Rocco's 77 K5 Blazer - Frame Off 6.2/6L80 Build

[RoccoK5]

RoccoK5 submitted a new Build:

Rocco's 77 K5 Blazer

I purchased this Blazer back in October 2015 with plans for a modest trail/camping rig in mind. It was in decent shape at the time, and I already had several other projects in the works, so I didn't want to get overly ambitious with the build -- mainly wanted to focus on the interior, cosmetic, and reliability/maintenance stuff. Here's some old pics I dug up of the Blazer when I purchased it:

Nothing amazing, 4" springs up front, 4" blocks in the rear. 33" all terrains. Rebuilt 350, TH350 trans, NP203 case. GM 12 bolt rear (with limited slip lol), GM 10 bolt front. 3.73 gears.

In the interest of getting this build thread caught up to where I am with the truck today, I'll skim over the details of the work I've done over the past 4+ years.

For the first few months I focused on the interior, completely stripping it and replacing most of it. I installed a new dash pad, carpet, seats, misc dash parts, door panels, and repainted the grey trim pieces black. Along the way I fixed some things like the turn signal switch, replaced the heater core, reworked the audio system, and made some new bedside panels. Here's a few pics.

Interior mostly stripped, insulated the floor pan:

Dash back together with new pad, bezel, steering wheel:

New carpet:

New seats (sourced from a Chrysler Town and Country if I remember correctly), and Tuffy console:

Replaced the door panels. Also replaced all the door rubber at this point:

Reupholstered the headliner, new visors:

Built an enclosure for the subwoofer:

And a new bedside panel with speaker:

Passenger side panel, with amps mounted:

...

Read more about this build here...

 

[6872xtc]

Subscribed. Cool work on this, I am looking forward to seeing the results!

Did you say that you took the frame to get powder coated? I believe that you already got the bump removed for the shock mounts, correct?

 

[RoccoK5]

Thanks!

The frame isn't quite ready for powder yet, still need to test fit a few things and weld the steering box frame repair on. I did get the front shock mounts cut out and sectioned in some flat stock in place, just need to grind and clean things up. I'll post some pics later today!

 

[max 02]

Nice work! The interior looks great with your refresh.

 

[RoccoK5]

Alright, so this post should get me caught up with how things stand today.

Work on my K5 stalled over the past couple of years, but late last year I finally gathered the motivation and made the decision to start on an LS swap. Part of this was due to the fact that I've been towing a bit (nothing heavy, just a 14 foot trailer and a side-by-side), and the 350 is absolutely gutless with anything hitched up (35s and 3.73 doesn't help, either). I've also wanted to plan longer trips, and screaming down the freeway at 75 with my TH350 (no overdrive) get's old fast.

Initial plans were for a 5.3 and 4L60e, and then some minor body work and paint to make for a clean driver suitable for light trail duty. However, plans have changed since (and I'm sure will change again). More info on that later.

This is going to be a driveway build. Unfortunately I don't have access to a shop, and my garage is too small and too full to do much of anything in there. Hoping to get a lot done before the Phoenix summers set in, but honestly I'm not in a huge rush and plan on taking my time to do everything right. So I wouldn't be surprised if this build drags on for a year, but hopefully not!

Anyway, in November I started pulling the old drivetrain. I had a buyer lined up for the 350/350/203, and made short work of pulling everything over a weekend.

Front clip removed:

Greasy boat anchor NP203 out:

Motor and trans coming out:

And out!

Undercarriage is pretty clean, aside from the ATF leak I had years ago. I'll need to strip it completely of all the old undercoating and figure out what to coat the underside with before reassembly:

I figured I'd come this far, so why not just remove everything from the firewall so I could clean it up and paint it. That led to stripping the interior along with the wiring harness. Not necessary, I know, but I suffer deeply from the "since I'm here, why not" disease.

I also came across a 14 bolt ff, so why not?

At this point, I only had 8 bolts to remove to just go ahead and remove the tub from frame. And since I'd need to replace the body mounts anyway, may as well go all in.

