Front-side Vibrations At Slow Deceleration On Cts

[CTS03]

I had car's front side vibrations twice on two different national roads and I started thinking that it might be a suspension problem and not related to roads' irregularities:

Near an exit/crossing I slowdown with 5th gear and I keep going with ~100km/h, slightly downhill, regulating the speed with little pressure on the gas pedal. Then I started feeling periodic-like vertical vibrations at the front side of the car (vertical movement of the steering wheel) like if the road had a periodic grid of grooves made by a heavy vehicle (not using tires) or intentionally prepared for new asfalt. However, there were no visible signs on the road and the vibrations remained when I shifted to a new construction lane.

The first time it happened, I was going at a slower speed (~80km/h), probably with 4th gear (or 5th) on a different road.

Has anyone experienced something similar? Any idea what the cause could be (if not the road)?

[PaulT]

Has anyone experienced something similar? Any idea what the cause could be (if not the road)?

Unbalanced wheels? Sometimes the balancing weights can fall off. I guess you might expect to get vibration all the time if that happened, though.

Paul.

[CTS03]

Unbalanced wheels?

Not possible. The tires are new (but 205/50/16) and the car runs very smoothly at 160 km/h.

It is not the "soft" vibration of unbalanced wheels but something strong, like termination of the suspension. It resembles somehow with a vibration on the steering wheel which I feel at very fast right turns (LH car), but this should be normal behaviour (suspension limits) of a front wheel drive car.

[nrgizerbunny]

it is possible.

the natural frequency of the wheel depends on the speed its rotating at and the amount of unbalance. It might be just that at a particular speed (100kph) you hit the natural frequency of the unbalanced wheel and get large accelerations through the steering wheel.

[CTS03]

I think what I experienced has a common source with the "wheel hop" problem; oscillations of the front side of the car when starting moving with spinning wheels (usual on wet road). This effect is attributed to combined oscillations of the suspension and the engine on its mounts.

I guess my engine's movements may come into reasonance as I apply a variable slight pressure on the gas pedal with 5th gear to keep constant the speed on downhill road (in both cases).

[CTS03]

Bad news! The problem seems to be related to ocassional locking of the brake of the rear left wheel while driving.

During a 70+70Km trip, I noticed in 2-3 cases some vibration with the 5th gear, which hapened independently of slope of road, exact speed, etc and it was imposisble to reproduce it anytime.

After parking the car, we noticed a strong "smoke"-like smell in the parking room (like burned matches) and after searching around we found that it was coming from the rear left wheel (!), which was the hottest wheel on the car. Much hotter than the normally hot front wheels and the relatively cool rear right wheel.

[K19NE G]

Bad news! The problem seems to be related to ocassional locking of the brake of the rear left wheel while driving.

During a 70+70Km trip, I noticed in 2-3 cases some vibration with the 5th gear, which hapened independently of slope of road, exact speed, etc and it was imposisble to reproduce it anytime.

After parking the car, we noticed a strong "smoke"-like smell in the parking room (like burned matches) and after searching around we found that it was coming from the rear left wheel (!), which was the hottest wheel on the car. Much hotter than the normally hot front wheels and the relatively cool rear right wheel.

I was back in Ireland for a trip recently and I experienced this problem!!! I took a couple of lads out for a spin on a newly laid tarmac by-pass and as I exited a roundabout I felt a great amount of shudder coming from the rear of the car :o First impressions were a blow out or loose wheel (recently had the new wheels fitted), but when I got out of the car there was no damage to be seen. There was a strong brake dust smell, but I put this down to the spot of hard driving I'd just done. I got back into the car and the problem went... only to return next day after another spot of hard driving...

Then it dawned on me that I had the handbrake tightened the day I got to Ireland as it was quite slack - my brother had tightened it far too much and this was causing the brakes to catch when pressure was put on the rear corner of the car - hope this clears up what your problem might have been???

I'm just feeling lucky that the brakes didn't snag/catch on a fast corner in slippery conditions! There was definitely someone watching out for me!

[CTS03]

We have obvioulsy experienced the same problem. Initially I thought that the vibration was coming from the front side but it was the result of rear braking. It is so easy to misinterpret a problem!

It seems that I could feel it only with 5th gear because of the low torque. And this happened only when I was on a longtrip where I could run at high speed most of the time.

Except of the vibrations observed twice within 2 months before my first post here, I had also noticed that the car was occassionaly "loosing" strength. For example, last summer I felt once the engine very stressed while accelerating above 6000rpm with 5th gear and I smelled gasoline.

Apparently my handbrake was problematic for long time but, in my case, only Toyota may have touched it.

Hopefully, this last trip on a free road with many bends and fast parts helped to reveal the problem (smell/heat!) without having an accident!

Toyota has replaced my rear brake disks and handbrake pads(?) under warantee. They were also very rusted.