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

[chevy3100truck]

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.


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


and off with the suspension & steering

[chevy3100truck]

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 -


some wire wheel action & marking out the cuts


Plasma cutting time (after welding on a brace)


Lots of test fitting & grinding to get everything lined up


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

[chevy3100truck]

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......


A bit of cutting & welding in new material -



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

[chevy3100truck]

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 -


Then cut away -


Leveled it back out and clamped & tacked it back together -

[EricU]

Originally Posted by chevy3100truck

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

What does "pancaking" the front cross member do for lowering the front end of the truck?

Is the point to allow raising the mounting of the cross member and suspension relative to the frame/body?

Great build thread BTW!

[SCOTI]

Originally Posted by EricU

What does "pancaking" the front cross member do for lowering the front end of the truck?

Is the point to allow raising the mounting of the cross member and suspension relative to the frame/body?

Great build thread BTW!

Correct.

[chevy3100truck]

Originally Posted by EricU

What does "pancaking" the front cross member do for lowering the front end of the truck?

Is the point to allow raising the mounting of the cross member and suspension relative to the frame/body?

Great build thread BTW!

Thanks - and yes, it is moving the suspension relative to the frame. I could have done a 3 1/2" frame Z instead of the 2" Z & 1 1/2" crossmember section, but that would virtually guarantee that I would need to move the trans tunnel etc. through the cab as the driveline would be raised substantially 3 1/2" (or I could re-lower the driveline, but that's another headache).

This way I get the same effect - the truck is lowered by 3 1/2" without touching the springs or spindles, but I shouldn't have to modify the transmission tunnel (though I'm targeting around 5 1/2"-6" of drop in the front, so the springs have been cut as well, but I won't be able to dial that in until I have the truck mostly assembled)

[chevy3100truck]

A bit more progress -

New shock mount on axle (2 1/4" longer than the stock ones)

The rest of the axle is just a rattle can rebuild for now lol

Quick clean & rattle can on the frame


Good old Belltech drop shocks...... Not the best, but OK and inexpensive


And here's where it's at now - About an 8-8 1/2" drop using stock springs. It has an axle flip, relocated front spring hangers, drop shackles, extended shock mounts, step notch etc. Still need to work out what gas tank I'll end up using - that will require some more fab work for sure.



About $400 into the rear suspension & frame fab, so pretty cheap drop overall. Not real pretty like a 4-link setup, but this truck is just being built on the cheap, so it is what it is.

Next up - cab rust.....

[SCOTI]

Originally Posted by chevy3100truck

A bit more progress -

New shock mount on axle (2 1/4" longer than the stock ones)
Attachment 2048149
The rest of the axle is just a rattle can rebuild for now lol

Quick clean & rattle can on the frame
Attachment 2048150

Good old Belltech drop shocks...... Not the best, but OK and inexpensive

And here's where it's at now - About an 8-8 1/2" drop using stock springs. It has an axle flip, relocated front spring hangers, drop shackles, extended shock mounts, step notch etc. Still need to work out what gas tank I'll end up using - that will require some more fab work for sure.

About $400 into the rear suspension & frame fab, so pretty cheap drop overall. Not real pretty like a 4-link setup, but this truck is just being built on the cheap, so it is what it is.

Next up - cab rust.....

The kool thing is you can always get a 'bolt-in' 4-bar kit @ a later date and bolt it in. Add new upper shock mounts for some coil-overs. Little if much extra fab.

Well done from a budget perspective!

[SCOTI]

Originally Posted by chevy3100truck

And here's where it's at now - About an 8-8 1/2" drop using stock springs. It has an axle flip, relocated front spring hangers, drop shackles, extended shock mounts, step notch etc. Still need to work out what gas tank I'll end up using - that will require some more fab work for sure.

67-72 Blazer tank? I suggest the 67-72 over the 73-87 for the smaller footprint. Technically you have the room for the 73-87 Blazer/Burb tank but they take up frame space all the way up to the rear-end housing. The 67-72 Blazer tank doesn't eat up that much frame length.

[tinydb84]

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

Why not just Z it the 3.5''?

[chevy3100truck]

Originally Posted by tinydb84

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

Why not just Z it the 3.5''?

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.

[tinydb84]

Originally Posted by chevy3100truck

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.

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.

[chevy3100truck]

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)

[evan]

Cool. In for the updates.

[Katrina/10]

Nice welding!

[SCOTI]

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.

[chevy3100truck]

Originally Posted by SCOTI

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.

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)

[chevy3100truck]

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 -


Chopped.....


Started on reassembly -


Frame transitions in -


Painted frame rails (bad decision lol)

[chevy3100truck]

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


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


Cut & tacked back into place


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

[focusedontheprize]

Great progress, turning lemons into lemonade with being home.

[tinydb84]

Looking good

[chevy3100truck]

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.



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

[SCOTI]

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.

[chevy3100truck]

Originally Posted by SCOTI

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.

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.