[Jarrett Drake]

I am replacing my subframe with another one with disk brakes. The brakes shouldn't matter, but the mounting hole sizes are different. My old frame has no rust (I crashed - damn drum brakes!), and the holes measured 1 1/2". My 'new' frame has 1 3/4" holes. There is quite a bit of slop with the new frame mounts in these bigger holes. Is this normal? Can I just bolt up the new frame and the rubber will expand to fit the bigger holes? Do I have a different frame? It looks exactly the same other than this. Please help, I'm stuck right from the begining!

[CarlC]

I'm not sure what the hole size should be but the body bushing should fit snuggly in the subframe holes before bolting. If there is excess slop in these holes it may be difficult to maintain frame alignment. All of the aftermarket companies such as Rick's offer subframe repair kits to fix rusted holes.

[Jarrett Drake]

Thank you Carl. I agree. I will weld in new plates with the 1 1/2" hole for the mounts to fit snugly into. Do the plates have to be level with the old mounting plates or can I just weld them to the top or bottom, offsetting the mount the width of the new steel plates? Will this offset affect alignment?

[SSMark]

I welded mine in from the bottom. The front holes have an alignment hole that you can use a bolt in to hold in place. The back ones were held in place with clamps as centered as possible.
Mark

[Go69]

Jarrett,
If your old subframe is not bent or otherwise damaged why would you not just transfer the spindles, calipers and rotors from the new subframe to your old subframe? This looks like the easiest route and would help you avoid the cost of purchasing and welding in plates to make the new subframe work. If your old sub frame is damaged you can take it to a frame shop to get it straightened and it would still be less than cobbling up the new subframe to make it work. Just my thoughts.

[JimM]

That basic subframe was used on a lot of different models, yours could be, for example, from a '74 Pontiac Ventura! Talk to some poly bushing manufacturers and try to get some bushings that fit the holes. Maybe the later models used a different size.