Hi there, if you live in Romania, I absolutely discourage you from letting those monkeys touch your gearbox. My experience in France is that they know absolutely nothing about gearboxes. Personally, I've been suing an ****ing monkey for over two years. I'm leaving France in November, and it's still not over.

Your gearbox is thumping (or whatever is the word). This is most likely because the fluid is thinner than spec. I would bet money that the dealer that changed your fluid used WS. This is what the ****ing dealer in France used in my car. It was extremely difficult to get them admit the mistake. Then, they just did a couple of drain and refill with T4. I've since changed four times myself.

There's a TSB when WS first came out. It specifically said that when WS is mistakenly used in other gearboxes, because the fluid is thinner, the gearbox will be thumping. Another issue I saw is that at speed when coasting, the RPM will drop to idle on WS. With the correct fluid, even when the torque converter clutch is disengaged the RPM will not drop that much (it will drop). Again, this is because the fluid is thinner. I guess (not engineer here), too much slip (drop to idle) will create higher amount of heat, too.

You need to buy a small fluid pump (electric) on ebay and suck out the fluid from the dipstick and refill -- at least five times. Stay away from ****ing monkeys. They will not put your gearbox back again. Also, this is not ZF, the valve body isn't always broken at 60k.

 

Hello again everyone! I'm happy to report my problem has been solved. I will post it here in case anyone else ever has a similar issue.

So after months of trying to diagnose the problem I went to an independent service specialized in gearboxes. After trying to diagnose it and driving for about 1 hour, the tech, to my surprise, said he didn't think the gearbox was at fault. I was puzzled and we went back to the service where they put the car on a lift. They identified a broken engine mount as the culprit. Not sure if its called a "mount" in English, basically the engine was loose on the left side of the car and it moved violently during shifts hence the kicks and lurches. In fact when going above 5k rpm it actually hit the inside of the hood... I ordered the mounts on both side since I figured if one broke, the other must not be in good shape either. After a long and painstaking installation of the new parts, I drove the car, and wow... problem fixed! That was it! I also now noticed the car seems to not vibrate at all when standing still, at times it used to do this slightly, as I said in a previous post.

I'm so happy this car is running properly again, it may not be the best car in the world, but at least in my country due to its rarity it is definitely an event driving it, especially since ours is extremely well maintained and it really looks like new even though its 12 years old now. I do enjoy driving it from time to time even though we have some far more expensive cars in the family. Can't believe that as old as it is, it's still a great car to cruise in on a nice day.

 

Hi and thanks for the suggestions. I was weary of letting them mess with the gearbox too, fortunately the gearbox is fine and the problem has been solved. I don't know which oil they used when they changed it but I did it at the Lexus dealer, I assume they put the correct oil in it. How can I check?

 

Wow, That is great! Thanks for letting us know what the problem was.

I don't know if I would have ever thought to look at the motor mounts, so I appreciate the heads-up.

 

Very cool, glad to hear that you got it solved. Interesting solution too.

 

ameer - congrats mostly on finding a good mechanic, a truly great thing to find

 

good to hear your problem is gone.

sorry, I'm not aware of any way you could tell whether the correct fluid is used. You could buy a small electric pump from ebay and do a few fluid replacements to freshen up the fluid and make sure if the wrong fluid has been used it's diluted.

I've done six fluid changes with the pump; it takes 20 min to do a clean job. The last time the fluid I got out was almost like new. I think I can let it be for a few years.

The pump is 20 eur and the fluid is maybe 8 / litre.

One tip: Start the car when cold, if the fluid level just passes the lowest notch, the level is good.

The warm level is measured when the car has been driven for 10 miles / 15 km in around 25 C environment. It is not the eventual operating temperature of the transmission after a long drive. I found out that on new cars it can take over 30 minutes / 50 km for it to reach the operating temperature. What you want is maybe 60 C... It's just easier to do from cold.

Also, I find that if you drain the fluid, it's necessary to add more than 1.8 litres (book value) to reach the correct level. If you add only 1.8 l, it doesn't even register on the dipstick when cold, and the transmission can slip at low speed under low throttle input.

I personally measure the cold level and then drive 15 km to measure again. If the warm level is slightly above the max mark, it's good. Slightly above means a few mm. My car shifts noticeably better when it's slightly above the max after a 15 km drive. Note: this is not over-filling the transmission, because the warm level is the level at a specific temperature, which correlates but isn't directly linked to the distance driven.

The above tip is my personal experience that may help others gauge their own fluid levels. Different fluid choices, different driving styles, and different ambient temperatures would affect the levels achieved; therefore, this is not meant to be an instruction. I cannot be held responsible if you mis-filling your transmission.

 

I am glad it all worked out. As an FYI, there are actually three mounts
2 Engine and 1 Transmission
http://www.ebay.com/itm/LEXUS-OEM-FACTORY-ENGINE-AND-TRANSMISSION-MOUNT-SET-2002-2010-SC430/231846796484?_trksid=p2047675.c100008.m2219&_trkparms=aid%3D444000%26algo%3DSOI.DEFAULT%26ao%3D1%26asc%3D39035%26meid%3Db239b68810254deba552995ff4e0c73b%26pid%3D100008%26rk%3D3%26rkt%3D14%26sd%3D231601971171

 

The motor mounts are a weak part on our cars but the transmission mount will hold up much longer. before I knew this, I too changed all three, both MM were shot but the transmission mount was fine, still replaced it.

 

You won't believe this but aside from him being great he was also honest! He charged me 25 euros for his time spent on diagnosing the car, saying he didn't really do much. Every time I go to the Lexus dealership I never pay less than 500 euros...

 

Actually, motor mount is a common wear and tear item. In terms of ride quality I think the two things you can do to restore the Lexus car to the original condition if its over 100k miles are replacing motor mount and structs. Given how well made the engine and trans are in SC430 I think most people would do well by changing those out at 100k to make the car drive like new again. You will be amazed how smooth, tight and quiet it drives once those things are changed.

 

Yeah, I think the struts on mine are weak. Driving on cobblestone today, I was afraid the engine would pop out. Not today.

Next summer if I still keep this car I'll get a set of coilovers.

 

Sc430 does not have "struts." Double wishbone suspension front and rear as far as I know

 

I mean shock absorbors.

 

Cool. We paid dearly not to have struts.

the double wishbone makes you feel like you are hung between the tires a bit.

jag feels like that and my old 98 accord