Clunking sound while driving.

[AZRanger346]

I have a stock 98 Explorer Sport 4wd. I have a loud banging clunking sound while I am driving. I have done the following and cannot locate what is causing it. I have replaced the transfercase, the planetary gears in the rear diff., the u joints, greased the rear slip yoke, new shocks, new sway bar links and bushings in the front, new exhaust system, new shift motor for the transfer case, the BWM, new tires, new brakes, made sure the spare tire is secure, checked the rear suspension, checked the front u joint and cv joint on the drive shaft. I know it has something to do with the drive line but I cant figure it out. Can someone help before I go insane. I dont know what else to change.

 

[Sams01XplrSprt]

welcome

 

[BrooklynBay]

Welcome to this forum! I've moved your thread into the stock 95-01 section.

 

[iwannabamedic]

Will it go away if you press on the gas pedal? does it seem louder if you let off the pedal?

 

[97sprt4x4]

i guess expanding on above... when does it happen, all the time, only when accelerating down a hill when you hit a bump?

It could be a body mount or a component hitting the frame under torque. it's not necessarily a drive train issue.

Justin

 

[AZRanger346]

It is noticeable mostly when driving on a level road that is smooth usually at about 40-45mph. It seems to happen intermitently. It makes a bang or clunk and you can feel the vehicle kinda jolt. Simlilar to when you changing gears on a bicycle if that makes sense.

 

[wisekise]

i had the same thing happen to me. turned out is was the tcase. but mine was only under acceleration. got a bw1350m from a junkyard and after a 1.5 days it started doing it again. got a bw1354m for a replacement because the jy has got a 30 day warranty on their stuff. clunk gone. maybe you have luck like mine and the replacement tcase needs replacing??

EDIT----lol.... ive got a 4405 and a 1350m ill sell you for real cheap!

 

[Carguy3J]

You said you "checked" the front driveshaft. Did you slide back the boot and regrease the cv? They are known to bind and clunk after awhile, and a regrease seems to cure it.

I would also check your motor/trans/t-case mounts. Check front suspension (Ball joints, control arm mounting bolts). Also, check your front diff mounts. There are 3 rubber bushings that attach the diff to the frame. Mine were worn. In fact, the right side bolt was a little loose, allowing the bolt hole on the frame to get a little oblonged. I ended up welding a thick grade 8 washer in top of the mounting tab, to reinforce the hole.

I seem to recall reading about a clunk that is caused by the kevlar isolation pad for the tosion bars wearing out. Anybody else have any more details on this?

You said you replaced some parts in the rear diff. Did you check for excessive backlash in the gears and/or slop in the pinion bearing?

 

[AZRanger346]

I jacked up the rear of the truck put it on stands put it in gear and at about 1600 rpms can hear the thunk sound also a loud roaring sound from the diff. Mechanic 1 says its the locker mechanic 2 says its the t-case trying to engage or an ignition problem mechanic 3 says its wheel bearing and mechanic 4 says its the clutch pack in the differential. I dont think its the t-case because its a rebuild and I have the BWM so it cant be engaging 4wd. I dont think its a clutch pack because according to my door sticker its an open rear end. I agree the roaring may be a bearing but not the thunk sound. I dont think its an ignition problem because it runs fine with the exception of needing to replace the timing chain tensioners. I had a couple buddies listen to it and they said its the diff. But the diff mechanic says no. So at this point I dont know who to believe I no for a fact its some thing with the drive line and no the suspension. Please help.

 

[97sprt4x4]

jack the whole truck up and do it again without the BWM engaged. If the tcase is bad or the connection on the BWM isn't great the t'case will still try to engage. That would eliminate the case, you can also use a stethoscope to diagnose where the sound is loudest on the differential. i wouldn't rely on the electronics because i still destroyed my transfer case using the BWM


Mechanic 1 is wrong because you don't have a locker.
Mechanic 2 is possible on the t-case, but i don't think an ignition problem would be a loud clunk, that would be a backfire...
mechanic 3 is possible but unlikely that it's a clunk, wheel bearings give more of a grind
mechanic 4 is wrong because you have an open diff

Check your U joints, probably not it because it's not at the beginning but it's a possibility
Justin

 

[AZRanger346]

So BWM will trash your case? If so good to know. If I jack up the rear with BWM allowing the auto 4wd to operate wont the truck go forward with the front wheels or are you saying to lift the whole truck. I also tonight drove the truck in 4 low and no clunk so maybe it is the t case again I dont know.

 

[Joe Dirt]

What about the torsion bar mounts/pads... Ball joints? When you look at the truck from the front at a slight distance, do your tires look like this: / \

 

[97sprt4x4]

So BWM will trash your case? If so good to know. If I jack up the rear with BWM allowing the auto 4wd to operate wont the truck go forward with the front wheels or are you saying to lift the whole truck. I also tonight drove the truck in 4 low and no clunk so maybe it is the t case again I dont know.

I did mean to Jack the whole truck up and if you read the discliamer the bwm stops something from actually catching but the ret of the system works so if the bwm isnt done correctly it may only partially limit thebclutch and it will burn out the clutches. That's what I did.

And Joe I don't think it could be the torsion bars or the ball joints be ause when he has the truck up in the Air the clunk is still present

Justin

 

[AZRanger346]

I followed the instructions for the BWM I think I did it right and the sound was still present even after the rebuilt t case was installed. I know it is definitely not suspension related. What about the GEM?

 

[Joe Dirt]

And Joe I don't think it could be the torsion bars or the ball joints because when he has the truck up in the Air the clunk is still present

Doh! I missed that part...

 

[97sprt4x4]

I followed the instructions for the BWM I think I did it right and the sound was still present even after the rebuilt t case was installed. I know it is definitely not suspension related. What about the GEM?

If it was the GEM i would think there would be a lot of other problems going on, but you could probably find one from a junk yard that would be easy enough to swap in the parking lot.

Like i said i would jack the entire truck up, and then if the clunk still persists you can pin point where it's coming from easier.

Justin

 

[AZRanger346]

Most of the other posts say the bwm wont hurt anything unless you're doin burnouts or running it excessively on a dyno. Which I havent. What about when i had it in 4low and no clunk? What do you think?

 

[97sprt4x4]

There's a lot of different things going on electronically in our case, When you're in A4wd, the GEM or computer i'm 'not sure which, senses wheel slip i believe based on the ABS sensor. when you put it in 4wd it engages the clutch for the front axle. In 4 low it engages planetary gears. If it doesn't make the noise in 4 low, it could be that whatever is making the noise isn't spinning fast enough because the planetary gears decrease the speed of the drive train and apply more torque. If you put the truck up in the air, and pull off the drive shafts you should be able to see if the noise is done from the case. If the noise is not present, then i would put the drive shafts back in and concentrate on the rear diff

Justin

 

[AZRanger346]

Well took the truck to another diff shop they want to look at it next week and they say they should be able to determine for sure if its the diff or t-case. If its the t-case the company I got it from says I got a 1 year parts and labor warranty and its not expired yet. I also think Im gonna disable the bwm.

 

[AZRanger346]

Just read a post where someone had a loud thump and whirring sound which is what Im getting and it was t-case. Also that it is a regular prob with them even after they have been rebuilt. Somethin about the shift fork breaking? So Im guessing maybe. Also still wondering if the GEM is sending mixed signals to the t-case.