C2 C3 removable crossmember

[00fxd]

I have cut and modified my cross member making it removable. The holes are all sleeved. The frame became a bit less rigid than I expected when the crossmember is not installed. I did have to push the frame rails apart to re-install, I expect that it will be more stable when the body is on. I drilled the holes and installed the plates before I made the cuts so everything is back right where it came from.

 

[mrvette]

I too had a stick car, so welded member, and got tired of it also...

when cutting mine out with the body in place, I took it and some 2" angle iron about 6-8" long per side, and also some 1.5" angle on bottom edge....IN REAR of the loose/center section, clamped/welded on each end, so it sets that 2" flange on top of the section welded to the frame, there is ONE 1/2" grade 8 bolt holding it from sliding aft with locknut on it/per side....

I also cut out the bottom of the exhaust loops and had the top reinforced as a structural arch for strength, that allows the exhaust pipes to fall a inch or so...but that whole damn mess can come in/out there in a flash now....tranny and all, drop the whole damn system , dunno about how the headers will fall, but the tranny is mine, without killing me over it....:banghead::gurney::drink:

 

[Twin_Turbo]

What you should do is fabricate a set of plates that can be welded to either cut end and bolted together so that there's no gap. it'll be much stiffer that way. I think someone here had a cutting pattern too, think it was Bullshark.

Still don't understand the need though, have installed autos and manuals, even a T56 & TKO600 without cutting, plenty of room..no issues at all.

 

[00fxd]

The non removable cross member has allways bugged me on these cars. Wraselin' the trans around, can't get at the shifter to adjust it. The gap is the width of the zip wheel blade. I'll be much happier. I could weld the plates to the crossmember on one side of each but this way is fine too.

 

[Twin_Turbo]

I'm just saying, you have access to it now. I would at least weld the ends shut with 2 plates that butt tight against each other. Shouldn't be an awful lot of work.

 

[pcf_mark]

Twin Turbo - I resisted a long time too but my bog block and T56 finally pushed me over the edge. I need to partially remove the engine to get the transmission to disengage so I can lower it. I gave up and cut the crossmember...

I agree on plating the ends. This is what I used then welded on two "ears" per side and used 1 1/2 tube as my crossmember with 1/2" bolts in double chear. No chance for movement under compression.

 

[mrvette]

Twin Turbo - I resisted a long time too but my bog block and T56 finally pushed me over the edge. I need to partially remove the engine to get the transmission to disengage so I can lower it. I gave up and cut the crossmember...

I agree on plating the ends. This is what I used then welded on two "ears" per side and used 1 1/2 tube as my crossmember with 1/2" bolts in double chear. No chance for movement under compression.

OH, didn't mention, car converted to auto 700 then 200 4r, either way, removable member is mandatory...

 

[Stingxray]

Removable x member brackets.

Ive been waiting & today finally arrived. Bullshark - Bob referred me to Ray Dowling owner of Montgomery Machine Tech LLC. who has the Water Jet Cad program to produce these plates (brackets). Charged me $50 for the set of 4. They fit 63-70's with welded in 4 speed x member (non removable). I cut my crossmember leaving 1/8th" gap on each side IE: abrasive wheel. These plates slide over the outside and allows the welding on the inside. This keeps everything square and centered. Also the ability to slide center section straight back over the exhaust pipes without removal is a nice benefit. If anyone interested in purchase E-mail me and Ill forwarded Ray's info. He has made multiple sets.

 

[69427]

What you should do is fabricate a set of plates that can be welded to either cut end and bolted together so that there's no gap. it'll be much stiffer that way. I think someone here had a cutting pattern too, think it was Bullshark.

Still don't understand the need though, have installed autos and manuals, even a T56 & TKO600 without cutting, plenty of room..no issues at all.

My car was a nightmare with the DN 5spd. Things were so tight when I first installed it that I ended up unbolting the body and lifting it up a few inches to slip the trans in. Every other time I just pulled the engine out with the transmission attached (easier than lifting the body again). Had no idea when I bought the trans that it was going to be that unpleasant to do simple R&R maintenance on it.

