mm88

Hello! I'm encountering a vibration that feels like it is coming from the rear of my 98 ls400 when driving at 50 & 65 mph. sometimes i can see the steering wheel shake slightly at these speeds. I also get what feels like a thud or bang coming from the rear when shifting from park to drive. I recently got the front inner tie rod ends & front tires replaced (1 moog problem solver, 1 raybestos professional grade part, & 2 michelin MxV4 H speed tires were used). I also got a 4 wheel alignment & got all 4 tires balanced. This helped in the vibration issues that i have, but they are still there.

Just last friday, i decided to replace the transmission mount to see if that would help. I got a new OEM transmission mount from sewell & replaced it. When compared to the new mount, this one was collapsed, but I didn't think it was too bad, but i replaced it with the new part anyway. replacing the tranny mount helped a bit in fixing the thud/bang that i would get when shifting from park to drive, but the thud/bang that i get is still there sometimes.

I decided to put the car up on jack stands & rev it till the speedometer hits 50 & 65 mph to see if i could find the location of the vibrations & i noticed that whenever i go 50+mph, i get what sounds like a rattle & vibration from the rear of the car. I also noticed that the inner side of rear tire on the driver's side is getting uneven wear. below is a video of the noise & vibration that im getting:



At this point, i'm not sure what is causing the noise & vibration. Could it be a bad differential/differential mount, or a bad strut bar bushing? what do you guys think? Thanks for your time!

mm88

just got back from a mechanic. turns out all 4 wheels were out of balance (even though balancing was just done less than 2 weeks ago). The mechanic that i spoke with also noticed that my rear rotors are warped & need to be replaced & my differential bushings need to be replaced as well. So far, the car feels a bit smoother driving at 50mph, but i haven't tried 65mph yet. But it strange how the tires went out of balance so quickly. I plan to get my alignment checked again later on today & will work on getting the differential bushings & rotors replaced some time next month & will (hopefully) update when that's done.

Legender

Burning question...is were those new tires? What brand and how did the balance and install? Not really likely they to out of balance so quickly... maybe the weights weren't put on correctly and were spun off as you were driving.
Rear rotors are on closeout at rockauto (Brembo) for $18 a piece... not a bad price.

mm88

the front tires are brand new, I replaced the driver's rear tire with a used one that was in better condition than the one i had on it before & the passenger rear tire has been on the vehicle for a while now (not new). both appear to be in good condition & do not show any signs of uneven wear. I got the alignment checked & it looks like all wheels are wearing evenly now.

As for the balance, every shop that i took it to used a spin balancing machine (the ones that spins the wheel for you & it tells you where to apply the weights). I was doing some research on balancing & it looks like the most accurate method is to use a road force balance machine (http://tires.about.com/od/Tire_Safet...-Balancing.htm). I came across a company named hunter that manufactures & sells a type of road force balancer called gsp9700. I was using their locator tool (http://www.gsp9700.com/search/findgsp9700.cfm) to locate a shop that has this balancer & it looks like this is the same type of balancer that many of the dealerships, including lexus of orlando, uses (pic attached). at this moment the shaking at 50 & 65 mph is much better & almost gone, but it is still there a bit. I might make some calls to some of these shops to see how much it would be to get this type of balancing done. Though at this point it may be my warped rotors or differential bushings that may be contributing more to the vibration now.



Yeah, that is a good deal. I was thinking about using raybestos Advanced Technology or Centric High Carbon Plain 125 Series Cyro-Treated Rotors for the rear as well, but it looks like the brembo is oem. I might go with that one instead. Nice find!

Legender

Can't see warped rotors causing the vibration... except when you hit the brakes and the calipers come into play.... but I'm not a brake expert. Glad you got some of it figured out.. hope you can get it all tweaked out...
Good luck and thanks for answering the question.

Greg5OH

my bet is still out of balance wheel. Had my new tires balanced by a local shop but i had vibration at 60 kph and 130 kph. Put it on my personal balancer, appears ot be 1.5 oz out. Havent test driven yet.

sorry ididnt read everything, but are u sure your carrier and uppper control arm bushings and BJ are good? My carrier bushign was shot and i also noticed the rear UCA bushings had some deflection to them. that owuld definitly contribute ot vibration.

mm88

hey guys. ok i have another problem, but not sure if i should put it here or in another thread since its unrelated (mods, feel free to move this thread if you think it should be moved).

anyway, I was using the procedure at (http://www.lexls.com/tutorials/trans...ransflush.html) to flush my transmission fluid today. In total, i took out 9 quarts (stopped when fluid coming out was red) & added only 8.5 (to make sure that i dont overfill the transmission). After this, i checked the fluid level on the dip stick, & it looks like it was overfilled (about one inch above the full mark). at first i though that it would be that way since I havent started the car yet & shifted through the gears as recommended in the tutorial. So i started the car & shifted slowly through at the gears & back as detailed in the above tutorial, but when i went to check the fluid level with the car idling, it still was about 1 inch above the full mark.

