Grinding, odd feeling

[JExpedition07]

So the last few thousand miles I’ve had a clunk when I put the truck into reverse. Also has felt like a lot of play in the spider gears in the rear end. I’ve been feeling downshifts and when I let off gas and re apply it feels like it grabs all of a sudden. At low speed when I come off gas and then go back into it (parking lots) there is a light clunk and the truck jumps a little. Today I have a grinding coming from the rear end sounds like and a rotational bounce feel. I’m assuming my rear end has taken a crap, any other ideas?

 

[iimagine]

U-joint?

 

[JExpedition07]

U-joint?

I replaced both those with the new driveshaft assembly about a month ago, no beans there

 

[Habbibie]

Sounds more like a motor & transmission mount. I had an awful clunk going into reverse when I got my expy, replaced the transmission mounts eliminated it all together

 

[Trainmaster]

Yea, look at the rear transmission mount.

 

[JExpedition07]

Thanks guys, Is there a sure fire way to test the mounts and what does it entail to replace? Don’t want to drive it much like this nothing feels right. Shifts perfectly so I don’t think it’s internal trans related.

 

[Boostedbus]

Thanks guys, Is there a sure fire way to test the mounts and what does it entail to replace? Don’t want to drive it much like this nothing feels right. Shifts perfectly so I don’t think it’s internal trans related.

I’ve always done the brake torque method with someone looking underneath at mounts or floor jack the tail of trans. up and look for splits in rubber mount.

 

[Habbibie]

Never knew about that^^

Yea beside checking the motor mounts by giving it some throttle while hard in the brakes.. that only tells you the motor mounts nothing about a transmission

 

[JExpedition07]

I think you guys def are on to something with the trans mount. This morning I put the truck into drive/reverse multiple times and every time it feels like something underneath the truck is moving the same time power is transferred with a clunk. You can tell something is moving on it’s own without the truck with the varying load changes. No grinding or light bounce feel this morning but it’s clear something is wrong with gear changes.

 

[JExpedition07]

Wondering with my mileage if I should replace all the motor mounts and rear trans mount just because.

 

[Habbibie]

Milage doesnt effect wear on mounts as much as weather does I think, but wouldn't hurt to change all mounts at the same time... though it will get expensive doing them all at once so if you can afford them all in one blow then go for it otherwise change the problematic ones for now and wait till spring or summer to do the others.

 

[1955moose]

I'm with boosted on the power brake method. You'll see it rock or clunk when bad. The transmount is where I'd start. Just be sure to buy a good replacement, but knowing you, it will be Ford or better quality. Who knows what garbage replacement rubber is being sold.

Sent from my N9131 using Tapatalk

 

[gixer2000]

Wondering with my mileage if I should replace all the motor mounts and rear trans mount just because.

It's a good idea and would probably feel like a new truck after

 

[Boostedbus]

Never knew about that^^

Yea beside checking the motor mounts by giving it some throttle while hard in the brakes.. that only tells you the motor mounts nothing about a transmission

When I had a vibration on my F150 the Broken trans mount showed up inder the brake torque test along with the broken engine mount. I suspected the engine mount failed

Wondering with my mileage if I should replace all the motor mounts and rear trans mount just because.

In my personal experience with my old F150, I had a vibration And found out it was a broken motor mount so I replaced it only to find out still had a little vibration. I then found the trans mount was also broken. After changing it all was good. My guess was engine mount failed first then over taxed the trans mount breaking it also. I would at least check engine mounts thoroughly because they could be the cause of trans mount failure. If you have used 4Low recently to pull something out or jumped on throttle too hard while in 4 Low that could have been the cause of breakage. In my case that’s what happened to me.... 4 Low lead foot disease ....Lol

 

[JExpedition07]

I inspected the rear trans mount, looks in good shape and feels solid. I’ll have to check motor mounts tommorow

 

[Habbibie]

I inspected the rear trans mount, looks in good shape and feels solid. I’ll have to check motor mounts tommorow

Looks can be deceiving my friend, mine looked like it had just came out of the box when I changed it... yet the clunk disappeared!

 

[Boostedbus]

Looks can be deceiving my friend, mine looked like it had just came out of the box when I changed it... yet the clunk disappeared!

I agree. The mount will look normal under compression just sitting there, it’s when it’s being pulled on is when the split ( if there is one ) will appear. Sometimes they break right at the rubber to steel bond but mostly I’ve seen them tear. I have broken quite a few engine mounts over the years with my old 73 dump truck trying to shake the debris out of the dumper after dumping. Of course it was easy to do with 4.56 rear gears and T18 granny 4 sp. popping the clutch to shake it loose in granny gear. You may want to take mount out and inspect in a vise with a pry bar.

 

[JExpedition07]

Wonder if I should put a camera under the truck facing the trans and shift gears repeatedly to see if I get excess movement around that mount. FordTeckMakuloco did that to diagnose a bad diff mount in a video I watched. He put the camera underneath and repeatedly shifted. Thanks for the advice guys I won’t cross the trans mount off as suspect then.

 

[Boostedbus]

Yeah I wouldn’t cross it off until you are 100 percent sure. Otherwise you could be chasing a phantom. Not sure how difficult your mount is to remove, but if you have enough room in trans. tunnel to jack up tail shaft of trans. and then just sneak it out. Put jack stand under driveshaft to hold up while bench testing mount.

 

[JExpedition07]

Checked the mounts this morning. Popped hood and had my father watch as I shifted, motor is solid as a rock doesn’t move mounts are good. I could also see it through since the hood was open. He Kneeled down and watched the transmission and also doesn’t budge with varying load changed and brake torque. Video recorded and no dice.