Yet to be named... ‘78 K10 Suburban

[Old65C10]

We are very lucky where I live. We don't get much rain, less than 9in per year. No salt or brine is ever used on the roads and there is always super low humidity. So my truck is completely rust free.
I even have a 65 C10 that is very solid, only rust is in the front fenders where they collect dirt and it sits and rots, ever 60's Chevy truck has rotten fenders.
At least most of that work can be done and you wont have to paint, just heavy undercoat.

[RyanAK]

Earl, my prior '71 C10 Suburban had pretty limited rust. He came from Utah. This truck I thought would be better than it is, being from Montana and supposedly not used through most winters.

I DO KNOW this is far and away better than pretty much ANYTHING that has lived most of it's life in the Northeast. I could probably sell this truck for at least 50% more than I paid for it simply because it's here in PA now... I know I got an offer on Earl the day I drove him into the driveway for the first time that was double what I had paid.

So... I still feel lucky. Just don't really have the $1000+ handy to get this done and waiting until there's room in the shop sometime in September is gonna drive me bonkers.

Ahhhhh, old trucks!

[AJC]

That is not to bad I was expecting much worse.

[RyanAK]

Originally Posted by AJC

That is not to bad I was expecting much worse.

All that matters is that the kid at the garage thought it was bad enough to not pass inspection. I really thought it was gonna be ok, but PA is really cracking down on rust... while contributing to the issue with the brine spray. The parts are cheap enough - $20 each for fronts, $140 for the rear. But this is beyond my skill set. So find the money and wait for the body guy to get space in the shop. The waiting is the toughest part. Like a kid on Christmas with a new toy but the batteries are backordered for 2 months!

[RyanAK]

So with all this enjoyable talk about rust and wheels, I never really spec'd out what the long-term build plan is for this truck. So, for your consideration and comment...

BUILD SPEC - July 31, 2019
Overall Goal
The plan is for a stock-plus build of a mild family hunt/fish/camp/adventure rig keeping it true to the mid- to late-'70s. It should be capable in the snow and on state forest roads but still a daily driver and comfortable and safe for longer highway trips.

Current Stats
1978 K10 Suburban Silverado
* New Crate GM 190hp 350 V8 <4000 miles
* Original Q-Jet
* TH350 - no apparent issues
* NP203 - full-time no apparent issues
* 3.73 gears - no apparent issues
* Brakes are new
* 15x6 stock steel wheels with dog dish caps
* Crappy Toyo tires - 235/75/R15s
* Air Conditioning - converted to R134a and working well. Front only.
* Cruise Control - speedo cable bypasses transducer so unknown if it works
* Comfortilt steering wheel
* Tailgate - glass motor works fine
* HD Transmission Oil Cooler
* Factory dual exhaust
* Two-tone paint 71 Metalic Red (Red Poly, later called 'Dark Carmine') 60 Santa Fe Tan
* Red special custom interior

Overall clean inside and out. Drive train seems solid and well maintained with a few suspect things to go through. Interior is overall good with a few bothersome things like cracked/torn piping on the driver's seat and a low front headliner. Body is solid with some decent quality rust repair here and there, but surface scabs popping up in a few places that mean eventually we're gonna need to address rust. Cab mounts rusted out, only inspection failure point.

