Building a Bulletproof Squarebody Suburban: Community Input Requesting

[buffydores]

Hello Folks. I've been playing around with building a Squarebody Suburban into a daily driver. I have a lot of opinions, but I want some feedback from fellow squarebody lovers. Here are the areas for discussion.

1989-1991 Suburban

Ride Quality: What's the best you can do with solid axles. Would boxing the frame actually make the ride worse?

Engine/Transmission: I like the 6.0L L96/6L90E or 6.2L L86/8L90E combos on paper. 8.1L L18/4L80E??

Axles: Upgraded Dana 44 Front / Upgraded 14BSF(9.5") < Want to manage unsprung weight.

Obvious additions: Vintage Air / Bluetooth Radio

[68Timber]

For ride quality, why not custom springs? Get them tailored to the height/capacity and stiffness you want based on their recommendations.

[buffydores]

Originally Posted by 68Timber

For ride quality, why not custom springs? Get them tailored to the height/capacity and stiffness you want based on their recommendations.

I run custom springs from ORD on the Blazer. Definitely a good upgrade. My only critique of leaf packs in general is periodic binding between the leaves. It takes away from the perceived refinement. I'd think a properly dialed in coil setup might be superior. Thanks John.

[RDrancher]

I'm old school when it comes to off road stuff and have always preferred leaves to coils, mainly for the simplicity of not having links to bend. You can also weld leaves together on the trail if need be. I had a set of Alcan springs on my stretched FJ40 that flexed like crazy and used the "open" style spring locating clamp which lete them move around as needed. I think that ORD uses a pinch clamp? Dunno, maybe that's what causes the bind. Before getting the Alcans, I bent up the pinch clamps and drilled them for keeper bolts on my stock springs. That worked pretty good too except the stock springs cracked from all the SOA flex (see welding comment above )

Anyway, please document your Suburban "journey". I'm heading that direction with the '89 I just brought home.

[buffydores]

Originally Posted by RDrancher

I had a set of Alcan springs on my stretched FJ40 that flexed like crazy and used the "open" style spring locating clamp which lete them move around as needed. I think that ORD uses a pinch clamp? Dunno, maybe that's what causes the bind. Before getting the Alcans, I bent up the pinch clamps and drilled them for keeper bolts on my stock springs. T.

I hear you. The clamps on my ORDs are open. They shimmy plenty. I just think grit works its way in there over time.

I like the idea of the 6.0L(L96)/6L90E combo up front. Seems like a strong combo. I could do a Raylar 8.1L, but the horrible fuel economy would suck.

[RDrancher]

Originally Posted by buffydores

I hear you. The clamps on my ORDs are open. They shimmy plenty. I just think grit works its way in there over time.

I like the idea of the 6.0L(L96)/6L90E combo up front. Seems like a strong combo. I could do a Raylar 8.1L, but the horrible fuel economy would suck.

If I could afford a Raylar, fuel economy would be the last thing on my mind.

[buffydores]

Lol, good point. My concern on fuel economy is more about range not fuel. The Suburban has a 40 gallon tank. Most of the 8.1s seem to get around 10mpg. I'm intrigued by bolting a Allison 1000 6-speed behind it because 1st gear is a little above 3.00 and the second overdrive is in the low .6s. That's attractive for the speeds I'm running on the highway. The 6L90e has a deeper 1st gear for launches, but no other advantage I know. If I could get 12 mpg out of the combo, I'd be rocking.

[LT7A]

I would follow a build thread on this with interest. I imagine that the stock frame flex might soften bumps a tad by flexing but react more harshly over repeated bumps than a boxed, stiffer frame would. A boxed frame with coils is an interesting (costly, tho) idea. The right Bilstein shocks have always impressed me by making just a little more improvement than I thought possible. They don't erase bumps but you do notice an immediate difference in places where you are used to putting up with a "truck" ride. Also, having tires with appreciable sidewalls. Sidewalls being the first "suspension component" impacted by the road surface.

[RDrancher]

I agree with the sidewall comment. If staying 6-lug, I'd stick with 15" wheels...maybe. That said, even though big wheels are all the rave, a 17" diameter wheel would be as large as I would go and I'd actually go 16" max with a 35" tire. If you were wanting to run 37's there are way more choices in a 17" wheel. See?...clear as mud.

[buffydores]

LT7A and RDrancher: Love the input. I concur with y'all's thinking. I want to run a skinny 33" tire. Probably a 16" rim. My max would be 18". There are too few tire options at 15" these days. Boxed frame. Coils. I'm gonna try to think through the Raylar 8.1 and Allison 1000 6-speed. The gearing looks good on the transmission and I think you can get them to talk together. Just need a competent guy on that transmission. I'd add tons and tons of insulation. Get rid of the spilt windows. Improve on the window actuator motors. Tons of relays controlling electric.

