[Speargun]

I have a spare front subframe for a first gen F body and was wondering what mods can be done to strengthen/improve it. I plan on powder coating it & swapping it out with the one in my '67.

I plan on boxing the K-member to make some clearance for the oil pan and I've been told to weld the frame seams solid from one end to the other. I'll be using Global West tubular A-arms with coil-overs so it shouldn't need the Gouldstrand mod.

What else is recommended?
Not recommended???
TX!

[JLMounce]

The 1st gen sub-frame is structurally a pretty decent piece. It actually has more torsional rigidity than the second gen subframe.

Boxing any place than can be boxed, including the k-member and fully welding the rail seems is a great place to start. If you plan on tracking the car or running heavy springs, you might consider reinforcing the upper spring purchases and shock mount. I've seen a couple rip open there.

Next best step is solid body bushings. What many performance builders are doing now is ditching the bushings all together and welding the subframe solid to the car itself. That's a lot of work however as there's usually a channel involved and you do typically need to follow that up with frame connectors through the body as well. Solid bushings though for sure.

Hotchkis also makes a product for the first gen they call Handle Bars, which tie the upper control arm mounts together and to the firewall.

[amcmike]

To add to JLs excellent information:

Welding the subframe directly to the body without body mounts (which is a great idea structurally), do consider you'll lose hood clearance to engine equivalent to the mount thickness. If this is problem for your situation, then solid mounts would be second best solution. Really ties everything together along with the connectors.

I also think the upper arm control mounts could be better reinforced. And although it's not something that Hotchkis states as a requirement when using their handlebars, I feel like it'd be even more important since you're now loading it even more by tying into the firewall.

[JLMounce]

Originally Posted by amcmike

To add to JLs excellent information:

Welding the subframe directly to the body without body mounts (which is a great idea structurally), do consider you'll lose hood clearance to engine equivalent to the mount thickness. If this is problem for your situation, then solid mounts would be second best solution. Really ties everything together along with the connectors.

I also think the upper arm control mounts could be better reinforced. And although it's not something that Hotchkis states as a requirement when using their handlebars, I feel like it'd be even more important since you're now loading it even more by tying into the firewall.

Yes, correct, I should have stated that as well. You'll drop the body of the car about an inch when welding the frame directly to the body. This is one of the ways higher end builders are getting killer low stances on first gens without completely compromising bump travel.

[amcmike]

Originally Posted by JLMounce

Yes, correct, I should have stated that as well. You'll drop the body of the car about an inch when welding the frame directly to the body. This is one of the ways higher end builders are getting killer low stances on first gens without completely compromising bump travel.

Yeah, I could not recall offhand the mount thickness. Also thinking about it, the fender to tire gap will also be reduced that amount as well (without impacting suspension travel). Something to think about it one is planning on lowering it via suspension mods as well.

[rohrt]

This is what I did.

1. Measured it all to make sure it was not bent
2. boxed in the front cross member and the top of the link piece too
3. fully welded. The factory weld were pretty good
4. Added a jack plate with tie downs from
5. Redid the bolt holes for the front sway bar. I made a plate with nut welded on.

[JLMounce]

The tow hooks / jacking plate is a nice touch!

[hojs69]

http://screaminperformance.com/index.htm

Link for the jack plate. I welded one in also.

[Speargun]

Great info! Keep it coming.
Love the jackplate/tow hook idea!
Anyone else have any pics?

[Speargun]

What are your thoughts on cutting the crossmember out and fabbing a bolt in piece so you can drop the pan without pulling the engine?
I've been told that this weakens the subframe.

[JLMounce]

Yeah that’s going to allow a good amount of twist if not engineered out properly.

I would say that if you’re to the point that you need the convenience of dropping the pan with engine in the car (meaning you do it often) then the stock sub probably isn’t the best bet for you anyhow.