Bang Noise?

Rosco · 08-18-2004, 09:22 PM

Ok...considering I just got my car back to NY from a 1400mile trip...I am a little concerned about this. I noticed that when I really get on the gas...higher rpms maybe about 4k, I hear somewhat of a bang coming from either behind me or from the rear end.. Now, I have no idea what this could be coming from.. So any help on diagnosing this more would be greatly appreciated. Thanks

~The Jester~ · 08-18-2004, 10:28 PM

First of all, congrats on gettin her home! How was the Motel stay?!?!?!?! hehehehehehe

Secondly, Worst case scenario, it's not the important (read expensive) things, ie engine, trans. So we have to look at the ass end. If it was the diff or a bearing it'd do it all the time to a varying degree. My guess: Sway bar links and/or bushings, or control arm bushings. Get under there, take a peek and let us know bro.

88fivepointoh · 08-18-2004, 10:49 PM

does it do it on excelleration or during decelleration etc? Could be Rear end gears, could be suspension, could be axle joints etc. best thing is get under there and check it out.

Rosco · 08-19-2004, 01:42 AM

Well ok. Considering it is so late at night.. 1 am.. I decided to road test it a little more. It seems to do it only under hard acceleration. 1st and 2nd gear the most. 1st being more then 2nd. It's an odd noise to describe. Maybe I can get someone to ride with me and record it. Going to have a guy drive it for me at the dealership I worked at and see what he thinks also.

Falcons Talon · 08-19-2004, 02:46 PM

U-joint? Dous it sound like a "thunk"?

Falcons Talon · 08-19-2004, 02:54 PM

sorry...dbl post

88fivepointoh · 08-19-2004, 02:55 PM

Could be U-joints, could be a tooth off a gear in the rear end bent or broken. I think its time for a look in the rear end. It shifts fine though right?

Rosco · 08-19-2004, 08:24 PM

Yeah, the car shifts fine. I just talked to the previous owner and he said it did the same thing when he had the car. He said he was pretty sure that it was something to do with either the driveshaft or something rotating in that general region. He was pretty sure that something was hitting the frame or something else when the rear would dip down. The car has saleen springs all around which lower it 1 3/4". Until I can get the car in the air I am going to somewhat go with that. If that is the case, what would fix that if it was a clearance issue? Aftermarket lower and upper control arms?

88fivepointoh · 08-19-2004, 08:53 PM

Dude, check your tail pipes, My Gt did that once. It may have shifted, and the tail pipe hangers like to come loose and move around under there.

200k5oh · 08-19-2004, 09:41 PM

is it 5spd or AOD?? my old AOD stang did this and all it was was the crossmember.

Rosco · 08-22-2004, 07:27 PM

Well I checked the tailpipes and mufflers and they are fine. Barely any movement in them at all. And it is a 5spd. I will have to get it up on a lift sometime and see if there are any clearance issues between any rotating parts and everything else.

crazypete · 08-23-2004, 09:25 AM

I vote crossmembers. That bangs under hard acceleration if they are worn or rotted and bounce around on the mounting bolt. Failing that....

I think the rear suspension is moving under load (obviously) but it is contacting something. Your 1rst and 2nd gear only comment means it's definatley about twisting under load. Check the driveshaft and look for scratches where it goes near the 2 mufflers. In mine, there is less than 1/2 inch of clearance at one point. If not, check the pinion snubber at the top of the axle snout. Is it there? If it is, is it rubber or an aftermarket piece. The hardened AM ones do make a little thump when they hit but you really need to punch it to get that happening and the suspension needs to be really low. Check the rear wells for rubbing signs but I dont suspect tire contact too much. If the tailpipes hit, you'd see a shiny spot where they hit. Get a 300 watt shoplight you see 300% more when you use the high output lights! Wedge some rubber on either side of the tailpipe where it goes near the fueltank. Then they wont move at all. Then go and race around some to try and get that sound happening.

If all else fails, put the back end on jackstands with the axel drooping and then jack up one end of the axel and then the other and see if it pops or moves freely. I suspect one of the swaybar mounts or control arms is binding. Finally, if this fails, while you got it up there, pop the diferential cover off and take a good look at the gears. Broken gears whine...loud! So you shouldnt find anything in there. But why not look? Replace the fluid with redline synthetic while you're in there.

