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'73 Bus - Suspension "Crunch" Noise

Posted: Mon May 01, 2017 7:57 am
by 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

Re: '73 Bus - Suspension "Crunch" Noise

Posted: Mon May 01, 2017 9:27 am
by 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

Re: '73 Bus - Suspension "Crunch" Noise

Posted: Mon May 01, 2017 11:09 am
by 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

Re: '73 Bus - Suspension "Crunch" Noise

Posted: Mon May 01, 2017 6:34 pm
by 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.

Re: '73 Bus - Suspension "Crunch" Noise

Posted: Mon May 01, 2017 6:35 pm
by a3inverter
And, no signs of abnormal tire rubbing.

Re: '73 Bus - Suspension "Crunch" Noise

Posted: Tue May 02, 2017 4:35 pm
by hambone
Keep pumping the grease gun until clean new grease comes out.

Re: '73 Bus - Suspension "Crunch" Noise

Posted: Wed May 03, 2017 12:08 pm
by 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.

Re: '73 Bus - Suspension "Crunch" Noise

Posted: Thu May 04, 2017 10:45 am
by a3inverter
All great suggestions. I shall do and report back.

Re: '73 Bus - Suspension "Crunch" Noise

Posted: Fri May 05, 2017 7:44 am
by Amskeptic
a3inverter wrote:
Thu May 04, 2017 10:45 am
All great suggestions. I shall do and report back.
I was going to say, remove shock absorbers and test drive.
Colin

Re: '73 Bus - Suspension "Crunch" Noise

Posted: Wed May 17, 2017 6:40 pm
by 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.

Re: '73 Bus - Suspension "Crunch" Noise

Posted: Sun May 21, 2017 6:55 am
by Amskeptic
a3inverter wrote:
Wed May 17, 2017 6:40 pm
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