or just ask for a measurment if your in question, got it when i had a 78 years ago.
 

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Here are scans from the Fisher Body manual. If you would like larger copies PM your email address to me.
After verifying the squareness of the front and rear frames then dimension G and F should be checked.



 
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