speculate on a noise from rear end - turns out it's a tranny problem

[SirRobyn0]

Ok, here's the deal drove the truck to the shop this morning all was well, same for the drive home until I got to the farm. Parked at the first gate and when I went to drive though it I felt one single catch. There was a clunk noise and catch sensation. I thought perhaps I ran over a bit of a rock but saw nothing. Went though the next gate ok, then backed into the parking spot. Backing up it did this several times in relatively quickly one after another clunk, and catch at the same time. Once in the parking spot I drove forward and back a few times and it did not do it. I have not checked anything, and tomorrow is a big ? As I'm taking one of the dogs in for surgery, so I may or may not have any free time at all.

Additional info, driving though the front gate requires about a quarter turn of the steering wheel to the left. Backing up requires turning to the left, and the noise and clunk occurred when in that low speed turn, but not when fully turn it quit doing it then.

Truck is:
1984 C20 305 - 700R4 rear end is 14 bolt 9.5 semi-float open. New U-joints about a year ago. Changed the fluid in the spring probably 5Kish on the fluid.

So I may or may not get to pull the cover tomorrow, I may or may not attempt to drive it to the shop on Wednesday as I need to make a run to the airport to pick up a friend I really don't need to launch on me. I'd rather check it out before it gets moved again if possible.

So the main thing is what do you think I should be looking for when I pull the cover, or do you think it might be something else. I'm kind of thinking spider gears, but I'm hardly rear end expert.

As you would expect I need the truck for a feed run this weekend

Thanks for your idea and thoughts.

 

[fast 99]

Jack up rear end spin the driveshaft and axles, check backlash. If nothing obvious pull the cover. Does sound like something broke, if that's the case should be pieces inside.

 

[SirRobyn0]

Jack up rear end spin the driveshaft and axles, check backlash. If nothing obvious pull the cover. Does sound like something broke, if that's the case should be pieces inside.

I don't really have anyway to measure backlash at the farm. The thing is once I was in the parking spot I was able to pull forward and backwards without any noise.

I did take a few minutes after dark tonight and went out and laid under the truck. All I really did was put it in neutral and checked for pinion play both up and down and twisting the driveline, for kind of an eye ball on gear play. I've always felt this diff had a lot of gear play, it's like about an 1/8th of turn, but it's always been like that and still seems the same today.

Well we'll see. My farm hand usually works weekday in the morning for a couple hours when I'm at the shop, since I won't be at the shop tomorrow I had told him he could take the day off, but I called and asked if he could come and work in tomorrow morning and he said he would, so that should free me up to pull the cover and see what I find. I can get a set of spider gears on Wednesday if needed, but if the ring and pinion are gone.... I guess if that's the case I'll need to get the Dodge ready for the feed haul, hopefully it doesn't come to that.

 

[PrairieDrifter]

I would say spider/side gears, and center pin, speaking from my experience. Some of it recently lol.

Ujoint would be extremely lucky but I really don't think that's it. Maybe a brake issue, like a shoe falling apart or something.

I would be VERY cautious driving it, you don't want it to lockup the rear end at moderate to high speeds, it'll be a fun ride. Luckily mine broke at 25 and started to lock up before it just completely locked. The second time didn't lock up at all, so I've been lucky in that regard.

Youre lucky in the fact that it gave you a warning.

 

[fast 99]

For quick diagnostic purposes turn the yoke by hand. Should be able to feel if there is excessive backlash.

 

[SirRobyn0]

@PrairieDrifter @fast 99 Well I pulled the cover after getting back from the Vet's office. Nothing. The fluid looked fine, pretty much like it did when I put it in there. No metal in the fluid. A bit of metal on the magnet in the diff, but nothing large or concerning. Jacked up both wheels put it in neutral and rolled it around, both by the wheels and by the driveline. Nothing no catches or anything. Everything looked the same as it did when I serviced it. All the gears are intact, no chipped teeth, no abnormal wear patterns that I could see. Watched the carrier bearings turn, and did not see anything but did not take the carrier out either. Checked over the U-joints even though they are new and they look just fine.

