6th gear worthless?

[HoosierDaddy]

That was a nice surprise and a real game changer for manual transmissions.

I've never been so nervous as the first 6to5 downshift .... LOL


Way back in the day, my 2 point(something) V6 Firebird manual, I was climbing a steep hill on I-8 (outside Yuma,Az) in top gear, it needed to downshift, so not paying attention, I did ....under full load at full throttle.
That motor about leapt out from under the hood because the cruise never backed off when I pushed the clutch in.

I noticed an immediate drop in oil pressure.
When it idled down at the next exit ..... BAM BAMBAMBAM .... rods-a-knocking!!!!

Tear down revealed a previous HACK job rebuild .... 6 cylinders, three rod caps stamped as #3 cylinder , not that it mattered at that point.
Anyways, two rod bearings spun and one main.

Got 'er all machined out and put back together (myself! first rebuild!!!) and ended up with a damn good running motor.

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[Tricky Mike]

My 6th gear has cobwebs on it. Not even useful at 80 mph unless the goal is to chug even more gas.

 

[HoosierDaddy]

My 6th gear has cobwebs on it. Not even useful at 80 mph unless the goal is to chug even more gas.

Same here.
35's, 4.46
Beauty is, 78 mph is about 2700 rpm in 5th , it pulls 21 mpg here in the flatlands.

6th gear just slaughters the fuel mileage.

 

[FJCruiser]

I use 6th all the time and I don't downshift for hills either. I live in an area with 60mph speed limits. The 4.70 gears on 33's is ideal gearing. The 2.3 has good low and mid range power if you learn to get used to it. The auto seems better to some of you because the computer knows when and how to shift better than most humans. I have the benefit of almost 40 years of professional driving experience on my side which helps me out. I could easily teach most of you how to get the most out of your 7mt and be happier with it. FYI the 7mt and the auto have a nearly identical final drive ratio so there is little difference when either are in top gear. A little food for thought would be learning about progressive(or short shifting) techniques. You'll get better performance and fuel mileage once you learn that. PS I never go over 2400 rpm,stay with traffic and average 19.7 to 20.7 mpg.

Been driving manuals since 1977. I bet you could teach me a few things! Gonna Google "progressive" (short shifting) techniques now. Thanks.

 

[FJCruiser]

I seldom get past 5th when around town (surface streets). But use 6th all the time when on the freeway. In Phoenix can't go very far without taking a freeway.

I can see how someone on the east coast would find little use for 6th, but once you get west of the Mississippi you'll use 6th anytime you leave town.

Upstate NY is wide open with 70 mph cruising speeds on interstates. No cactus!

 

[FJCruiser]

We have a 85 mph toll road around Austin, and at that speed it doesn't matter what gear I'm in the mpg drops like a rock due to wind resistance.
I typically don't use 6th gear unless I'm going 70 mph or higher.

So, my additional random comment here:

FOr all of us that have driven manuals for years - yeah, RPM is important, and knowing the torque curve of your engine so you don't bog it down - you get a feel for that as you drive it.

Now, the Bronco was my first turbocharged engine, so it took me a bit to figure this out.

I was used to trying to sit at as low an RPM as I could - that's how you normally shift for best fuel economy, at least on a N/A engine.

Here, yeah, I can shift into 6th gear. And my RPMs do drop. But the turbo starts to spool up to make up the difference due to wind resistance and the torque curve.

Once the turbo starts to pick up, it absolutely destroys fuel economy. Even at low boost levels.

When I first started driving - I could get into 6th on straight highways, about 65+ MPH, and be sitting in the low 2ks on RPM, but also would be sitting at a near constant 1-5 psi on turbo, kind of depending on head wind and if I had a big truck in front of me and such.

I found it was better for fuel economy, and the general consensus around here is it's better for the engine (although that's not proven, just the general sentiment) - that it's better to be at a slightly higher RPM than it is to be at a higher boost.

So downshifting to 5th, so that while cruising I'm at 0 boost - while it may be more RPM, is better fuel economy, and possibly better for the engine.

Now that I'm sitting on a bit more lift, I see 5th gear start to flicker at 1-2 psi boost on occasion, a bad headwind will do it, or if I am passing someone and in their turbulence. I went up half an inch on lift with new shocks (0.5"), and my MPG dropped by 0.5 MPG, and I started to see the flicker in 5th gear due to the additional air resistance. The aerodynamics of a brick are really killer, and lift has a huge factor.

So bigger tires and bigger lifts - it all plays an important role. And don't get stuck just thinking about RPM - the turbo has a much bigger impact.

Thanks for this. It will be my 1st turbo after 50 years of driving manuals.

 

[CalvinT]

Upstate NY is wide open with 70 mph cruising speeds on interstates. No cactus!

Just poison oak and poison ivy.

 

[burgerking]

I use it quite a bit. Just have stock 32s and I'm not at high elevation or anything. If I have to give it the beans I just drop down to 3rd.

 

[CalvinT]

I just made a weekend trip from Phoenix, AZ (1140 ft elevation) to Flagstaff, AZ (6900 ft elevation). I did 75-80 both directions when traffic permitted. I was in 6th gear except when I was forced to slow to around 60 while going uphill. Then I dropped to 5th until I got my speed back up to 70 or so.

For me 6th gear is definely not worthless.

 

[HertiageMerica]

Our highways are 70mph speed limit so 6th gear is around 2100 RPM which is about right for just cruising along. My last road trip I got around 21 which is better than my Pilot ever did. I will drop into 5th on any long upgrades or if I want some more power.

 

[HPNQ420]

Same here.
35's, 4.46
Beauty is, 78 mph is about 2700 rpm in 5th , it pulls 21 mpg here in the flatlands.

6th gear just slaughters the fuel mileage.

33’s with 4.46 here. If I ever go to 35’s it will be with 4.88 gears.

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