Thump / clunk sound from front

adrenalnjunky · Post by **adrenalnjunky** » Wed Jan 12, 2005 11:19 pm

Split topic-HJ

well, I got off lucky actually - I found my culprit today at lunch.

A while back I took my battery out and re-wired my audip system and foglight relays (I had the relays mounted below the battery tray near the 4wd actuator.)

in the process I had to unbolt the passenger side horn.

I forgot to put the horn back where it was supposed to go I guess, and it had been riding around just kinda sitting inside the fender and inner fender area, and has been like that for God knows how long without moving around I guess. - but I gues this week it shifted or jarred itself into a spot where it was clanking around in there. I unplugged it and drove home without another sound out of the front end.

malkavian · Post by **malkavian** » Thu Jan 13, 2005 9:57 am

forgive me but that was

adrenalnjunky · Post by **adrenalnjunky** » Thu Jan 13, 2005 10:03 am

Yeah,

I know it sounded ghetto. I'm a little ashamed to admit that that is what it was. I have years of car audio shop experience, and I don't like doing things "half-assed" but I had tucked the horn out of sight/out of the way in the inner fender, without unplugging it. Apparently it just stayed there and heck - I forgot to bolt it back in. When I armed my keyless entry, the horns still honked normally, so I never thought about it.

Now it sounds like a little 4-banger import, because the horn on the driver side is the high-pitched one, and that's all that is working until I can get a new bolt for the thing.

F9K9 · Post by **F9K9** » Thu Jan 13, 2005 5:39 pm

Well, I had hoped I wouldn't have to post on this topic but, looks like I have to now.

I am getting an inconsistent dull audible thud with some of it "felt" coming from the passenger front. I cannot reproduce it consistently but, it occurs more often when backing up with the wheels in a turned position and then applying the brakes. It happens occasionally when wheels are straight ahead on a surface like gravel at speeds under 10 mph.

Have not done any troubleshooting yet but I plan on doing the "lifted wheel wobble" check. I will also check my aftermarket Bilstien shock installation for tightness.

Any other things I can check for before I confront my friendly local service manager (am under 7K)

Post by **HenryJ** » Thu Jan 13, 2005 5:53 pm

f9k9 wrote:...I am getting an inconsistent dull audible thud with some of it "felt" coming from the passenger front. I cannot reproduce it consistently but, it occurs more often when backing up with the wheels in a turned position and then applying the brakes. It happens occasionally when wheels are straight ahead on a surface like gravel at speeds under 10 mph. ...Any other things I can check for before I confront my friendly local service manager (am under 7K)

T-bar mount: check for shiny spots where it bumps the frame.
T-bar sockets: Lube them with some spray grease. (not WD-40

)
Motor mounts: Check for cracked or broken mounts.

Just a few more things to check.

Hey! while you're under there get some follow up pictures of the adjuster bolts. I'd like to see exactly how much they backed them off.

F9K9 · Post by **F9K9** » Thu Jan 13, 2005 6:12 pm

HenryJ wrote:

Hey! while you're under there get some follow up pictures of the adjuster bolts. I'd like to see exactly how much they backed them off.

You actually didn't think that I had forgotten I promised you those pics, did you?

We're now enduring weird weather. that keeps changing from 70 to below 20 degrees

Was going to do my trailer hitch/brake light wiring tonight but too much water was dripping off the rig inside the "sallyport"

Will get them for you, ASAP.

adrenalnjunky · Post by **adrenalnjunky** » Thu Jan 13, 2005 10:34 pm

I had something very similar that I couldnt find under my truck, until I found all of the lube points in the front end - 11 of them I think. I hit them all once and the sound went away.

I tdoesn't make sense in ym head that that would fix it, but, it did.

F9K9 · Post by **F9K9** » Sat Jan 15, 2005 3:13 pm

HenryJ wrote:
T-bar mount: check for shiny spots where it bumps the frame.

It appeared shiny in the area between the cracked rubber and the frame. The pic didn't light up the area.

HenryJ wrote:
T-bar sockets: Lube them with some spray grease. (not WD-40 )

Very bad pic but, if this is where the T-bar sockets are, I lubed it with lithium grease and also around the area close to where the T-bar adjusters are.

