C4 Frame Project

cool, nice work. thanks for sharing Brian. :anim_25:

Wow, you've got skills! Thanks for sharing. Nice use of the '90 'Vette parts. It's amazing how close the two cars are in weight and track width!

Yes good job , mIke

Frame Center Section Progess

Here are some pics of how I built the frame center section. This was from April / May of 2015.


This is the first bulkhead for the center section. I made it with 3/4" x 1 1/2" rectangular tubing and 1/8" x 3" flat steel. The exhaust cut outs are made from 4" o.d x1/8" wall round tubing.


Tacked in place in the frame.


2nd cross bulkhead and center bulkheads in place


Mocking up the front part of the Center section. I made the bends in the rectangular pieces by making pie cuts and welding them back together.


2nd side mocked up ready to tack weld together.


Clamped in the drill press to drill the hole for the exhaust cut out.


Both front sections ready to tack weld in place.


Flange added for the trans cross member


All welded in place.


All the suspension bolted back in place with wheels and tires to double check that everything lined up correctly before removing the frame from the table.



Off the table and on the ground for the first time. Almost ready to get the body off the original frame and start test fitting on the new frame.
The next post I'll show that process. I ended up building a 4 post body lift to make that process a lot easier.

That is some great work!!! Very gifted I say...

That's some real fabrication right there, nice work! :anim_25:

Wow! I love your fabrication! You build four post lift...what? Please, post more pics :congrats:

Great thread to follow! Keep it coming thanks. And by the way you are one very talented person.

Body lift build

The next step in the process was to build a lift to safely remove the body off my original frame and be able to drop it on and off the new frame several times to fit everything for the conversion. What I ended up building was farily simple and ended up working very well.


I made a 4 post type lift using 2 x 2 square tubing with plates welded to the bottom to anchor them into the floor. The post are drilled every 6" for anchor pins like a jack stand. I tied it all together at the top with cross braces, corner braces and anchored the whole thing into the shelves which are attached to the walls and ceiling of my shop.


I made a trolley like this one for each post out of 1/8" flat stock. I drilled the plates to bolt lift arms to the plates, and pin holes that align with the holes in the posts. The rollers to ride on the posts are 1" dom tubing with 1/2" id. I made spacers to allow the rollers to move freely from 1/2" od tubing with a 3/8" id. to go inside the rollers.


Here I have the lift arm installed on 1 side. The lift arms will go under the rocker panels on the body but still clear the frame. The lift mechanism will be high lift jacks. They will go under the lift arms with the lift handles pointing toward each other. This worked out very well as I could operate 2 jacks at one time. I got lucky on that one as it was the only way I could put them and still clear my work benches.


Here is the lift all set up to get the body off the old frame. I just taped some high density foam to the arms to protect the rocker panels. I used outdoor sports type seat cushions from Menards for the foam. The only downside to this set up is the lift arms have to be removed to back the car in and then be bolted back on to lift the body off. If I planed to be using it all the time It would be better with pivoting lift arms but it would have to be built more heavy duty and made it cost more time and money to build. I ended up spending about $550. to $600. to build my lift including the 4 high lift jacks which were $65. each. The rest was for the steel and bolts.


My car backed into the lift ready to re-install the lift arms. At this point I had all the body mounts unbolted, wiring, shocks, gas tank & lines removed. Everything came apart pretty easy since I had done a body off restoration in the late 80's to early 90's and the car has rarely even seen rain since. The hood came off when my son got home from work. I couldn't do that by myself.


Body lifted off and the old frame rolled out. My son was home to help me jack it so we just stood on opposite sides and each did 2 jacks at a time, so it only took a few minutes to lift it off. I was able to do it by myself also by just lifting 2 clicks on the jacks on the first side, then alternating 4 clicks at a time from side to side so the body was never very far from level side to side.


Body sitting on the lift ready to test fit the new frame.


Body down on the new frame for the first time. I used wheel skates to make it easier to line the frame to the body as I lowered it down.


I had to make a little mod to the floor pan under the rear seat area to clear the rear suspension dog bones for the C4 rear end. After a couple of times on and off the new frame I had the hole I need to clear everything dialed in.


I made this piece to fill the hole. I made this from 3 pieces that were welded together.


Opposite side test fit and held in place with sheet metal screws.


