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Later-A-body
05-25-2017, 11:21 AM
I'm almost ready to get my Pontiac on the road. After modifying and reinforcing the original frame I realized that I wanted to modify the sway bar mounting area to install larger bolts that secure the front sway bar. The existing holes take 3/8" bolts. I would like to increase the bolt size to 7/16" or M12. The frame is powder coated which makes it harder to hide any welding if needed. I am wondering if anyone has increased the bolt size on their frames or welded a small plate to the frame where the front bar mounts and if that created any issues with sway bar alignment. I am going to autocross the car, and thought it would be a good idea to add some strength to the mounting pad. I'm looking for any help and opinions. Or, am I overthinking this? Thanks.
https://static1.pt-content.com/images/pt/2017/05/20170503_181551-1.jpg (http://s1189.photobucket.com/user/Later-A-body/media/Pontiac%20Build/20170503_181551.jpg.html)
https://static1.pt-content.com/images/pt/2017/05/20151124_104055-1.jpg (http://s1189.photobucket.com/user/Later-A-body/media/Pontiac%20Build/20151124_104055.jpg.html)

Skip Fix
05-25-2017, 03:57 PM
Pretty sure my TA and Camaro front bar are just 3/8 in Nut serts n the frame. Autcrossed hard with road race slicks and no issues. Another issue even with 3/8 is the bolt head to bushing bracket clearance. Factory even used small head bolts liek header bolts or Allen head bolts.

Nice tranny mount as well as entire project!

F-Body International
05-25-2017, 05:43 PM
Lab-14 has designed this but for F-Body. Here are mine I installed two days ago. You may want to contact John at Lab-14. His forum name is NOT A TA.

https://lab-14.myshopify.com

https://static1.pt-content.com/images/pt/2017/05/IMG_0352_zpseptcdnv1-1.jpg (http://s1183.photobucket.com/user/jonathonar89/media/IMG_0352_zpseptcdnv1.jpg.html)

https://static1.pt-content.com/images/pt/2017/05/IMG_0353_zpsy7cchqcg-1.jpg (http://s1183.photobucket.com/user/jonathonar89/media/IMG_0353_zpsy7cchqcg.jpg.html)

Later-A-body
05-25-2017, 06:09 PM
That is an option as well since my Grand Am's front suspension is '70-'81 F-Body.

F-Body International
05-25-2017, 06:50 PM
That is an option as well since my Grand Am's front suspension is '70-'81 F-Body.

Might as well do that then. When you get the plates, they come with bolts and washers as well.

rohrt
05-26-2017, 07:39 AM
Here is my thought. Make a flat plate with the 7/16 nuts welded to it. tap the center for a smaller screw.

Drill the holes out on the frame to accommodate the lager bolts and drill a smaller hole in the center to correspond to the plate.

Place the flat plate with the nuts on the inside of the frame and secure it by either welding the center or use a short beveled screw to hold it in place. I would think this would keep from messing up the frame.

NOT A TA
05-26-2017, 07:42 AM
Although Skip hasn't had a problem a lot of the 2nd gen F bodys do have issues. Sometimes the nutserts fail while other sub frames didn't even have nutserts at all and were only threaded into the sheet metal frame. Still others have put stiff anti-sway bars on and pulled the bolts out of the frames. In the case of the ones without nutserts it's often a mechanics fault when damage occurs from over tightening which strips the threads in the frame. The stock bolts are only supposed to be tightened to 24-27 lb ft. depending on the year which may have been due to nutserts (or lack of) in certain years. Also as Skip mentioned, the hex head bolt head to bushing bracket clearance is an issue with big bars so I've spaced out the bolts a bit in my plate kits and include Allen bolts for even easier bracket installation.

There shouldn't be any need to go with bigger diameter bolts if quality bolts and washers are used with a good solid mount on the frame and the 1/8" plate thickness won't affect performance or fitment. In the plate kits I use grade 8 nuts on the backside with grade 5 Allen head bolts (easier installation for fat bar applications like your Hotchkis than hex head) with hardened clipped washers. Back sides are coated with 3M weld thru corrosion resistant coating. Torque to 30 lb ft. There's 2 different plates for early (70-74) or later (75-81) 2nd gen F body frames. Although I'm planning on expanding the line to other models I haven't looked closely at any A body frames yet so I don't know if either of the current plates would work. If you want you could e-mail me some pics & dimensions of the bracket mount area of your frame laboratoryfourteen@gmail.com

Pic below is a Lab-14 kit for the late 2nd gen sub frames. The extra studs & nuts included are used when welding the plates to the frame to act as a heat sink and keep the threads in the nuts/plates from distorting while welding. Third hole in the plate is for plug weld. https://lab-14.myshopify.com/products/75-81-late-2nd-gen-f-body-front-sway-bar-mounts

https://static1.pt-content.com/images/pt/2017/05/20160922_155217_zpsollq26zb-1.jpg (http://s240.photobucket.com/user/NOTATA/media/Lab%2014%20products/20160922_155217_zpsollq26zb.jpg.html)

Later-A-body
05-26-2017, 08:22 AM
Thank you for the good information. My frame does not have inserts that I can see, just threaded into the frame.

Skip Fix
05-26-2017, 12:25 PM
NotA TA did you space them out a little further to use aftermarket bushings and brackets for a bigger bar?

NOT A TA
05-27-2017, 05:14 AM
NotA TA did you space them out a little further to use aftermarket bushings and brackets for a bigger bar?

Yes, and I recommend when the plates are welded in that the front bolt hole is moved forward a little so you get back some clearance between the bar and idler arm.

chuckd71
05-27-2017, 05:21 PM
I was going to try doing it this way sometime this week http://www.chevelles.com/forums/9158929-post277.html