I eventually got so fed up with that method that I bought a spare '69 (automatic) frame off ebay and planned to just swap the body, suspension and drivetrain off the car (I didn't want to cut up the original frame). After tripping over some spare C4 suspension parts while I was working on the "new" frame, I thought, WTH, if I'm going to go to all the work to put a suspension on the new frame, why don't I put a decent suspension on it. So the simple frame swap project kind of snowballed a bit. But, despite the extra work, I'm glad I did it, and wish I had done it 20 years earlier.

 

[redvetracr]

The frame became a bit less rigid than I expected when the crossmember is not installed. I did have to push the frame rails apart to re-install, I expect that it will be more stable when the body is on ]

as long as your this far into it have you considered finish welding and gusseting the frame? it should stiffen it up some

 

[00fxd]

The frame became a bit less rigid than I expected when the crossmember is not installed. I did have to push the frame rails apart to re-install, I expect that it will be more stable when the body is on ]

as long as your this far into it have you considered finish welding and gusseting the frame? it should stiffen it up some

My frame is all perimeter welded and powder coated. The point that I was trying to make was that the cross-member really adds rigidity .. I took a lot of measurements before and after cutting and finishing.
The car is all together now - this is and old thread. Been driving it for 3 years
Note ;
Before with the old frame and still with the new all welded frame, when I cross train tracks etc, If I look at the door gaps on the pass side [convertible] I can see the gaps opening and closing. Probably don't have that effect on a coupe.

 

[68/70Vette]

Ive been waiting & today finally arrived. Bullshark - Bob referred me to Ray Dowling owner of Montgomery Machine Tech LLC. who has the Water Jet Cad program to produce these plates (brackets). Charged me $50 for the set of 4. They fit 63-70's with welded in 4 speed x member (non removable). I cut my crossmember leaving 1/8th" gap on each side IE: abrasive wheel. These plates slide over the outside and allows the welding on the inside. This keeps everything square and centered. Also the ability to slide center section straight back over the exhaust pipes without removal is a nice benefit. If anyone interested in purchase E-mail me and Ill forwarded Ray's info. He has made multiple sets.

[/IMG]

I'll send you a PM. I'd like a set. I used some previous drawings of these plates and took them to J&D Corvette in Bellflower, Ca. They made plates from the drawings and installed them on my 68 as part of my TKO600 installation. They did a beautiful job. I'd like to buy some plates just in case their fabricator is not there when I bring my 70 in.

 

[Stingxray]

68/70 vette.........I sent you Rays contact info.

Today I welded the inner plates on the crossmember. 21 inches total across square. The beauty of this is hidden Welds (on the inside only). I'll use Gloss POR15 to touch up the black powder coating.

 

[68/70Vette]

Ive been waiting & today finally arrived. Bullshark - Bob referred me to Ray Dowling owner of Montgomery Machine Tech LLC. who has the Water Jet Cad program to produce these plates (brackets). Charged me $50 for the set of 4. They fit 63-70's with welded in 4 speed x member (non removable). I cut my crossmember leaving 1/8th" gap on each side IE: abrasive wheel. These plates slide over the outside and allows the welding on the inside. This keeps everything square and centered. Also the ability to slide center section straight back over the exhaust pipes without removal is a nice benefit. If anyone interested in purchase E-mail me and Ill forwarded Ray's info. He has made multiple sets.

I ordered several sets today. I only need one set, for my 70. I think some of my friends might like to modify their crossmembers also. I already have a removable crossmember in my 68. This is really the way to go for in/out manual tranny activities. Ray Dowling apparently has bunch of these brackets already fabricated. When I ordered mine in the afternoon, he said he'd ship at the end of the day.
......................
I myself would never try to replace a manual transmission ...with the engine still in the car and with a non-removeable crossmember. I know it's commonly done. After talking to people who have done it (or reading their postings) I just would not attempt it. A main reason is I work alone. Most of my previous in/out activities have involved removing the engine/bellhousing/tranny as a complete stack and then replacing it as a complete stack. This works for me with a non-removeable crossmember. To facilitate tranny changes, I've decided to go to removable crossmembers.