#corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

Hey, so I had a 77 C-10 that was going to wait until my new shop gets built before I started on anything, then the current situation happened....... Figured I'd start on this thing while there wasn't a whole lot else to do....

Basically the plan is to static drop it low, with the ability to put bags on it and lay frame if I get around to it.

Lots more photos etc on instagram at @badgaragebc if you're interested

This is what I started with - nothing special, just a beat up 77 C-10 that the previous owner had put new fenders, hood & 1 new door on. Bought it without a box, but have one now.
Attachment 2031658Attachment 2031648

Stripped down the front end & took out the old boat anchor....
Attachment 2031659

and off with the suspension & steering
Attachment 2031660

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

with the frontend stripped down it was time to start on the crossmember. Went with a 1 1/2" pancake on the crossmember, mostly just to see how it would work, how much work it takes etc.

Rusty & crusty -
Attachment 2031665

some wire wheel action & marking out the cuts
Attachment 2031666

Plasma cutting time (after welding on a brace)
Attachment 2031667

Lots of test fitting & grinding to get everything lined up
Attachment 2031668

Back together it goes - nothing fancy, just a 1 1/2" drop now
Attachment 2031669

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

The crossmember also had some cancer to be taken care of (this was a cheap truck, but it had been off the road for quite some time and we are in an area that is prone to rusty vehicles)

It was like this on both sides......
Attachment 2031670

A bit of cutting & welding in new material -
Attachment 2031671


And the dropped/pancaked crossmember is done (and test fitted etc.)
Attachment 2031672

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

I started this project when we were under quarantine around here, so I was just trying to use stuff I had laying around (and not spend any $$$$ lol)

The next step was to "Z" the frame. This was to do two things, lower the truck another 2", and also to stretch the wheelbase out by 1" to center the front end. Using the small Z & the stretch I *think* I'll be able to get a driveline in without having to build a custom tunnel for the floor (that's the idea anyhow)

Starting with behind the front suspension - I made sure the frame was leveled, then made sketches for dimensions in a bunch of spots to make sure it would go back together square and level (or at least as square and level as it started lol)
Welded in some bracing -
Attachment 2031676

Then cut away -
Attachment 2031677

Leveled it back out and clamped & tacked it back together -
Attachment 2031679Attachment 2031680

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

Work looks good. I followed you on Insta as well.

Why not just Z it the 3.5''?

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

2 reasons - I wanted to try chopping a crossmember (I was bored lol)

And also I didn't want to raise the driveline by 3 1/2", not 100% sure what I'm going to do with the driveline, but wanted to keep my options open and not guarantee having to make a new tunnel.

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

Got it. Ive done a few cross members and one Z. I did my Z 4'' and had to do some sheet metal work but was able to lower the engine a bit to prevent the massive tunnel. I am thinking you can get away with no tunnel work.

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

So - I had 3/16" plate left over from a BBQ build, so I just used that to form supports. Not totally happy with how the look is, but it'll work (and once the truck is together you won't really see these anyhow)

Attachment 2031686

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Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

Cool. In for the updates.

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

Nice welding!

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

I like the approach. The mild Z along w/the pancaked x-member get's you the free monetary drop, helps center the wheels better, & should allow the un-cut floor pan. A bigger Z, lowering the motor & tweaking the x-member for clearance as needed (or a high-hump floor piece) would prob work best as far as steering.

I'll keep an eye out for more updates.

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

That's the idea - could have done it either way, but figured I'd try this way on this truck before I get to my 70 GMC again (this one's a beater, that one will actually be nice lol)

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

So the front needed to drop & move back an equal amount to the Z, so time to cut away up there. (I'll regret this later lol)

Front cut marked out on both sides -
Attachment 2032631

Chopped.....
Attachment 2032632

Started on reassembly -
Attachment 2032634

Frame transitions in -
Attachment 2032635

Painted frame rails (bad decision lol)
Attachment 2032636

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

Next up - control arms. This truck had huge stacks of spacers on the upper control arms which I wanted to reduce if possible as well as wanting to tuck in the track width a bit. I ended up narrowing the lower control arms by 1/2" each and on the uppers relocated the ball joint 1/4" in & 1/4" rearward to improve caster a bit.

Lower control arms with the ugly bumpstops removed
Attachment 2032637

Marked out some cuts to slide the ball joint 1/2" in
Attachment 2032639

Cut & tacked back into place
Attachment 2032640

Welded back up (the welds are ground down on the top - these are also welded on the backside & not ground)

Attachment 2032646Attachment 2032647

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

Great progress, turning lemons into lemonade with being home.

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

Looking good

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

So I mocked up the front suspension, and as I kind of expected, the steering was an issue..... The 1 1/2" crossmember drop put the steering in contact with both the frame and the lower control arms.

Attachment 2032893Attachment 2032894

I ended up deciding I'd move the steering up 1 1/4" to gain the clearance necessary. The passenger side is nice and easy, but the driver side is a bit more of a headache with the steering box & contoured framerail around the steering box.


cut cut cut, weld weld weld

Attachment 2032899Attachment 2032900

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

So.... Your steering was raised w/the 'Z' or did you used a different dimension?

My dually has a 1.5" notched x-member & the only clearance work required was around the lower shaft U-bolt nuts (one side of each L&R on the x-member) for the TRE's.

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

The drivers side is a bit more of a headache......
With the frame contours I decided to simply chop out the section the steering box bolts to & raise it by 1 1/4". Of course this meant cutting out the drop that I had just completed on the drivers front as part of the frame Z.....

Attachment 2032903

Then for test fitting......

Attachment 2032904
Attachment 2032905

And finally completed with frame bracing etc
Attachment 2032906
Attachment 2032907

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

And basically here's where it sits now.

1 1/2" Pancaked crossmember
2" frame "Z"
1" Stretched wheelbase
1/2" narrowed lower control arms
1/4" narrowed & 1/4" rearward upper ball joints
1 1/4" raised steering
1 coil chopped off the springs

Front is good enough now to roll around, but still needs steering (going to need to use a U-joint style steering shaft with 3 U-joints to clear the upper control arm). I'll probably take care of the rear suspension before I get to the steering, I'd like the chassis fab to be complete, then the cab repairs, then mock up a driveline etc.

Attachment 2032908

Attachment 2032909

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

Z'ing the frame raises the steering and the suspension, but raising the steering the additional 1 1/4" was due to the crossmember pancake. The drag link was hitting the lower control arms at full droop.

I know some people seem to have success with a 1 1/2" crossmember drop and stock steering, but when I cycled everything through full travel I was having interference.

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

Gotcha. You raised the steering in addition to the amount it was raised w/the 'Z'.

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

Another possible option is to use the dodger style flat arms that Michigan Metal works has.

http://michiganmetalworks.com/store/...&product_id=79

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

Nope. They won't work (they didn't work for my 1.5" sectioned x-member). They only work if the x-member is in the original position as it attaches to the frame & that's all they said would work. I bought them to see if they would work. The front bushing barrel occupies the same real estate as the steering shaft if the distance between them is altered which requires a multi U-joint arrangement.

Re: #corona10truck - 77 C-10, pancaked crossmember - z'd frame etc etc etc
 

I missed the part about running it static for now. My initial plan was to do the Z and run the stock springs. I like the fab work. Whats the plan for the rear?