[rohrt]

This is not a question just a random thought.

I'm surprised more people don't modify there frames with a removable cross member under the engine. I was just thinking how convenient that would be for those rare occasions for changing the pan gasket, replacing the oil pump, inspections or accidently dropping something in the engine.

[b-man]

Probably because it’s a major load bearing part of the frame that’s not easily made removable without a lot of fabrication and engineering.

That part of the frame is known for collapsing inward slowly over time and road miles, not at all uncommon to have the crossmember and frame spread back out on a frame rack.

[25stevem]

Such has been done when racing GM cars In stock and super stock classes.

[ZeGermanHam]

Agree that it's a major structural component, but I do wonder if a properly engineered bolt-in crossmember could provide similar strength to the factory setup. That said, you shouldn't need to replace the oil pan gasket, oil pump, or be dropping things into your engine with enough regularity to necessitate a removable crossmember in the first place.

I was alarmed at how terrible the factory crossmember welds were on my frame when I stripped it down during restoration. Lots of popcorn and porosity. I ended up doing some remedial cleanup and re-welded them. Here's what they looked like beforehand from the factory:

[Jim Moshier]

That There looks like a Monday morning job ....after the Superbowl to me! that is terrible work!

[ZeGermanHam]

Agree, and that's why we have robots these days that don't get hangovers.

[RocktimusPryme]

Originally Posted by b-man

Probably because it’s a major load bearing part of the frame that’s not easily made removable without a lot of fabrication and engineering.

That part of the frame is known for collapsing inward slowly over time and road miles, not at all uncommon to have the crossmember and frame spread back out on a frame rack.

Is that why so many of us with first gen firebird have issues with needing to space up our engine mounts so the oil pan doesnt rub?

I assumed it was the frame mounts bending and sagging over time. I am thinking about pulling my engine this winter to go to a better oil pan. I was thinking if I do that I might replace those frame mounts and see if it doesnt raise the engine slightly.

Now that said to the OPs point, there are lots of other cars that have removable K members. So its a reasonable idea, but you would have to put some real engineering thought into how to do it so it wouldnt be just hackery.

[Scarebird]

I think it would be easier to build an oil pan with a detachable sump.

[dataway]

As a welder it was all I could do to not reweld half my frame when I had it blasted ... I think I did touch up a few areas where it appeared welds were missing. I also wanted to box the side rails, and brace several areas .... but I realized I'll never be racing, or even beating this car ... so I left it alone ... it was difficult

[ZeGermanHam]

Originally Posted by dataway

As a welder it was all I could do to not reweld half my frame when I had it blasted ... I think I did touch up a few areas where it appeared welds were missing. I also wanted to box the side rails, and brace several areas .... but I realized I'll never be racing, or even beating this car ... so I left it alone ... it was difficult

Yeah, after discovering the Ray Charles popcorn welds on my crossmember, I couldn't leave them alone. But I also boxed in my frame and am using an updated suspension, brakes, and steering, so our cars are built with different goals in mind. I fully plan to beat on mine. Your car is so beautiful and the work you've done is incredible.

The factory welds you found on your frame must have been driving you nuts. I guess they'd be classified as ugly but (mostly) functional. Certainly lots to be desired.

[dataway]

I had visions of putting on a bunch of beautiful TIG welds, maybe even silicon bronze

In retrospect ... I should have done it, although this car will never be beat, it will most likely never be in a show of any kind either ... so "stock" won't be much of an issue. Even if I didn't want to box the whole frame ... could have added a few bridges from the top to the bottom in the weak areas.

Already having dreams of finding a 68 Lemans and doing a sleeper style resto-mod

[track73]

I have removed the pan twice from my 79 Transam. in the car. I didn't think it was that hard. To me it's a whole lot easier than pulling the engine.

[Scarebird]

Originally Posted by dataway

I had visions of putting on a bunch of beautiful TIG welds, maybe even silicon bronze

In retrospect ... I should have done it, although this car will never be beat, it will most likely never be in a show of any kind either...

I did, no telling what future abuse a car may see. I reinforced the rear mount for the front control arm as they do have a habit of tearing.



Also I made a brace for the rear shock mount since it is cantilevered out a bit... and cut holes for clip nuts for the shocks. I wish I would have made spring locators for both sides - something wrong with the Koni's as they are too long and the springs can fall out.

[Tom Vaught]

Lil Jack had the front cross-member on his race GTO modded for a "drop out" cross-member. Pictures out there somewhere on the forums.

A Bunch of work, but it seems to work ok on his GTO (as he has a very good roll cage in his vehicle) and race only.

Question: Street Section, race car mod, what would be the benefit here if you had a proper engine build??? Just wondering.

Tom V.

[sdbob]

Back in late 70s in NHRA stock you could lo d modify crossmember. That is cut it enough to remove a bolt in section to get at oil pan. I personally saw one car. He also acid dipped the complete front suspension on a 68 RA II car. It didnt work well as it left the crossmember very weak, alignment, to the point it was junk after a few races.

[dataway]

Scarebird ... very nice work. Now I wish I had done that. Not a chance in Hades that anyone would have ever noticed or cared except me.

Those are some nice looking MIG welds ... what welder and wire did you use?

[gman005]

I have a removable crossmember on my 71. I will post pictures later.

[PunchT37]

My 2000 chevy truck’s got one.

[Scarebird]

Originally Posted by dataway

Scarebird ... very nice work. Now I wish I had done that. Not a chance in Hades that anyone would have ever noticed or cared except me.

Those are some nice looking MIG welds ... what welder and wire did you use?

thanks - been doing it awhile. Miller 175 with ER70 0.035" wire, 75/25 mix gas

just general purpose stuff. If you are going to get a machine get a 230v unit.

[Scarebird]

Originally Posted by gman005

I have a removable crossmember on my 71. I will post pictures later.

This would be interesting to see - was wondering how this would be solved.