Vibration on downshift
02-10-02, 01:41 AM
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Vibration on downshift
Hi,
Anyone else with this problem? Sometimes when the tranny shifts from 3rd to 2nd, the car vibrates for maybe 0.5 seconds. Feels and sounds like going over a short strip of rough road.
The problem only occurs occasionally. Seems to me that I have it most often when I slowly accellerate while going uphill. But I am not sure about this.
Any ideas what this could be? Don't have any mechanics over here who know the SC4 really well, so it sure would help if I could point them into the right direction ...
Thanks
Anyone else with this problem? Sometimes when the tranny shifts from 3rd to 2nd, the car vibrates for maybe 0.5 seconds. Feels and sounds like going over a short strip of rough road.
The problem only occurs occasionally. Seems to me that I have it most often when I slowly accellerate while going uphill. But I am not sure about this.
Any ideas what this could be? Don't have any mechanics over here who know the SC4 really well, so it sure would help if I could point them into the right direction ...
Thanks
02-10-02, 06:34 AM
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Acctis:
Next time out watch your speedometer and see if this occurs at around 40 MPH...
I have heard that one negative issue of the SC400 and LS400 automatic trannie was that the lock-up of the torque converter did cause what was described by owners as "washboard rumble vibration" at or just around 40 MPH, especially when going up inclines like the entrance ramp to a highway. It was told to me that this rumble occured when you were slowly going thru the lock-up and not at speed.
I suspect the downshift vibration is the same thing. Since this had not occured with me I am describing this from memory and a conversation I had with a former Lexus mechanic who works in a speed shop.
Perhaps others here can add more data for you.
What I would do is check the Automatic Transmission fluid level and smell and look. If it smells burnt or looks dirty I would have it changed. It uses a special Lexus/Toyota type of fluid so adhere to that specification.
Sorry I cannot provide more help.
Next time out watch your speedometer and see if this occurs at around 40 MPH...
I have heard that one negative issue of the SC400 and LS400 automatic trannie was that the lock-up of the torque converter did cause what was described by owners as "washboard rumble vibration" at or just around 40 MPH, especially when going up inclines like the entrance ramp to a highway. It was told to me that this rumble occured when you were slowly going thru the lock-up and not at speed.
I suspect the downshift vibration is the same thing. Since this had not occured with me I am describing this from memory and a conversation I had with a former Lexus mechanic who works in a speed shop.
Perhaps others here can add more data for you.
What I would do is check the Automatic Transmission fluid level and smell and look. If it smells burnt or looks dirty I would have it changed. It uses a special Lexus/Toyota type of fluid so adhere to that specification.
Sorry I cannot provide more help.
02-10-02, 01:09 PM
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That's it
Thanks for your reply. 'washboard rumble vibration' at 40mph ... that's exactly what it is like.
I checked the tranny fluid already, and as far as I can tell there's nothing wrong with it. Anything else I could do? Would that be a good 'excuse'
to get an aftermarket torque converter, or could that make things even worse?
I checked the tranny fluid already, and as far as I can tell there's nothing wrong with it. Anything else I could do? Would that be a good 'excuse'
to get an aftermarket torque converter, or could that make things even worse?
02-11-02, 07:01 AM
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I am not sure if the so called "rumble" means that there is something going wrong or wearing. You do have two options, do nothing or do something. It may just be a "feature", bad as that sounds. I speak from ignorance on that aspect.
I would contact your local Lexus dealer and ask their opionion. Have them pull up the detailed maintenance records for you car to see if the previous owner had also complained about this rumble. this could give you grounds for a claim???
Then ask the dealer what causes the rumble, can it do harm? What is the remedy and the price for the remedy in parts and labor (broken out).
Then, assuming the remedy is a new factory OEM torque converter, find out what the price is of the custom torque converter including shipping. Get the details on the warantee with the quote.
You may also want to ask you dealer, if you are doing a torque converter change, what else could or should be changed or maintenanced at the same time?
The SC400 BTW, has a transmission oil cooler. It is built into the front radiator lower section. Depending upon the age of your SC you may want to have them inspect those AT lines that go to the cooler, drop and clean the AT pan and magnets and totally flush the transmission with new fluid. The dry AT takes about 8 quarts but if you just pull the lower pan plug you drop only about 2 to 3 quarts.
Lastly, The new torque converter is supposed to give you great low end lock up to the point of turning the car into a real rear tire rubber burner. How that will effect your car and its driveability is not known by me. I am suspicious of this mod as the trannies ECU is probably not aware of the new torque converter. Some guys here have it installed. They can perhaps help out with some input.
I would contact your local Lexus dealer and ask their opionion. Have them pull up the detailed maintenance records for you car to see if the previous owner had also complained about this rumble. this could give you grounds for a claim???
Then ask the dealer what causes the rumble, can it do harm? What is the remedy and the price for the remedy in parts and labor (broken out).
Then, assuming the remedy is a new factory OEM torque converter, find out what the price is of the custom torque converter including shipping. Get the details on the warantee with the quote.
You may also want to ask you dealer, if you are doing a torque converter change, what else could or should be changed or maintenanced at the same time?
The SC400 BTW, has a transmission oil cooler. It is built into the front radiator lower section. Depending upon the age of your SC you may want to have them inspect those AT lines that go to the cooler, drop and clean the AT pan and magnets and totally flush the transmission with new fluid. The dry AT takes about 8 quarts but if you just pull the lower pan plug you drop only about 2 to 3 quarts.
Lastly, The new torque converter is supposed to give you great low end lock up to the point of turning the car into a real rear tire rubber burner. How that will effect your car and its driveability is not known by me. I am suspicious of this mod as the trannies ECU is probably not aware of the new torque converter. Some guys here have it installed. They can perhaps help out with some input.
02-11-02, 07:41 AM
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Acctis, I've got the same problem with my 92sc4. Around 40 mph, downshifting from 4th-3rd causes a slight vibration. This only happens when accelerating slowly, if I deck it it never happens. I've had this issue for about 40k miles now. Started around 100k now at 140k - or more. I doesn't seem to get worse or develop any new symptoms. I'm %100 sure this is not due to lack of maintainance. I've simply been driving around town with the OD off so I'm never in 4th gear. On the freeway I never drop below 60 (unless the other cars are in my way), so it really doesn't bother me. Anyways, you're not the only one, and (at least in my case) it doesn't get any worse or cause other damage.
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