8 Speed Auto for HD trucks

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.

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.

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.

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.

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.

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.

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!

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.

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.

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!