BUILD PLAN
DRIVE TRIAN
* Engine - New 350, so not much to worry about here. Whoever did the install did a nice job and everything seems right. Runs smooth, if a little mild for such a heavy truck. Open to suggestions for some performance improvements! Nothing too radical and I like carbs, though I'm still learning about them.
* Transmission - Not going to an OD transmission. Doesn't appeal to me on this truck. The TH350 seems to be doing exactly what it needs to do. Shifts smoothly. Going to do a fluid change.
* Transfer Case - I've decided to stick with the NP203 and not convert to part-time. I do want to get it to someone who knows the 203 case and understands them to go through it and service it if needed. Minimum, I want new 30w oil in it.
* Differentials - pull covers, inspect, fluid change.
* Drive shafts - I have a "cabin boom" at 45-50mph that I'm trying to get rid of. U-joints were my first suspect, so I'm in the process of changing them. We don't have a driveshaft shop anywhere local, so I don't have the opportunity to have the shafts balanced or the double cardan (CV) or slip joints serviced. Hopefully the new U-joints eliminate the boom. It's the only issue in an otherwise nice driving truck. Honestly, if this doesn't do it, I'm open to picking up a new front driveshaft for $250.
* Front end - tie-rod ends, ball joints, bearings, hubs, steering components all seem good. The truck is pretty tight. But I'm persnickety, so I'll eventually be going through all this and replacing most. Any suggestions on mild upgrades?
* Brakes - new shoes, everything looks good and stops like it should. Could stop better. Any suggestions on upgrades here?
* Shocks - no complaints, truck rides like it should. Shocks look like they've been on there for decades though. I like Bilstein yellows, so the Suburban will eventually be getting a set.
* Springs - quiet and provide a nice ride, so not much to worry about here. I'll replace bushings eventually. Also a zero-rate 1" add-a-leaf for the rear to correct the saggy butt.
* Body mounts - These are on the list to do when the truck goes to the body man for the cab support work. I haven't been able to find a full Suburban rubber and hardware kit for a '78. LMC has poly, but I prefer the ride of the rubber bushings.
* Wheels/Tires - Here's where I'd like to make an upgrade... I want to run a 31"-32" tire, but the stock 15x6 steelies stop that plan dead. So... 15x8 OE-style steel wheels with stock hub caps or a 16" aftermarket wheel appropriate to the late '70s. Thoughts/suggestions welcome. Wagon wheels? Outlaws? Rallys? My preference is to run the original caps, but tires trump wheels. BF Goodrich All-Terrains for rubber.

EXTERIOR
* Bodywork - The big thing is gonna be rust control/repair and an eventual repaint. I hate the idea of a full re-paint, because part of the charm of these old trucks for me is that they look like an old truck! But I don't see a way to attack the rust without a full spray considering how oxidized/crazed the original red paint is. I really like the look of the faded/patina'd Metallic Red, but I'm not super keen on it as a newly sprayed color. So while I'm usually a "stock, as-built" kind of guy, I may consider a color change to another GM truck color. The red interior will certainly limit appropriate choices. It'll be a while until I can afford bodywork/paint, so I have time to drive myself crazy thinking about color. Any thoughts?
* Trim - tough to put original dinged-up trim on a freshly painted truck, so I'll probably spring for new shiny bits for whatever parts I can't clean up.
* Rubber - truck could use new weather strip all around. Nothing is leaking horribly, but it's probably worth doing sooner than later.
* Rubber #2 - there IS a leak at the windshield. There's no rust there now, and I want to prevent any from starting. Rubber around windshield looks good and is still soft, but it looks like there are places where it's not seated correctly against the sheet metal. It's definitely a rubber-to-metal seal that's leaking, not rubber-to-glass. Maybe an auto glass place and fix this?
* Lighting - I'd consider a headlight upgrade if I could find an option that truly looks like stock sealed-beams but functions like modern high output headlights. Otherwise, relay upgrade. I need to research this...
* Accessory lights - '70s-style KC Daylighters and fog lights on the front. Looking for a mounting option for the KCs that will let me avoid drilling the bumper.
* Roof rack - a roof rack would be super useful for our family, but I absolutely shudder at the thought of drilling holes in the roof... Ditto a rear spoiler.
* Running boards - I took the aluminum full-length boards off because I'm not keen on how they look, but there's no denying that they protect the lower body from road rash. Maybe decent mud flaps?

