Square up front sub frame??

[Phillip_L]

He search and I see it mentioned, but no details.

I am replacing all the sub frame bushing and while I have it loose, I would see if it is strait. Is there a proper way to do this or is there not enough play to make a difference?

Thanks.

Phillip

[ProdigyCustoms]

There are a couple holes on either side of the bushings at the firewall. A couple tire irons, or a 5/8 dowel is perfect for lining up the frame. Once in, you want to measure from the upper cowl fender nut to the front of the frame on each side, then in a X pattern.

[baz67]

Frank is right on, but since the frame is sort of vague, nice Frank, use the holes for the radiator bracket to frame on the frame, that hole was a referance point for the original frame manufacture so it is a known dimention.

[Mean 69]

I think David P's website has a cool engineering drawing from back in the day that shows where the various datum(plural?) are, and what the dimensions are supposed to be.

I can tell you, it is something you should really pay attention to, on my 69, I didn't, at least not as well as I should have. Now, with welded SFC's, I have far more shims on one side of the UCA's for alignment than the other side, and there ain't a whole lot I can do about it. Take the extra time to square it out.

Good luck,
Mark

[Q ship]

This is something (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=7985426870&category=6762&rd=1) I just found today on Ebay, looks very handy if it's any good. I'll be ordering one for my car soon, I'll post if it's worth it. Note that if you scroll down you can search by your car model.

[rickk]

brian , how are you . camaro is comming along .

rick kirkindall:revto9k:

[Q ship]

brian , how are you . camaro is comming along .

Hey Rick, that's good to hear. I'll give you a call before to long, I still have your number.

[CarlC]

The ebay listing is a drawing that is in the Body by Fisher chassis manual. The manual is available at any resto parts house. If you are really hard up let me know and I'll fax a copy from my '68 manual. This book and the factory assembly manual are your best friends when putting things back together correctly.

Concerning the alignment pins, there's a lot more to it. There are multiple master gauge holes on the car, and the first gen had it's share of difficulties due to the hood being a captured design, i.e. surrounded by four fixed panels. The 5/8" dia. master gauge holes on the firewall mounting pads, aligned using the pins, gets things pretty close. For another check, use four plumb bobs hung from the centers of the master gauge holes on the firewall mounting pad and on the rear frame rail just in front of the leaf spring mount. Measure the X and the linear distances and compare to the Fisher manual.

[mr5231]

CarlC is right on. I just went through this when I changed by body bushings (DSE) and welded in subframe connectors (DSE). The easiest way for me to take measurements was to use a plumb bob attached to the appropriate subframe and body locations and make 4 marks on the floor. 2 of the subframe and 2 off the car or rear frame. Then I simply ran string across diag across 2 of the points and marked the string. Then when you run the string across the other 2 points if mark on the string lines up with the marks on the floor the body should be square with the frame. Also, it's important to perform this proceedure on the subframe itself to insure that it is square and not bent. I performed these steps 4 or 5 times on multiple locations to insure everything was nice and square.

[Steve Chryssos]

My sub was laser aligned on a rack at a frame straightening shop. That way the sub is aligned relative to the back half of the car as well. The unibody is squared onto the rack. Two gauges are hung from the sub and another is hung between the rear frame rails. My frame is aligned down to three bazillionths of a micron--or at least better than it ever was from the factory.
At almost 40 years old, cowls, A-pillars, etc. may (will) have sagged or moved around. So if possible, get it as close as possible using the above methods and then drive it to a frame shop. Then add subframe connectors and a roll bar if applicable.

Edit: Also if you plan on running a bunch of caster, pull that subframe as far forward as possible, so that the front wheels sit nice in the wheel arches.

[Phillip_L]

Thanks for all the help. I will give a shot when the part arrive.