a few weeks ago i posted about a clunk in my drive line, i received a few comments but nothing that helped. So i installed a new OEM transmission mount, changed the tranny fluid again, transfer case fluid again, checked my brand new u-joints greased my slip joint again for the third time! ever time i stop at a red light or something and hit the gas to go i get this funny thud sound like something is slipping and them grabbing real fast? i don't think its the gears since they are only two years old i had 4.30's installed. Could the LS clutches be causing this? i had it rebuilt when the gears were installed but they are shot again already they wont even work in flat dirt anymore? i need this fixed fast its been going on for months now and i threw money into all the normal things so far. Also could it be my tranny? i just turned 88 thousand miles with very Little light towing normal two year flushes for the tranny but it seems like the 1-2 shift is getting very abrupt but it could be my factory tech valve body i hope? desprete

 

Positive it's the driveline? Perhaps body mounts? Just a thought...

 

i checked the body cab bolts allready, and my 04 has larger front bolts than the rear. from what i found mine are two MM larger than what ever one says they are? And it feels like when you first take off that there is a little hop or bump in the driveline?. As if the rear is skipping a tooth before it grabs

 

I have co-worker with a 4x4 Ranger and does the same exact thing you mentioned. He said that it was his transfer case and it didn't hurt the truck any. ???

 

have you checked your torque converter?

 

I would consider taking your truck back to whoever set up your gears and ask them to take a look. If your Limited Slip clutches are shot then you could have other issues in there as well. The one word that jumps out at me is 'again'. Have you been having a re-occurrence with LS clutch issues? That doesn't sound normal to me.

 

What happens when you two-foot it and load the driveline a little and then take off from a stop? Does it still thump?

 

I would also check your engine mounts.

Do you get a clunk when in 4 wheel drive?

 

have you checked tire pressures, I had a noise in my rear end and it turned out I had an inside duel flat. It was causing noise from the ls clutches in the rear end. I aired them back up and the noises went away.

 

OK guys here what i did yesterday, i got that awesome Haynes repair book(what a joke that thing is) and checked torque of ever nut and bolt in my under carriage. started from the motor back to the rear bumper. motor mount was half turn loose, tranny to motor bolts tight as hell. tranny mount tight just installed a new mount last week drive shaft tight all new joints. leaf spring tight BUT the inner ubolts for the axle were both a good three turns loose on both driver and passenger side???? The outer ubolts were completely tight but the inners were like i said a good two to three turns loose?? when i installed the payload leaf three years ago the spring shop said torque the new bolts he made to 200ftlbs at 500 miles at 1500 miles and one more at 3000miles after the install which i did but for some reason both the inner ones were loose. the clunking feeling is almost completely gone now but it still has a very light faint one. which is mostly just driveline slack.

 

hotpocket - no i did not check the torque converter bolts but i will today i never thought about them thanks
gchaves - when i had the gears installed i wanted a truetract but didnt have the money so the guy said ford offers a repair kit for the LS, it was 80 bucks for new clutches so i said go ahead, but the new ones are already shot i guess hunting and all the snow wheeling ive been doing smoked the clutches again.
pmdracer - if i hold my foot on the brake and give it a little gas it's allot less sever but after tightening all the bolts yesterday i dont have to do now to keep it quiet
redford - in 4wd it clunks worse like the front axle has a problem too? i didnt check it after yesterday but ill check today

 

one thing when i had the truck jacked up and i spin the rear tire forward shouldnt the other tire spin backwards?? mine spin together both forward or both backwards? my 78 f-150 has factory LS and the rear tires spin opposite when i do this?

 

That depends on the condition of your posi and where the trans is set.

With the trans in neutral:

If the posi is good, both tires will spin the same.
If the posi is bad, it could go either way, depending on how bad the clutches are.

With the trans in Park (or in gear with a manual trans):

If the posi is good, nothing should move. It will be essentially locked unless you use a breaker bar on lug nut and lean on it until you hit the breakaway torque value for the posi.
If the posi is bad, the tires would spin in opposite directions.

 

ok still have that dam clunk! i thought it was gone but i must have been day dreaming this morning. drove around after work doing things and sure enough that f$cing clunk is back. \This is how it feels im at a stop light it turns green i hit the gas not hard just normal sunday cruise type of throttle input and it feels as if the diff grabs first and the truck moves but right after the truck moves you get this annoying thud like the tranny/t-case slack finally cought up to the rst of the truck??? its very weird whats going on almost like there is too much playin the transfer case or in thetransmission?? all i know is i can drive my dads 2000 4x4 F-350 with DP tuner and its like butter! no thuds clunks bangs or sounds of anykind! Just low down power.

 

just keep lookin around for that right diesel to come along like me i haven't found the right one yet...but i search at least 3 times a week on autotrader and a few other locals sites.. anyways...good luck with your truck