=)

Good luck!

08-18-2004, 09:22 PM	#1
Rosco Registered Member Join Date: Mar 2002 Location: Vestal, NY Posts: 307	Bang Noise? Ok...considering I just got my car back to NY from a 1400mile trip...I am a little concerned about this. I noticed that when I really get on the gas...higher rpms maybe about 4k, I hear somewhat of a bang coming from either behind me or from the rear end.. Now, I have no idea what this could be coming from.. So any help on diagnosing this more would be greatly appreciated. Thanks __________________ 1989 Mustang 5.0 Conversion, Full Saleen ground effects and spoiler, '94 saleen decal set, '93 Saleen Seats, Black interior from a '93, Steeda quadrant, smog pump delete, a/c delete, Steeda Tri-Ax shifter, '97 rear differential, aluminum driveshaft, 5 lug conversion, '97 rear disc brakes, southside upper and lower control arms, '99 GT Anniversary wheels, flowtech longtubes, flowtech offroad H-pipe, saleen lowering springs, kyb shocks, caster/camber plates

08-18-2004, 10:28 PM	#2
~The Jester~ Rat Killer Join Date: Aug 2002 Location: Cold ass Ohio Posts: 1,143	First of all, congrats on gettin her home! How was the Motel stay?!?!?!?! hehehehehehe Secondly, Worst case scenario, it's not the important (read expensive) things, ie engine, trans. So we have to look at the ass end. If it was the diff or a bearing it'd do it all the time to a varying degree. My guess: Sway bar links and/or bushings, or control arm bushings. Get under there, take a peek and let us know bro. __________________ d-Con Racing "Nothing fancy, just 347 inches of RAT POISON!" MICE need not apply.....

08-19-2004, 01:42 AM	#4
Rosco Registered Member Join Date: Mar 2002 Location: Vestal, NY Posts: 307	Well ok. Considering it is so late at night.. 1 am.. I decided to road test it a little more. It seems to do it only under hard acceleration. 1st and 2nd gear the most. 1st being more then 2nd. It's an odd noise to describe. Maybe I can get someone to ride with me and record it. Going to have a guy drive it for me at the dealership I worked at and see what he thinks also. __________________ 1989 Mustang 5.0 Conversion, Full Saleen ground effects and spoiler, '94 saleen decal set, '93 Saleen Seats, Black interior from a '93, Steeda quadrant, smog pump delete, a/c delete, Steeda Tri-Ax shifter, '97 rear differential, aluminum driveshaft, 5 lug conversion, '97 rear disc brakes, southside upper and lower control arms, '99 GT Anniversary wheels, flowtech longtubes, flowtech offroad H-pipe, saleen lowering springs, kyb shocks, caster/camber plates

08-19-2004, 02:46 PM	#5
Falcons Talon T.P.M. President Join Date: May 2002 Location: Brownsville Posts: 265	U-joint? Dous it sound like a "thunk"? __________________

08-19-2004, 02:54 PM	#6
Falcons Talon T.P.M. President Join Date: May 2002 Location: Brownsville Posts: 265	sorry...dbl post __________________

08-18-2004, 10:49 PM	#3
88fivepointoh Registered Member Join Date: Aug 2002 Location: Rochester Posts: 553	does it do it on excelleration or during decelleration etc? Could be Rear end gears, could be suspension, could be axle joints etc. best thing is get under there and check it out.

08-19-2004, 02:55 PM	#7
88fivepointoh Registered Member Join Date: Aug 2002 Location: Rochester Posts: 553	Could be U-joints, could be a tooth off a gear in the rear end bent or broken. I think its time for a look in the rear end. It shifts fine though right?