HenryJ wrote:Motor mounts: Check for cracked or broken mounts.........Just a few more things to check.

Checked them the old fashioned way (foot on brake and giving gas in drive and reverse).

HenryJ wrote:Hey! while you're under there get some follow up pictures of the adjuster bolts. I'd like to see exactly how much they backed them off.

adrenalnjunky wrote:I had something very similar that I couldnt find under my truck, until I found all of the lube points in the front end - 11 of them I think. I hit them all once and the sound went away. It doesn't make sense in my head that that would fix it, but, it did.

Sound advice and appreciate it but, I have been pretty regular on that.

Post by **HenryJ** » Sat Jan 15, 2005 4:04 pm

Looks like they backed one side off quite a bit. It looks like it was the drivers side too? That doesn't make much sense unless your t-bars are pretty mismatched. Oh, well as long as it is sitting evenly and aligned correctly you're good.

Those are the t-bars sockets, they need to be able to slide fore and aft as things flex.

Someone mentioned shimming the mounts to eliminate the t-bar mount thump. I'm not sure what exactly they did. Replacement of the mount is something to consider if they are shot.

Another thing to think about would be the shields. Those spring washers don't do a very good job of isolating the differential shield. It can tend to rattle a little. I added some self adhesive edge trim to my oil door too.

Don't forget the hood hinge. It can sound like something in the front end too. Wedge a piece of rubber , or foam in there to see if it could be a culprit.

Spend some time under there with a dead blow hammer banging on things. That is how I do it.

F9K9 · Post by **F9K9** » Sat Jan 15, 2005 4:20 pm

It is definitely not a rattle like a shield. It's a dull thud/clunk that can be felt in the steering wheel and the seat (when you do feel it).

Am just going to use general terms to describe the front wheel movement when frame was on a jackstand.

Holding the tire. at 12 and 6 o:clock and attempting it move it resulted in zero movement. At 9 and 3 o:clock had movement (moderate). The driver's front was on the ground.

Was the one area depicted in the picts where I should see a "shiny" spot?

Anyway, just trying to figure it out. It is a definite physical "feeling" that made me paranoid enough to check the spacers torque and all for wheel's lug nut's

Post by **HenryJ** » Sat Jan 15, 2005 4:30 pm

f9k9 wrote:...Was the one area depicted in the picts where I should see a "shiny" spot?

There and higher. Obviously the rubber isn't going to make much sound , it would be any metal to metal contact that might make the sound.

Check those a-arm bolts too. One member here found one loose ,creating his noise.

I had a thump in the floor boards after my 2" BL. It was the EGR tube from the LH exhaust manifold bumping the body seam behind the LH cylinder head. A little persuasion with a prybar solved that.

2bunik · Post by **2bunik** » Sun Jan 16, 2005 11:12 pm

I dont rememeber you haveing a 2 body lift. but if you do .. get under the truck and retighten the bed bolts.. dont try wiggleing the bed or checking if it is loose.. just get under there with a ratchet and tighten them down.. I had a loud thud when backing up and could not figure out what it was. turned out it was my bed was a just loose enough, but not loose enough to be shaken and felt.. weird.. heck it takes five minutes to do ..and it could work ..

F9K9 · Post by **F9K9** » Sun Jan 16, 2005 11:35 pm

2bunik wrote:I dont rememeber you haveing a 2 body lift. but if you do .. get under the truck and retighten the bed bolts.. dont try wiggleing the bed or checking if it is loose.. just get under there with a ratchet and tighten them down.. I had a loud thud when backing up and could not figure out what it was. turned out it was my bed was a just loose enough, but not loose enough to be shaken and felt.. weird.. heck it takes five minutes to do ..and it could work ..

No lift as of yet but thanks

killian96ss · Post by **killian96ss** » Sat Jan 22, 2005 10:32 pm

HenryJ wrote:Someone mentioned shimming the mounts to eliminate the t-bar mount thump. I'm not sure what exactly they did. Replacement of the mount is something to consider if they are shot.