Installed permanently in place. I used pop rivets and epoxy to install them. The notch in the wheelwell pinch weld is to allow removing the top dog bone bolt with the body on the frame. I would have ideally welded them in place, but since the interior was still in the car and the floor pans are covered with hushmat I figured welding in that area wasn't a very good idea.
This is where I was at about a year or so ago. My next post I will show the process of moving the gas tank and setting up the engine mounts.

P.S. Thanks to everyone for the nice comments. I don't think that I have any special talents though. I learn from my mistakes (trial and error) as much as anything. It just takes practice, patience and hard work. I started out with small projects and always try to make the next project better than the last. I like to share what I am doing because I've learned a ton from seeing what everybody else is working on.

Outstanding work. :congrats:

I may not do this or ne able to do this, but your work interests me. Good job. Mike

Nice job! Creative.

Gas tank relocation

My next project on the build was to move the gas tank back to make room for the C4 rear end.


I needed to move the tank back about 3" to clear everything so the first step was to remove the original tank brackets from the body. Then I made a 2" wide strip of 18 gauge and bent it to fit around the trunk pan where the original brackets were located.


I then put a bend in the original front bracket and welded the front and rear to the strip of 18 gauge. The holes drilled in the strip are to spot weld the whole thing to the trunk floor to relocate the brackets 3" further back.


Here the strips are spot welded to the trunk floor ready to put the tank back in.


In the trunk the holes for the carriage bolts moved back 3" also.


Gas tank back in place with the filler neck installed. I just angled the filler neck back towards the filler door. I just needed to re-bend the tab on the filler neck top mount and add a spacer to make it work.


With the tank back 3" the filler neck clearance was a bit tight here. I just ground away some of the pinch weld to give it better clearance.

The next project was to build new motor mounts. To clear the C4 steering rack the engine needs to move up, I also moved it forward 3/4" to clear the firewall better.


The Corvette motor mounts removed from the cross member. They wouldn't work without recessing the firewall about 4" and they are offset 1" to the passenger side of the car also. I think this is for better drivers side footwell size on the stock C4 Corvettes.


Engine mocked up in position. It is positioned to just clear the steering rack with a 6 5/8 balancer and pulleys. My engine is a 283 from a 62 Chevy with just a hub for the pulleys but I wanted to make sure a balancer would clear if I put a different engine in the car down the road. I made brackets bolted to the original front mounts to help position the engine. I used the side mounts for the new set up.


I made pieces from 1/8" to fit the Corvette cross member that will be bolted in place eventually. Then made pieces to fill the gap between the motor mount and the plate. The motor mounts are two piece aluminum from Speedway Motors with the arms reversed to point more downward.


View from the drivers side


View from above the mount. I have the spacers so the engine can be moved forward or backward if needed


Completed mount ready to bolt in place. I installed threaded inserts in the Corvette cross member to bolt them in place.


Ready to bolt in place on the cross member.

Trans Crossmember & Steering Column

My next projects were the trans crossmember and the steering column.
The crossmember was just a short piece to span the gap of the chassis center section.


I made this from 4 pieces welded together to form a single piece. Here the bottom is cut to size and the top piece bent to shape.


All welded together and ground to size.


This shows the top nut plates to bolt the crossmember in place. It will bolt in place underneath the center section flanges and the nut plates will sandwich the flanges from the top.


Bolted in place holding the transmission in place.

The next project was to build a tilt steering column to replace the original.
I couldn't use the original column with the C4 set up as the original doesn't have it's own steering shaft as it is part of the steering box.


Here you can see the Original column (red) compared to the 70's chevy van column I will be modifying. I had bought the van column quite a few years ago at a swap meet after reading the article in Classic Chevy Word on modifying it for use in a classic chevy.


Here is the initial test fit. As you can see it will need to be shortened, both the outer tube and the shaft are to long to work as is.


Here it is all disassembled ready for mods. The Classic Chevy World article from July 1993 is a great guide for taking it apart, and also for matching the wiring to the original harness.


Here is the amount I shortened the outer tube of the column (about and inch). I shortened it where the shift levers come out at the bottom since I have a floor shifter I don't need that opening anyway.


Here the end is tacked back in place and a small filler piece made from the section removed.


All welded up and ground smooth.


Inner tube shortened the same amount. No need to get this one perfect as you won't ever see it once the column is back together.


The upper tilt head cover had a hole for the shift indicator light that needed to be filled along with the screw holes for the shift indicator.