Luckily, all the body mount bolts were pretty easy to remove. Just had to grind the spot welds from the two rear-most bolts in the bed:

After the bolts were free, I used my engine hoist (bolted through the rear seat mounting points) to raise the rear, and used a floor jack and a block of wood up front to carefully separate the body from the frame. I placed blocks between the frame and body until the two were separated enough to span a 4x4 between them:

The plan was to then raise the entire frame/body and build some supports from 4x4s to lower the body on to. However, the wood was getting sketchy, and I really wanted something safe and sturdy enough to feel comfortable working under. Also, who knows how long the frame and body will be separated. So, ended up welding a steel frame that can be raised and lowered:

Once supported, I simply rolled the frame out from under the body. Added bonus, I can roll it back under when I'm not working on it to help keep things semi-clean around here to hopefully avoid pissing off the neighbors too much:

 

[RoccoK5]

Planning to clean up the frame, install ORD FUSH, shackle flip, engine crossmember, do something with the front shock mounts, and then have the frame powdercoated. Also contemplating going with some new ORD springs. While the frame is at powder, will need to rebuild the 14 bolt, clean up the 10 bolt and swap on 8 lug outers, and get them ready to bolt back under the frame. Still need to decide on gear ratios and whether a traction aid is in order (ARB front and rear? )

I need to start thinking about cleaning up the undercarriage too, and the paint and body, but not really excited about that yet...what I'm excited about is this 6.2/6L80 that I picked up this weekend!

More to come!

 

[ogur]

Awesome. I have the same issue.. gone this far why stop now.

Good luck

 

[ktmoutfront]

The "might as well" bug is a mighty disease.

Nice welding cart.

 

[RoccoK5]

Been working on cleaning up the bare frame so I can drop it off at the powdercoaters. I still need to weld up the steering box frame reinforcement and test fit the bolt-on parts like the FUSH, shackle flip, engine crossmember, etc.

Since I'll be extending my front shocks, I figured I'd clean things up and remove the formed area of the frame where the factory front shocks mount up (I posted some of this in The Garage, so you may have already seen it).

Plan was to shave this stuff off and section in a flat piece of stock:

Some ugly stop/starts there. I beveled the frame and the flat stock and welded both sides, so fairly confident of 100% penetration. Just need to grind this down now.

Hoping to drop the frame off next week and then get started on rebuilding and regearing my axles!

 

[RoccoK5]

Parts are arriving almost everyday. Today I received some of the stuff I'll need to rebuild my axles: ARB for the 14 bolt, 4.56 gears and master install kits. More fun stuff on the way!

As a sidenote, I am already wondering if I should go with deeper gears...planning to run 37" tires and a 6L80 trans, so I think the 4.56 will be OK, but with the trans' double OD I could probably get away with something shorter and still have reasonable RPMs on the highway. Realistically this truck will spend most of its time on the street with light/medium trail duty. Thoughts?

 

[Justin V]

Yeah go deeper. 5.13's for sure

 

[Justin V]

My 4.56's and 38's are below peak torque on my 350 and 700r4 at 70. And my 350 doesn't have enough powah to maintain any faster...

Put the 700 in 3rd and the engine is much happier.

 

[ktmoutfront]

Same here with 4.56 and 35's. 700r4 hunts at the smallest incline. I just down shift nd run it. Should have gone 4.88.

 

[RoccoK5]

Thanks for the input, everyone!

Here was my thought process in going with the 4.56 ratio: The 6L80 has a super low first gear (4:1), so I figure that, coupled with the NP241's 2.72:1 low gear, would be low enough for wheeling without having to go super deep. Will also be running the Gen IV 6.2 which is rated (stock) at around 400hp/400tq. The torque curve is pretty flat, making 300+ at just 1200 RPM or so. At 75 mph in 6th gear, I should be sitting at ~2000 rpm with 4.56, that jumps to ~2350 with 5.13. Granted, that actually doesn't sound like that big of a jump...

I was thinking 4.56 would be a good balance for both highway and off road, but that said, I really have no idea since this combo is new to me and I'm making all these changes at once. I'd really like to take this truck on long trips (Moab!) and obviously hit some trails too, so I understand I will need to make some trade-offs. I also know I am probably oversimplifying things here by just looking at engine RPM at 75mph, but I'm a newb when it comes to this...would just hate to get everything done and wish I went with 4.88s or 5.13s!

 

[LNielson]

That’s a sweet welder cart you have there.

 

[RoccoK5]

That’s a sweet welder cart you have there.

Thanks! That was actually my first welding project several years back.

 

[iblyles]

Alright, so this post should get me caught up with how things stand today.