INTERIOR
* Seats - Only issue is the piping has cracked and the seam opened on the driver's seat. Foam is a little soft there too. Hoping I can restore it and keep running the original seats.
* Dash - dash has two small cracks in the pad. I couldn't care less at this point. Everything else looks nice and functions as it should.
* Doors - plastic/vinyl needs cleaned up, but everything is pretty nice. Need one window crank handle.
* Headliner - the rigid headliner is low in the front. Hopefully this will just need to be taken down, re-folded, and put back up. While it's down I'll add some Dynamat or similar for thermal and sound insulation.
* Carpet - good enough. I may pull back sections to add products for thermal/sound insulation.
* Floor mats - I need a set and I'm open to suggestions.
* Accessories - I need a place to mount my phone and a charge port. Maybe 12v accessory plugs at the rear seats for the kids and one back to the tailgate. Cup holders were taken care of with an aftermarket bench seat console. If the sound system is ever upgraded, it'll be a stock head unit retrofit with Aurora Designs guts by Gary Tayman... though the radio is pretty low priority. If I could find a vintage aftermarket clock or a compass, that would be neat. Maybe a tach or a vacuum gauge down the road...
* Overall the interior is really pretty nice and I want to do as little as possible. Certainly not a full re-do. Again, part of the charm of these old trucks is that they look like an old truck.


So. There. Now it's all written down.

[RyanAK]

Page 2 and no picture. That’s probably against forum rules...

Got the three u-joints replaced and that reduced the “body boom” by about 80%. I didn’t attack the double cardan CV joint on the front axle. Seems tight, but it probably needs gone through. Also, we don’t have a driveshaft shop anywhere within 2 hours, so I didn’t balance the shafts. So the last 20% might be the CV or a shaft slightly out of balance?

Or maybe these square Suburbans are huge, cavernous echo chambers and a certain amount of rumble is to be expected without doing some sound deadening?

Anyway, the annoying “body boom” has been significantly reduced and I can concentrate on all the other noises a 41 year old truck makes. It rumbles pretty good at 65... I need to be able to drive on the interstate at speed now and then. Anyone have suggestions on things that appear at higher speeds? Should I be ok driving 70 with an unconverted NP203 in full-time 4wd? With the 29” stock-size tires the RPMs are spun up pretty good.

Here’s a pic...

[Old65C10]

There are some things that you can do. They are a big metal box, and so some booming is to be expected, however you can cut it down quite a bit if you want.
Home Depot and other hardware store carry Flashing tape. It is almost as good as the expensive sound deadener that you can buy, but way cheaper. Put this on the roof under the headliner, in the doors, under the carpet, rear quarter panels, anywhere there is large expanses of sheet metal. It will deaden it and cut down a lot on the booming. https://www.homedepot.com/p/Nashua-T...3003/206495170

The other thing is to keep doing what you are doing, reduce vibrations. Balance the drive shafts, maybe use balance beads in the tires or have them balanced. Exhaust can cause booming also, make sure it is in good shape and exiting out the back corner, not straight back. Exhaust fumes can get sucked in around faulty rear window/door seals.

Shocks and suspension bushings can also add to the noise in the cabin, make sure they are all in good shape.

I would highly recommend replacing all the door striker bolts. From the factory they had a plastic bushing on them, over time this bushing goes bad and falls off. Now the doors rattle and add to the booming. I just did all 4 on my 90 Sub and it made a huge difference. Then adjust the hinges so the door closes correctly and does not bang or pop up when the door hits the striker. I also tightened up the rear doors (barn doors) and that helped too.
I just drove my Sub this morning and it was nice and quiet. They will never be as quiet as a 2019 Suburban, but you can get them fairly close with some minor work.

[1976gmc20]

a roof rack would be super useful for our family, but I absolutely shudder at the thought of drilling holes in the roof

Not so bad if you drill in the flat top of the stiffening "rails" on the roof. That's what I did to put a boat rack on our old 1977 Suburban. Of course you have to have the headliner down to tighten the nuts. Our old beast didn't have a headliner so it was no problem! I'm not sure if it never had a headliner (rubber floor mats and bare steel in the back) or if somebody tore it out and never put it back.

[ShortHaul]

Nicely done on the build plan sheet. Years from now you'll love being able to look back at that page and have it all referenced right in one post.

