Running in 5th gear

[lynnmor]

Originally Posted by crossup

Unrelated but this begs the question with no 1:1 what gear does one use on a dyno? This is the first time I was aware there is a tranny without 1:1, and makes me wonder if we are robbing Peter to pay Paul with more trans ratios but likely more losses from running power thru more gears

You have some good points there. Transmissions without 1:1 have been out for quite a few years. What I get a kick out of is the debating about rear end ratios. You can't compare today's trucks with the old ones that have 1:1 transmissions and much smaller tires.

[crossup]

What gets me about all the progress with transmissions, power vs displacement and emphasis on mileage- which I believe is well into the ridiculous in terms of added complexity vs mileage gained- is it seems to not help vans...
My van is a perfect example- 6 speed 6 liter 329hp with 3.42 gears getting 16mpg on a good day
contrast with my 400 small block(6.5L) turbo 350 3 speed w/2.71 gears 1978 G-20 van getting 20mpg. This van was the last year for NO pollution controls(for 3/4 ton unless you count the PCV) and cranked out a mighty 250hp. I've had people point out the new van is heavier but the 20mpg was done with 2 dirt bikes and a lot of gear and up to 3 passengers so likely very similar weights. I will say this, I find I find SEFI much nicer than monkeying with the Quadrajet carb. If I were a rich man I'd build my own custom van with a circa 1995 G-20 and 2017 6.2L Silverado powertrain

[1bigmess]

Originally Posted by crossup

Unrelated but this begs the question with no 1:1 what gear does one use on a dyno?

The same way they always have with so many variables in play: math.

I am pretty sure that every decade or so there is a small discovery or new technique for power transfer that makes having the multiple gear ratios grow in number work out well and reduce losses. It's not like they are taking new engine designs and using the same old drivelines, gears, and transmissions from thirty years ago. More power is being made in smaller packages, and the various drive components are getting smaller, longer lasting, and more efficient too.

I'm not driving my grandfather's pickup in almost any way, and you're not driving your grandfather's van either.

[jacknife]

Expect nothing in the way of problems . That is how they work in tow haul

[lynnmor]

Originally Posted by crossup

What gets me about all the progress with transmissions, power vs displacement and emphasis on mileage- which I believe is well into the ridiculous in terms of added complexity vs mileage gained- is it seems to not help vans...
My van is a perfect example- 6 speed 6 liter 329hp with 3.42 gears getting 16mpg on a good day
contrast with my 400 small block(6.5L) turbo 350 3 speed w/2.71 gears 1978 G-20 van getting 20mpg. This van was the last year for NO pollution controls(for 3/4 ton unless you count the PCV) and cranked out a mighty 250hp. I've had people point out the new van is heavier but the 20mpg was done with 2 dirt bikes and a lot of gear and up to 3 passengers so likely very similar weights. I will say this, I find I find SEFI much nicer than monkeying with the Quadrajet carb. If I were a rich man I'd build my own custom van with a circa 1995 G-20 and 2017 6.2L Silverado powertrain

I have a 1979 Chevy G20 Beauville 8 passenger van with a 350 165 HP engine, 3 speed automatic transmission and a 3.08 rear. I have never seen over 13.5 MPG in the past 38 years. Yes, it has been in limited use all these years and made a Harbor Freight run just a while ago.

From the factory it was missing one oil ring, had a grooved rod bearing from a metal chip and a cracked rocker arm. I fixed those problems myself, dealer was useless. At 79,000 miles it was using too much oil down the valve guides and the cam was spent. I pulled the engine and totally rebuilt it with the best parts available and it has been great ever since. My guess it is slightly over 200 HP now with 355 cu. in. and an Edelbrock cam. Gas mileage actually improved about 1 MPG after the rebuild.

Next project is to replace the standard rear carrier with a posi-traction unit. The standard parts are the same as in a Chevelle and cannot hold up in a 3/4 ton van. I replaced it once before. The side gears wear the holes big because they take a small portion of the weight.

[Ray,IN]

Originally Posted by cfowler55

Running is fifth gear is less taxing on the drivetrain than constantly down/up shifting as load conditions change. Lock out sixth unless on fairly flat highway. Your oil life index is a conditions based system so should show more frequent svc. interval. I would guess +/- a grand for gear change unless carrier has to be replaced. Going to a lower tooth count pinion gear does not allow a proper pinion to ring gear fit at times due to smaller diameter. That should be easy enough to figure out in a parts catalog.

