DONT SLEEP

iTrader: (8)

Hey guys,

So about a couple months ago I had a 5spd swap done to my SC with a W58 out of a 92 sc300 into my 98 sc300. I used the w58, got a new clutch / pilot bearing for it, used the existing manual driveshaft for it. After the swap, I'm getting a weird vibration from directly underneath the car when I accelerate, but the weird thing is it doesn't happen when I'm in a turn (coming off an exit ramp and accelerating).

Could this be driveshaft related? As far as I know, when I got the driveshaft it was all in one piece so I'm not sure if it needs rebalancing or not. I'm just trying to see if anyone here has experienced something similar so I can narrow down the problem. Thanks!

DONT SLEEP

iTrader: (8)

bump... any ideas?

Biggu

iTrader: (12)

If i had to guess id say its the drive shaft,

mtnrat

iTrader: (1)

I would replace the transmission mount. It is the cause of a lot of vibration troubles for many. It is also cheap.

DONT SLEEP

iTrader: (8)

Any other ideas? bumpppp... anyone have any experience with the bearing in the middle of the driveshaft?

cartmill

iTrader: (3)

a transmission mount would cause more of a high frequency (and almost constant) vibration. i recently replaced mine.

i would put $5 on it being those 20 year old u-joints you just installed.

SC YAA

Nope i had the same problem with my car when i did the swap. It ended up being the flywheel bolts were not tight enough. I pulled the trans again torqued them down another half turn and had it all back together in 2and a half hours. problem solved :P

mtnrat

iTrader: (1)

I think I would start with a new tranny mount. That was my problem and it is very easy and cheap to do. Mine looked good, but on comparison to the new one it was crushed down a little from the new one. Huge difference for me.

DONT SLEEP

iTrader: (8)

So you had vibration with steering? I noticed that turning to the left vibrates more, having the steering centered is slight, and then to the right it's none at all.

g4ebguy90

I would think if it was the driveshaft it would do it all the time. Some of them also have weights on them... but I doub't it would be that significant. Sounds like mounts to me to.

mr2tosc4

iTrader: (1)

Gotta be mounts, makes sense -- the weight of the car when turning shifts, if one side of the mount is compressed over the other, naturally when you turn and weight shifts over, a bad mount would flex enough to cause vibration due to unequal weight distribution. It vibrates less turning the other way because that side of the mount still has enough to keep it from flexing too much.

cartmill

iTrader: (3)

it really depends on the frequency of the vibration.

is it high frequency and RPM dependent, or is it low frequency and speed dependent?
high frequency rpm dependent = clutch/flywheel/engine
low frequency road speed dependent = driveshaft/drivetrain

you could have a combination of the two (bad trans mount AND bad driveshaft u-joints).

99SC42

iTrader: (44)

Clutch is brand new

Driveshaft is from a 92 SC300.

The mount is Old , not broken atleast when it got installed.

It's not the flywheel,. It's driveshaft or motor mount.

cartmill

iTrader: (3)

^^^^^^^^^^^

DONT SLEEP

iTrader: (8)

Motor mounts had no issues prior to the swap... could this have changed after the swap?

Is it safe to put the car on a lift and have it run to see where exactly the vibration is coming from?