My 1970 3/4 Ton Suburban Carryall

It's a station wagon built on a truck chassis!

The BridgeHunt Mobile

Introduction

These are the chronicles of my Suburban. I bought the Suburban in February 2009 After seeing it in the Kansas City Craig's list. Finding a 67-72 Chevy Suburban is somewhat a tricky proposition, and though this one is far from perfect, it also far from being too gone or unserviceable. And for the purpose I have for it, just right. For all its virtues, taking the truck on bridge hunts or trips with more than 2 people is cramped. Especially on bridge hunts where we did do 2 or 3 3-man hunts. That left little room for atlases, cameras, snacks, and anything else required to come along. We have done some 3-man hunts in my 1975 Chevrolet Chevelle Malibu, but the person stuck in the back seat was always at a disadvantage, both for room and being to see outside during the trips. Additionally, the Malibu sits too low to the ground. So, what was needed was a machine that combined the truck with a car: A truck station wagon, or Suburban was the answer. Of course I would want something with as many common parts and features as could be shared with the truck, so a 67-72 Suburban was the answer.

The Suburban

The suburban is basically the same as the truck. It uses the same front end sheet metal, windshield, and front doors (with a very minor difference). And it basically uses the same frame. What is different is that from the front doors back the Suburban has a station wagon body. My suburban was born in March 1970 at the Flint, Michigan GM plant. Original color was Hugger orange inside & outside with Sandalwood interior trim. This would have actually looked pretty good, I've seen a few trucks still in this condition and the almond/ivory color of the seats, armrests, sun visors, and door panels, with a light honey brown dash pad, steering wheel and column actually looks good with an all-orange interior. However, sometime in the early to mid 1980's (I am guestimating here) the truck was painted dark metallic green with a gold top outside, some body work was done and a new grill was installed (the present grill is not a production 1970 grill, but a replacement made by a second run supplier) and some body work was done. The interior was painted gold, the door panels green, and the seats either reupholstered in dark green, or traded out for some 'burb seats in dark green. I cannot be too certain about the front seat, because when I gout the 'burb it had a green cloth covered bench seat out of a 70's era midsized Ford car. I have since found a Suburban front seat for it (they are the same seat as is used in the trucks, but with a cover on the back side). At some point still later, they painted over the gold top white. The suburban was available with two or three rows of seats. Mine has two rows. Orange painted plugs are still in the rear floor where the holes are for the optional 3rd seat.

Mechanically, the Suburban is basically the same as the truck. It has a basically unaltered 350 engine with Q-jet carburetor. The transmission is the SM465, which was GM's heavy duty truck 4-speed and was used on trucks ranging from C-10 1/2 tons to C-50 2 ton models. The SM 465 has some pretty wide gear ratios:

Gear Ratio

1st

6.55:1
2nd 3.58:1
3rd 1.57:1
4th 1:1
Reverse 6.09:1

Couple this with the 4.10:1 rear end ratio and you have some mighty fine towing gears, but slow highway gearing. Except for occasional use in low speed conditions in parking lots, I never use 1st gear, which is not synchronized. As for driving on the open road, sustained 55 mph is tolerable, even 60 mph occasionally or on short trips is ok. At 60 mph with the tires that are on her, the engine speed is 2900 rpm.  Since I desire this to be a vehicle capable of doing much highway driving at sustained highway speeds, an overdrive will be required. For this, I plan to swap out the manual SM 465 for a automatic TH700R4:

Gear Ratio

1st

3.06:1
2nd 1.63:1
3rd 1:1
4th 0.70:1
Reverse 2.30:1

Yes, I will loose the stump-pulling gears, but I don't use them now. This combination will give a final drive ratio of 2.87:1 when in 4th gear, plenty low for highway driving.

The rear axle is a full-floating Eaton HO52. 4.10:1 is the lowest ratio made for this axle. Compared to the semi-floating design used in cars and 1/2 tons, the HO52 is a much better axle. Each wheel has a pair of tapered roller bearings, and the axle shaft transmits torque only, it carries no load.

 

Styling

I really think GM did a fine job styling the 67-72 Suburban series. Just like the 67-72 trucks, Suburbans have a much cleaner look than previous styling series, and the clean lines of the truck cab are simply extended back the whole length of the truck.

What's NEW...

JANUARY 2010

It's Power Steering time. Hurray!!! With a break in the weather, I was finally able to add power steering. Here are a few pictures, and I am sorry that there are no 'in progress' shots:

Above, getting started, we see the old manual box still in place. This box was actually in great shape and still pretty tight. Note the massive front brake drum. These are much bigger than those on the truck.

Above, the power box in place, with hoses attached. This is the same box that the 1/2 ton uses, and was used on 1/2 and 3/4 trucks from 68-75.

Above, power steering pump in place hanging down low between the crankshaft and frame.  Since the water pump had an extra pulley, I went ahead and routed the belt around it and the crankshaft, in case the alternator belt breaks.

 OCTOBER 2009

I HATE FEDEX AND WILL NEVER USE THEIR SERVICES AGAIN.

Parts were ordered from a member of the 67-72 chevtrucks board, a member I have dealt with before without issue. These parts were to add power steering and brakes to the suburban, and came off a '71 chevy 3/4 ton. Well, the parts never arrive despite claims by fedex that they were delivered 2 days later. Sorry, but UPS has never lost a parcel shipped to me, and surprisingly, thought it may take them forever, the post office has never lost anything major either. But ask fedex to ship 35 pounds of truck parts form Kansas to Oklahoma, and you'll never see them. I am extremely PISSED. Some of those parts can never be replaced, they are simply not made anymore. Given the total loss, it would have been cheaper to actually drive up to Kansas to get the parts than pay for fedex ground to "ship" them.

FEDEX: NEVER AGAIN.

Sorry, just a little rant, but I'm still very pissed.

Pictures

The first few pictures were taken just shortly after I brought her home. She is still wearing Missouri plates.

Above, a general view. The tri-pod mirrors are factory.

Above, Idiot Lights!!!! They were very promptly removed and replaced with a gauge cluster. You can also see the ugly Ford seat.

Below, that's better, gauges. I also added a tach to aid in gear shifting. With the SM465 4-speed and 4.10:1 rear gears, I do 2900 RPM @ 60 MPH.

Below, looking back. As you can see, there  is plenty of room.

Above, no more fighting over who sits in the back seat. I have since installed seatbelts for three passengers on this seat.

Above, another view from the front.

Above, OK, this is what you really wanted to see, engine pics.

Above, another engine pic.

Above, and another. I rebuilt the carb not long after getting her home, and was surprised by how clean it was.

Above, a picture of the 'burb on its first bridgehunt in May, 09

Links

67-72chevytrucks.com, the message boards for 1947-1998 Chevy & GMC trucks, has a section for 67-72 models only

The Chevrolet Longhorn Truck Page More info on 67-72 Chevrolet trucks.

The Stovebolt Page Has lots of useful info and photo galleries, as well as a focus on all Chevy & GMC trucks from 1918 to 1972.

Early Suburban Owner's Club Has a history of the Suburban, photos, etc.

A Station Wagon History Answers question such as "why are they called station wagons?" and more!

Technical & Tuning Related

Quadrajet Tuning and Tips

Edelbrock performer series carburetors

Questions or Comments? Send Email

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