Strange feel and sound when turning left

[Astrodokk]

As I was going through customs from Vancouver to the US, I had to make a left very slowly into one of the five lanes available. I heard a sound kind of like a bbrp bbrp bbrp every rotation of the tire, and I felt it too, almost like one would feel when trying to turn with a flat tire.
After passing through, I stopped at a rest stop to inspect visually. I did not see any flat, but I didn't check air pressure. I would think either of the duallys in back would show flat, yes?
I was worried that maybe some lug nuts may have come loose too, as that's happened in a race car before and it felt similar. I don't know how to take off those darn wheel covers, so I went home which took a couple of hours and no problems. But I'm worried there may be something else too, like a wheel bearing or something like that.
I'm going to take it to Les Schwab tomorrow to check it ouuut. <---just been to Canada

[Blue~Go]

I'm not sure what to think about the sound, but on the "simulators" (what our wheel covers are called) most of the lug nuts are fake. If you try to remove them you will ruin the simulator. But two of them actually do something. They are 180º across from each other. On mine the two "real" ones have little raised marks on the sides of the nut.

The reason I put "real" in quotes is that none of these are the real lug nuts. Those are all under the simulator. But two of the simulator nuts come off and they screw onto the bit of real stud that protrudes from the real wheel after the real lug nut is on.

On all the ones I've seen it's easiest just to remove the cover and "real" (simulator) lug nut together. I think it's 1-1/8" socket if memory serves? (But I might be confusing that with the water heater socket.)

I usually remove them at home prior to going to a tire shop as they are famous for messing them up (even though I know Les Schwab is often above average).

Also, when you put the simulators back on, note that you can rotate them slightly just before you tighten them up. That's a good time to make sure they are not touching the valve stems (they can saw into them).

[Astrodokk]

Ok didn’t know about the raised marks on the side of the removable ones. Good to know. I’ll look tomorrow and take them off. I have weird valve stems that protrude from the duallys so I have to be careful. I’ll take pics.

[caconcourse]

As I was going through customs from Vancouver to the US, I had to make a left very slowly into one of the five lanes available. I heard a sound kind of like a bbrp bbrp bbrp every rotation of the tire, and I felt it too, almost like one would feel when trying to turn with a flat tire.
After passing through, I stopped at a rest stop to inspect visually. I did not see any flat, but I didn't check air pressure. I would think either of the duallys in back would show flat, yes?
I was worried that maybe some lug nuts may have come loose too, as that's happened in a race car before and it felt similar. I don't know how to take off those darn wheel covers, so I went home which took a couple of hours and no problems. But I'm worried there may be something else too, like a wheel bearing or something like that.
I'm going to take it to Les Schwab tomorrow to check it ouuut. <---just been to Canada

I have read of similar symptoms of odd noise and feel when turning, and it turned out to be improper differential fluid service. Because the differential is limited slip, there is an additive that needs to be added when the oil is changed, and sometimes the service people are not aware. I just had mine changed recently at the Ford dealer, and mentioned that they should remember to add the "special additive". The service man mentioned that they did add the additive and I think he called it "slippery fluid" or something like that. I know it sounds odd, but the people writing were very happy to find out it was a simple and relatively cheap solution.

More info on the simulators, as Blue noted there are two "special nuts" that are not simulated, and are marked with an indent (which is really a crimp of the fake lug cover on a real nut). The socket happens to be the same as the water heater anode, and I think it is 1 1/8. My unit came with a special wimpy lug wrench for these nuts (in my jack compartment), but I use a plumber's "cow bell" socket that is the right size. There is a set of "cowbell" wrenches that are used in plumbing for reaching shower faucets and such in the wall. They are stored with a metal rod clip going through them, so they look similar to a set of cowbells. You use a philips screwdriver or some rod as a lever for turning them. Here are some at Amazon:

https://www.amazon.com/Eastman-45041-Pl ... B00065DMHC

[Dano]

Clay;
It's "Limited Slip Differential Friction Modifier"....lot's of different manufacturers but whatever you use, it should work with 80W90 gear oil and probably a different brand or type if you run with synthetic inside the differential....the garage I went to forgot to add it into mine and I had to tell him it was required!...geez...