Work on my K5 stalled over the past couple of years, but late last year I finally gathered the motivation and made the decision to start on an LS swap. Part of this was due to the fact that I've been towing a bit (nothing heavy, just a 14 foot trailer and a side-by-side), and the 350 is absolutely gutless with anything hitched up (35s and 3.73 doesn't help, either). I've also wanted to plan longer trips, and screaming down the freeway at 75 with my TH350 (no overdrive) get's old fast.

Initial plans were for a 5.3 and 4L60e, and then some minor body work and paint to make for a clean driver suitable for light trail duty. However, plans have changed since (and I'm sure will change again). More info on that later.

This is going to be a driveway build. Unfortunately I don't have access to a shop, and my garage is too small and too full to do much of anything in there. Hoping to get a lot done before the Phoenix summers set in, but honestly I'm not in a huge rush and plan on taking my time to do everything right. So I wouldn't be surprised if this build drags on for a year, but hopefully not!

Anyway, in November I started pulling the old drivetrain. I had a buyer lined up for the 350/350/203, and made short work of pulling everything over a weekend.

Front clip removed:

Greasy boat anchor NP203 out:

Motor and trans coming out:

And out!

Undercarriage is pretty clean, aside from the ATF leak I had years ago. I'll need to strip it completely of all the old undercoating and figure out what to coat the underside with before reassembly:

I figured I'd come this far, so why not just remove everything from the firewall so I could clean it up and paint it. That led to stripping the interior along with the wiring harness. Not necessary, I know, but I suffer deeply from the "since I'm here, why not" disease.

I also came across a 14 bolt ff, so why not?

At this point, I only had 8 bolts to remove to just go ahead and remove the tub from frame. And since I'd need to replace the body mounts anyway, may as well go all in.

Luckily, all the body mount bolts were pretty easy to remove. Just had to grind the spot welds from the two rear-most bolts in the bed:

After the bolts were free, I used my engine hoist (bolted through the rear seat mounting points) to raise the rear, and used a floor jack and a block of wood up front to carefully separate the body from the frame. I placed blocks between the frame and body until the two were separated enough to span a 4x4 between them:

The plan was to then raise the entire frame/body and build some supports from 4x4s to lower the body on to. However, the wood was getting sketchy, and I really wanted something safe and sturdy enough to feel comfortable working under. Also, who knows how long the frame and body will be separated. So, ended up welding a steel frame that can be raised and lowered:

Once supported, I simply rolled the frame out from under the body. Added bonus, I can roll it back under when I'm not working on it to help keep things semi-clean around here to hopefully avoid pissing off the neighbors too much:

That stand is genius. My tub has been sitting on 4x4s for a while now, but I finally bought a body cart. Yours is a better design as you can roll the frame in and out. Nice work!

 

[Justin V]

Thanks for the input, everyone!

Here was my thought process in going with the 4.56 ratio: The 6L80 has a super low first gear (4:1), so I figure that, coupled with the NP241's 2.72:1 low gear, would be low enough for wheeling without having to go super deep. Will also be running the Gen IV 6.2 which is rated (stock) at around 400hp/400tq. The torque curve is pretty flat, making 300+ at just 1200 RPM or so. At 75 mph in 6th gear, I should be sitting at ~2000 rpm with 4.56, that jumps to ~2350 with 5.13. Granted, that actually doesn't sound like that big of a jump...

I was thinking 4.56 would be a good balance for both highway and off road, but that said, I really have no idea since this combo is new to me and I'm making all these changes at once. I'd really like to take this truck on long trips (Moab!) and obviously hit some trails too, so I understand I will need to make some trade-offs. I also know I am probably oversimplifying things here by just looking at engine RPM at 75mph, but I'm a newb when it comes to this...would just hate to get everything done and wish I went with 4.88s or 5.13s!

Gotta factor in the tall truck with heavier tires thing as well. Huge aero loss and lots of rotating mass means the "proper" gear ratio usually ends up being slightly too tall, so err on the deep side.

 

[bsgreen]

Not necessary, I know, but I suffer deeply from the "since I'm here, why not" disease.

I have the same affliction.. sweet build

 

[RoccoK5]

Finished the removal of the factory front shock mounts and enlarged the shackle hanger holes for the ORD FUSH.

Now I need to weld on the frame reinforcement pieces for the steering box and test fit the engine cross member, then off to powdercoating!