60mph Vibration

[suprabad]

I have a speed sensitive vibration at around 60mph, it doesn't matter if your coasting, accelerating, in neutral, or in gear. It's a vibration you can feel through the bottom of the seat and it's bad enough to make the rear view mirror totally blurry. Any other speed and the car is totally smooth.

My first thought was that it might be driveshaft or center carrier bearing but when I put the rear wheels up on jack-stands it didn't look like the driveshaft was moving (although it was a bit tough to see).

Also, I took the rear wheels off, and with just the lug nuts on... the vibration got worse. So now I'm thinking wheel bearings maybe. But their not making any noise so I'm not sure of that either.

One last thing, I recently replaced my blown a340e with a JDM that I rebuilt. The trans is fine but I used the Soarer rear trans mount that was on the tranny when I bought it, (cause mine was shot) and now I'm wondering if this mount could be slightly different than the supra mount it replaced, causing uneven drive shaft angles and my vibration.

I dunno....I'm stumped. Any helpful advice or insight would be greatly appreciated.

 

[IJ.]

Mine was shaft balance.

 

[supra-addiction]

mines is sorta like that..just a little..
but when i have it in overdrive, i can go well over 60 mph.
a friend of mines did the same and it was his rotors/shocks..thats what he told me..

but it could be a off balanced shaft.:icon_razz

 

[suprabad]

I've had the rear tires up in the air and it didn't look like anything was obviously boncing around when I brought it up to 60mph with the wheels up on jackstands.

Any methods to isolate this vibration?

Any ideas on why it's worse when I took the rear wheels off?

 

[Ric]

driveshaft?

I had a bad u-joint on my car..

It sounded like a blender full of ice under my car, and viabrated like no end.

 

[mkIIIman089]

60mph on jack stands with the suspension at full droop... you're crazy. LOL

Rotors/shocks? Your friend is a bit off the beaten path if he thinks those are interchangeable.

Driveshaft
Half shafts
Tires
Wheels
Wheel bearing (unlikely it would present with only vibration though)
Differential

Grab the drive shaft near the middle and rock it around, I'll put my money on that carrier bearing 1st.

 

[suprabad]

60mph on jack stands with the suspension at full droop... you're crazy. LOL

Grab the drive shaft near the middle and rock it around, I'll put my money on that carrier bearing 1st.

At least I didn't crawl under it while my girlfriend brought it up to sixty (I was considering it).

How much play is acceptable in the center carrier bearing? There is very little (almost nothing) in mine.

Wouldn't the center carrier bearing be vibing all the time? I am only getting this vibration at @ 60 mph.

And why would it get worse with the wheels off?

Any ideas?

I'm heading out to the garage right now to pull the DS and see If I can find anything obvious.

 

[Ric]

maybe you broke a tooth off the ring gear

 

[suprabad]

maybe you broke a tooth off the ring gear

If that were the case wouldn't it make noise and vibrate at all speed? Mine just vibes at 60.

 

[Ric]

then dont drive 60

 

[flight doc89]

u joint prolly

 

[Shytheed Dumas]

Mine was a rear caliper that was hanging up, and caused the same kind of vibration from 45 to 65 mph. Check 'em out.

 

[suprabad]

Mine was a rear caliper that was hanging up, and caused the same kind of vibration from 45 to 65 mph. Check 'em out.

I'll check that out.

then dont drive 60

LMAO
Funny you should say that, because as it happens, I almost never do....so I'm not really sure when I picked up this vibration.

Anyone got any ideas why it's worse with the wheels off?

 

[mkIIIman089]

Shake your arm up and down.

Put a 40lb weight in your hand and use the same amount of force.

 

[Ric]

^ yup. you might want to get your GF to do that actually.

 

[rs4rush]

Ya my bet its the drive shaft. Its what happends when you dicide to go sidways and drive it hard, So my bet its the u joint. take the drive shaft off and spin it. Look to see if the bearing are bent/flat or the U joint cracked.... Just look for damage!

 

[IJ.]

SB: Grab a big hose clamp that will fit around the shaft and place it down near the rear Uni, Tighten it and make the shaft with a Sharpie where the Screw part is and take it for a drive.

See if it makes a difference then move the screw part and repeat, My "guess" would be it's a phasing issue created when the rear part of the shaft turns on it's bonded rubber section. (stock shaft is actually a 3 piece not a 2)

 

[suprabad]

SB: Grab a big hose clamp that will fit around the shaft and place it down near the rear Uni, Tighten it and make the shaft with a Sharpie where the Screw part is and take it for a drive.

See if it makes a difference then move the screw part and repeat, My "guess" would be it's a phasing issue created when the rear part of the shaft turns on it's bonded rubber section. (stock shaft is actually a 3 piece not a 2)

I will try this right away and post back. When you say "phasing issue", I assume you mean the two shafts that make up the propeller are "out of phase". I'm not really clear on exactly what that means and how it would exactly manifest itself or how to deal with it. Maybe you could set me straight?

Ya my bet its the drive shaft. Its what happends when you dicide to go sidways and drive it hard, So my bet its the u joint. take the drive shaft off and spin it. Look to see if the bearing are bent/flat or the U joint cracked.... Just look for damage!

I am going to pull it off right now and inspect it. Thanks.

 

[IJ.]

SB: The rear section is bonded inside the next tube and can slip inside making the Uni joints out of phase, if you look at it the Uni Joints should all be perfectly in line along the shaft.

If they're out of phase you can skip the clamp test.

 

[suprabad]

SB: The rear section is bonded inside the next tube and can slip inside making the Uni joints out of phase, if you look at it the Uni Joints should all be perfectly in line along the shaft.

I looked at my driveshaft and it looks like IJ is right...it appears to have slipped where the rear half of the drive shaft is "bonded".

How the hell did I do this? I recently (two weeks ago) swapped in a transmission I rebuilt. I can only assume I did it then. I've had the motor and trans out more times then I care to remember and this has never happened.

Do I chuck the DS or is it fixable?

I would have never even thought of an "out of phase" drive shaft had it not be for IJ. Probably would have eventually lost my mind and gone "postal" trying to figure it out. Muchas gracias amigo!

I'll know more tomorrow when I pull the driveshaft.