After that I put the cover back on and filled it with fluid. This afternoon I'll take it out locally at slow speeds and see if it does it. If I does it I'll be better prepared to see where it is coming from. Could be transmission issue traveling down the driveline, causing the shock sensation, or like Mason said maybe it's the brakes. It's got age old shoes on the back and frankly that could explain the noise and shock but did not think to pull the wheels so I appreciate that idea, for sure. Will report back, at some point but it'll probably be late tonight or in the morning. Thanks guys.

 

[SirRobyn0]

Bad news, it's in the tranny. More later......

 

[Bextreme04]

Bad news, it's in the tranny. More later......

Well... that's not good. Must have been from that new fancy switch you put on.

 

[SirRobyn0]

Well... that's not good. Must have been from that new fancy switch you put on.

I don't think so since it performed the same function as the one that had been there for 4 years lol.

Well so here is the update guys. Now when I take it out on the road in first gear, or in reverse if I drive it fast enough I hear bearing growl sounds coming from the tunnel area, as soon as it shifts, the noise stops. Put it in manual 1st and run the RPM up the noise gets pretty loud so I've definitely lost something related to 1st / Rev. I'm guessing what I must have felt last night was the shaft / whatever bearing related to those gears only binding and now that bearing is damaged.

Now I have to make a decision if I can put 200 miles on this coming Saturday as is 1/2 of that mileage loaded..... Or pull the Dodge out and hope for the best with it and a smaller load of feed.....

Note I'll probably start a tranny thread to ask what guys think that noise is. And so I can cuss about repair costs and time.

 

[idahovette]

Must have bragged a little too much on the old girl, Rob. @SirRobyn0 .. It's always something, isn't it?

 

[Bextreme04]

I don't think so since it performed the same function as the one that had been there for 4 years lol.

Well so here is the update guys. Now when I take it out on the road in first gear, or in reverse if I drive it fast enough I hear bearing growl sounds coming from the tunnel area, as soon as it shifts, the noise stops. Put it in manual 1st and run the RPM up the noise gets pretty loud so I've definitely lost something related to 1st / Rev. I'm guessing what I must have felt last night was the shaft / whatever bearing related to those gears only binding and now that bearing is damaged.

Now I have to make a decision if I can put 200 miles on this coming Saturday as is 1/2 of that mileage loaded..... Or pull the Dodge out and hope for the best with it and a smaller load of feed.....

Note I'll probably start a tranny thread to ask what guys think that noise is. And so I can cuss about repair costs and time.

Oh, I know it wasn't actually the switch, but considering the amount of grief you got about it that was my first thought

I'm not very familiar with a 700R4, but maybe @Vbb199 or @Matt69olds can give you a direction to look.

In my experience, that kind of noise in an automatic trans is a "stop now and inspect" action. Trying to keep driving with that kind of noise is just asking for an expensive or catastrophic end.

 

[Bextreme04]

I don't think so since it performed the same function as the one that had been there for 4 years lol.

Well so here is the update guys. Now when I take it out on the road in first gear, or in reverse if I drive it fast enough I hear bearing growl sounds coming from the tunnel area, as soon as it shifts, the noise stops. Put it in manual 1st and run the RPM up the noise gets pretty loud so I've definitely lost something related to 1st / Rev. I'm guessing what I must have felt last night was the shaft / whatever bearing related to those gears only binding and now that bearing is damaged.

Now I have to make a decision if I can put 200 miles on this coming Saturday as is 1/2 of that mileage loaded..... Or pull the Dodge out and hope for the best with it and a smaller load of feed.....

Note I'll probably start a tranny thread to ask what guys think that noise is. And so I can cuss about repair costs and time.

At a minimum, I would drop the pan and see what kind of garbage is floating around in there.

 

[Vbb199]

Low reverse planetary noise it sounds like to me.
Possibly one of the pinion gears has excess thrust and causing a whine


Or a worn out bushing/thrust washer at the low Rev planet set causing them to whine

Either way, that's at the very bottom of the case right at the output

 

[Vbb199]

I hate to say this, but it seems like you've had alot of issues with this 700r4, didn't someone build that for you and its been in and out a few times ?

Lol I can relate on this subject with letting other people do the work for me, I build everyone else's transmission.... I'm about to get married and in a pinch so someone else built my 700r4.... ew

 

[Vbb199]

I was thinking broke sunshell also, but as i recall, You dont lose 1st and 3rd with broke shell.

Only Rev, 2nd, and 4th.

So sounds like low/Rev planetary set