I have been having a thump noise also, and the only thing I can find that could even possibly make this noise is the t-bar crossmember moving side to side hitting the frame. I have tightened everything up as much as possible, but the noise still persists. Could the t-bar crank be causing this problem? I never had this noise until the 3/4" crank. How much does this crossmember need to flex? I can see how shimming the upper mounts would prevent side to side movement, but there is obviously a reason GM designed it to move a little. I guess I could just shim a little at a time until the noise goes away? What do you think?

Steve

Post by **HenryJ** » Sun Jan 23, 2005 7:49 am

killian96ss wrote:... How much does this crossmember need to flex? I can see how shimming the upper mounts would prevent side to side movement, but there is obviously a reason GM designed it to move a little...

I'm not real sure what the reasoning was here. Older models as well as fullsize are mounted solid.
I'm sure that it prevents vibration and road noise transfer, but the attempt may have backfired and created a new problem.

killian96ss · Post by **killian96ss** » Sun Jan 23, 2005 9:17 am

HenryJ wrote:I'm not real sure what the reasoning was here. Older models as well as fullsize are mounted solid.
I'm sure that it prevents vibration and road noise transfer, but the attempt may have backfired and created a new problem.

By looking at the design, it appears GM wanted the crossmember to move for and aft, but not side to side. As you mentioned earlier, the t-bars are already designed to slide in the sockets, so I still don't understand this design change.

Maybe there was a slight binding problem with the earlier designs? If the bushings were polyurethane, then that would help also, but I don't think anyone makes these for our trucks. Any idea what year GM switched the design on the S10's?

Steve

Post by **HenryJ** » Sun Jan 23, 2005 9:28 am

I think that you are on the right track there.
The fullsize does have a problem with premature wear to the sockets/bars. This may have been their attempt to solve that issue.
I'm not sure why though since the olders S-10's did not have that problem. Perhaps the frames for the second gen S-10's are a little more flexible and they thought there might be a problem.

I am not really sure when they started using the bog bone mounts. I am pretty sure that the '91's were still solidly mounted, so it may have come in with the body change in '94?

duglasfur · Post by **duglasfur** » Fri Feb 04, 2005 1:27 pm

What y'all are describing is definitely the Tbar crossmember hitting the frame. I had the same problem that can be fixed for a short while by spraying in lithium grease w/ a fine nozzle into the "pork-chop" articulating area. Chevy shimmed both sides, but I read in another thread that there service bulletin was wrong and only shouls the side that's hitting (which makes sense) I haven't removed the other shim (lazy) now that I know it's not a safety or wear issue.

ZoSo · Post by **ZoSo** » Tue Feb 08, 2005 7:34 pm

Exact same thing with my CC... 3/4 turn and I got the noise
I'll try the grease.

Thanks

killian96ss · Post by **killian96ss** » Tue Mar 08, 2005 6:42 pm

I finally got tired of hearing the clunking noise, so I shimmed both sides of the T-Bar crossmember, and now the noise is gone.

All I did was put a washer on the frame side of each dog bone mount. The washers were the same OD as the dog bone, and the ID was just big enough to slide over the serrated inner sleeve. I think the washers were about 1/8" thick. There is still room for side to side movement, but not much. I'm just glad that annoying noise is gone.

Steve

kf6kmx · Post by **kf6kmx** » Tue Mar 08, 2005 10:31 pm

Not sure if its the same sound, but I've been getting a thud ever since installing my stiffer shocks..
I put the Rancho 5000's on it, and it developed what sounds like the exhaust pipe banging the frame under the drivers side when you hit bumps.. It wont do it every time, but enough.. You can feel it in the floorboard.. haven't been able to recreate it with the truck standing still.. My tire shop checked the shock installed, they said they were good.. I didn't like the little bit of play in the shock so we shimmed it with grade-8 washers between the shock head and the mount.. noise still there..
haven't tried the bed tightness check yet, but I don't think the noise is coming from the back..
Also, on mine its only when you are going straight, at moderate to high speed, and hit a bump.. Slow speed and turning it has never done it.. Only noise I get at slow speed is the rear springs squeak (guess I'll have to go under there with some white lithium spray grease

).

