Tow vehicle mod on an older Suburban

[A W Warn]

Yes, your vehicle is adequate if it is equipped properly and the trailer hitching and sway control is set up properly. A 1500 suburban with a 350 engine, if the gear ratio is low enough, should be able to handle your Overlander.

If you want specific answers, you need to provide specific information. Your answers about your equipment have been generic, except for engine size.

1. You say you are having problems towing, but should we assume the truck is having "trouble towing". What do you mean? Are you having problems with pulling power, steering, the vehicles ability to carry the load (rear sag), etc.?
2. What is the gear ratio? If it is geared to high the truck will not have enough power to pull.
3. The truck should stop itself. The trailer should stop itself. If you are having problems stopping, the brakes are not working properly. How have you tested the trailer brake function?
4. If you are having problems with rear sag or steering, it is a hitching issue or cargo loading issue. Have you weighed your whole rig to know that it is set up correctly?
5. If you are having problems with handling, it could be the tire type, tire inflation, worn out steering, out of align tires, etc.
6. Are you towing up and down steep grades, or driving in the flatlands?
7. What specific brake controller are you using.
8. What type of weight distribution are you using?
9. How much weight transfer is your weight distribution system doing?
10. Are you having sway problems?
11. Is your trailer level when it is loaded and hitched to the tow vehicle?
12. What are the GVRW and the GCRW of the tow vehicle? (If the rear axle ratio has been changed, the door tag is no longer correct. Instead, use the chart in the owners manual)

As you can see, you have not provided enough information for us to really contribute many useful answers. What you are getting is speculation and half answers. Tell us your specific issues and specifically how your tow vehicle is equipped. We will try to help!

[Glenritas]

Ok so you have a '69 'Burb' with a 350 V-8 and a TH350 trans and it most likely came with 3.42 gears that you have changed to ??? hopefully to 4.10 or 4.30 It also came with drum brakes all around and it has P235-75Rx15" tires. How am I doing ?

If the above is close this is what I would suggest ,

Convert to front disc brakes from a '71or'72 Chevy or GMC 1/2 ton PU.

Change the wheels and tires to P275-60Rx17" on 9x17" wheels.

Add a set of ceramic coated exhaust headers, dual exhaust system low restriction quiet mufflers and a crossover H pipe.

Change the trans to a TH 700R4 or TH 4L60 These have a lower 1st gear and overdrive.
Or go heavy duty with a TH 400 or TH 4L80 These are geared more like the TH350 + overdrive.
In any case add a drain plug to the Trans Pan better yet change to a PLM cast aluminum Trans Pan it gives more strength to the trans case and has a drain plug + more capacity.

Also add a stacked plate Trans cooler . B&M makes a nice 10,000 # one.

Be sure your Radiator is large enough for the task super coolers fins help a lot.

If you don't have 4.10 or 4.30 gears I'd rethink that.
Also add a PLM cast aluminum Diff Cover, it has a drain plug and more capacity and run a synthetic fluid.

If your engine has a 2 Venturi carb or a 4 Venturi carb I'd replace the cast iron intake manifold with an Edelbrock aluminum air gap manifold and add Electronic Throttle Body Fuel Injection with O2 feed back so it will run in closed loop. This will reduce emissions and give you way better MPG. You're now getting around 10-12 MPG this will go up to 15-17 MPG not towing.

Another thing to consider is you cam and lifters. Todays oils have less zinc because of Catalytic Converters on new cars. The cure for them is roller lifters .

You could go several ways to combat lifter and cam wear, add ZDDP at each oil change, Use Lucas Hot Rod & Classic High Zinc Oil , Jeg's has it. Or Upgrade to a roller cam and lifter set.

And to make the mountains easier to handle Add a GearVendors Under / Over drive unit behind the Trans. this will give you more gear selections for the just right gear for whatever condition you find on the road.

You'll also want to add rear airbags in your coil springs to help level the rear.

Of course check out all the suspension and steering components and repair as necessary.

Another thought is to Upgrade to a 6.0Liter V-8 and 4L80E Trans or 6L80E trans from a very late model GM PU.

[Action]

Originally Posted by criswellrl

I have also changed the gear ratio on the rear end for stronger towing ability.

For your Suburban -
What axle ratio is on there now?
Is this 2 wheel drive or four wheel drive?
Are the tires the stock? Or better yet what is the tire size?

It will be difficult to know what to do until we know what you have. Kind of like going to a given campground, if you don't know where you are at traveling to the campground will just be a random shot in the dark.

