2015 GM Trucks will get 8 speed Transmission
Article here.
Forum Discussion
- The six speeds are actually four speeds with double overdrives. The eight speed is a six speed with double overdrive. The overdrives are a wash. When a four speed has to shift down from 1:1, it goes to third. When a six speed has to shift down from 1:1 it has fourth and fifth to chose from before it gets to third.
N-Trouble wrote:
And 10 even better than that... Then 12....
It starts to become a matter of diminishing returns at some point. Personally I wouldn't want a tranny that's always hunting between gears as that is what an 8-speed is going to do. 6-speeds seem more than enough to me but what do I know
While I agree that there should be a ceiling for optimal number of gears, you've got it backwards when it comes "hunting".
A transmission hunts when there are too FEW ratios. Imagine a 2 speed Powerglide - if you tow with it, it'll always be shifting from 1st to 2nd and back to 1st on hills, because you're rarely in the sweet-spot of either gear (only 2 sweet spots).
With an 8 speed, there are 8 sweet spots. It may shift more, but as an owner, I can tell you it NEVER hunts. It'll shift until you're in the perfect gear, at the perfect throttle position, then hold it until conditions change (hill is over, etc).wilber1 wrote:
Hard to say how far the CVT can be developed but they have come a long way. Nissan is using one behind 3.5L V6's putting out 290 HP in the Murano and Maxima.
We have a CVT with the 4 cyl in a 2014 Honda Accord, Honda's largest sedan. It gets excellent mileage.- Hard to say how far the CVT can be developed but they have come a long way. Nissan is using one behind 3.5L V6's putting out 290 HP in the Murano and Maxima.
mkirsch wrote:
Whether it hunts for gears or not shouldn't be relevant. The shifts are smooth and almost imperceptible.
The point of having the extra gears is to keep the engine in a narrow RPM range where it is most efficient. It's going to shift more frequently than a 4-speed, where you are lugging and revving the engine over a much wider RPM range. If that's a problem for you, you better hope your current truck lasts forever because it's the future.
Eventually CVT will come to pickup trucks and heavy towing.
Nope I don't think you will see a CVT in anything bigger then a compact car. The Jeep Patriot, Compass and Dodge Caliber had a CVT and most buyers hated them. Honda, Nissan, Mitsubishi, Toyota and even Subaru have CVT but not in anything big. Damn-Lire tired but they would not hold up and gave up on the idea.
Don't say it will never happen. People said automatics would never be any good in trucks when the first Powerglide came out in 1950. Now you can hardly get a stick in a pickup truck anymore.- Whether it hunts for gears or not shouldn't be relevant. The shifts are smooth and almost imperceptible.
The point of having the extra gears is to keep the engine in a narrow RPM range where it is most efficient. It's going to shift more frequently than a 4-speed, where you are lugging and revving the engine over a much wider RPM range. If that's a problem for you, you better hope your current truck lasts forever because it's the future.
Eventually CVT will come to pickup trucks and heavy towing.
Don't say it will never happen. People said automatics would never be any good in trucks when the first Powerglide came out in 1950. Now you can hardly get a stick in a pickup truck anymore. - So Ford and GM gave up on the ten speed and are going with a 8 then? BTW the 8 speed will not go behind the D-Max. "Ford Motor Co. and General Motors are developing nine- and 10-speed transmissions jointly for use in cars, crossovers, pickups and SUVs.Both companies likely would use the rwd 10-speed in some pickups, SUVs and performance cars, perhaps including the Ford Mustang and Chevrolet Camaro. GM could also use it on rwd Cadillac nameplates, which now include the CTS and ATS - LINK
Don N-Trouble wrote:
And 10 even better than that... Then 12....
It starts to become a matter of diminishing returns at some point. Personally I wouldn't want a tranny that's always hunting between gears as that is what an 8-speed is going to do. 6-speeds seem more than enough to me but what do I know
You do know that GM/Ford has a joint development project to design and build both a 9 and 10 speed transmission for SUVs/Trucks/etcgoducks10 wrote:
srt20 wrote:
I have an 8 speed, and it definitely does not hunt for gears.
Do you tow heavy with it?
Shouldn't matter if they get the software right. We already have tow haul modes that adjust for heavy towing. Transmissions hunt because they can't find a gear that is the right ratio for the particular condition, so they go back and forth between two, neither of which are suitable for the speed and power required. More gears just gives a better chance of having that right ratio and should result in less hunting.goducks10 wrote:
srt20 wrote:
I have an 8 speed, and it definitely does not hunt for gears.
Do you tow heavy with it?
I too have towed about 60% of its tow rating. It shifted when it needed to and stayed in there until that extra power wasn't needed. It also has manual gear control. It will not let you lug the engine, but it will let you hit the rev limiter.
The only time the TC is unlocked is when stopped or moving very slow. It's a much better trans than the trans of old. My bud has a 2012 3500 Denali duramax that I have driven a lot, loaded and empty. The 8-speed trans is very similar to his Allison as far as the way it acts. Obviously his engine is much stronger and the trans shifts much less, but put the 8-sp behind the big engines and I'm am positive the MAJORITY of people will prefer it. Always will have some haters.
The 8sp isn't using crazy OD ratios. It's similar to the 5 and 6 sp. But the first gear is much steeper, and it stays steeper up until about 5th or 6th.
I'm not saying it's the greatest innovation since sliced bread, but IMO it's a good step in the continual process of improvement. Yes I'm sure there will come a time when the limit has been reached. 8sp or maybe a 24sp, I don't know what that limit is.