Re: wheels. I'm a HUGE proponent of the "stock appearance but wider and in manageable size" plan. Try Stockton Wheel. They will build you a set of wheels according to your specs. The series 20's look like they'll do the trick.

http://www.stocktonwheel.com/heavy_duty.html

Going 16x8 will make a world of difference in tire selection. 15's are ok for hot rod tires, but lousy in all terrains and E load range tires.

I would spend the extra dough to get the right wheel. A solid set of rolling stock can make ALL the difference in your ride's appearance. 16x8's with caps. and a cool set of white letter all terrains, a nice level/lift and you're in business!

Check out Stockton wheel, or even give Wheel Vintiques a call, I'd bet they would build you a set if you asked.

Engine wise, check out Blueprint for crate motors. A buddy of mine just picked up their 365hp 350 and put it in his 70 C10. Has nothing but good things to say. Pretty hard to beat, fully dressed minus headers, 50K mile 30 month warranty for 4k... and it'll bolt right up.

https://blueprintengines.com/product...tor-bp3501ctc1

Keep up the good work, you'll get that rust patched up soon, and be on the road before you know it. BTW that pic of your daughter behind the wheel is priceless! I'd frame that one!

[RyanAK]

Old65C10 - thanks for the continued interest and advice. I plan to do some significant sound deadening eventually but don't have the cash and/or time to dig into it now. That butyl flashing tape might be a good and inexpensive way to get something on the floors, quarters and roof (when I go after the headliner...) in the short term. Have you used it? The remaining 'boom' seems to be located in the rear.

I'd love to get the drive shafts balanced... I'm still searching for a shop within a reasonable distance to get to.

Tires... when I can spring for new wheels and tires I'm hoping that does a lot to improve ride/noise. These 235/75R15 Toyos that have been on the truck for who knows how long may be a significant contributor. I may spring for a balance if it looks like wheels/tires are going to be way off into the future.

Stock dual exhaust seems in good shape. Nice and quiet and exit at the corners. I could see how a deep, loud exhaust could contribute to serious cabin noise, especially with that large, uninterrupted expanse of floor acting as a drum head...

Getting new Bilstein 4600s soon. Doesn't feel like it needs new shocks, but they look like they've been on for decades. Hope for a ride and noise improvement there. Especially for the money. Suspension bushings look ok... they're on the list for replacement eventually. Body mounts I'm going to tackle while the truck is at the body shop and on a lift for the cab and tailgate support rust issue. They're smooshed.

Door striker bolts are an interesting thought... The driver door sags a bit and I have the pin/bushing kits for all doors and will adjust the hinges/alignment, but the striker never occurred to me. I'm not sure if the '78s had the plastic bushing... and the doors close tight... I am going to replace the weatherstrip on all doors and tailgate. Those pieces are currently in my LMC shopping cart along with the cab and tailgate supports that need replaced to pass inspection. Maybe I'll add the striker bolts too...

Great thoughts all around. Thanks!!

[RyanAK]

Originally Posted by 1976gmc20

Not so bad if you drill in the flat top of the stiffening "rails" on the roof. That's what I did to put a boat rack on our old 1977 Suburban. Of course you have to have the headliner down to tighten the nuts. Our old beast didn't have a headliner so it was no problem! I'm not sure if it never had a headliner (rubber floor mats and bare steel in the back) or if somebody tore it out and never put it back.

Oh I don't think the work will be all that involved, it's just... you know... drilling holes in a good roof that doesn't leak and doesn't have rust!!

I just don't have the constitution. Ha.

[RyanAK]

ShortHaul - Thanks, man. I like lists. I have lists of lists. I hope to update that post as things get done, but I think there's an edit time window...

I love Sweet Pea. That truck and your build is one of just a handful that I really can take inspiration from. You're doing a great job.

