8 Speed Auto for HD trucks

[ib516]

Apparently, ZF is making an 8 Speed HD trans that can handle 1000 lb-ft. 2020 release date. I see it as the next trans in the Ram 2500 and 3500s.

LINK

[Me_Again]

Maybe Diesel/Electric will take over like Locomotives and Ships!

[wilber1]

valhalla 360 wrote:
And the old guys probably said the same thing when automatics went from 2 to 3 gears.

Ya, I have a 66 Chrysler 300 convertible with a 440 TNT and Torqueflite transmission. Great tranny in its day, three speeds compared to GM's Powerglide two speed, but terrible compared to today's transmissions

[wilber1]

CVT's have come a long way. Nissan's use a steel belt or chain and a planetary gear.

...Nissan's many programming changes to the CVT are so substantial and so mimic a regular gearbox that if you did not know a CVT from a sock drawer, you would never question how the power from the engine is transferred..”- Autotrader

[wnjj]

Me Again wrote:
OK, so in 1976 to 1979 I drove a truck with a 13 speed Roadranger tranny. Along came people have did not know how to drive a manual tranny, so Firetrucks and garbage trucks got automatics. The CVT trannies will complete the circle. BTW, I really liked the 13 speed, let the clutch out in the tank yard in Port Angeles and put it back in at Forks 70 miles away! With lots of shift in between.

Chris

I think you may be interchanging "not know how" and "have no desire to". I for one would not want a job driving a garbage truck while having to push a heavy clutch in hundreds of times a day. It's probably important not to stall a firetruck engine when it's running pumps and other equipment, no matter how unlikely that is with an experienced driver.

My first tractor-trailer experience was on a 13-speed too. 😉

[Me_Again]

valhalla360 wrote:

Me Again wrote:


I towed with a 2001.5 gear bound 47RE for years. The 6 speed Aisin resolved that. I see not need for more gears.

I have golf carts and had snowmobiles with CVT setups. The higher powered snowmobiles required routine maintenance. The golf cart's not so much.

And the old guys probably said the same thing when automatics went from 2 to 3 gears.

CVT's used in trucks will be nothing like the snowmobile transmissions. Of course they aren't going to use a simple rubber belt for a truck towing 15k lbs. That's also why they haven't put the trucks out with CVT's yet but I can guarantee someone is working on it.

PS: Just looked up and there is a consortium of semi tractor manufacturers working on one.

OK, so in 1976 to 1979 I drove a truck with a 13 speed Roadranger tranny. Along came people have did not know how to drive a manual tranny, so Firetrucks and garbage trucks got automatics. The CVT trannies will complete the circle. BTW, I really liked the 13 speed, let the clutch out in the tank yard in Port Angeles and put it back in at Forks 70 miles away! With lots of shift in between.

Chris

[valhalla360]

Me Again wrote:


I towed with a 2001.5 gear bound 47RE for years. The 6 speed Aisin resolved that. I see not need for more gears.

I have golf carts and had snowmobiles with CVT setups. The higher powered snowmobiles required routine maintenance. The golf cart's not so much.

And the old guys probably said the same thing when automatics went from 2 to 3 gears.

CVT's used in trucks will be nothing like the snowmobile transmissions. Of course they aren't going to use a simple rubber belt for a truck towing 15k lbs. That's also why they haven't put the trucks out with CVT's yet but I can guarantee someone is working on it.

PS: Just looked up and there is a consortium of semi tractor manufacturers working on one.

[Me_Again]

srt20 wrote:
I'm guessing the folks that dont like the 8sp havent driven a vehicle with it.

I own a 8sp, and a 10sp. And they are both nicer than a 4sp or 6sp.

A hemi going through 8 gears at WOT is wonderful music. My ecoboost going through 10 gears doesnt sound nearly as nice, but it gets there quicker.

And these trans are way better for towing. They will find the correct gear and hold it there. No more TC unlocking and locking all day long.
Im sure someone will tell me their 6sp doesnt do that, but I have thousands of towing miles in the mountains with a 12 duramax/allison, and yeah the TC unlocks.

Yep, gas rigs can benefit from more gears. TC locking and unlocking is a program issue, not the number of gears. My custom 47RE 4 speed shifted lock to lock with the DTT smart controller.

[srt20]

I'm guessing the folks that dont like the 8sp havent driven a vehicle with it.

I own a 8sp, and a 10sp. And they are both nicer than a 4sp or 6sp.

A hemi going through 8 gears at WOT is wonderful music. My ecoboost going through 10 gears doesnt sound nearly as nice, but it gets there quicker.

And these trans are way better for towing. They will find the correct gear and hold it there. No more TC unlocking and locking all day long.
Im sure someone will tell me their 6sp doesnt do that, but I have thousands of towing miles in the mountains with a 12 duramax/allison, and yeah the TC unlocks.

[ScottG]

Personally, I hate CVT's. I owned one car with one and have a Jeep Patriot loaner right now that has it. Just like the first one, you can never predict what it's going to do (if anything) and what ever it randomly decides to do, it takes forever.

[FishOnOne]

Me Again wrote:

wilber1 wrote:

Me Again wrote:
With diesel engines wide flat torque curves, I just do not understand the need for more than 6 gears. Except for maybe RAM 68RFE that has tall 1st and 2 gears. Might be easier to just fix the ratios of the existing box than add more gears.

But how about two reverse gears, with a granny gears for the second one. Would be great for spotting trailers etc.

You want a gear that can give you max HP at WOT. More gears make it more likely you will have one instead of being in between gears and shifting back and forth as you go from a gear that doesn't give you enough power to one that puts you on the rev limiter and back again. Also 900 Lbft at 2000 RPM makes about 340 HP, at 2500 RPM it is closer to 428 HP. If you had an in between gear you could make 386 HP at 2250 RPM. So more gears can actually mean less shifting.