08-19-2004, 08:24 PM	#8
Rosco Registered Member Join Date: Mar 2002 Location: Vestal, NY Posts: 307	Yeah, the car shifts fine. I just talked to the previous owner and he said it did the same thing when he had the car. He said he was pretty sure that it was something to do with either the driveshaft or something rotating in that general region. He was pretty sure that something was hitting the frame or something else when the rear would dip down. The car has saleen springs all around which lower it 1 3/4". Until I can get the car in the air I am going to somewhat go with that. If that is the case, what would fix that if it was a clearance issue? Aftermarket lower and upper control arms? __________________ 1989 Mustang 5.0 Conversion, Full Saleen ground effects and spoiler, '94 saleen decal set, '93 Saleen Seats, Black interior from a '93, Steeda quadrant, smog pump delete, a/c delete, Steeda Tri-Ax shifter, '97 rear differential, aluminum driveshaft, 5 lug conversion, '97 rear disc brakes, southside upper and lower control arms, '99 GT Anniversary wheels, flowtech longtubes, flowtech offroad H-pipe, saleen lowering springs, kyb shocks, caster/camber plates

08-19-2004, 08:53 PM	#9
88fivepointoh Registered Member Join Date: Aug 2002 Location: Rochester Posts: 553	Dude, check your tail pipes, My Gt did that once. It may have shifted, and the tail pipe hangers like to come loose and move around under there.

08-19-2004, 09:41 PM	#10
200k5oh Registered Member Join Date: Sep 2003 Location: Hometown, il Posts: 30	is it 5spd or AOD?? my old AOD stang did this and all it was was the crossmember. __________________ 86 stang-sold

08-22-2004, 07:27 PM	#11
Rosco Registered Member Join Date: Mar 2002 Location: Vestal, NY Posts: 307	Well I checked the tailpipes and mufflers and they are fine. Barely any movement in them at all. And it is a 5spd. I will have to get it up on a lift sometime and see if there are any clearance issues between any rotating parts and everything else. __________________ 1989 Mustang 5.0 Conversion, Full Saleen ground effects and spoiler, '94 saleen decal set, '93 Saleen Seats, Black interior from a '93, Steeda quadrant, smog pump delete, a/c delete, Steeda Tri-Ax shifter, '97 rear differential, aluminum driveshaft, 5 lug conversion, '97 rear disc brakes, southside upper and lower control arms, '99 GT Anniversary wheels, flowtech longtubes, flowtech offroad H-pipe, saleen lowering springs, kyb shocks, caster/camber plates

08-23-2004, 09:25 AM	#12
crazypete Registered Member Join Date: Sep 2002 Location: Boston Posts: 592	I vote crossmembers. That bangs under hard acceleration if they are worn or rotted and bounce around on the mounting bolt. Failing that.... I think the rear suspension is moving under load (obviously) but it is contacting something. Your 1rst and 2nd gear only comment means it's definatley about twisting under load. Check the driveshaft and look for scratches where it goes near the 2 mufflers. In mine, there is less than 1/2 inch of clearance at one point. If not, check the pinion snubber at the top of the axle snout. Is it there? If it is, is it rubber or an aftermarket piece. The hardened AM ones do make a little thump when they hit but you really need to punch it to get that happening and the suspension needs to be really low. Check the rear wells for rubbing signs but I dont suspect tire contact too much. If the tailpipes hit, you'd see a shiny spot where they hit. Get a 300 watt shoplight you see 300% more when you use the high output lights! Wedge some rubber on either side of the tailpipe where it goes near the fueltank. Then they wont move at all. Then go and race around some to try and get that sound happening. If all else fails, put the back end on jackstands with the axel drooping and then jack up one end of the axel and then the other and see if it pops or moves freely. I suspect one of the swaybar mounts or control arms is binding. Finally, if this fails, while you got it up there, pop the diferential cover off and take a good look at the gears. Broken gears whine...loud! So you shouldnt find anything in there. But why not look? Replace the fluid with redline synthetic while you're in there. =) Good luck! __________________ 91 GT Carb conversion, holley 600 double pumper, edelbrock performer intake, FMS "C" drop springs, march 1000 underdrive pullies, crane 1.7 roller rockers, GT-40P headers, bassani x pipe, american thunder catback, FMS 4.56's, msd aL6, trunkmount battery, A/C eliminator kit, 3000 stall tci streetfighter, AOD with transgo kit, A+ servo, 300M hardened lockup shaft, kevlar bands and 28,000 gvw trans cooler, 3 core radiator, 300 lbs stripped with a full interior

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