I agree with most of what you said, but installing a different gear set in the diff. will not involve diameter issues, the ring gear will be larger, pinion gears smaller. I had the gearing in my old Dodge PU changed from 3:53 to 4:11 without any problem. The person who sets-up the gear backlash clearance determines how well the new gear-set performs.

Running in 5 gear prevents the GM AFM= Active Fuel Management feature from shutting off 4 cylinders when driving at a constant speed on level ground(feature only works in 6 gear). IMO this is a good thing when empty, but not when towing, as the lag time although short, is very annoying to me when pulling/hauling a load in rolling terrain.

If one desires to drive in 6 gear and prevent the AFM from engaging, I use a Range AFM disable device
It works as advertised. I have noticed a 1 MPG less change in mileage, but eliminating the annoying delay is worth the drop.

[crossup]

What you are seeing is the effect of pollution controls killing mileage. I got my '78 G-20 solely because I first bought a '77 G-10.
'77 was the 3rd year for 1/2 ton vans to use EGR, air pump, cat converter etc. and it totally sucked. The 350 motor had lame power, dead throttle response, sucked gas and was cold blooded as hell. I also made the mistake of buying a silver one, which after 3 dealer repaints still had bad tiger stripes.
After 9 months of that nonsense, I found the '78 G-20 as a Contempo conversion van. It had factory dual exhaust and as mentioned NO pollution BS. It would start in freezing weather and drive immediately without warmup, got better city mileage than my '77 got on the highway and would literary smoke the tires, I ended up putting mag wheels(the exact General Lee Dukes of Hazard wheels) w/G60s on the front and L60s in back and it would still spin them.
I put 99k miles on it although I did have to rebuild the Turbo 350 twice- it was not up to the torque but it was only a 6 hr job to pull it and replace the clutches at under $100 for parts and throw it back in and easy enough I had no problems even though I'd never even owned an automatic before the vans much less worked on one.
It was a great vehicle, survived being totaled into an oak tree and being rebuilt by Maaco as a student training project. I sold it 2 years ago after 37 years of abuse, it still ran great and as far as I know the drive train is still in service in another vehicle.
I support the need for emissions controls(I like to breath clean air ) and applaud the power and torque we now get without an mpg penalty but the downside is pretty significant- I would not even consider rebuilding a 6L90, I understand they have 3x the parts count of the old 350 and if it werent for Chinese clone Tech 2/MDI scanners I couldnt even be able work on the engine.

Originally Posted by lynnmor

I have a 1979 Chevy G20 Beauville 8 passenger van with a 350 165 HP engine, 3 speed automatic transmission and a 3.08 rear. I have never seen over 13.5 MPG in the past 38 years. Yes, it has been in limited use all these years and made a Harbor Freight run just a while ago.

From the factory it was missing one oil ring, had a grooved rod bearing from a metal chip and a cracked rocker arm. I fixed those problems myself, dealer was useless. At 79,000 miles it was using too much oil down the valve guides and the cam was spent. I pulled the engine and totally rebuilt it with the best parts available and it has been great ever since. My guess it is slightly over 200 HP now with 355 cu. in. and an Edelbrock cam. Gas mileage actually improved about 1 MPG after the rebuild.

Next project is to replace the standard rear carrier with a posi-traction unit. The standard parts are the same as in a Chevelle and cannot hold up in a 3/4 ton van. I replaced it once before. The side gears wear the holes big because they take a small portion of the weight.

[crossup]

Good info but does not apply to my van: the L96 does not use AFM. As is a lot of van gear, its a generation behind pickups. The Vortec is at the end its life cycle but does use VVT to get more grunt yet when bolted into a van chasis the L96 is as much as 31 hp down vs other L96 installs.
You are correct about the ring and pinion

Originally Posted by Ray,IN

I agree with most of what you said, but installing a different gear set in the diff. will not involve diameter issues, the ring gear will be larger, pinion gears smaller. I had the gearing in my old Dodge PU changed from 3:53 to 4:11 without any problem. The person who sets-up the gear backlash clearance determines how well the new gear-set performs.

Running in 5 gear prevents the GM AFM= Active Fuel Management feature from shutting off 4 cylinders when driving at a constant speed on level ground(feature only works in 6 gear). IMO this is a good thing when empty, but not when towing, as the lag time although short, is very annoying to me when pulling/hauling a load in rolling terrain.