When you hit the right size bump, the noise will repeat itself two or three times like something is bouncing..
I swear its the same noise we got on the '66 Mustang when the dual exhaust was first installed at the read axle was hitting it and driving it up against the frame.. but we cant see anything on the exhaust thats loose, and nothing on the exhaust system has been changed when the noise started.. The ONLY change to the truck was the stiffer shocks, and the noise started immediately.. the very first test drive with the ranchos had the noise in it..

killian96ss · Post by **killian96ss** » Wed Mar 09, 2005 9:33 am

kf6kmx wrote:You can feel it in the floorboard.. haven't been able to recreate it with the truck standing still..

This is the same sound I was having after the new shocks and T-Bar crank. I couldn't duplicate it either, but I could see the shiny marks the T-Bar mounts were making when they hit the frame.

Also, on mine its only when you are going straight, at moderate to high speed, and hit a bump..

Mine only did it when going over big bumps like train tracks, pot holes, or rough roads.

When you hit the right size bump, the noise will repeat itself two or three times like something is bouncing..

Once again, this is exactly how mine sounded. Do you have the 2" BL and T-Bar crank?

Steve

kf6kmx · Post by **kf6kmx** » Wed Mar 09, 2005 1:15 pm

killian96ss wrote:
kf6kmx wrote:You can feel it in the floorboard.. haven't been able to recreate it with the truck standing still..
This is the same sound I was having after the new shocks and T-Bar crank. I couldn't duplicate it either, but I could see the shiny marks the T-Bar mounts were making when they hit the frame.

I'll have to check that and see if I can see anything..

killian96ss wrote:
Also, on mine its only when you are going straight, at moderate to high speed, and hit a bump..
Mine only did it when going over big bumps like train tracks, pot holes, or rough roads.

It does it every time on tracks, most big intersections, most of the road here to the back way out on base (pot holes the size of compact cars).. Washboard surface makes it go absolutely NUTS with the sound..

killian96ss wrote:
When you hit the right size bump, the noise will repeat itself two or three times like something is bouncing..
Once again, this is exactly how mine sounded. Do you have the 2" BL and T-Bar crank?

Steve

I'll check that since yours was doing the same.. maybe we just missed it when we were looking, since we werent looking for anything specific at the time and just looking at everything we could think of!
Nope, so far the only suspension mod to mine has been the Rancho's..

kf6kmx · Post by **kf6kmx** » Wed Mar 09, 2005 1:17 pm

killian96ss wrote:I finally got tired of hearing the clunking noise, so I shimmed both sides of the T-Bar crossmember, and now the noise is gone. All I did was put a washer on the frame side of each dog bone mount. The washers were the same OD as the dog bone, and the ID was just big enough to slide over the serrated inner sleeve. I think the washers were about 1/8" thick. There is still room for side to side movement, but not much. I'm just glad that annoying noise is gone.

Steve

In case that is the problem on mine, happen to have any photos of the location/process?

We still need to come up with something offroad for the few of us in CA..

jeff024 · Post by **jeff024** » Wed Mar 09, 2005 1:18 pm

"kf6kmx"Not sure if its the same sound, but I've been getting a thud ever since installing my stiffer shocks..
I put the Rancho 5000's on it,

I also have the 5000s they seem to just make a thud sometimes Im guessing from being stiffer,I have checked them several times to make sure they were tight and they are fine. I also had the knock under the driver floor and it has since gone away after my BL

killian96ss · Post by **killian96ss** » Wed Mar 09, 2005 8:42 pm

kf6kmx wrote:In case that is the problem on mine, happen to have any photos of the location/process?

I still don't have a digital, but I might be able to borrow a friends camera to take some pics for this topic and several others. I'm way behind here on getting some pics posted.

If you go under your truck and grab the T-Bar crossmember, you should be able to move it from side to side, and you will see where it can hit the frame on either side. Look for shiny marks around this area.

kf6kmx wrote:We still need to come up with something offroad for the few of us in CA..

For sure, and the weather has been really nice lately. Today it was 81* in Napa.

Steve

gocntry · Post by **gocntry** » Fri Mar 11, 2005 10:49 am

Hey Everybody...

Rancho 5000's Here.......And The Stupid Thunking Noise Is Here Too.....AARRGGHH!!!.....