Copper back up piece is place to weld in the patch.


Patch ready to weld in place.


All welded up and ground smooth.


Here is the shift collar with the gear indicator bump ground off, and the shift lever boss ready to be cut off.


All ground off ready to fill the holes.


To fill these openings I filler pieces that I epoxied in place. I didn't want to attempt welding because of this piece being pot metal. Even though they make welding rods for pot metal this piece is pretty thin at the big end that meets up with the tilt head so I wasn't taking any chances.


Filler piece for the shifter boss hole.


Shift collar with body filler applied and sanded out ready for priming. I used fiber glass reinforced filler for the first coat of filler and finished with Rage Evercoat Gold filler as it sands much easier.
Next post I will continue the colum modification process.

Steering Column mods continued.


I made an opening to match the original column for the tab in the bracket that holds the column up to the dash.


The wiring on the van column I bought just had the wiring running under a cover on the outside of the column. I wanted the wiring hidden inside so I made and openings to run the wiring inside until it was under the dash. This is the lower opening.


Here the wiring goes into the column at an opening I added at the top which will be just under the shift collar, coming back out at the lower opening using the cover from the original column.


I made this cover for the back up light switch opening. I didn't weld this one shut in case I needed it held pull the wiring through once everything is reassembled.



Before reassembly I put a couple of coats of paint on everything so there wouldn't be any spots missing paint after reassembly.


The lower bearing in my van column was shot and I could not find a replacement (not at a reasonable price anyway) for it. What I did find for under 20 bucks was one for a 70's Jeep CJ. The only problem with this was the shaft on my column is 3/4" and the Jeep Column is 1". I solved this with a simple 3/4" x 1" steel bushing tack welded to the shaft. As it turned out though when reassembling the bottom of the van column is also slightly bigger than Jeep columns so the only part of the Jeep bearing kit I ended up using was the bearing itself. This was fine though as it was the only part that needed to be replaced.


Here is the bushing on the shaft. It fit snug enough that it probably would not had to be tack welded in place but I eventually did just to be safe.


I decided to turn the steering shaft into a 3/4" DD shaft by grinding and filing it down. At this point its a bit long so I can trim to proper length later. I wasn't comfortable with cutting the shaft off and welding back together as they did in the Classic Chevy article to maintain the splined shaft end.


Fit up to the 3/4" DD steering universal joint.


Shaft trimmed to length with the bushing tacked in place.


Ready to reassemble. I made this stand which I clamped to the work bench to aid in the process.


Shift collar and tilt head back in place.


Turn signal wiring pulled in place. I used a couple of wires crimped to the turn signal wires to ease the process. Some baby powder helped things slide through much easier also.


All back together sanded out ready for final coats of paint.


All painted and ready to go into the car.


On the left is the turn signal lever for the van column and the original 55 Chevy lever on the right. I was able to file the 55 lever end to fit the van turn signal switch but the angle was wrong to fit the opening in the tilt head.


I fixed that problem by bending the 55 lever to match the van column lever.


Now it fits like it should.


The next mod was the horn button. I had to cut the 55 style plunger off to work with the Van column horn ring which has a plunger which comes up through the steering wheel/adapter as opposed the 55 Chevy column which has a plunger going down through the steering wheel/adapter.


Shortened 55 Chevy style plunger.


Shortened plunger installed in the steering wheel adapter. The Van column horn ring is under the adapter with the spring loaded plunger coming up into the steering wheel adapter.


I was able to use the original lower column clamp by filing the hole a bit bigger to go over the end of the van column.


Column in the car clamped in place.


In the car ready for the steering wheel. I have since replaced the ugly Van column tilt lever with a 55 Chevy turn signal switch lever. I just shortened it and cut threads to match the tilt head (1/4" fine thread)


One last issue was the clearance between the end of the column and the steering wheel adapter cover. I fixed this with a 1/16" thick spacer. This may have been because the steering wheel adapter kit was for a 55 Column and not the Van Column, even though the dia. was the same.


With the spacer in place the clearance is good.


Steering wheel in place.


Looks like it could have been an original option
Total cost to do the tilt column was probably around $60. to $70. worth of materials including the $30. I paid for the column at the the Iola swap meet. The only thing I had to purchase was the bearing kit and the bushing for the lower bearing. I had almost everything else on hand from previous projects. Labor wise it wouldn't make sense unless you can do it yourself though. I have quite a few hours in the whole process.
My next post I'll show how I set up the emergency brakes to merge the E-brakes on the Corvette rear calipers to the original 55 Chevy E-brake lever inside the car.

