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Steelrat
08-01-2010, 06:31 PM
Took the car out for a spin today and a new issue, oh joy. When shifting the 700R4 from 3 to 2 or 2 to 1 when not under load and low speed down shifting I get a big clunk in the rear end. One time when shifting when not under load, just coasting and going 3rd to 2nd and back to 3rd a few times listening for the clunk it seemed like the rear gears would not mesh, I got a bucking clunk clunk then it went away and engaged. Also when turning ( mostly left) it feels like I am driving over a rough surface, like gravel. Trans was serviced 2 weeks ago. 100%. U joints front and back replaced 2 months ago. Rear is full of fluid. Would adding more gear additive resolve, or drain all fluid and put in new? Current fluid is a year old. Broken spider gears or worn positraction clutches? I have no experience in rear/diff work. Any advice on assessing this?

Thanks

big gear head
08-02-2010, 02:59 PM
What rear end do you have and what differential is in it? Do you have leaf springs? What type of traction devices do you have?

Steelrat
08-02-2010, 03:09 PM
8.5
eaton posi
leaf springs
slide a links

rohrt
08-03-2010, 05:17 AM
Kinda sounds like an issue I had with my rear. I didn't get the pinion preload correct when I put my rear together, and would get a very loud clunk when I would accelerate or decelerate. I didn't have a gravel road feel when turning though.

Steelrat
08-03-2010, 12:33 PM
Kinda sounds like an issue I had with my rear. I didn't get the pinion preload correct when I put my rear together, and would get a very loud clunk when I would accelerate or decelerate. .
Hmm, I wonder if my rear shifted and threw out the pinion angle. I was out last week and the car hooked real hard on nice new black asphalt, I thought I felt a big clunk in the back as it hooked. I have checked leaf spring mounts front and back, tranny mount/crossmember and engine mounts. All are A OK.

rohrt
08-03-2010, 12:46 PM
I was able to put the car in park and roll the back wheel back and forth enough to get it to clunk. Thats how I knew the sound was coming from the rear and not something else. I could feel nothing at the pinion with the drive shaft off. I couldn't move it in or out and it felt fine spining it around. May not be your issue but its easy to check.

Steelrat
08-03-2010, 01:48 PM
thanks rohrt, will try that.

big gear head
08-03-2010, 03:38 PM
Did you use the limited slip oil additive. and was it the GM or Ford additive? One bottle of GM additive should be enough to take care of that noise when turning. The other problems might be in the transmission or the suspension.

Steelrat
08-03-2010, 04:22 PM
Did you use the limited slip oil additive. and was it the GM or Ford additive? One bottle of GM additive should be enough to take care of that noise when turning. The other problems might be in the transmission or the suspension.

yes I do have limited slip additive. Rear fluids changed last summer. May be do for a change. My next plan of action was to dump all the rear oil, and put new in with new additive.

Steelrat
08-10-2010, 12:38 PM
ok, have removed driveshaft, replaced u joints, tightened every conceivable mount, bolt, bracket, etc. Motor mounts are good, tranny mount and cross member good. Slide a links tight, frame connectors tight, , shocks tight, all u bolts tight. leaf springs good and tight.
Still has the clunk, so I thik it is in the rear. Here are 2 vids.

http://www.youtube.com/watch?v=Dr1nLZz-c6o&feature=player_embedded

http://www.youtube.com/watch?v=98BoEl59jjk&feature=player_embedded


Edit, video's were sent to a rear end guy, he says looks like the pinion nut that holds the pinion in is loose.
That is why is good under load, but clunks when coasting or no load.

Z06vet
08-10-2010, 03:07 PM
I'm no expert on rear ends, but I'd say something is definately broken or loose inside the diff. It seems it does this on the upshift & under braking, if I'm seeing that right. I'd pull the cover & have a look before that chunk goes out the rear cover...
Take some pics once you get the cover off
Scott

Steelrat
08-10-2010, 04:02 PM
the shifts are 2nd to 1st back to 2nd

JEFFTATE
08-10-2010, 05:44 PM
Disconnect the driveshaft again and remove the rear diff cover.
Feel for play between the gears ( too much backlash)and inspect the gears for damage or wear.
It sounds like you have a loose pinion nut and the gears are noisy because of the changing preload on the pinion gear .

Steelrat
09-04-2010, 07:19 PM
the culprit - broken tooth on ring gear :(
https://static1.pt-content.com/images/pt/2010/09/brknthth-1.jpg

big gear head
09-05-2010, 07:00 PM
Looks like there might be some damage to the clutch pack too. The gaps between the plates are not even.