How are my motor mounts?

[Skandocious]

Brad and I were talking on the phone yesterday and tossing around ideas as to why my truck vibrates so damned much. One of his idea's was motor mounts and I told him I knew how to test my motor mounts, with the reverse engine rev thing, but I didn't know what an appropriate amount of flex was for the motor... So I said I'd take a video of myself torquing the engine and post it so you guys could tell me whatchu think. The first revs are in REVERSE and then there's a pause, and then following are in DRIVE. You'll notice on the first DRIVE rev the camera jumped -- the truck overcame the brakes a bit and it lurched forward about an inch, scared the hell out of my sister holding the camera






Whatchu guys think?

 

[bowtiehatr]

that flex is about right, that still doesnt mean that one or both mounts are grounding out.

 

[Fellro]

It looks basically normal to me. How's your harmonic balancer?

 

[Skandocious]

How's your harmonic balancer?

What about it?

 

[Fellro]

It is a likely candidate for causing vibrations...If the outer ring moves around, it can get out of sync, it also won't dampen the vibrations caused by the crankshaft and pistons doing their jobs...

 

[Skandocious]

It is a likely candidate for causing vibrations...If the outer ring moves around, it can get out of sync, it also won't dampen the vibrations caused by the crankshaft and pistons doing their jobs...

I'm not completely familiar with the harmonic balancer, so you'll have to forgive my ignorance... But which outer ring are you talking about? And what constitutes 'moving around'? Should it be totally stationary? This is the harmonic balancer right?

 

[89frankenford]

correct that is the harmonic balancer. it could be "worn" out enough and not be able to dampen the vibration that the engine puts out.

 

[Fellro]

That would be it. The outer ring and the center hub are supposed to stay set in relation to each other. See that rubber in between the ring and the hub? It doesn't look overly healthy... What tends to happen is the glue lets go, or the rubber deteriorates to the point the ring actually shifts. If you try to time a motor that the ring has shifted, you wil not find it with a timing light due to the fact the timing mark is not properly set in relation to the hub.

 

[lil_dq]

Yeah no kiddin motor mounts are good.

 

[Skandocious]

Thanks Roger. Brad called me and explained the function harmonic balancer in detail. So does it look to you like I need a new one?

 

[lil_dq]

Hey chris just outta curiosity did you check the rear driveshaft for missing wheights? I had a wheight come off of mine right when I put the new wheels on the truck and thought it was them. don't even wanna think about how much i spent breaking those things down and spinning them on the wheels. That could be some of it if that is the case. I felt my vibration all the way through the steering wheel, floor, everything. just curious though.

 

[Skandocious]

That was the first thing I checked Doc. There's no visible evidence of a missing weight... Although I'm not totally sure that my driveshaft is in balance. I've been trying to get it in for a good balance for quite some time but its hard to do cuz the shop is far and I can't drive my truck with no shaft on it

 

[89frankenford]

just drive it as FWD hahahaha





no don't really do that

 

[Skandocious]

just drive it as FWD hahahaha

On the freeway for 40+ miles at 65mph? I don't think so

Plus if I remove the yoke from the tcase it spews ATF.

 

[Mr. Stroker]

It will balance itself, just drive it 90 mph and wait for it to let go hahahahaahha, After all the clanking it should be niiice and smooth lol jk

 

[lil_dq]

Skan do you have a shop that has a lathe? if so they can run it in there to check for balance also. The shop that built mine just run them in the lathe to make sure they run true.

 

[Skandocious]

Skan do you have a shop that has a lathe? if so they can run it in there to check for balance also. The shop that built mine just run them in the lathe to make sure they run true.

No I don't know anyone nearby with a lathe... Even if I did, I'm not sure it would be possible to run a 2-piece driveshaft on a lathe, would it? I guess maybe they could balance the sections separately...

 

[lil_dq]

yeah we had that done on the dually and they ran each seperatly. But..................oh wait a minute......did you look at the carrier bearing of your drivshaft. We had that go on the dually and though it was the shafts. vibrated pretty good too.

 

[Skandocious]

yeah we had that done on the dually and they ran each seperatly. But..................oh wait a minute......did you look at the carrier bearing of your drivshaft. We had that go on the dually and though it was the shafts. vibrated pretty good too.

The hanger bearing is new as of about 6 months ago.

 

[Fellro]

Is the vibration all the time, even at idle, or only going down the road? If it is constant, then I would say balancer. If only at certain speeds, it would be driveline/tires/wheels, or possibly bearings. Axle bearings would also have oil leaks though.