Deccelleration vibration above 3,000 rpm with 5AT

**DEWFPO** · 08-09-2007, 07:32 PM

Going down steep mountain roads I always manually downshift the 5AT in my FJ. Always, at 3,200 rpm and higher there is a noticeable vibration in the engine/driveline. I assume it is normal. This is in 2wd, haven't tried it in 4wd.

Are others feeling this as well. Below 3,200 rpm it is smooth.

DEWFPO

MarkBNJ · 08-09-2007, 08:33 PM

No, I can't say I have. One of the things I like best about the truck is how smooth the drive-train is. I also manually downshift on some steep hills (despite the fact that the truck will do it for you in most circumstances), but I have never experienced that vibration.

Fjamming · 08-09-2007, 08:56 PM

Check your brake rotors. Could be warped. Might want to also check the control arm bushings. Try hard stops in neutral and see if there's still an issue.

fjcruzer123 · 08-10-2007, 02:22 PM

Do you get the same when accelerating in that RPM range?

**DEWFPO** · 08-10-2007, 03:07 PM

I do get more vibration the higher I go up in the rpm range when accellerating. Always thought that was odd, but thought it might be a Toyota thing (my first).

On decel., there's no vibration, then it's there at 3,200rpm and up. Very noticeable difference at 3,200 rpm.

Thanks,

DEWFPO

**DEWFPO** · 08-10-2007, 03:10 PM

Quote:

Fjamming previously said:

Check your brake rotors. Could be warped. Might want to also check the control arm bushings. Try hard stops in neutral and see if there's still an issue.

I'm not applying the brakes at all. This is a high rpm deccelleration locking the 5AT into a gear. Any gear above 3K rpm.

The suspension still feels very tight, only 8,000 miles on it.

Thanks

DEWFPO

Briman42487 · 08-10-2007, 03:13 PM

with higher engine speeds does the vibration get smoother (not going away, but smoother), or does it start to go away?

Fjamming · 08-10-2007, 03:25 PM

So you're saying that you get vibration at rpms above 3000. Vibration occurring just by you lifting off at high rpms? Which is worse, accelerating or decelerating?

**DEWFPO** · 08-10-2007, 03:35 PM

The highest rpm I have taken the engine has been about 4,300 rpm. The vibration on medium acceleration seems fairly consistent above 3,200 rpm to at least 4,200 rpm. Maybe a little worse the higher you go but not much.

On deceleration, I haven't taken it above 3,200 rpm because of the vibration. It kicks in all of a sudden and is fairly noticeable so I try to keep it under 3,200 rpm when on hard deccel to avoid the vibration.

Thanks

DEWFPO

RMGST · 08-10-2007, 03:36 PM

Odd, I have a slight vibration that comes on at about 2100 rpm and only lasts until 2200, where it then smooths back out again. I just chalked it up to mechanical harmonics of the drivetrain. Of course the higher up in the RPM band I go the more vibration I get, but it feels completely normal. It's a truck, so I don't expect the engine mounts to be as isolation as say a Lexus LS430.

Perhaps what you are feeling is actually exhaust system vibration, the throttle body is closed, the engine will be scavenging for air.

One other thing off the top of my head, a slighly unbalanced driveshaft that only shows up when it is not under powered load.

I dunno... describe the vibration a little more. Like spare change rattling in the cup holder, or something you can just feel through the steering wheel and your seat?