Nice work on the column!

E-Brake set up

My next project was to set up the e-brake cables to the corvette rear calipers.
The calipers for the 90 Vette parts I used has the e-brake built into the calipers, so I just needed to mate up the front half of the original e-brake cable to some universal Lokar cables back to the calipers.


I couldn't leave the front cable routed to it's original position in the trans tunnel with the frame center section I built so I fabbed up a bracket to re-route it over just behind the drivers seat.


All ready to tack weld into the frame.


Clamped in position under the car.


With the body back off the frame all welded in. I welded a tab to the frame for the return spring instead of using the tab on the floor pan.


I ended up making a notch in the center section bulkhead to allow full travel of the e-brake lever in the car. This is one of those things I would do differently the second time around. Could have avoided the notch by moving the bulkhead an inch or so closer the front of the car.


Crappy picture here but this shows the brackets and hardware to mate the Lokar rear cables to the front half of the e-brake system. Lokar makes e-brake pedals and handles that use a sheathed cable for the front half of the system also, but I made it work with the original to save a few bucks and keep the original look inside the car.


I didn't like the clevis that Lokar sold to hook the cables to the Corvette calipers so I made my own. The original Corvette cable is on top and the end I made is on the bottom in the photo.


Here is the cable hooked to the caliper with the clevis end I made.


Rear cable routing, the passenger side cable will be held off the drive shaft with a rubber lined clamp once the body goes back on.


View from above.

Exhaust system

The next project was the exhaust system. I built this by using mandrel bends and straight sections welded together. I used stainless band clamps with butt joints at the spots it would need to come apart for installation and removal.


The first thing I did was make a couple of these spacer rings out of aluminum plate to keep the exhaust centered where it goes through the cut out in the frame.


Spacer holding the exhaust tubing in place. I used 2 1/4" tubing throughout the system. I could go much bigger down the road if I need to as the cut outs are 3 7/8" I.D.


Jog over in the front section tacked up.


Passenger side front section.


Passenger side back to the muffler.


Mufflers mocked up in place to build the tail pipes.


Tail pipe tacked up. I routed them under the rear end as it is done on C4 Corvettes. I would have needed to notch the trunk pan to route them over the top. I think wagons and nomads may have enough room to go over the top but not sure on that.


Another view of the tail pipes.


Brackets for tail pipe hanger off the rear end.


View from the back of the completed system.

And you said I do good work, you do great work. My plan is after I finish that truck is to do the vette front clip on my 55 210.

Once again really nice work.

I went back through the last 2 complete pages of pictures. Outstanding work guys. Mike

Odds and Ends

I had a few odds and ends to finish up before getting the frame ready to disassemble, prep and paint and put the whole thing back together and ready to drive.


Tab tack welded in place for the rear brake hose.


Checking where the brake lines would need to go.


To compensate for the repositioning of the engine the clutch shaft bracket needed to repositioned also. I just drilled new holes in the bracket to accomplish this.


New bracket made for the frame side.


Bracket tacked to the frame and clutch shaft test fitted.


Needed to put jog over bends to clear the steering shaft.


To move the radiator in front of the core support I made aluminum adapter plates (V8 radiator in 6 cylinder position) I flipped the core support top bar around to make it into a 6 cylinder support.


To reuse my V8 fan shroud I cut off the mounting tabs. (just a cheap plastic version)


I remounted the shroud with some small metal tabs. (I was running out of time to get the car ready for Back to the 50's, June 2016, so I just needed to get it done at that point)


Bolted in place to check alignment to the fan.


I welded the nuts for the pinion support to a plate so no wrench would be needed. Access would be very difficult with the body in place.


Bolted in place. No wrench needed now.


Frame disassembled and on my makeshift rotisserie to do a bit of final welding, and prep for paint.
The plan was for a quick and dirty paint job on the frame at this point, since I plan to drive the car for a few years to make sure everything works so if I need to change something I'm not messing up a nice paint job.

Great photos of a really neat build. You have a gift for problem solving. I had to buy my chassis and solve the problem of how to pay for it.
Can't wait to see more....great job

Looking good!

Thanks Guys. It's always a challenge to figure out how to pay for everything!!!