Increase towing capacity 72 Blazer

[phlegm]

Hi guys, I have a line on a blazer that is already off the frame and in pieces. Lots of talking yet to do around whats there and whats not, etc... but its from somebody I trust so that will work itself out. Its a 350 with a TH350 automatic and AC Cab

I have a question, this is a 4x4 blazer and I think (but not sure) those are leaf springs all around. If I were to go to a 5 leaf setup in the rear would that increase my towing capacity? And if so to around how much? I have read through the different threads on here and see a lot of NO NEVER DO IT posts, but i havent seen anything that addresses beefing up the suspension. ** looks like it may be 5 leaves stock, not sure**

I have a 5000lb boat thats 24ft, but it has a long tongue and is on a tandem axel. I would like to get the Blazer to the point that i could put it in, take it out and tow it around town. I expect to move near a lake soon, so the only long distance tow would be 3 hrs to the new house and I could borrow a truck for that, and even if I have to use the blazer I would use a weight distribution hitch if I had to go any distance behind a short base like that. This would let me have a cool blazer and get my wife out of the big ole suburban now that the kids are driving and leaving us.

[truckster]

The biggest problem the Blazer has with towing is the wheelbase. If your tongue weight is 10 - 12% (which it should be), it should be within the rated capacity of the Blazer. Trailer sway is the biggest problem, and it's multiplied the longer the trailer is vs the shorter the tow vehicle is.

In short, I don't think you need to add capacity for the springs, but I would be really careful about towing at highway speeds. I've towed a loaded car hauler around town with my Blazer with no problem, but at freeway speeds it gets a little scary.

[phlegm]

Originally Posted by truckster

The biggest problem the Blazer has with towing is the wheelbase. If your tongue weight is 10 - 12% (which it should be), it should be within the rated capacity of the Blazer. Trailer sway is the biggest problem, and it's multiplied the longer the trailer is vs the shorter the tow vehicle is.

In short, I don't think you need to add capacity for the springs, but I would be really careful about towing at highway speeds. I've towed a loaded car hauler around town with my Blazer with no problem, but at freeway speeds it gets a little scary.

Thanks! When you did the car hauler, did you use a Weight Dist Hitch? Wondering how much those help...

[truckster]

Originally Posted by phlegm

Thanks! When you did the car hauler, did you use a Weight Dist Hitch? Wondering how much those help...

I didn't. I'm sure it would help, though.

[randy500]

The blazer wheelbase is way to short for anything other than super light duty towing. A 24 foot boat no matter how you set it up will whip the blazer side to side and you will loose control.

[HO455]

Information is power. Here is some information on the subject that may help you. I have a friend who has pulled his Super Gas race car all over the west coast with his 74 4x4 Blazer for decades. A lot of it is about preparing and knowing what to expect.

Hensley hitch
https://hensleymfg.com/trailer-sway-101/

https://rvfavorites.com/trailer-sway-control/

[hemi43]

I tow a 4000lb+ 17ft travel trailer, and while it tows OK, you really need to watch your speed and keep your eyes on the road. I wouldn't want to tow anything heavier. I only do this once a year when attending the Syracuse Nationals which is 4 hours drive.
As far as increasing the number of leaves, waste of time IMO. A 5000Lb trailer should have a maximum tongue weight of 750lbs, which is fine for the Blazer. Definitely use a weight distribution hitch.

[cleszkie]

I see this question come up a lot. Just because your Blazer can move your trailer and not bottom out the suspension doesn't mean it is ready to be a tow vehicle. Leaf spring capacity and wheelbase are only two things to consider when towing heavy loads with your Blazer. You also need to think about your brakes, transmission, rear axle (load capacity and gearing), suspension sway control, engine cooling, etc. The stock 1/2 ton rated brakes, TH350 tranny, and 12 bolt rear axle will be pushed to their limits towing 6000 lbs or more. The brakes will fade, the tranny will overheat, the outer bearings in the semi-float rear axle will wear out, there will be body roll, and the engine will run hot. Ask me how I know. I have used my Blazer to tow a car trailer and a 27-foot boat for years and have had to make many modifications to make it a safe and reliable hauler. The following is a list of the major modifications:

- Tossed the 1/2 ton axles with 3.08 gears. Installed 1 ton Dana 60 front and 14 bolt full-floating rear with 4.10 gears.

- Tossed drum brakes on 14 bolt. Installed disc brakes.

- Tossed vacuum brake booster. Installed hydro-boost system.

- Tossed TH350. Installed an SM 465 manual 4 speed with Gear Vendors over/under drive.

- Installed air bag sway control/load assist system on real axle.

- Installed a traction bar on rear axle to prevent axle wrap under load.

