: 6th Gear, Slowest Speed ??

03-20-12, 11:34 PM
I read on here a while back about not using 6th gear while driving slow.
I noticed in a neighborhood that I can put it in 6th, and idle at 29 mph. =) lets see a 4-cyl try that. lol
Anyways... sometimes around town at 35-40 I can put it in 6th and cruise at 1000 - 1200 rpms.

What would you guys consider the lowest safe speed for 6th ?? Seems like I read its hard on the trans if going too slow.

03-20-12, 11:42 PM
I dont go any slower then 51mph in 6th gear and thats with only light light load..55+ is pretty safe IMO.. if i think im going to have to dip in to the 40s, i coast or rev match to 5th.. 5th is really not that bad on the mileage as long as you are keeping the engine load light..

always downshift to 4th to pass.. 5th gear is prone to damage as well.. there was a recent thread on here with some good info on exactly what is prone to failure.

03-21-12, 01:46 AM
Lugging around in 6th at 1000-1200 RPM's isnt great on the trans. I stay in 4th until I know I'll be sustaining speeds at or above high 40's and I don't bother shifting into 6th until I know I'm gonna be above 55 for more than a few minutes.

03-21-12, 02:06 AM
^ This. Seems alot of 5th and 6th gear vibes happen from putting it under decent load at low RPMs.

03-21-12, 06:41 AM
I believe the large mass of the OEM flywheel may have been deemed by GM to be at least partly necessary to help dampen the low-RPM lopiness of the motor which sends little torque spikes into the transmission causing problems. For me, this became really noticeable when I installed a lightweight flywheel and heard horrible sounds in the trans under light throttle application in 5th at 25 MPH and 6th gear at 35 MPH. I now upshift into 5th at 35 MPH and shift into 6th only after I've reached about 44-45 MPH and have, so far, had no issues.

03-21-12, 07:50 AM
I believe I am least likely to damage all of my gears if I drive the car the way it is intended to be driven. I keep the rpms between 1800-2200 for cruising in any gear and this gets me around 20 mpg. in the city and 25-27 on the highway. I usually shift between 2500-3000 rpms. If I don't feel like getting as good gas mileage I drive either the Toyota Tundra 4x4 Dbl cab or the Land Cruiser.

03-21-12, 12:42 PM
I noticed in a neighborhood that I can put it in 6th, and idle at 29 mph. =) lets see a 4-cyl try that. lol
lol My non-turbo Subaru Legacy, with it's whopping ~185hp, will do that. lol It only takes a few horsepower to roll along at low speed.


03-21-12, 07:56 PM
My powerstroke pulls a 19,000lb Toyhauler uphill at idle without touching the gas pedal :D