Bad shuttering at even low speed

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Maddogz
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Bad shuttering at even low speed

Post by Maddogz » Sun Sep 09, 2018 6:37 am

So back story: left my hmmwv at a friends farm for a few days. Picked it up and got it home and zero ebrake. Friend did take it out on his farm and obviously left the ebrake on. Anyways, pull out the TM and go to work. No problem, tighten it, ebrake works fine so take it out for a quick spin. After less then .5 of a mile it starts shuttering and bad. Whole vehicle is shaking bad. I pull over, notice a smell (had the heat on full blast) and look underneath at the ebrake rotor. Looks fine and cool to the touch. So I stopped and go, applying the ebrake a bunch of time and after 5 minutes I was good to go. Drove 30mph home. Nothing. This morning, right away, it is doing the same thing. But I can feel it at 2-3 mph. Play with the ebrake, even slowing the vehicle down from about 6 mph. Still doing it. Does it in reverse drive and even neutral. Put it in all ranges, still does it. So redo the ebrake again, loosening it a bit but still snug as per the TM(using feeler gauge). No improvement. Check everything quickly underneath and nothing obvious. Any ideas of what to check? I honestly cant tell where it is coming from cause it is so bad the whole vehicle is shaking shuttering and vibrating, it is almost like something is grinding, almost. Only leak is transmission but not bad and keep it topped up. I removed the undercarriage protection kit and havent put it back on incase something like this happened. Going to jack it up and check that the wheels spin freely. It is a 6.5 3l80 supp armor slant back. Thanks everyone.

Update: rear tires move freely but front are clicking a bit 90% sure it is the same type of feel when im Driving it. guessing my front dif is toast?


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Re: Bad shuttering at even low speed

Post by Action » Sun Sep 09, 2018 7:22 am

E-brake on propshaft? It could be warped. When you check fitment, it could be in a normal part of the warp. Jack a back tire of the ground and put in gear. The rear shaft will spin along with the tire in the air. Listen for anything scraping under there.
Of Corse, use common sense safety practices. Like don't lay in front of the tire spinning, etc, etc.

Are you sure it isn't coming from another brake caliper?

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Re: Bad shuttering at even low speed

Post by wooody1 » Sun Sep 09, 2018 7:34 am

Check centre bearing on propshaft maybe is has collapsed, or yoke etc

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Re: Bad shuttering at even low speed

Post by dilvoy » Sun Sep 09, 2018 11:00 am

If it is not a warped parking brake caliper the parking brake caliper may need to be removed for inspection. Two holes in the caliper slide over two pins mounted to the chassis with tight tolerances. Also the little brake pads are held on with some weird springs. Maybe they are mangled or broken.
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Maddogz
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Re: Bad shuttering at even low speed

Post by Maddogz » Sun Sep 09, 2018 3:35 pm

Ok thanks everyone. Probably wont be able to get at it till Thursday but will update.

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Re: Bad shuttering at even low speed

Post by Retired War Horses » Mon Sep 10, 2018 6:36 pm

Warped rotors....
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Re: Bad shuttering at even low speed

Post by wooody1 » Thu Sep 13, 2018 7:25 pm

Moral of the story, do not let anyone drive your truck

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Re: Bad shuttering at even low speed

Post by DockRocker » Fri Sep 14, 2018 1:54 am

wooody1 wrote:Moral of the story, do not let anyone drive your truck
No kidding. If someone is going to do something stupid to my truck, I want it to be me!


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Re: Bad shuttering at even low speed

Post by Maddogz » Tue Apr 09, 2019 12:49 pm

Ok so, i moved and had the hmmwv flat bedded to my new house. Just got the rest of my tools plus warmer weather is here so went to work. Went under to check the driveshaft/U joints (mechanic at military museum was 90% it was a u joint) and yep, Center bearing was destroyed. Thanks wooody1.



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Re: Bad shuttering at even low speed

Post by Retired War Horses » Tue Apr 09, 2019 1:52 pm

Just replace the shaft..easier for sure.
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Re: Bad shuttering at even low speed

Post by Maddogz » Wed Apr 10, 2019 3:05 pm

Ok now even more to the story, go to take it out for a spin today, in 2 wheel drive, start it up and wont budge. Turn it off and go underneath to check the ebrake. It is fine. So start it up and put it into HL, and then drop it into D, she works. Drove it a mile and tried H again and nothing. So HL and L work but not H. The gears work so guessing my transfer case is screwed? Any suggestions? Would the center bearing blowing up have had anything to do with wrecking the transfer case? Thanks guys.

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Re: Bad shuttering at even low speed

Post by Action » Wed Apr 10, 2019 3:45 pm

Put the propshaft back in and H will work.

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Re: Bad shuttering at even low speed

Post by ryanruck » Wed Apr 10, 2019 9:05 pm

Maddogz wrote:
Wed Apr 10, 2019 3:05 pm
Ok now even more to the story, go to take it out for a spin today, in 2 wheel drive, start it up and wont budge. Turn it off and go underneath to check the ebrake. It is fine. So start it up and put it into HL, and then drop it into D, she works. Drove it a mile and tried H again and nothing. So HL and L work but not H. The gears work so guessing my transfer case is screwed? Any suggestions? Would the center bearing blowing up have had anything to do with wrecking the transfer case? Thanks guys.
Normal transfer case operation. Remember, this is a full time 4wd vehicle.

Because the transfer case is a full time 4wd case, the transfer case has to allow the front and rear "axles" to turn at different speeds for conditions since both the front and rear outputs are always engaged. If it didn't, you'd get driveline binding when driving on dry, hard surfaces. It's similar to an open diff when it is in H. As such, the power will take the path of least resistance which is your front output since there is no shaft there.

HL locks the front and rear outputs together distributing power to the front and rear equally instead of the path of least resistance. Thus allowing you to put power to the rear without the front shaft in place.

Emergency self recovery with a broken driveshaft or half shaft includes shifting to HL, if you aren't already, so that the power is sent to the good end.

A good demonstrational video:

https://www.youtube.com/watch?v=mhTVQh7bFtw

As Action said, when you replace your driveshaft, your truck will work fine in H.

And a look inside your transfer case where you can see that center diff which is all mechanical, unlike some transfer cases which use a weaker viscous coupling.

https://www.youtube.com/watch?v=NZdCfHCug4A

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Re: Bad shuttering at even low speed

Post by Maddogz » Thu Apr 11, 2019 8:46 am

Great Info guys. Thanks a bunch!!! Love this site. Would be lost without it.


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