[Z15CAM]

I've a Question that’s been bugging me over the years. Because of the Aluminum Bumpers and Extended Grill, are the 74 Front Sub Frames the same as the 71 to 73 Front Sub Frames or do the 74 front brackets simply attach to the 71 to 73 sub frames?

I suspect my 70 Front Sub Frame is different then the 71 to 73's because the Control Arms (which may be different – possibly same as 69 Chevelle ) have Larger Ball Joints, the same size as a 69 Chevelle and probably mount in different locations where the Control arms attach to the Sub Frame. The 70 also has a Rubber/Aluminum Bumper mounted to the lower Control Arm which I've not seen on later models.

Could anyone enlighten me on this?

[radial72]

Okay, this is a bit involved.

'70 is unique, the A-arms are different, and some of the early frames are a little different than the later ones cosmetically, BUT all 70-74 subframes are a bolt-in.

'71 is very similar to '70, but have the later a-arms and related stuff

'72 goes to the later engine mounts

'73 pretty much the same as '72 with more tapped holes

'74 Again UNIQUE, last year of this bolt pattern subframe which was shortened in '75 for cat converters, there are more holes for bracketry.

'75-81 new shorter subframes.

All of the a-arms are actually interchangeable IF you use the entire setup from wheel to wheel, that is you can use an '81 a-arms and steering linkage on a '70 if you use it all and don't try to mix and match.

Clear as mud? (I've probably missed a few minor and major points but that's the highlights)

[Z15CAM]

Radical72: Thanks you have confirmed my suspicions that control arms are interchangeable as long as you use the corresponding steering linkages. I imagine that would include the Pitman and Idler Arms.

[davidpozzi]

74 and up used larger OD upper A arm bushings.
The idler arm bolt spacing to the subframe was changed around 74 and up.
The Moog catalog actually said our 73 idler arm was the later style, but it wouldn't fit, we had to use the 70-73 idler arm.

[Z15CAM]

Dave: What can I say after visiting your site = WOW!! Do you have room for a slightly worn out 60's Style Mechanic in your Garage - LOL

[davidpozzi]

Sure! Maybe then I'd get something DONE!
David

[BIGBLOCK70Z]

where are the vin# located on these subframes, and dont the later subframes have metric bolts and nuts. just wondering i have a 70z and think it is bent a little cuz the ds inner tie rod hits the center section under oil pan. and have a nice subframe out of 77 firebird.

[davidpozzi]

Originally Posted by BIGBLOCK70Z

where are the vin# located on these subframes, and dont the later subframes have metric bolts and nuts. just wondering i have a 70z and think it is bent a little cuz the ds inner tie rod hits the center section under oil pan. and have a nice subframe out of 77 firebird.

The GM manual indicates the tie rod clamps have to be positioned in a particular "clocking" position or they will hit the frame or suspension components. I don't recall the exact postion they should be in, but generally it's forward and down a bit.
David

[Z15CAM]

Johnnie: I've had my 70z down to the metal and have inspected about every square inch of that car over the years. Other then the Driver Side Dash Location and Protector Plate on the Cowl there are only 2 other locations on the car were the VIN # is located on a 70z Camaro: 1 - Just under the Heater encasement on the firewall and 2 - about 1/2 down the bottom of the Drivers side rocker panel. I never saw a VIN# on the Sub Frame and believe me I had it polished down to the bare metal before I applied Epoxy Primer and painted it with Gloss Black Auto-Tremclad.

[BIGBLOCK70Z]

thanks