Thumping noise on stopping
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Thumping noise on stopping
I have a 78 f100 and have been noticing a thumping noise just when I stop but also may happen when I am slowing down fairly quickly. My suspicians are as follows:
rear shocks - haven't done anything with these for the 3 years that I've owned the truck and don't know when they were serviced prior to that.
Rear springs might be getting ready to pack in in. Apparently the springs in the rear are misaligned and my mechanic tells me it takes a bit to get them to go this way.
Box coming loose somehow? It is kinda misaligned right now but its always been this way since I've had it.
Any help would be appreciated.
Thanks.
rear shocks - haven't done anything with these for the 3 years that I've owned the truck and don't know when they were serviced prior to that.
Rear springs might be getting ready to pack in in. Apparently the springs in the rear are misaligned and my mechanic tells me it takes a bit to get them to go this way.
Box coming loose somehow? It is kinda misaligned right now but its always been this way since I've had it.
Any help would be appreciated.
Thanks.
Senior User
Joined: May 2003
Posts: 213
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From: Cedar Falls, IA
Sounds like loose suspension components somewhere. If it was a 4x4, I'd guess something in the radius arms, such as bushings being worn out allowing the axle to compress things when stopping. In the rear, this could be worn shackle bushings for the same reasons.
But, it does sound like you need to put in some quality time with your suspension, front and rear, to make sure it doesn't turn catastrophic.
Good luck with the search and let us know what you find!
John
But, it does sound like you need to put in some quality time with your suspension, front and rear, to make sure it doesn't turn catastrophic.
Good luck with the search and let us know what you find!
John
Elder User
Joined: Mar 2004
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From: Kansas City, Missouri
If it is when you are applying the brakes, I would check the trueness of the rotors/drums. Sometimes they will warp and even though you don't get the pulsing feel you can get the thumping noise.
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Joined: Sep 2004
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Since you seem to be sure it's coming from the rear, spare tire? Exhaust pipe hanger let go? Wiggle the spare tire around, it'll rattle around giving you all sorts of unwholesome notions if it's loose. When I first picked up my oversized garden cart, the spare tire mount was rusty and the whole assembly was flapping around when I applied the brakes. Bump, rattle, bump, bump, bump. That noise just had to go. I'm seriously tempting fate, too, because I haven't remounted it since bolting in the Class III hitch, and I've been driving around without that god-awful noise for months, and sometimes I forget to throw the spare back into the bed...
Posting Guru
Joined: Jun 2004
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From: Dracut, Massachusetts
how do you know its coming from the rear? check the front brak calipers, the support bracket may have spread apart over time. and when you apply the break it grips the caliper and moves, thus the thump. hope that helps
Senior User
Joined: Jan 2002
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From: Fairbanks USA
Check your radius arm bushings. My wifes truck was doing the same thing and turned out they were bad. Bought a new set of polyurethane ones for 20 bucks. Sometimes undercarriage sounds will fool you on their location.
1 Peter 5:8
1 Peter 5:8
Postmaster
Joined: Feb 2003
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From: Spokane WA
everyboby is saying brakes/suspention, but to me it sounds like a bad passenger side motor mount.
they will make a thump on hard braking as the engine lifts a bit then falls back down.
they will make a thump on hard braking as the engine lifts a bit then falls back down.
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Elder User
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From: Kansas City, Missouri
That is a thought, but the information given made it appear the noise was in the rear of the truck. 
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Posting Guru
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From: Murray
Hey,
Is it possible that your tranny mount might be loose at all, that might explain the reason it sounds like its coming from the rear, my friends t-bird suffered from this problem and it sounded like the rear end was loose but it was the tranny.
Hope it helps,
-Chris
Is it possible that your tranny mount might be loose at all, that might explain the reason it sounds like its coming from the rear, my friends t-bird suffered from this problem and it sounded like the rear end was loose but it was the tranny.
Hope it helps,
-Chris
Posting Guru
Joined: Jul 2001
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From: Gainesville, FL
Grizz,
I don't think we have enough info to speculate:
1. How does the vehicle roll under highway cruising? Smooth? Rough? Steering wheel shake?
2. How old are the tires? What size?
3. Any known brake problems?
4. Rear axle leaks?
5. Does the steering wheel shake when you brake?
6. How tight is the steering gear?
Throw in any info you have overlooked.
KingFisher
I don't think we have enough info to speculate:
1. How does the vehicle roll under highway cruising? Smooth? Rough? Steering wheel shake?
2. How old are the tires? What size?
3. Any known brake problems?
4. Rear axle leaks?
5. Does the steering wheel shake when you brake?
6. How tight is the steering gear?
Throw in any info you have overlooked.
KingFisher
Elder User
Joined: Jun 2003
Posts: 686
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From: Edgewood, Wa
I think that I have the same noise on my rig... as I slow down, and come to an almost full stop, I get a "thump" as well (best way to describe it)
best as I can tell from mine, it's the rear shackle bushings. It also will do it when taking off, and it is definately from the rear. on a side note, ALL mounts are within a year old, shocks, brakes are new as well. Looking at the shackle bushings, they seem pretty wasted, there is upwards of 1/8 inch gap at the ends...... gonna replace them next week, we'll see if it cures it.
best as I can tell from mine, it's the rear shackle bushings. It also will do it when taking off, and it is definately from the rear. on a side note, ALL mounts are within a year old, shocks, brakes are new as well. Looking at the shackle bushings, they seem pretty wasted, there is upwards of 1/8 inch gap at the ends...... gonna replace them next week, we'll see if it cures it.
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Kingfisher
Truck does okay on the freeway, but have noticed that its a bit rougher than previously. MAy need to balance tires.
I am due for a major brake overhaulsoon - as soon as I have time and weather to do it. Probably will be doing the rears first - I think the drums might be warped but I will find out when I take the drums off.
The rear tires are relatively new but used. The fronts probably will be replaced in the not too distant future. I think they're 235 80R16s that I have on.
There are no known rear axle leaks that I have been able to find.
There is an increasing amount of shimmy when I have to brake from higher speeds. Another reason why I need to work on the braking system first - might be something more, but I can eliminate the brakes as the culprit soon. Steering gear seems okay to me.
The noise that I was actually asking about happens at the point where I stop. It seems like at the point where the wheels have stopped, but the rest of the truck haven't caught up yet, there is this thump at the end. I'm hoping to overall the suspension system. Yep, there's work ahead. Hopefully it'll be worth it.
Truck does okay on the freeway, but have noticed that its a bit rougher than previously. MAy need to balance tires.
I am due for a major brake overhaulsoon - as soon as I have time and weather to do it. Probably will be doing the rears first - I think the drums might be warped but I will find out when I take the drums off.
The rear tires are relatively new but used. The fronts probably will be replaced in the not too distant future. I think they're 235 80R16s that I have on.
There are no known rear axle leaks that I have been able to find.
There is an increasing amount of shimmy when I have to brake from higher speeds. Another reason why I need to work on the braking system first - might be something more, but I can eliminate the brakes as the culprit soon. Steering gear seems okay to me.
The noise that I was actually asking about happens at the point where I stop. It seems like at the point where the wheels have stopped, but the rest of the truck haven't caught up yet, there is this thump at the end. I'm hoping to overall the suspension system. Yep, there's work ahead. Hopefully it'll be worth it.
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From: Murray
Originally Posted by spitfire51786
My tbird only did that when I accelerated hard, where as his f100 does it when he stops, and possibly when he is slowing down 
-Chris