Also what has been stated above, the mods necessary to do the job safely may exceed a different (period correct) Suburban. This will alos vary depending on if you a re a DIY or you will pay some one to do this. And it is difficult to say not knowing what you have.

One other thing you have stated about putting on air bags. The typical reason to install air bags in addition to the stock springs is because the stock springs are worn out! At best this is a poor way to fix worn out stock springs. At worst you will cause roadability issues either loaded or unloaded that are not good for vehicle control.


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[Glenritas]

Also check out The 1967 - 1972 Chevy/GMC Suburbans & Panels Message Board - The 1947 - Present Chevrolet & GMC Truck Message Board Network

AND http://67-72chevytrucks.com/vboard/f...play.php?f=212

for a wealth of info on the subject.

[Action]

BTW your Overlander will come in just under 5000 pounds, excluding any modifications. However it would be highly recommended to weight the trailer at a scale in as close to full blown travle mode as possible. In fact I would fill all the tanks (Water, black & grey) and have the propane tanks filled.
Whatever weight you weigh out at add another 15% to that. (Like people RVs gain weight as they age) Then target your TV to handle that total.

I am all about making vintage tow vintage. However the overriding condition should be to do it safely. A 45 year old vehicle with 45 year old technology typically has maintence that has been deferred. And usually this is in the steering, suspension and brake systems because every one is focused on the engine/transmission. And while the engine and transmission are very important all systems become equally important under a major load. And a vacation goes swiftly down hill when the TV isn't ready for the job.

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[JustSomeGuy]

I know this is not what you want to hear, but the easiest, cheapest, safest and most stress-free and trouble-free way is to buy a newer tow vehicle. I used to (and still do) love vintage cars and trucks, but finally gave in to new. Technology and reliability have come a long way, especially in the last 10 years. In fact, I'd go so far as to say that the worst car today is as good as the best car was 20 or 25 years ago.

For sure there would be nothing cooler than towing a late 60s/early 70s Airstream with a similar vintage tow vehicle, and a '69 Suburban has the looks! But, as others have suggested, the mods you probably need to make are not going to be cheap, and you'll still be driving a 50 year old vehicle, technology and reliability with some newer technology mods. I'm not sure if you're mechanically inclined or a gear head. I'm not. When I got my 25' Airstream Excella, my rear wheel drive 2005 Chevy Astro minivan could have done the job - it was one of the most popular tow vehicles in its heyday in the 1980s and 1990s. (Although mine was a 2000s it was really using 1980s/90s truck technology, ride and reliability). Big 4.3 V6 with a "ground stomping" 186 HP, 4 speed automatic, high center of gravity. The factory tow rating was 5500# and my Airstream is 5100 dry, and I was going to have Can-Am RV in London make a custom hitch.

But in the end, I got a 2012 Chrysler Town & Country minivan with nearly 300 HP and nearly 300 lb/ft of torque, 6 speed automatic with dash mounted tap shifter for easy manual upshifts and downshifts, electronic vehicle stability control, ABS, traction control, modern crash protection and airbags, etc. Not to mention satellite radio, navigation, backup camera, power everything. I'm in heaven. Not to start a heated debate on my choice of tow vehicle, because there are plenty of naysayers out there, and I don't want this thread to go off-topic. But substitute in any newer vehicle... a Toyota Tundra/Sequoia 4Runner, Dodge/Ram, Chevy GMC pickup or Suburban, Ford F-series pickup, etc in 3/4 ton form. If my front-wheel drive V6 minivan can handle my 25 foot Airstream, any of those newer trucks will be able to as well. Now, your '69 Suburban would beat my 2012 Chrysler minivan hands down for the coolness and retro factor. Why not keep the vintage 'Burb for local driving, not towing. Or cut your losses and just sell it. For peace of mind, and less headaches as well as not driving a money pit on a long distance road trip towing a 3 ton trailer, consider a newer tow vehicle. In the back of your head, you probably know this, but you (and many others, myself included until just recently) would make a choice based on emotion instead of reason and go with the cool looking vintage ride instead.

Most people assume any Airstream is vintage. They sometimes say "oh, do they still make those?" So, to most non-RV people, or more importantly, most non-Airstream people, they wouldn't be able to tell the difference between a 1969 or a 2009 Airstream - at least from the outside. And most people are towing with a fairly new tow vehicles. Myself, personally, I'd be willing to give up the coolness factor of towing a vintage Airstream with a vintage Suburban for the safety, peace of mind, power and braking capacity and reliability of a newer tow vehicle. And don't get me wrong. I love vintage. The inside of my home is mostly mid-century modern 1960s furniture (non-mechanical stuff, so it won't break down, lol!). My Airstream is a 1990, but has few mechanical parts to break down. It was hard, but I've given up on vintage cars and trucks. I'm not a mechanic, and found them just to be unreliable money pits. Lots of old, vintage things will be like that. Cars, houses, etc.

