'73 Bus - Suspension "Crunch" Noise

[a3inverter]

Hi all,

I have a '73 bus that recently developed a crunching noise when the suspension travel is more extreme. I'm going to lube the front beam tonight to see if that resolves, but wanted to reach out here to see if anyone had any suggestions.

Thanks,

Scott

[asiab3]

Hi there, and welcome to IAC!

I'll start with the obvious and easiest questions first, then we can go deeper if needed. What size tires do you have? All stock brakes and rims too? Rubbing tires can sound like a crunch or a whir, depending on tread pattern. Any sign of rubber on your wheel wells/frame?

Does it happen more or less when the wheels are turned or straight?

Good call on lubing the beam; make sure both front wheels are off the ground, and don't forget the center pin zerk.

Good luck,
Robbie

[a3inverter]

Same tires for years and this sound just started recently. All stock brakes and rims. Will check for rubber on wheel wells/frame. Definitely happens when the wheels are straight, can't recall if turned. Going to crawl underneath tonight with a light and perform a comprehensive review and report back.

Scott

[a3inverter]

Update:

Lubed up the front beam and I would say we have a 50% improvement. Crunch/Creak is still there for certain road undulations that cause major front suspension movements, but overall improvement. Gave each zerk about 30 strokes of grease and got great gobs of the old stuff flowing out.

[a3inverter]

And, no signs of abnormal tire rubbing.

[hambone]

Keep pumping the grease gun until clean new grease comes out.

[sgkent]

what hambone said. Also use rubber lube on the shock bushings, sway bar bushings, and damper bushings. Check closely for any cracks on the beam uprights. If it continues you may need to pull the leaves and clean them. I had some flakes of rust get into the leaves on my 1971 and it made noises - I had to pull, clean and reinstall the leaves. Dry rubber bushings can do it too. Oh - and don't forget to check the lug nuts.

[a3inverter]

All great suggestions. I shall do and report back.

[Amskeptic]

All great suggestions. I shall do and report back.

I was going to say, remove shock absorbers and test drive.
Colin

[a3inverter]

Following up....

The noise has simply gone away for now. I'll lube the shock mounts just to be sure, but no more noise.

[Amskeptic]

Following up....

The noise has simply gone away for now. I'll lube the shock mounts just to be sure, but no more noise.

I was gonna say, "don't lubricate rubber." Rubber is supposed to bent internally, not slide ever. Lube quiets down the sliding that should not be occurring. Sliding causes rapid wear. All suspension and shock bushings are to have no moving. Once movement (noise like graunching or squeaking) begins to occur (usually from tightening them down when the car is NOT at proper ride height) the interference fit is damaged.
Colin

[cellobus1]

I know it's been a while since this was posted, but I'd just like to chime in and say that I have occasionally gotten this noise also. It sounds like a gigantic tree frog. It happens during extreme front end bottoming out in say, a deep sewer depression coming slowly around a corner, and it's more likely in cold weather. I learned to drive on a '73 bus that was bought new. My dad had scheduled maintenance done on it for 5 years or so. It made this noise even with the dealer maintenance and only ~30,000 miles on it. Before I knew anything about buses I thought this was just the frame tearing up, but 45 years later my guess is that the noise indicates extreme torsion leaf travel.

Andy