- Beefed up my cooling system with big two-row aluminum radiator, performance water pump, and twin electric puller fans.

- Installed hydraulic line lock on rear brakes to use as a parking brake assist when trailer is attached.

I also make sure that the loads I am hauling are properly situated on the trailers such that I am getting enough tongue weight to prevent trailer sway at highway speeds. I probably went farther than most people go to make their Blazers into tow vehicles. But I can now safely haul heavy loads for long distances at highway speeds without exceeding my Blazer's mechanical limits.

[jjzepplin]

And don't forget the most important piece of the puzzle IMHO. Rims and tires. A heavy duty set of wheels and some heavy sidewall tires will help BIG time. I did the same as above with the one ton axles etc but also opted for some thick aluminum wheels and a set of 10 ply Super Swampers and holy cow. I turned my mushy lane swapper into a train on rails. The 4.10 gears help a lot and the overdrive is heaven. I installed a 203 splitter on mine so that backing up and launching in super low gear was divine. I had a 20ft Baja with a 200 yami and it towed like the trailer was not even there. Springs help with weight carrying capacity but not side to side sway. I would just opt for air bag helpers for big heavy loads though. I always go for heavy sidewall tires now as I use my truck as a truck. If I want something comfy I use my wife's car. She digs my truck so it's a win win. The rear axle is the scary part when towing real heavy. Remember 12 bolts are held together by C clips. Floaters are held by large locking bolts and if and axle breaks you just pull over. If a C clip breaks you lose your wheel possibly.

[HO455]

These are a couple of great write ups. Good solid information.
And if you have not looked at trailer brake controllers lately they are much more sophisticated than those of 10 years ago.

[jjzepplin]

Originally Posted by HO455

These are a couple of great write ups. Good solid information.
And if you have not looked at trailer brake controllers lately they are much more sophisticated than those of 10 years ago.

Oh yeah... I forgot trailer brakes. RUN them! I always set mine to kick in the trailer brakes first to straighten me out if I get wobbly. Its amazing how well you can stop a rig with 8 tires on the ground.

[mister.freeze]

+1 on the cooling and Hydraboost. + a million on the tires:

Big balloon tires are awesome but suck for towing. Even a light load. This is me with my 500lb motorcycle. Couldn't go more than 65 without the rear end swimming around on me. 3.73 gears, 700r4 transmission, 4 row radiator (this trip was in August from Houton to Lubbock), 3/4 ton springs. but the tires were the weak link.

[RunsWithScissors]

Don't worry so much about it.

A 1971 Blazer lifted 2" on 31/33 tires and 15 inch steelies took my family ALL OVER the place pulling a 1973 Ideal trailer weighing in at around 7000 pounds. Never worried about the sway. I towed it when I turned 16 also.

We ALWAYS used an Equal-I-Zer (spelling?) hitch.

No, we weren't goin 80 mph at the time. Max was about 65 we'd ever do. Yes, we made sure the weight was correct, and took care around semi trucks and high winds.



That being said, I plan to tow my 4500 lb boat to the lake with it this summer. I'll still put the equalizer on it. The newer, just as heavy trailer will be towed by the newer longer wheelbase F150 6.2L.

[kwmech]

You know this is 2 years old right?

[RunsWithScissors]

Originally Posted by kwmech

You know this is 2 years old right?

Sure. Thanks for the warm welcome.

Maybe threads that are too old for comment should be locked or better yet deleted, since others finding the threads on a search engine might be inspired to join the forum and comment.

[truckster]

Originally Posted by RunsWithScissors

Sure. Thanks for the warm welcome.

Maybe threads that are too old for comment should be locked or better yet deleted, since others finding the threads on a search engine might be inspired to join the forum and comment.

Welcome to the forum.

We'd love to see picture of your Blazer... we're kind of sick that way.

[Thealien]

Originally Posted by RunsWithScissors

Sure. Thanks for the warm welcome.

Maybe threads that are too old for comment should be locked or better yet deleted, since others finding the threads on a search engine might be inspired to join the forum and comment.

I don’t see a problem with keeping old posts open and adding to them. The only problem I see is the original poster may not be on the forum anymore or the information being two or five or 10 years old may not be as relevant as it once was.

I find it interesting that sometimes someone will start a topic and then get told on other forums to do a search. And then get piled on for posting in an old thread.

It’s all good and welcome to the forum. And I agree about pictures of your blazer.

[hemi43]

Welcome! will you be attending the Syracuse Nationals this year?

[RunsWithScissors]

I'll get some pictures up soon in my profile. I haven't had much time to do restoration with it yet, and could use some enthusiast advice on a few things. Thanks.