Incidentally, if you have a spare 16 minutes, watch this video comparing a VERY cool vintage Chrysler station wagon to a brand new Mercedes AMG 4Matic wagon. The "Icon Derelict" is a 1952 Town & Country station wagon (rebuilt with current 2000's technology so you have the vintage look with modern reliability, but I hear it cost $150,000). Both very nice rides and both out of my price range. From an emotional standpoint, I'd take the vintage ride. From a practical standpoint, I'd take the new one. It doesn't even have to be a Mercedes that's worth as much as my condo, though I wouldn't turn it down if someone gave it to me.

https://www.youtube.com/watch?v=ZBksUjg2sJE

[TomKirk]

Back in the day, 1969 Chevy half ton pickups had really lousy brakes. This would include your Suburban. The braking systems are all the same.

BTW - Don't get me wrong, there have been brake issues over the years. But, 1969 seems to have set the standard for really lousy brakes.

FYI - I'm a retired Chevy parts guy. Back in 1969, replacing brakes with less than 10,000 miles was not out of the ordinary.

Tom

[Forrest]

If you're running over-sized tires then that contributes to your problems, both pulling and braking. If you go with slightly undersized tires, as long as they have adequate rating, that will help and is one of the easiest things to do. By under-sizing, I mean tires with slightly smaller overall diameter. If there is clearance you could go with slightly wider as well to improve footprint e.g. traction. However, if you do this, you will need to readjust your hitch.

[NavyCorpsman]

I believe the 69's came with several engine options. 230ci, 292ci L6, 283,307, 350, 396 ci V8. If you have the 292, there are several things that are bolt on that can give you 80-100 RWHP. If you have the thriftmaster 230, it will run like it has asthma no matter what you do.
All of the SBC engines were underbuilt, and are a great foundation for low buck performance upgrades.
The type of transmission will affect how well your vehicle tows. A well maintained Automatic, IMO works the best. The reason being is that you get Torque Multiplication with an automatic on the order of X1.5.
With that said, Engine/Trans/Rear Ratio have to be considered as a "package". You cant stuff a wild cam in it and expect a miracle. The most dramatic change you can do without breaking the bank is to change the rear axle ratio by installing a new Ring and Pinion Gearset. You would have to go with a numerically higher (lower ratio)gear to achieve breakaway torque, and desired sustaining torque. Sounds complicated but it's not too tough. Let us know what you are running, Eng, Trans, Rear Ratio, 2/4WD, Coil Spring or Leaf Spring, and the weight of your AS, and I will work out a couple of options for you that will have the power that you need.
If you are interested, I replaced the vacuum brake system on my GMC Sprint to the Hydro boost system. PM me and I will send you the pics and parts that you will need.
That car can bury the speedo (120) in 15 seconds, and it use to be a terror to stop. Not any more.
I think it's awesome that you want to tow with an older Surbuban. Just want to see you happy AND safe.
Clayton

[PaulnGina]

An earlier post said "the answer to your question is a 350 engine with a quadrajet 4 barre l carb. and a 350 transmission."

Sounds like a great place to start.

[NavyCorpsman]

A MOST EXCELLENT PLACE TO START. Properly tuned, and with a good tranny cooler set up, you will be just fine. A lower stall speed torque converter helps to get it rolling easier, and will help drop the fluid temp a bit. If your engine is stone stock it makes about 260 hp and 280 ft/lbs TQ. Its not a stretch to make a street-able engine that makes 375 HP on pump gas.

[pappy19]

As was stated above, changing the rear ratio to a lower 4:10 or 4:30 will help. If you have an automatic, it's probably a 350 version, which needs a lot of help. Rebuild with a good kit and for sure add a Transgo Tugger Shift Kit. In addition, a $120 extra tranny cooler is in order. If it is a 4-speed manual, then you are stuck with it but you can still change the rear end ratio for better towing. Lastly, for about $350, you can install a set of rear air bags that will help your tired springs and re-align the "Burb" with the AS. Brakes are marginal and the fronts can be switched to disc first and then the rears if you get the bread. All in all, the '69 Burb is a groovy ride if set up right.