[Bluestep]

I have had a '89 V1500 Suburban since 1992. I would say if what you want is a good reliable vehicle get one and restore it to original. There is no need to go to an aftermarket air conditioner as the stock one works very well, the windows don't need an "upgrade" just lubrication and rubber seals that are in good shape. It drives me crazy to see people throw money away on aftermarket stuff that is supposedly an upgrade when all the vehicle needs is maintenance and repair. The original equipment parts are engineered to work flawlessly for a very long time and are usually manufactured to a high standard that I don't feel is there for many aftermarket parts.

Our Suburban still works very well and I would trust it for any long distant drive. I am always amazed how short a turning radius the old style straight axle has compared to newer vehicles. It is a comfortable car with a pretty decent ride.

[buffydores]

I totally appreciate your viewpoint. For the most part, I like original stuff. Just look at my Blazer build below. But, the old stuff has limitations. The factory AC cannot remotely keep up with the heat we experience down south. When the square bodies were built, speed limits were 55mph. It's 75 mph for most of our highways now. A double overdrive transmission can give me manageable fuel economy. We can also make the riding dynamics better. I like the old stuff, but a better version of it.

[buffydores]

I'm leaning L96 / 6L90E with a roots supercharger. I've been trying to figure out if NP242 guts would work in a NP241. Probably not. I'd love to be able to have full time four wheel drive. Rear axle will probably be a AAM9.75 out of a 6.2 K1 truck. I still think the 10 bolt may be the ticket up front with some beef. The D60 would be great, but think for my purposes overkill and heavy.

I've moved away from the 8.1. It's just poorly supported.

[SBTork]

Originally Posted by buffydores

I'm leaning L96 / 6L90E with a roots supercharger. I've been trying to figure out if NP242 guts would work in a NP241. Probably not. I'd love to be able to have full time four wheel drive. Rear axle will probably be a AAM9.75 out of a 6.2 K1 truck. I still think the 10 bolt may be the ticket up front with some beef. The D60 would be great, but think for my purposes overkill and heavy.

I've moved away from the 8.1. It's just poorly supported.

I can't help at all on your transfer case question, but it is a good one and maybe someone will know. Your engine/trans idea is great and I think ideal for your goal. I believe you're correct in thinking a beef'd up 10 bolt up front will be ideal too. I believe off road design has chrome molly axle shafts available for them and I think those alone would be more than durable enough for a daily/trail rig. Looking forward to this build as I am a huge fan of your K5!

[OutlawDrifter]

The 6.0/6L90e combo is a good one. I drove a 2500HD daily for a year with that setup. It ran like a scalded dog with a custom tune. It would easily see 16-16.5 on the highway at 68-74mph. Pickup weighed 6300lbs and was a 4x4 with 3.73 gears. If it wouldn't have rode so rough, I'd probably still be driving it.

I see you stated tall skinny 33" tire, how much lift are you planning, 4"?

In northeast KS we regularly see extreme heat/humidity in the summer, the humidity is generally 50% or more where I'm at, so I understand wanting a good AC setup.


When the 700R4 dies in my 89 Jimmy, I'll be LS swapping my K5. But I'll keep it simple with a 5.3l and 4l65E....maybe an 80E, maybe. It's just for back and forth to work and I don't need it to pull a trailer.

[Ryan Hubbard]

I have been working on a similar project for my Suburban, The updates I have done on this 1990 V2500 is: 4L80E transmission, 4" lift with Deaver Springs and Bilstein 5100 shocks (This was a night and day difference in ride quality) , rebuilt the rear axle and put a Eaton Truetrac in, Wilwood calipers on the front, 2003 HD Rims with 33" tires. The next few items will be a LS3 EROD engine, rebuild the front axle and install a true trac. I also plan to put leather seats from a 2009is suburban in. You can see all the interior stuff I have done in my thread.

http://67-72chevytrucks.com/vboard/s...d.php?t=727736

We use this vehicle for family vacations and camping trips. I have put over 15,000 miles on this since I got it almost 2 years ago. It is reliable and comfortable for a family of 5.

[phillipm]

I'm super happy you're still working on this idea Buffy. Excited to see it come together. The 6.0 with a magnacharger is a great setup.

[rideair]

As someone that just built a 1988 Suburban DD, I agree with Bluestep on this one. I found that if you replace both the door/window rubber, then use the following products and thought process of sound deadening/temp control, the factory AC will work great. The standard 350 and 700r4 are tried and true, parts found on any street corner, and purchased as a new crate engine and trans rebuild, you will have a 50,000-100,000 mile warranty to boot! You are going to get a certain level on noise out of the doors based on the door panel design (only covers 2/3rd, thus the reason they now use full door covers in new cars)

Start off reading information about sound/temp control here:
https://www.sounddeadenershowdown.com/

I then used the following products in the floor, doors and roof for sound/temp control.

https://www.amazon.com/Noico-deadeni.../dp/B00URUIKAK

https://www.acoustimac.com/soundproo...SABEgJp_vD_BwE

https://www.ebay.com/i/131754566187?...r=431129497605

Not saying I'm right, I'm just lazy and hate reinventing the wheel.