I'm on the fence... Summit now has the 15x8 OE-style wheels from WV in stock, so I could run the stock caps with 32x11.5-15 BFG T/As. Or General Grabbers. Both are LT tires, but 'C' rated. That's about the only choices for a 15x8. (I see you're running those Generals... impression?) Or keep looking for a 16x8 6-lug wheel. 3/4 ton is so much easier for running stock caps on OE-style wheels and getting into an E rated tire. Appreciate the input.

Lift/level will be a 1" zero-rate to take out the sag in the butt. And lift from +1 or +2 tires. Stock plus just a li'l bit...

Hard to justify a new engine considering there's a new GM crate with 4,000 miles on it and still under warranty.... Eventually I'd like to put a 400 in it or maybe build a 383 stroker. I was actually initially looking specifically for a truck with a 400 because Pap had one when I was a kid. But for now I'm considering what I can do to wake up this brand new but very mild 350...

Thanks so much for the encouragement. Looks like my body guy can get to it in the next week or two. Kids will be excited to finally go on an adventure. Time to start some memories.

[1976gmc20]

Originally Posted by RyanAK

Oh I don't think the work will be all that involved, it's just... you know... drilling holes in a good roof that doesn't leak and doesn't have rust!!

I just don't have the constitution. Ha.

What I meant was, it shouldn't leak if the bolt holes are in the top of the "rails" stamped into the factory roof. I can't seem to remember what those should be called; they would be grooves if looking at from the inside without the headliner. Same principle as corrugated metal roofing, only they don't go all the way up over the front seat.

I just bolted the oak directly down to the raised rails, with an extra piece of oak about 6" long sandwiched in for a spacer. Drilled through both pieces of wood for the carriage bolt, and I think I drilled a couple of small holes and drove in some finish nails just to keep the oak spacers straight with the oak cross-rails.

If your using or making a metal rack, then you probably need some flat rubber washers between the rack and the roof, for a cushion and leak prevention. But it shouldn't leak unless you are upside down in a lake or river

I hear you about not drilling holes in your Suburban roof, but I just can't imagine putting much of anything at all up there on the roof and depending on drip rails to hold it. Maybe consider a small trailer or one of those hitch receiver racks ???

[AJC]

You can check the tires date codes if you want to know how old they are.

[LT7A]

The paint on that rig looks so good in the pictures that I hate to see where rust is bubbling through. I wonder if you can catch it at those spots and dremel it out like a cavity and then touch it up. If you did that it might buy you some time. Protect it with a good paint sealer and see how it lasts. If the rust bubbles occurred again, I would be tempted to go panel by panel and get each one in bare metal and get paint matched, even in a rattle can and repaint each panel as you go. Could easily look as good as it does now and cost pennies compared to a repaint. I'm concerned that your kids won't care about "adventures" by the time you get it back from the painters and you may have spent their college funds equivalent to get it painted.

[LT7A]

dbl post

[RyanAK]

Originally Posted by LT7A

The paint on that rig looks so good in the pictures that I hate to see where rust is bubbling through. I wonder if you can catch it at those spots and dremel it out like a cavity and then touch it up. If you did that it might buy you some time. Protect it with a good paint sealer and see how it lasts. If the rust bubbles occurred again, I would be tempted to go panel by panel and get each one in bare metal and get paint matched, even in a rattle can and repaint each panel as you go. Could easily look as good as it does now and cost pennies compared to a repaint. I'm concerned that your kids won't care about "adventures" by the time you get it back from the painters and you may have spent their college funds equivalent to get it painted.

Yeah, something like that plan is definitely my preference. I’m not keen on a full repaint for a few reasons. Certainly time and $$ are part of it. But I really prefer keeping old, mostly original, and less than perfect paint. A $15K paint job will make me treat and use the truck differently.

My current body guy is a “kill ALL the rust with big patches and new panels and then repaint the whole truck” kind of guy. It’s probably the right way to get a lasting job. But I’d really like to find a way to deal with the scabs and blisters in a localized way. There’s a guy in the next small town that does true restoration work as opposed to collision repair and repaint. Probably worth going to have a chat with him. He specializes in Nash Metropolitans (and Ferguson tractors...)... but what’s a Suburban except for a HUGE Metropolitan?

