Good evening to the forum. I hope to commence the rear axle swap on our 1966 Ninety-Eight, the conversion being to a limited slip assembly. The rear control arm bolts to the axle are in quite ugly condition, I may have a fight on my hands to remove them. This being said, I wish to get proper replacement bolts and nuts, not something from the hardware store. Will a kit made for a 1964-72 Cutlass work for my project? Thanks in advance for any help from the experienced or those with the part number books! Best regards, Howie.

 

Why the hesitation to use hardware store bolts? Bolts are bolts - the OEM were sourced from the same manufacturers as aftermarket. GM didn’t make them, they bought them.

Get Grade 8 with similar dimensions and there shouldn’t be any issues.

 

The OEM bolts have a shoulder that locates the bushing in the bracket. While I've used Grade 8 hardware store bolts, they don't have this feature. The full size cars use rear suspension bushings that are dimensionally identical to those on the A-body cars, so yes those kits will work. The rear lower control arms are even the same P/N.

 

Joe thank you so much, you answered many other questions too I was thinking about. Best regards! Onwards and forwards in little steps I go with the project!

 

I have nice original control arm bolts as Joe described, PM me how many you may need.

 

The originals look like this. Note both the shoulder under the head and the pointed end to facilitate getting everything lined up as you install them. AMK also sell new ones.

 

Thanks, I certainly will! Best regards, Howie. Edit, PM sent!

 

Thanks Joe, that is exactly what I am looking for. When it comes to important parts like this, I trust an (the ) engineer much more then using a general multi-use bolt! Best regards, Howie.

 

Yes but they were made to GM's specifications. Like Joe mentioned most oem bolts have a purpose made profile that is not the same as "any old" bolt.

I hear plenty of people say this but in the real world the hardware store bolts are never the same as the oem ones. Take a file to a grade 8 GM bolt and then to a grade 8 from Home Depot and you will see what I mean.

 

I was just going by my personal experience back in high school using hardware store bolts on the rear lower control arms. There weren’t any restoration houses back then.

 

I wish to thank all who stepped in with thoughts and suggestions, and offers. I have been able to locate the correct parts up here (locally!) in Canada. The input has taught me a lot about fitment and why these parts look the way they do. Best regards to all, Howie.

 

IF you look at that bolt GM bolt does not touch the inner sleeve of the bushing only the shoulder and the threads touch...Reason?? Do not know. BUT a aftermarket bolt will have a large shoulder all the way to the thread and have the same thickness the complete distance from under head bolt to thread end....SOOO really the aftermarket bolt will support the inside of the bushings...BUT may never come out if it gets rusted in...lol.
It could be that GM designed the bolt not to get welded in by rust so it only touches a little on the bolt head shank and the threads on the other. So you can hammer it out and not have the bolt touch as much in the bushing sleeve.
JUST more thoughts here. Jim
JD Race

 

If true, this would be the first time in history GM ever gave a rip about being able to disassemble something if there was rust - and frankly I've had to cut out plenty of factory GM suspension bolts that have rusted. The reality is that this is all about simplifying assembly on the line. A precise fit at the ends only (and the pointed lead-in) make this much easier to put together. The "support" in the bushings is meaningless - the only load is at the ends where the walls of the control arms encircle the bushing. The primary load on the bushing is in torsion.