[buffydores]

That's super helpful

[rideair]

Buffydores,

If you are really wanting some gas mileage out of either of the transmissions you are thinking about, you can always add a "GearVendors overdrive unit". This would give you the mileage you want at the lower RPM's and the high speeds going down the road.

https://www.gearvendors.com/4x4gm4s.html

Just a thought, but all idea's come at a price.

[SBTork]

Originally Posted by rideair

As someone that just built a 1988 Suburban DD, I agree with Bluestep on this one. I found that if you replace both the door/window rubber, then use the following products and thought process of sound deadening/temp control, the factory AC will work great. The standard 350 and 700r4 are tried and true, parts found on any street corner, and purchased as a new crate engine and trans rebuild, you will have a 50,000-100,000 mile warranty to boot! You are going to get a certain level on noise out of the doors based on the door panel design (only covers 2/3rd, thus the reason they now use full door covers in new cars)

Start off reading information about sound/temp control here:
https://www.sounddeadenershowdown.com/

I then used the following products in the floor, doors and roof for sound/temp control.

https://www.amazon.com/Noico-deadeni.../dp/B00URUIKAK

https://www.acoustimac.com/soundproo...SABEgJp_vD_BwE

https://www.ebay.com/i/131754566187?...r=431129497605

Not saying I'm right, I'm just lazy and hate reinventing the wheel.

I can attest to the effectiveness of the Noico product. I used their sound deadener and closed cell foam on my '85 Suburban, and noticed a HUGE difference. Last fall I went through and did the entire floor and sides on my Suburban. I'll be doing the roof next spring to fully complete the job, then the doors after that. With just the floor done it made a tremendous difference. The product is top quality and very reasonably priced on Amazon, easy to work with too.

[rideair]

SBTork,

I used the 3M SM400L (3/4 inch) in the roof, and the 3M SM600L (1 1/2 inch) in the doors.

You will be GREATLY impressed with how this stuff keeps the heat out.

Before putting the headliner back in place, I found even on a hot sunny day here in Virginia, where I had not finished my install, you could not touch the metal area where I had not installed it yet, but the areas covered with it, the backsides were just warm to the touch.

The reason for the thinner SM400L in the roof, the bows that go across are only about 1/2-3/4 deep, so it filled the void and was not compressed. Whereas in the doors, I could use the 1 1/2 to make sure it helped keep the sound out and filled the void better.

[kwmech]

Originally Posted by rideair

SBTork,................................

Whereas in the doors, I could use the 1 1/2 to make sure it helped keep the sound out and filled the void better.

So what about when it rains and water passes through the doors to the drains? Does it retain the water/moisture to create future rust issues?

[rideair]

kwmech,

"No".

The way you install the three products in/on the doors are the following.

1. Install the Noico product on the backside of the outer door skin (product installs like Dynamat, peel, press, role). Window will have to be fully rolled up reaching through holes in the inner door panel.

2. Install a layer of Noico on the inner door skin that will be behind the door panel facing you.

3. Place a layer of the Mass Loaded Vinyl over Noico and inner door panel creating a vapor barrier (much like new cars do now)

4. Install a layer of 3M SM600L on the backside of the door panel 9where it stays nice and dry)

By using this method, you will take the "ting" out of both the outer/inner door skins with the Noico, add a sound/vapor barrier with the MLV, finally adding additional sound proofing and heat/cool barrier with the 3M SM600L.

Make Sense?

[rpmerf]

Originally Posted by Bluestep

I have had a '89 V1500 Suburban since 1992. I would say if what you want is a good reliable vehicle get one and restore it to original. There is no need to go to an aftermarket air conditioner as the stock one works very well, the windows don't need an "upgrade" just lubrication and rubber seals that are in good shape. It drives me crazy to see people throw money away on aftermarket stuff that is supposedly an upgrade when all the vehicle needs is maintenance and repair. The original equipment parts are engineered to work flawlessly for a very long time and are usually manufactured to a high standard that I don't feel is there for many aftermarket parts.

Our Suburban still works very well and I would trust it for any long distant drive. I am always amazed how short a turning radius the old style straight axle has compared to newer vehicles. It is a comfortable car with a pretty decent ride.

Was thinking the same thing. Between me and my father we've had about 4 burbs (87, 89, 94, 97), a Blazer (89), and 3 pickups (70, 87, 99). The biggest issue on just about all of them has been rust. Engines and transmissions have been perfect past 200K. A couple of them had issues in the rear, but nothing a rebuild didn't fix. Overall extremely reliable.