I made sure that i took out 9 quarts (in 2 qt intervals) & put in 8.5, so im trying to figure out how its overfilled. For fear of destroying the transmission pump, i did not try driving it. One thing to note though is that I used a synthetic transmission fluid (amsoil: http://www.amsoil.com/shop/by-produc...?code=ATFQT-EA ) instead of the OEM. I know that OEM fluid is typically recommended for these cars, but i have had success with using this fluid on an es300 before (this issue did not occur when i did a drain & fill on the car with synthetic fluid).

There are only 2 reasons that i can think of for why its high:
1.) fluid viscosity for the synthetic fluid is different than the OEM fluid
2.) the inlet hose that goes to the transmission may be getting pinched by the hose clamp (it didnt look like it was when i was under the vehicle, just a guess...).


any suggestions (especially from people who have successfully performed the above transmission flush) would be greatly appreciated. (again, let me know if its ok to post this question here or if i should add it to or create another thread for it). Thanks for your time!

sha4000

iTrader: (1)

I did this procedure years ago and did not experience your issue but if your worried just unhook the hose and drain a little out. I'm pretty sure that you were already thinking that but I had to say it nonetheless. A quart is a quart whether T4 or synthetic.

mm88

sha4000, thanks for your response. I'm hoping that the level will go down on its own overnight & will check it again in the morning tomorrow. If it doesn't, then I'll do a drain & fill (i haven't dropped the pan on this car since i had it & i have the filter, so it will give me a chance to change it). Hopefully that will get the level right.

sha4000

iTrader: (1)

Ok let us know.

mm88

ok, i drained the transmission fluid from the drain of the transmission pan & tried to drop the transmission, but the bottom lip of the pan got caught on what looks like a small metal bar whenever i tried to take it out (not the dip stick, i was able to remove that). So i just dumped the fluid from the pan into a bucked & measured about 3 quarts. i then reinstalled everything & fill the car with fluid (1.5 quarts). i left it idling for about 10 -15 minutes & checked it & noticed that it was still around the cold mark. i added another half quart & it still appeared to be low. i shifted through all the gears & left it idling for a few more minutes, but the level was above cold but below the bottom of the low mark (for hot). I added another half quart & now it looks like its over filled again. not sure why im having so many problems with this. Im currently at work now, so ill probably drain about 1/4 of a quart out & idle the car for a bit to see if that helps when i get the chance later on today.

EDIT: how long should you wait before checking the fluid when the car is idling? do you wait untill the coolant temp on the dash gets half way? I noticed that before i changed my fluid (when i had the old fluid in the car), it would always stay at the full mark (both when the car was cold & when it was hot). Isn't it supposed to be at the cold mark when its cold? & hot when its hot?

mm88

i did another drain & fill. this time, instead of putting 2 quarts in, i just added 60 oz (about 1.9 qts). I think i figured out why i was running into so many problems. my driveway is on a slight incline. normally when im changing fluids, i park the car so that the nose of the vehicle is on the higher side of the incline & the tail is at the lower part of the incline. when i did the fluid change the last 2 times, they were with the nose pointing at the lower end of the incline.

i tried parking the car on a level surface & the fluid level looks like its just below the low mark when hot. however, i know that the transmission is almost at max capacity, so im not too worried about it (better to have a transmission under-filled than overfilled. However, i did notice that the fluid level on these transmissions are very tricky to get just right. I'll probably add another ounce or 2 later on tonight when im driving. but so far, the car shifts smooth (which isn't saying much since the shifts were virtually unnoticeable before i did the change.

sha4000

iTrader: (1)

You should always check the fluid after the car is warmed up and on level ground. Are you sure the dipstick is original? Its always better to be a lil overfilled than to be under filled by too much.

mm88

Thanks for your response. yeah, i plan to start taking more measurements from the dipstick when on level ground in the future. unfortunately, my driveway isn't level, so ill have to do it while stopped somewhere like a gas station or something. Yeah, it looks like the same dipstick that they show in the illustrations in the service manual. I'm not sure if its better to have it overfilled than under. Many of the articles & mechanics that i spoke to stated that its better to have engine oil overfilled than under-filled but better to have a transmission under-filled than overfilled, as the added fluid may cause foaming, which may increase pressure in the system & in turn, killing the transmission pump. I think this is what happened to my Acura when i did a drain & fill on it last year. Guess i overfilled it by 1-1.5 quarts & a month later, the car just stopped moving when i was driving.

I did check it again last night while driving for 30 minutes (on a level surface at a gas station i might add). & Found that the level when hot is actually between the lower & upper marker on the hot portion of the dip stick. I believe that it another problem that i was running into. When i was changing the fluid, i was idling the car until the temp gauge got to normal operating temperature (about half way). However, the transmission fluid would only be warm when doing it this way (it was not truly hot). According to the service manual:

In other words, if you can touch the fluid on the dipstick without saying "ouch", then its not hot enough. Though i suppose you could also use an infrared thermometer to be 100% sure (not sure if the OBD on the car reports transmission temperature). The above makes sense as i intentionally left 4 oz out after performing the drain & fill. So it seems like if your in doubt about the fluid level & if your worried that its overfilled, doing a drain & fill should tell you whether it was overfilled or not & assuming that you drained all of the fluid out of the pan. The specified 2 qts in the service manual should get you to the full mark (or at least very close to it without significant danger of overfilling/under-filling).

Anyway, I believe the above is correct. I'll keep checking & may add a bit more over the next couple of weeks.