If one desires to drive in 6 gear and prevent the AFM from engaging, I use a Range AFM disable device
It works as advertised. I have noticed a 1 MPG less change in mileage, but eliminating the annoying delay is worth the drop.

[Jimwelch01]

I have a 2015 F-350 DWD 4X4 crew cab with 8ft bed . It has all the heavy duty options for the suspension Ford has except snow plow. I tow a 2014 28 ft V-Lite by Flagstaff. Dry weight is 6287. I can safely add 1874 . All this to say I hardly ever get out of 6 th gear going up most hills. Now, before you get all up set about too much Truck, I bought it to tow my37 Ft Mobile Suites at around 15,000 lb. I hardly knew it was back there. Drove from Panama City Beach to Semi Valley California. Towed like a dream. Never moved when Semi's passed. Tried to stay around 65 mph at2100 RPM (Truck has a 4:30 rear) I use J rated tires on both trailers. No tire problems in three years. Average 9 mpg. This Truck will pull anything you can Hitch up to. Rated at 35,000 lbs capacity in this configuration. This is my third F-350 starting with 2012 King Ranch all configured the same. I love this Truck. If I could have found a Better one I would have bought it.

[Wireman1]

Whatever you do, be on the proactive side and do your drive train maintenance earlier than later.

Especially the tranny fluid & filter change. A lot of these new vehicle claim that the fluid is 150,000 miles or even lifetime fluid.

When towing that has to be taken with a grain of salt. My TV claims lifetime fluid but I will be changing at around 40K miles just because of towing.

A lot cheaper than a new tranny.

[crossup]

Totally agree and plan on doing a low mileage fluid service as that is the only way to monitor wear - by looking for metal and/or clutch friction material in the fluids. Might be worth sending out for analysis too. A couple checks with no issues would be a good basis to extend the service interval to something significant. Plan is to monitor no load tranny temps for comparision to towing and then base the initial service on what temps I see.

Originally Posted by Wireman1

Whatever you do, be on the proactive side and do your drive train maintenance earlier than later.

Especially the tranny fluid & filter change. A lot of these new vehicle claim that the fluid is 150,000 miles or even lifetime fluid.

When towing that has to be taken with a grain of salt. My TV claims lifetime fluid but I will be changing at around 40K miles just because of towing.

A lot cheaper than a new tranny.

[Wireman1]

Originally Posted by crossup

Totally agree and plan on doing a low mileage fluid service as that is the only way to monitor wear - by looking for metal and/or clutch friction material in the fluids. Might be worth sending out for analysis too. A couple checks with no issues would be a good basis to extend the service interval to something significant. Plan is to monitor no load tranny temps for comparision to towing and then base the initial service on what temps I see.

The new synthetic oil & tranny fluids a vast improvement over the old stuff.

But no more dipstick to check tranny fluid levels or color.

I also monitor my fluid temps while towing with the dash menu, and a Scan Gauge II for actual water temp and EGT.

When towing I always use the paddle shifters to select the gear I feel is best for the situation and to keep the transmission from gear hunting.

I have a 2015 Jeep Grand Cherokee Eco Diesel V6 as a tow vehicle. I've attached a file I saved with info on temps I monitored on a long grade while towing.

JEEP TOWING TEMPS ON BAKER GRADE 8-2016.pdf

[Ray,IN]

Originally Posted by Wireman1

Whatever you do, be on the proactive side and do your drive train maintenance earlier than later.

Especially the tranny fluid & filter change. A lot of these new vehicle claim that the fluid is 150,000 miles or even lifetime fluid.

When towing that has to be taken with a grain of salt. My TV claims lifetime fluid but I will be changing at around 40K miles just because of towing.

A lot cheaper than a new tranny.

That includes flushing and replacing brake fluid. Found out the hard way during our Alaska trip. Brakes on my dually became weak, had brakes checked at Whitehorse, the Chevrolet service dept. found my brake fluid was a dirty brown color=had been overheated. That's when I found out Chevrolet has this procedure in the regular maintenance schedule.

[crossup]

Off topic but had to post this: for the first time today, no wife, clear road. I punched it from a 5 mph roll and all I can say is it take a LOT to impress me given my GTO is 503hp at the wheels. I would expect its about a 6 seconds 0-60, that thing is stupid quick for 6000 lbs.