Jeff

jeff024 · Post by **jeff024** » Fri Mar 11, 2005 10:52 am

Yup I think its just the stiff shocks . But my driver floor knock is gone

F9K9 · Post by **F9K9** » Tue Mar 29, 2005 5:00 pm

Okay, it's getting worse and happening 99.9% of the time when I back up have wheels turned, like out of a parking spot. I can see where the rear T bar assembly is hitting the frame of both sides.

Then I remembered Brule telling me that on someone's differential shield install that the correct bolt length was difficult to insert on the rear passenger side bracket and he had lost the nut off of it using the stock bolt. Mine is okay but am wondering if the gap seen in the photos is normal. Both sides have the gap and I really tightened the suckers down.

I have lubed all 11 points

I have sprayed lithium grease in all the recommended places and the not so recommended places

Checked the Bilstiens to avoid that hassle.

hammered the shields, good and solid

Ideas?

Thanks in advance

twodoorblazer · Post by **twodoorblazer** » Tue Apr 26, 2005 7:09 pm

Where is everyone on this issue still? Any fixes that seam to work well?

Mine just started doing it when I replaced the front shocks. It only happens when making left turns, never on right turns for some reason.....

Some of you have mentioned it is the tbar cross member that runs width wise hitting the frame and the procedure to correct this is with shims? What exactly do you shim and where? Any photos or detailed descriptions would help immensely. Many thanks

jeff024 · Post by **jeff024** » Wed Apr 27, 2005 1:04 am

twodoorblazer
are you getting a knock or a THUD noise and what shocks did you put on?

twodoorblazer · Post by **twodoorblazer** » Wed Apr 27, 2005 12:47 pm

I put on some monroe sensa tracs.... I don't think it is the shocks, it used to do it before I changed them, but it was not as loud or as often...

I would say is is more of a THUD sound like something binds up and "POPS" on 3/4 left hand turns........it happens everytime I drive it.

Post by **HenryJ** » Wed Apr 27, 2005 2:19 pm

twodoorblazer wrote:...sound like something binds up and "POPS" on 3/4 left hand turns........it happens everytime I drive it.

Lube the T-bar sockets.
Use some spray grease and spray around where the torsion bars enter the lower a-arms.

twodoorblazer · Post by **twodoorblazer** » Fri Apr 29, 2005 9:19 pm

I picked up some lithium spray grease..... seamed to work somewhat, doesn't happen near as often, but not a complete fix......hmm....

bubaloo1983 · Post by **bubaloo1983** » Sat Apr 30, 2005 5:24 am

i havent followed this thread much but i had the same problem...and now come to think of it since the t bar relocator install there hasnt been any grease hanging out of the torsion bars sockets on the a arms...bad?? i better get some and see if my trouble goes away

killian96ss · Post by **killian96ss** » Sat Apr 30, 2005 6:20 am

twodoorblazer wrote:Some of you have mentioned it is the tbar cross member that runs width wise hitting the frame and the procedure to correct this is with shims? What exactly do you shim and where?

There are 2 bolts that mount the t-bar x-member to the frame, one on each side. Attached to each bolt is a flexible end link with a threaded rod. When the bolt is fully tightened there is still enough play to allow the x-member to hit each side when going over bumps. I just used an equal amount of washers on each side of the flexible end link to limit side to side movement to the point where there is still a small amount of movement, but not so much that it will bind up.

This along with lubing the t-bar sockets and back side of the adjusters has cured my knocking problem.

Steve

twodoorblazer · Post by **twodoorblazer** » Mon May 02, 2005 9:04 pm

you put the washers where the crossmember endlink connects to the frame, do you need to support the tbar cross member when you do this?

what about some sort of rubber shims on the cross member, will this work?

killian96ss · Post by **killian96ss** » Tue May 03, 2005 6:11 pm

twodoorblazer wrote:you put the washers where the crossmember endlink connects to the frame

I put one washer one each side of the end link where it bolts to the frame

do you need to support the tbar cross member when you do this?

Yes, I used a floor jack to hold the t-bar x-member in place, and I only did one side at a time. Make sure that the x-member is supported because those t-bars are under a good load.

what about some sort of rubber shims on the cross member, will this work?

Where were you thinking of putting them?

The best solution would be to find an end link, or rod end that only swings in one direction (fore and aft) instead of the stock pivoting style. Some urethane bushings on the threaded rod intsead of the stock rubber ones might work also.

Steve