But why! I am towing at 24,500 combined without any issues, lack of power and/or starting issues!

I'm sure you as well as others said the same with the release of the 6 speed. Same argument with trucks that didn't require DEF vs DEF equipped trucks. We all know who eventually won that argument.

On another note I though ram was is bed with aisin. Perhaps this tranny is for GM.

[Me_Again]

wilber1 wrote:

Me Again wrote:

wilber1 wrote:

Me Again wrote:
With diesel engines wide flat torque curves, I just do not understand the need for more than 6 gears. Except for maybe RAM 68RFE that has tall 1st and 2 gears. Might be easier to just fix the ratios of the existing box than add more gears.

But how about two reverse gears, with a granny gears for the second one. Would be great for spotting trailers etc.

You want a gear that can give you max HP at WOT. More gears make it more likely you will have one instead of being in between gears and shifting back and forth as you go from a gear that doesn't give you enough power to one that puts you on the rev limiter and back again. Also 900 Lbft at 2000 RPM makes about 340 HP, at 2500 RPM it is closer to 428 HP. If you had an in between gear you could make 386 HP at 2250 RPM. So more gears can actually mean less shifting.

But why! I am towing at 24,500 combined without any issues, lack of power and/or starting issues!

So? What's your point? Torque to HP is a pretty simple calculation. I've towed the same weight with both four and six speed transmissions in diesels with flat torque curves from 1600 RPM to 2800 RPM. I would get stuck shifting back and forth between two ratios on hills quite often with the four speed. The six speed is much better but eight speeds would be even better still. I have a ZF 8 speed in my car and it is by far and away the best transmission I have ever had and always seems to be in the right gear.

CVT's aren't popular but one thing they can do is keep an engine operating at peak HP without getting stuck between two ratios.

I towed with a 2001.5 gear bound 47RE for years. The 6 speed Aisin resolved that. I see not need for more gears.

I have golf carts and had snowmobiles with CVT setups. The higher powered snowmobiles required routine maintenance. The golf cart's not so much.

[wilber1]

Me Again wrote:

wilber1 wrote:

Me Again wrote:
With diesel engines wide flat torque curves, I just do not understand the need for more than 6 gears. Except for maybe RAM 68RFE that has tall 1st and 2 gears. Might be easier to just fix the ratios of the existing box than add more gears.

But how about two reverse gears, with a granny gears for the second one. Would be great for spotting trailers etc.

You want a gear that can give you max HP at WOT. More gears make it more likely you will have one instead of being in between gears and shifting back and forth as you go from a gear that doesn't give you enough power to one that puts you on the rev limiter and back again. Also 900 Lbft at 2000 RPM makes about 340 HP, at 2500 RPM it is closer to 428 HP. If you had an in between gear you could make 386 HP at 2250 RPM. So more gears can actually mean less shifting.

But why! I am towing at 24,500 combined without any issues, lack of power and/or starting issues!

So? What's your point? Torque to HP is a pretty simple calculation. I've towed the same weight with both four and six speed transmissions in diesels with flat torque curves from 1600 RPM to 2800 RPM. I would get stuck shifting back and forth between two ratios on hills quite often with the four speed. The six speed is much better but eight speeds would be even better still. I have a ZF 8 speed in my car and it is by far and away the best transmission I have ever had and always seems to be in the right gear.

CVT's aren't popular but one thing they can do is keep an engine operating at peak HP without getting stuck between two ratios.

[Me_Again]

wilber1 wrote:

Me Again wrote:
With diesel engines wide flat torque curves, I just do not understand the need for more than 6 gears. Except for maybe RAM 68RFE that has tall 1st and 2 gears. Might be easier to just fix the ratios of the existing box than add more gears.

But how about two reverse gears, with a granny gears for the second one. Would be great for spotting trailers etc.

You want a gear that can give you max HP at WOT. More gears make it more likely you will have one instead of being in between gears and shifting back and forth as you go from a gear that doesn't give you enough power to one that puts you on the rev limiter and back again. Also 900 Lbft at 2000 RPM makes about 340 HP, at 2500 RPM it is closer to 428 HP. If you had an in between gear you could make 386 HP at 2250 RPM. So more gears can actually mean less shifting.

But why! I am towing at 24,500 combined without any issues, lack of power and/or starting issues!

[wilber1]

Me Again wrote:
With diesel engines wide flat torque curves, I just do not understand the need for more than 6 gears. Except for maybe RAM 68RFE that has tall 1st and 2 gears. Might be easier to just fix the ratios of the existing box than add more gears.

But how about two reverse gears, with a granny gears for the second one. Would be great for spotting trailers etc.

You want a gear that can give you max HP at WOT. More gears make it more likely you will have one instead of being in between gears and shifting back and forth as you go from a gear that doesn't give you enough power to one that puts you on the rev limiter and back again. Also 900 Lbft at 2000 RPM makes about 340 HP, at 2500 RPM it is closer to 428 HP. If you had an in between gear you could make 386 HP at 2250 RPM. So more gears can actually mean less shifting.

[ScottG]

Cummins12V98 wrote:

ScottG wrote:
I think the advantage here will be because of the deep first gear of the ZF's and the 3.42 gearing your stuck with in the RAM. Hopefully that low gear will improve the SRW 3500 off-the-line performance and bring it up to that of the current trans with 4.10's.

Already a simple solution, get the AISIN with MORE power to boot!

Oh I would get the Aisin but 4.10's even with the Aisin get off the line a lot quicker. Not positive but I suspect my ZF has an even lower first gear. It's all but useless in a light car with lots of power.
The ZF also shifts a lot faster than the Aisin.