Hey everyone!

Hope you are all well.

I wondered if anybody here got the Renntech TCU Tune on their GT and if they have any comments about it.

Take care!

No, and I haven't considered it. I love my transmission as is. The Renntech website description seems void of details and high on price to me. Looks like a typical up-sell to me. Let me know if you find input that says otherwise.

I can't speak for renntech, but the PTG transmission tune makes a pretty noticeable difference in shift speeds, it's also cheaper.

I have no doubt that by hacking the software, tuners can get the shifts to be a bit quicker. What I'm skeptical about is the promise for faster shifting, while also lessening the stress and torque on the system. There are laws of physics, and there are laws of marketing. I think the latter are winning out in most instances when it comes to TCU mods. Personally, unless I was using my AMG GTR specifically for the track and money was on the line, I wouldn't mess with my TCU. In the most aggressive settings I find the shifts to be more than adequate. Certainly better than I could ever do with a manual transmission and all of the milliseconds saved don't add up to justify the potential downside. My two cents.

I haven’t spent time looking into what exactly the TCU tunes claim to enhance, but the potential for warranty denial caused by very little ‘gain’ is undeniable.

The DCT in the car is excellent imho and runs a very, very close second to the Porsche PDK unit which is widely regarded as the best on the market. The shifts are responsive and are totally appropriate for the mode the transmission is in. Anyone who thinks the shift algorithm is deficient needs to place it in Race and head to the track; it’s sublime even in ‘D’.

If the tunes remove the torque limitation in the early gear sets in order to try and make the driver feel more ‘connected’ somehow; (and I’m not saying they do), then there’s a lot more stress being applied to the transmission.

If you’ve gone to a high power build in the engine and have had the transmission modified with upgraded clutch packs; gear sets, etc. then an appropriate TCU update makes perfect sense; just not for an OEM or Stage 1 ECU tune . Again, just my opinion.

I have used my GTR before i got stage 2 tune with downpipes and it used to shift seamlessly.. but it’s different when u have a stage 2 tune, stock tcu tune feels slow and not seamless it was before..

i do not have a tcu tune but i am definitely interested in getting it done, would be gr8 to have that same seamless shift like before

Here is my experience with Weistec TCU on GTC Stage 1 (About 640-680 HP, depending which tuner or dyno you want to believe):

Weistec claim that they increase the torque limit – Probably. However, I don’t think it’s possible to verify by "feeling it" with engine producing lower than… 800HP?

They claim that the shift is faster and firmer - Unless my brain can process a fraction of a millisecond shift differentials, I can’t say it's faster. Maybe just negligibly faster. Firmer? I think my imagination is telling me that I hear a stronger clank when shifting. It probably is, but not noticeable to the “unaided eye (ear)”.

One thing Weistec stated: “they do not change shifting points”.

It is very difficult to tell if there is any improvement. By the time I sent my original TCU and got it back, I already lost perception of the speed and noises of shifts make in race mode. Again, hard to tell without specialized equipment.

The bottom line is that I haven’t seen even a fraction of a second lap time improvement on a racetrack I frequent often.

I reverted it to stock and maybe reconsider reinstalling the tune when and if I decide to go to stage 3.

Same experience here, did Weistec TCU on my M157 S63 Cp. and if there was any improvement at all, it would be like 10%. By Dragy acceleration measure, no improvement. The tune costed me 2k USD. Don’t really know if I needed it at all.

The candle that burns at both ends burns twice as bright but only half as long. Is it worth it?

Well said...

I think like anything, boils down to the experience of the one doing the tuning. By experience I don’t mean someone that has done in quantity, but someone who has superior knowledge levels of the platform, the factory TCU tuning, what opportunities exist within it for improvement, and how to properly, and safely, extract that potential.

heres sound clip of what mine sounds like now. Windows are up and its on my
iphone. Renntech mods sound check let me know what you think