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Bad rear diff?

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Old Oct 5, 2014 | 02:41 PM
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NW 150's Avatar
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Bad rear diff?

Since I've had my 1978 F250 it's always been a little tough to put in reverse from either park or drive. When I put it in reverse it bangs in to gear and sometimes even makes kinda like a clank noise. It'll do it as well if I manually shift from d-1st coming to a stop. I thought it was the transmission, but today I heard it clank pretty bad and it sounded as if it was coming from the rear. I;m just wondering what I can do to pinpoint this.
 
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Old Oct 5, 2014 | 03:23 PM
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Rebuild the rear deff or fill it with sawdust and banana peelings
than sell it.

But first check the U joints
 
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Old Oct 5, 2014 | 03:46 PM
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2x ujoints
 
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Old Oct 5, 2014 | 04:26 PM
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Checked both u-joints and they are good with no play. The u-bolts are good and snug. I took the driveshaft off of the transfer case to see how the tranny would react to that and it shifted fine no it not connected.
 
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Old Oct 5, 2014 | 04:43 PM
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IMO 1st stop doing this since its an auto.... "manually shift from d-1st coming to a stop". Its not standard practice to use engine braking unless you have a trailer on and suddenly need more braking ability. FYI trailer brakes are suppose serve that purpose.

Maybe you need to ck the master cylinder and power brake booster. Vacuum lines ect... Have you bleed the brakes lately? Maybe do a hydra boost swap to get better brakes, if that why you engine brake.

Have you done a rear diff drain and flush ever? And look at the fluid, does it look to have glitter in it? When you drop the pan cover if there are chunks of teeth in the bottom, its repair time.

Ok since the u-joints are ok, how it the pinion nut, tight? Sounds like your idle is a little high if it bangs in gear. Also ck the pinion play there is a certain amount of play you should have, but not a "bang" amount.

Sound like it might be time to ck the backlash on the R&P? What weight of rear gear fluid are you using? 80/90 or what?

"a little tough to put in reverse from either park or drive", sound like a trans linkage or trans issue and not a rear end problem.

All else fails, turn up the radio. lol JK
 
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Old Oct 5, 2014 | 05:33 PM
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I only manually shifted twice, both times for two reasons. One, to see what reaction I would get (It was done under 25mph) and it ended up making that same noise, and two, because my brake currently don't work as well at the moment due to the bleeder screws being shot on the front calipers. We temporarily bled the brakes by unscrewing the brake line. New calipers are on the way along with new screws.

I have flushed the transmission and when I did nothing came out but fluid and the filter was spotless. Filled with Type-F.

I have not flushed the rear diff although I've checked the fluid level and when doing so the fluid looked good. It's something that I will do possibly even tomorrow though to see if anything comes out other than oil.

I'll check the pinion nut but it looks to be good. While inspecting it today and with the t-case side of the driveshaft dismounted, I could turn the diff pinion about a 1/4" or so both ways. If you ask me that seems a bit much?
 
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Old Oct 6, 2014 | 07:12 AM
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Oh ok, so that was just a trouble shooting step..got it.

New calipers and proper bleed brakes will be nice.

Once you get the cover off you can get and eye in there and see what's going on.

Yea a 1/2" of play in that pinion, seem excessive.
 
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