Driving in M5 to disable the AFM, transmission question

[tom3]

(Originally posted in wrong forum)

I have been looking to disable the AFM deal and see that driving in low range and selected 5th gear seems to work. At 60 mph I'm at about 1700 rpm and the torque converter is fully locked up in V8 mode. Looks perfect to me. Drives a bit better too. Trans. temp on 85 degree day running at 155 degrees. I don't know much about automatic transmissions and I wonder if there would be anything that would affect the transmission long term by doing this?

 

[Fless]

No need to double-post; mods are here to move things around if needed.

 

[Marky Dissod]

... been looking to disable AFM, see that driving in L & selecting 5th seems to work.
At 60MpH I'm @ ~1700RpM and the TCC is fully locked in V8 mode.
Looks perfect to me. Drives a bit better too. On 85F day ATF is @ 155F.

don't know much about automatic transmissions and I wonder if there would be anything that would affect the transmission long term by doing this?

Since you manually select L5, I'll assume 6L80?
When you select D & tcm selects 5th, I KNOW the overrun clutches are not in use.
When you select L5 & tcm cannot select 6th, I do NOT know if the overrun clutches are in use ... ?
Bet @NickTransmissions knows ...

Were you willing to tolerate a 'Check Engine' light, there is an electrical connector on the brake booster.
If you disconnect it, Engine Half@$$ is disabled. This will let you compare ATF temps in different scenarios.

It'd be better to get your ecm & tcm tuned to disable Engine Half@$$ under 230F, of course.

 

[tom3]

I ordered a Range last night. I don't like the always on condition with this device but I'll use it on trips and just drive in L5 locally maybe. I am feeling some vibration in V4 mode already at 33k miles. Can't be good on those four cylinders pulling near 3 tons. Our Tahoe sits in the garage a lot while I drive my old pickup mostly. Can't go the "tune" route due to the extended warranty for 3 more years. Son had his Sierra tuned after a trans. failure, sure a different (better) drive now. Thanks for the reply!

 

[C1E2]

I have a '16 Tahoe with 165k on it and I've been using the L5 method for about 2 months now. No issues at all, in fact I've seen an increase in MPG - slightly. I'm about to get one of the disablers so I don't have to remember to use L5 each time I shift into drive. Plus, when I go on a longer trip on the highway I want that 6th gear. I'm waiting for the warranty to expire (bought used) before I do the programming. I've had no issues with running in L5 everyday.