ameer

Hello everyone, I'm having an issue with my beloved 2004 SC430. I'll detail the problem below as the techs at my local dealer can't seem to suggest anything but gearbox replacement, I'm hoping to find a cheaper solution for my troubles.

So it started happening a few months ago, when shifting from 4th to 5th gear the car jerks, the higher the rpm the harder it jerks, it kind of lunges forward for a moment, even at very low rpm. This jerk becomes quite violent at high speed. It also sometimes does it from 3rd to 4th. It only happens after the car is warmed up, never when cold, and usually after driving it a bit harder. At first I changed the gearbox oil and filter, and indeed shifts are smoother but the problem hasn't gone away. Has anyone had similar problems that could give me some advice on what was wrong? My car has only 90,000 kms, it's been in the family since it was new, nothing ever happened to it, and was always well maintained.

Any help or suggestions are much appreciated. Thank you.

jasone36

I can't help, but gearbox problems on the SC430 are nearly unheard of.

Have you been doing the tranns flushes?

ameer

Thanks for answering. What do you mean by trans flushes? I simply took it to the dealer, and they suggested an gearbox oil change and did it.

Harold57

By "gearbox" are you referring to the transmission or the differential?

JohnnyCake

That's what I was going to say -- been on this forum for a decade and this may be the first problem with a transmission (not counting the zillion threads on the lag at startup )

DshngDaryl

I am going to assume it is a transmission issue and not a gearbox issue and ask a few more questions.

Did the technician give you any Diagnostic codes? If it is a Lexus/Toyota dealer, they should be able to talk to the TCU.

It is possible it is a bad solenoid. Read this article about transmission solenoids and see if it matches your problems http://www.transmissionrepaircostgui...sion-solenoid/

Sadly a cars transmission has a lot of moving parts and under constant stress. It is possible that something inside is broken and it is time for a new transmission. Of course that does not mean you have to buy a new one from the dealer. There are many second hand transmissions on ebay.

I would take it to a transmission shop. They should be able to read your transmission codes, determine if it is a simple solenoid, tell you if you can rebuild your old transmission or whether you really need a new one.

ameer

Transmission I guess.

The Lexus dealer did not find any faults in the transmission, I have contacted a specialized transmission shop, they asked me to bring the car in. They said it's most likely torque converter or bad valves in the transmission. They were surprised as well that I'm having trouble with it, as they said transmissions on toyota/lexus cars are bullet proof. Thanks for the help.

JohnnyCake

Good luck -- please circle back and let us know what you find out so that people in the future can benefit from this thread.

lexixel

Maybe it's good to make sure it's a tablespoon problem. Could be a differential/axle problem. Maybe it's the mounts. Send like it has more to do with speed than gears.

I read many cars with this transmission had problem with water ingress from the radiator. I would change the radiator as a preventive thing but it's too expensive here and I prefer to gamble. You can check for signs of water.

If no water present, it's unlikely to be the transmission. Btw, they call it gearbox in Europe, and in French "transmission is the final drive".

Bgw70

You said they changed the transmission fluid (gearbox oil) and filter. They most likely only changed 3-4 litres.
you said it shifted better after the fluid change.
the transmission will hold many more litres and you need all of the fluid changed.
also, what type of fluid did they use to replace the old fluid.

all of this is very important...please ask them and report back.

V300Graham

My gearbox is dying now, it has that jerk too, on the way into and the way out, of second gear.
I see quite a few elderly LS430's for sale in the UK with a gearbox problem (same box), though most are over 150,000 miles.
I have 130,000 miles on mine. I'm hoping to get a good low mileage second hand one.
I changed the fluid over a period of weeks to change over 90% of the fluid and the box got a lot better in all regards, except for this jerk.
Simple fact is the clutches are worn, nothing lasts forever.

lexixel

From another site I seem to remember that this gearbox engages clutch 1 and 2 for 2nd and releases clutch 1 for 3rd (engages clutch 1 only for 1st). So the jerk in AND out of 2nd is unlikely to be caused by worn clutches (because if clutch 2 is worn it would be downshifts from 4th to 3rd that jerks). It could be something else.

Also, 130k miles is a bit low for clutch wear problems. Even Audis can last 150k+ with awd. And when my Audi's box crept out at 150k+ it wasn't due to clutch wear.

V300Graham

I've given mine a hard life, I'm a qualified motor mechanioc, I know a slipping autobox when I hear (feel) one.... 2nd clunks in both directions after a particularly vicious trackday hunting well minded Ferraris.... Nothing lasts forever.
Audi gearboxes, especially autos, can be blown to bits at 80,000 kms:
Source, I helped set up a German airline and still talk to my mates there.... Audi boxes are dirt, at least amongst my hard charging mates...

degmla

iTrader: (1)

Guys,

Certainly not wanting to detract from any of the suggestions above, but how long has it been since you've changed your battery? -- or make sure you are not getting corrosion at its terminals?

I seem to recall people having shifting problems with auto tranmissions that were later attributed to battery issues. Maybe a fresh clean of the terminals could at least be an easy check-off?

Or, maybe, I am only recalling some silly !?@$ that has no merit?

ameer

Hello everyone, thank you for all the suggestions. I've taken the car to a service specialized in gearboxes. They couldn't find any fault with it, however they suggested that the valve block (whatever that means) needs reconditioning or replacement. They told me they'd have to take the gearbox apart to be sure. The problem now simply seems to happen randomly regardless of gear, hot/cold, slow speed or high speed, high rpm or low rpm. It could go a full day acting completely normal and then out of the blue start jerking without doing anything special. The jerk simply feels like a small kick in the back, and the car seems to lunge forward after the kick. I don't know how it feels when an auto gearbox slips, I do have experience with a manual gearbox slipping because of the clutch. It does not feel the same.

To answer the questions above. The battery, was changed in 2014. The gearbox oil was changed at my local Lexus dealership with the oil recommended by Lexus/Toyota. I don't recall how many litres they used. I've now spoken to another gearbox specialist and he suggested the same, if there are no faults in the ECU, they have to remove the gearbox and check it themselves to see if there's anything wrong with it. I'm a bit reluctant to let them. I will schedule another test at the Lexus dealership, perhaps this time they can check auxiliary stuff like suggested above, differential, battery etc.

Also another thing I feel I should mention is that, indeed I think the car needs replacement engine mounts. Sometimes when sitting idle the car trembles, and it shouldn't. Dealership said it's an easy fix with the mounts. Perhaps the gearbox mounts have a problem too? But then shouldn't the jerks happen all the time? And this doesn't seem to explain the car lunging forward after the gearchange. Could the dif have anything to do with it?

I will investigate further and post on here for future reference, haven't had the time as I was out of the country on vacation.