The lower body has had a respray in the original color. The tan on the mid should be easier to blend in. It’s the hood, fenders... the upper third... that poses a challenge.

[Originalthor]

Congrats on your new DD. I did the same thing and sold my 04 duramax for a 89 suburban. Talk about losing 200 hp but it looks way better in the driveway.

I was chasing maybe your same booming issue and I did a alot of things until this weekend and it finally went away. I changed both back shock mounts on the frame to the 67 72 ones they were a little bigger cause my holes were a little rounded out and I cleaned the frame rails beside the gas tank they were right filled with dirt.
I also built a wood drawer system level with the wheel wells and filled it with tools. 200 pounds or so. So maybe the floor was echoing I dunno but it finally disappeared.

For the sound deadening I used this aluminum blue skin type roof flashing that is 9 inches wide by 25 feet long and put 9 by 12 inch pieces inside all the doors then cut pieces and put over all the little holes where the door panel goes. Made a huge difference.

Mine was a old department of hwys truck and was bone stock as they come. So it was pretty loud in there.
Good luck with the builds I'll be watching. Interested in what tires you go with cause I'm in the same boat

[LT7A]

Originally Posted by RyanAK

what’s a Suburban except for a HUGE Metropolitan?

Agreed, haha. If the Metropolitan is the city then the Suburban would be everything around it.

We have WESCO auto paints out here where you can get spray cans matched to your paint. They come out and shoot/scan it with their little laser beam and plug it into the computer and it drips the right drops into the base color and they give you a can with aerosol or a little touch-up vial. I'd try that, not much to lose. They can even do different batches for different panels or vert/horiz, etc.

[RyanAK]

Thanks, guys. Originalthor - hope you’re happy with the switch from your Duramax to a square Suburban. I’m slowly working up a plan. Peel ‘n Seal on floors and doors and roof when I go after the headliner. I’m gonna start in the cargo area as that’s where the boom seems to be coming from. Maybe just a few squares will reduce the resonance and eliminate the rest of the boom. Just hope I don’t mask sounds from mechanical issues that need addressing. I’d bet your toolbox was the main component of reducing your boom. Weight in the bed would certainly reduce the ability of the cargo floor to act like a big speaker. I’ll take a look at shock mounts when I’m ready to do shocks and have a look at the frame around the big ol’ gas tank.

LT7A - paint matched rattle cans are a great idea, but I’m beyond my abilities when it comes to bodywork and paint. I’ll be interested in what the restoration guy has to say. A Suburban is a huge canvas compared to a Metropolitan!

[AJC]

Is the Peel ‘n Seal tar based? If it is I heard it has a smell on hot days. I have used automotive carpet padding before with good results. It comes in a few different wights and is available at a fabric store that sell automotive fabric. Its cheap too. Helps a lot with noise coming through the floor.

[Originalthor]

I love everyday driving it accept I put way to loud of a muffler on it so i got to change it out. Sounds good but not for a daily.
I wouldn't recommend peel and seal I just put a pile of that down on a roof and it does stink. The stuff i used is resisto aluminum waterproofing membrane and i don't smell it at all. Just the mouse smell from the power window locks and window motors I got from the mouse infested suburban. Kick myself in the butt there cause now I got to rip it all out again and clean it with lysol or something.

[RyanAK]

Back from body man with new cab mounts and tailgate support. I don’t want to talk about the money. Now for an inspection and dig into my list. Kids are excited! Spencer helped replace a broken window crank. In a serious voice (for a 4 year old...) “Working on trucks is hard work, Dad.”

[Originalthor]

Right on. Kids look like there having a blast. I remember the boy helping me rip apart the 68 c10. Good times.

[RyanAK]

I have great memories of helping Dad and Pap work on their trucks growing up, so this is just an amazing feeling. Nora even got into working on “Dad-Dad’s Twuck” by cleaning up the drive shaft when we had it out for U-Joints. Even did a detailed QC inspection. “Wup, all kween!”