Stovebolt.com Forums The Shop Area The HiPo Shop Not happy with the front straight axle

If the springs have never been replaced, what about the spring bushings and shackles? Those could be the source of your problem.

You said you "replaced everything". What does that include in your mind? Apparently not the springs.

Shocks? Drag link? King pins?

There is nothing inherantly wrong with solid axles, pretty much every big truck being made still uses them.

Weak springs will allow the axle to hop all over tarnation instead of resisting the hill or valley that the wheel goes over.

How many miles would you estimate your truck's suspension has on it?



Yes, a handling improvement of any kind would be welcome, I think.

How many miles would you estimate your truck's suspension has on it?

Probably 100 thousand miles

Elmo

I would bet the rear spring hanger pins and bushings are worn. A small amount of wear in these will make them act really stupid. Even with regular greasing, mine had lots of wear at 10k miles after replacement.

Personally, I would repair the existing suspension and steering systems before trying to re-engineer the truck.

I'm certainly not an expert on the handling characteristics of the AD series truck. I am, however, extremely familiar with the handling characteristics of antique vehicles in general. Unlike most people that own antique vehicles for weekend cruises or tooling around the neighborhood once a month, and who drive modern vehicles for the majority of the time on the road, I have never owned a modern vehicle.

All of the vehicles in my signature line are used as daily transportation, rush hour interstate travel, and vacation trips of over 1000miles (the 1995 F-150 is actually my mom's - I just maintain it.)

I will categorically state that the handling characteristics of vehicles of the era we're discussing are not anywhere close to being as bad as many people assume. The big cars of the '50s are not lumbering dinosaurs that wallow in turns and curves or have loose steering or anything like what is often described by those who have never driven them.

When properly repaired/restored and driven within their respective limits, these vehicles, including your AD 3/4 ton truck will perform extremely well and without scaring the daylights out of you every time you hit a pothole or sharp curve.

With modern shocks and radial tires, the performance is even better.

If you do decide to replace your springs and bushings, etc, I would do both front and rear to keep the truck level and prevent the front end from doing one thing while the rear end does something else on the same bump in the road.

That's really a function of failed shock absorbers. Weak (sagged) springs will just change the height of the suspension. They'll likely have the same amount of spring rate (springiness) although seized bushings can make them stiffer (unable to move like designed.)

Spring rates on front and rear were different as the came from the factory, so the front and rear will always to different things on the same bump. But changing from the factory spring rates on one axle would make the truck act differently. But again, shock absorbers control the bounce or hop.

Straight front axles are still used today (many 4x4 trucks), and they ride satisfactorily.

Elmo, my 54 did that a couple of times and I finally said enough. As I said above I replaced it with an AMC Pacer front end. It was not cheap then and it is not cheap now comparatively now.

Just to jump on Kevin, Ed and Otto's bandwagon ...

Replacing/upgrading your front end because you *want* to is one thing. And if that's the reason, more power to you and we'll help all we can.

Replacing/upgrading your front end because you think you *need* to is entirely another. And for all the reasons stated above. I'll just add that from pickups to tractor trailer trucks, I've put a fair amount of highway and back road miles in on straight axle trucks. The truck I drive for work most days has a straight axle (but with 11R22.5 tires, I don't mind the power steering ...;) ) and I hit plenty of pot holes around the Nation's Capitol ... I have no problem or hesitation to take my unrestored (but well maintained ) '49 1-Ton on the interstate -- and have, many times. It will cruise nicely all day at 65 MPH and sprint to 70 when needed. Straight axle, Huck brakes and bias ply tires. It has a little wander above 60, but its manageable. Potholes? Not too bad. At speeds above 60 MPH, I just try to hold the wheel straight and the truck will quickly resume course just fine after a few milliseconds of hinkyness.

Why is it able to do this? Have I put sway bars on it? Have I upgraded to an IFS? Do I have Power steering?? No to all of those. I am running the truck in its original configuration (suspension wise I did put a 261 and a 4.10 gear set in the truck) because *everything* is still within spec -- Springs, shackles, steering box, tie rod ends, pitman arm, front alignment, etc, etc. Just *one* of these things out of whack will cause issues at modern highway speeds.

Does my truck drive as well as a modern truck? No, of course not. But it drives fine. It's a different experience and requires a little more attention to what you are doing. Doable? yes. Enjoyable? Certainly.

The '65 GMC 1.5 ton I used to own was the real teller. It was a firetruck and it only had 8,000 miles on it when I bought it in 2007. Mechanically, it was still new. There was zero wear in the front end. You could drive that truck with one finger, even at slow speeds. At 65 MPH (um, I removed the governor and replaced the crappy Stromberg carburetor with a Holly 300), that truck handled like it was on rails!

So ... in my opinion, FWIW ... The factory straight axle/spring suspension/manual steering set up is perfectly adequate for today's highways as the boys have said above ... IF ... and this is a big if ... *everything* in the front end is within spec -- king pins, alignment, tie rod ends, pitman arm, drag link ends, steering box adjustment, springs, spring shackles, spring shackle pins, tires (age, tread, balance and pressure). The more *any* of those are off, the less enjoyable your driving experience will be.

Bottom line -- If you *want* to upgrade the front end, you go right ahead and we'll help you all the way. Just don't think you have to because the straight axle set up is "bad."

If you have a straight axle truck and it handles poorly, it just needs to be fixed, not heavily modified. Not at all against performance upgrades (Evan ... Heck, I'm a Group W Bench Stovebolter myself -- I put a 261 in my '49 ... and created a nuisance ... ) -- Just do them because you want to, not because you think you have to.

Respectfully,
John

You just need to take apart and inspect every single part of the suspension, front and rear, and replace what is worn and adjust what is not worn out.
Spring shackle pins and bushings.
Tierod ends. They need to be thoroughly cleaned and inspected. Make sure balls are round and not egg-shaped. Adjust them according to the Chevrolet Truck Shop Manual.
Draglink ends. Ditto, see tierods above.
Properly adjust the steering box with draglink separated from pitman arm.
New tires would help.