Bouncy clunk rub clunk rub rub rub...... Looking for a thread on fixing a noisy cab latch / air suspension

[Reworked LMTV]

Looking for a thread on fixing a noisy cab latch / air suspension. Tried to search for it.

Clunk rub clunk rub rub rub...... Yeah

Latch has been rebuilt.

Thank you

 

[BKubu]

Any chance it has something to do with the air bags? My truck made a noise like that before I replaced the air bags. I initially thought it was the cab latch. In my case, it wasn't.

 

[Keith Knight]

Are you running original cab suspension?
If so you replaced the air bags. While doing that the small shock absorber inside has polyurethane bushings that rot out causing lots of noise. 8 years ago when I replaced my air bags I couldn’t find new bushings or shocks so I machined new bushings out of rubber.

 

[Ronmar]

Yep could be shock absorber bushings, the ones on mine I disassembled, the shocks were fine, the bushings had disintegrated, and of course the airbags looked like a cat scratching post…

if it is squeaking, look to the hooks from the cab that hook over the pins on the arch. Lube them to quiet them up…

 

[GeneralDisorder]

All some of the reasons the Army deleted that stupid system. It doesn't help ride quality enough to even bother with. Too bad it's more work to delete it than to fix it.

Shock bushings are shot. They always are. Rest of the noises are adjustments and lube.

 

[Ronmar]

Actually deleting it would be quite easy. Some say 4” box or round tube cut to length and welded in place of the shock assemblies… way easier than building my own system:O

 

[GeneralDisorder]

Actually deleting it would be quite easy. Some say 4” box or round tube cut to length and welded in place of the shock assemblies… way easier than building my own system:O

Nice. Yeah do that. Get air ride seats if you must have the truck feel like a water bed. No one will argue that these trucks NEED seats.

They don't need the cab air ride. The A1R rides essentially the same. It's tough to notice a difference once you delete the coil springs and put some decent seats in them, They deleted the air ride cab and installed "suspension" seats which are just *not* a steel slab under some foam. Helps a little - about as much as the actual air ride funny enough.

 

[Ronmar]

But I did design my own works great!

 

[canadacountry]

@GeneralDisorder I know you weren't talking about that but in a book I have about trucking humour (real stories nevertheless) he talked about the old tractors that didn't have airbag suspension so you had to practically hang off the steering wheel itself every time you hit a bump. "nothing like hitting the ceiling then your spine slam back into whatever they called a seat! no wonder many drivers ended up short and chubby from this." he more or less moaned about

I'm sure someone in the military would have the same thing to say about this! (ignoring these crazy young soldiers who drive their willy jeeps' recklessly fast far off the road tho..)

 

[Reworked LMTV]

Any chance it has something to do with the air bags? My truck made a noise like that before I replaced the air bags. I initially thought it was the cab latch. In my case, it wasn't.

Replaced the bags. Guess I need to replace the rubber bushings.

 

[GeneralDisorder]

Replaced the bags. Guess I need to replace the rubber bushings.

The bags have the bushings inside them...... those must have been used or old stock eh?

 

[GeneralDisorder]

@GeneralDisorder I know you weren't talking about that but in a book I have about trucking humour (real stories nevertheless) he talked about the old tractors that didn't have airbag suspension so you had to practically hang off the steering wheel itself every time you hit a bump. "nothing like hitting the ceiling then your spine slam back into whatever they called a seat! no wonder many drivers ended up short and chubby from this." he more or less moaned about

I'm sure someone in the military would have the same thing to say about this! (ignoring these crazy young soldiers who drive their willy jeeps' recklessly fast far off the road tho..)

Tractors - especially old one's - don't tend to have "suspension" in the normal sense. They tend to have the axles bolted directly to the engine and the drive wheels just sticking out of the transmission and not an actual frame. The suspension is literally the tires. Thus "removing" the engine or transmission effectively means you are splitting the whole machine in half. They also don't have much weight on their own in terms of the body and frame (there's not one of either really), so they don't have any mass and the drivers seat accelerates up and down in a rapid and violent way......

Mostly it's just tires full of beet juice connected directly to your (solid steel) seat.

FMTV suspension is a LONG, LONG way from being an old tractor.

 

[Reworked LMTV]

The bags have the bushings inside them...... those must have been used or old stock eh?

New from Factory.

 

[GeneralDisorder]

New from Factory.

That's not a rave review.

Delete the system. Delete the problems.

 

[Ronmar]

Yea, too much unobtanium in the system anyway…

 

[Reworked LMTV]

But I did design my own works great!

View attachment 945582

Nice build. Do you have a thread on your build or a part list by chance. I weld, so this shouldn't be too bad.

 

[chucky]

Mine didnt stop squeaking till i put rubber backed aluminum tape around the 2 tubes the hooks rest on . I keep the air turned off to the bags and the bag saddle pinned to not move .

 

[GCecchetto]

Nice. Yeah do that. Get air ride seats if you must have the truck feel like a water bed. No one will argue that these trucks NEED seats.

They don't need the cab air ride. The A1R rides essentially the same. It's tough to notice a difference once you delete the coil springs and put some decent seats in them, They deleted the air ride cab and installed "suspension" seats which are just *not* a steel slab under some foam. Helps a little - about as much as the actual air ride funny enough.

Speaking of the A1R rear cab mount, mine literally has zero clearance to the spare tire hoist frame. Clunks like crazy and drives me nuts! Curious if any other A1R owners have this same condition?

 

[GeneralDisorder]

Speaking of the A1R rear cab mount, mine literally has zero clearance to the spare tire hoist frame. Clunks like crazy and drives me nuts! Curious if any other A1R owners have this same condition?

That whole mess back there should have got several someone's reprimanded or fired. To be fair it was a REALLY quarter-arse setup that was quickly implemented to delete the air ride because the cost to install it on trucks that were (at the time) going to have the cabs upgraded to armor did not make sense. I spent like a year messing around with it. Mine never hit the spare crane but had MANY other issues - primarily the whole cab would shift like 1" to the left when the pin engaged the latch. I actually got a new bracket - which according to the TM had a revised part number. I was SO convinced they must have changed the dimensions.... Nope! Same $hit. I ended up doing multiple shim revisions of the whole mess. The latch had to be angled up in the front, and the latch bracket had to leveled left to right.

Every one was different is what I came to the realization of. The tolerance stack up between all the parts is obscene and so your only choice is to iteratively zero in on each truck's unique problems and address them.

Sorry I don't have a magic bullet on it. It's royally F'd and I wish it wasn't. FWIW mine has about 3/4" between the latch pin triangular plate and the crane. And that's pretty much immovable. You may have better luck moving the crane back a little.

 

[Ronmar]

And yet another variable are the front cab mounts and pivots... Is your cab on square? Clamp a straight edge onto the frame and measure out to the rear cab edges. Depending on how the front was bolted together or impacts the chassis may have sustained, your cab may be askew IRT the frame causing your interferences at the rear. In building up my habitat frame I discovered my cab is twisted 1/2" to the drivers side at the rear...