Hello guys
Does anyone else experience when coming to a stop and start suddenly braking (in normal mode during easy drive) gearbox is not smooth and jerk / stutter from 5th to 3rd gear? Almost feels like the transmission didn't expect the revs to drop so quickly and has to quickly blip the throttle to keep the engine from stalling. It feels like gearbox slip a bit. It is very noticeable and happen just from 5 to 3. When I brake softly problem does not exist and gearbox downshifting gears one by one. Beside that there is also noticeable clunk noise when gearbox stutter - coming from the bottom of car, drive-train

When up shifting everything seems to be good. In Sport+ in manual mode downshifting is pretty brutal and jerky (definitely not smooth) as well but I reckon it is part of this mode and gearbox

2015 RCF with 37k kilometers
Oil was changed 1k kilometers ago ( oem oil).
Gearbox adaptation was done.

BR
Lukasz

 

It is rev matching when the throttle is blipped. I did it back in the day in my 6 speed manual. When your revs are dropping, the engine speed is mismatched to the speed at which the wheels are turning. In order to prevent from having wheels locked up, the rev matching allows the load transfer to occur more smoothly. Everything else you described, sounds normal behavior.

Regarding the clunk noise, that should not happen. Not sure, but definitely should get that checked out.

 

I get a little jerk/clunk if I try to down shift to 1st at a slow stop in Manual mode. When I down shift through the gears, I stop at 2nd as I roll to a stop. The automatically shifts to 1st as I stop without and clunk/jerk. I don't think it happens in ECO or possibly Normal modes. Might have something do with the car changes gear shifting in Sport and Sport+. Driving in Auto is always smooth.

 

Before my trans is fully warmed up, it will also hesitate on upshifts but it goes away once at normal temps.

 

I would have the trans fluid level checked. These transmissions are very temperamental about the fluid level. Even just a tad low can cause weird behaviour.

 

I've got a 2024 RC F with 6500km on it. Bought it new without ever being in one before so I don't know what it's suppose to be like. But I find the tranmission kinda slow and clumsy is the best way I can describe it. I don't drive the car hard, but when I get into it a bit I find it upshifts hard. I don't have much to compare it to other than an Audi S3 I had which was a dual clutch, those shifts were crisp and quick, really clean.
RC F is the opposite, which I'm fine with, as long as it's normal.

Any feedback from other RC F owners?

Thanks very much.

 

It happens when the transmission is cold. Once it is warmed up and especially when you are in SPORT+ as well as MANUAL mode, it completely changes character. You can look at some track hotlaps and you will see it shifts lightning quick when you are going all out in the red zone. However, due to AI in the transmission software, it learns from your driving patterns so if you drive leisurely and below 5000 rpm all the time, it is going to want to prioritize ease of shifts for comfort. SPORT+ with MANUAL mode and when you do some spirited driving, the transmission will learn from it. Hope it explains it.

Also in the RCF, the jerk is due to the torque converter locking up to make a mechanical engagement and eliminate loss of power through slippage creating a direct link between the shift and power to the ground.

Also, have the transmission fluid checked. If the level is off, the transmission goes into safe mode as well.

 

I’ve felt something similar on my RCF, usually during harder braking when the trans has to skip gears quickly. From what I’ve read, it’s fairly common with the 8-speed in these cars. Sometimes a re-adaptation helps a bit, but it won’t completely get rid of the jerk because the gearbox is trying to protect itself. If it’s getting worse or you’re hearing louder clunks, it might be worth checking the drivetrain mounts or the diff bushings too.

 

The 8 speed is the RCF's achilles heel. I find you need to let it warm up before in Normal mode before you do any thing in Sport/Sport+ in auto or manual mode.

 

I let it warm up in SPORT+ and MANUAL mode. I just shift up at 3000 rpm. Method has been working fine for many years.

 

As others have stated, most importantly the engine and transmission have to be fully warmed up.

And secondly and this is based on my observations, the shifting speeds are directly related to how much you have your foot in it.

Auto downshifting has always been painfully
slow especially if your cruising in a higher gear and suddenly need that power but up shifts will depend on how much gas you are giving it.

In manual it is all up to you after the engine and trans are fully warmed up. Until then it will still restrict you and be laggy.

 

Thanks for the input.

I use mine as a daily, so mostly city driving and with kids in. If i was getting into it a bit it was just in Sport mode, either in auto or manual and the shifting just plain sucks. It was slow and not smooth at all, it actully made me second guess the car the shifts were that clunky.
If driving sensible it's smooth as silk.

After my post and seeing the replies, I went out this evening, warmed it up and put it in sport +.
Oh my - it's not the same car. Shifts were like butter, and so fast. Revs beautifully right to the rev limiter and just grab the next gear and listen to it sing.
So it's clear that in Sport mode, or custom (with power turned on), that's for when the family is aboard.
When it's go time, you need to be in Sport +.

Thanks very much for the replies, very glad I asked and you guys answered.

Jeff

 

Glad it is all fixed for you. Yeah, in the nearly 8 years of owning the RCF, I have never bothered to go below SPORT+ mode. Lexus tuned the ECO/NORMAL/SPORT mode very similar to each other. SPORT mode basically makes a very mild differences from ECO/NORMAL mode basically with a bit sharper throttle response. If your car has AVS then the suspension is also soft in SPORT.

When you dial it up to SPORT+ mode, it is the mode they designed for the race track so the the suspension goes into stiff mode and steering is much heavier, stiffer as well as the transmission shifting is much faster. Once you switch over the MANUAL mode, it will lockup the torque converter for crisp shifts due to the torque converter being disengaged. It will whip your head back shifting at redline.

Here are the differences between SPORT and SPORT+ mode.