Removable X-member, anyone done it?

[TurboRagtop]

I am contemplating removing the welded-in X-member and fabricating a bolt-in version.
Two objectives here:
1. Achieve better maintainability for when I have to drop the transmission, like replacing the clutch. I hate having to pull the engine and transmission every time.
2. Install larger exhaust pipe pass-through tubes to accommodate 3 inch exhaust

Thoughts?

[Linda]

Great idea Karl!
OK, I'll buy one....

Linda

[jamesw]

That is a really really good idea. I hope you let us know how it goes.

If possible please figure out a way to add a temporary engine mount for when the trans is taken off.

Cheers
James

[theunz]

I've seen pics where someone did it, maybe Alvin has them. The big problem will be loss of rigidity. It will be hard to eliminate all the flex that bolts will allow. I bet that any of us that has replaced a clutch has given this idea some thought.

[TurboRagtop]

I've seen pics where someone did it, maybe Alvin has them. The big problem will be loss of rigidity. It will be hard to eliminate all the flex that bolts will allow. I bet that any of us that has replaced a clutch has given this idea some thought.

OK Alvin, any pics to share?

On the concern about rigidity, I found a shop that builds sand drag race trucks putting out around 1,500 hp. These guys know rigid frames and have the equipment to pull it off. They have proposed a rectangular tubing X-member with four square mounting plates attached (welded) to the frame rails. Each square plate has a matching plate on the X member with four 1/2 inch mounting bolts. I am thinking that 16 half-inch bolts will yield a pretty rigid set up, but I lack the engineering resources to perform a full finite element analysis to predict just how rigid it will turn out.
I'm going to go ahead with it, I'll keep you all posted as to the results.

Karl

[theunz]

Karl, I'm thinking of longer than 500 feet, like 500 or 5000 miles. No matter how many bolts you use, when you hit a pothole or a dip at 60mph that X member is going to move. Eventually the holes in the plates are going to wallow out resulting in more and more flex. Maybe you could attach the plates together by running softer bolts through hardened bushings and replacing the bolts from time to time. Another consideration would be that if one side of the frame was to get tweeked just a little bit it could cause a big headache trying to get the X member to line back up after removal. Good luck, I hope you can prove my concerned to be unfounded! Mike

[fairladyproducts.com]

Ralph Kenyon did it years ago when he installed a built L22 and a long 5 speed. Was a silver '69 that came originally with a red interior. I think his uncle ended up with the car.

Stan
////

[GoldHawg]

I'm not at home looking at the frame, so this could be stupid*, but would it be possible to move the X back toward the rear (and weld it in), and add a removable transmission support forward that also connects the front part of the cross member?

*Remember, as the late Paul Harvey said, to have great ideas you have to have lots of ideas. I'm still waiting for a good one!

[fj20spl311]

My two cars are both different....LOL
The yellow one had the cross member completely removed and replaced by a single 3x1 channel and two bolts going completely through the frame.
My frame is in very good condition (not rusted) and I drove the car hard, there was very little movement and the paint on the doors didn't get chipped.
With a rusted frame, things might be very different.

The blue car had the bottom of the muffler passage cut off with most of the interior of the cross member removed to install a larger pipe and them a 1/8" plate welded over the bottom of the hole. I just cut the welds off before I took it in for a new pipe and had the muffler shop weld it back.


I like the weld the plate idea more. I would suggest bolted flange on the top and welded plate on the bottom. Its very easy to design a system so the weld can easily be cut.....you will not be removing it very often, if ever again.

[TurboRagtop]

Mike,
The plan is to use threaded precision locating dowels like machine builders use. Once the X-member is bolted into place, the mating plates are match-drilled and precision reamed to the correct size. Then the dowels are driven home with the threaded hole exposed so they can be extracted when necessary.

https://www.mcmaster.com/#standard-dowel-pins/=159tkkj

Hope the link works, but if not the dowels are pretty easy to find.

Karl

[Alvin]

http://unnfair.com/

Eric Hankinson had one on his 302 V8/T-5 car. Great site with full documentation of the frame mods. Site is not around anymore?

[fj20spl311]

You can use the Wayback machine

[fj20spl311]

Mike,
The plan is to use threaded precision locating dowels like machine builders use. Once the X-member is bolted into place, the mating plates are match-drilled and precision reamed to the correct size. Then the dowels are driven home with the threaded hole exposed so they can be extracted when necessary.

https://www.mcmaster.com/#standard-dowel-pins/=159tkkj

Hope the link works, but if not the dowels are pretty easy to find.

Karl

Great idea...or just weld the bottom of the flange........LOL

[TurboRagtop]

OK Phil, I will weld the doggone thing! LOL

[redroadster]

The body provides a good deal of strength especially with a roll bar .
roads in the sixty's were terrible esp. rural roads ,all kinds of out of kilter as were roads in Asia
the X frame almost required for a hard driving sports car , but thats not the case today with the roads .
it depends what your going to do with the 311 , I say take it out & put in a removable cross bar let us know how it is I thought about do it to mine .
it adds so safety for sure , in a T bone accident , but minimal ( stop your 311 in frt. of a SUV and ponder the impact)