[SMan]

My near 20 y/o Jeep wrangler has a similar symptom. With mine it is the rear diff. (I always use royal purple in the diffs) Fluids help but typical in Jeeps. That said I have no comparable complaint with the Chinook.

[sm350bl]

Just throwing this out there, I had a rub scenario when I put new duratracs on my concourse. There is a metal guard that covers a LPG line that runs in the right rear wheel well area. At some point the back tire's had got tangled with some object and the guard cover took a good smack and bent it. then once I put the new tires on it started to rub on left hand turns. I have removed it for now pending getting it into a press to straighten it out but just something to put eyes on when your under there looking for anything.

[Blue~Go]

Oh, I forgot about the differential! For some reason I was thinking of the front making the sound. Plus the diff was more of a feel that felt like a sound, if you know what I mean.

Anyway, maybe this is it?

I have a thread on this, probably from this summer, when it was current.

Anyway, I started to notice this "juddering" "sound" that was actually not a sound but more of a feel. It would happen at slow speeds turning. I first noticed it when I had to circle around a few times to get comfortable at a boondock. Then too when pulling away from being parked alongside a wall. But not always. It seemed like it was coming from the rear.

Online research pointed to it possibly being low on Limited Slip fuid (I have the Dana 70 LS differential). I was hoping that was it and not something more sinister (clutch packs, or worse).

I took it to a differential specialist (West Coast Differential, great shop) and they drove it then racked it and had a look inside. I was sure hoping it was just needing Limited Slip additive. Actually, I had bought some and was going to add it as a first try on my own, but then realized it was time for a service anyway, and I wanted eyeballs on the whole thing, all new fluid, etc.

Everything looked shiny and clean inside, nothing bad in the fluid. Yay! They put in new fluid and new Ford Limited Slip additive and nary a problem since. Ahhhh. (Had a big traveling summer so that's been over 10,000 miles now.)

A note if you add your own: You can buy the Ford recommended additive at the dealer parts department. it's important NOT to put too much in (also note: it reeks). Basically, the clutches not totally slipping on each other is what gives you Limited Slip ability. You want to go juuuuuuust past when they make noise (by adding fluid). But if you add more than that, it's all quiet but you have no Limited Slip anymore! So their advice to me (before I decided to just bring it in to them) was to add just a little bit, drive it, then only add more if necessary and just a little at a time.

Another note is that the Ford manual section where they talk about which fluid to use (the main fluid, not the additive) is super confusing. I would love to meet the person who wrote it (probably better if I don't). So I contacted a few people, including Dana with the BOM. (We have a Dana 70 in my era Concourse.) They said to use the regular 80/90 with the Ford additive (vs. the synthetic or etc.). They also confirmed that the note in the Ford manual to change the fluid every 3,000 miles was wrong (I knew that sounded completely ridiculous). WCD recommended every 60k or so.

WCD (and I think Dana but it's been awhile so if I said something different in my thread go by that) did not recommend the synthetic or the "pre-additived" differential fluids. Reason being they can be too slippery so it all sounds great but you don't get the Limited Slip action and might as well have an open diff. And/or you can't tailor it like you can with the additive where you can add just enough to quiet the clutches but no more. So you want the "dino" 80/90 which is more "sticky" and then juuuuuuust enough additive to quiet the clutches. Mine looked great inside and had been running on that combo (had about 70k then) so I went with it again.

[Astrodokk]

Thanks guys. I'll look into that after I take off the simulators in case it's wheel bearings or something else.

[Blue~Go]

Just checking in to your thread here. How goes it? Did you find the source of the issue? I'm especially curious if it was the LS additive since I had that happen last spring.

And how'd it go with the simulators?