I drove the new 8-speed yesterday

[Zane]

I had my first chance to try out the new Hydra-Matic 8L90 yesterday at GM's Milford Proving Grounds. Although it was in a Corvette Stingray, I feel that I can give you all a preview of what the new 8-speed might add to the Silverado, Sierra, and other K2 platform models.



If you want to hear about the 8L90 in the Stingray, head over to autoinsane.com and read my article: 8 new reasons to love the Corvette Stingray.



On the pickup side, the new 8L90 will add a considerable amount of polish and refinement. It's an all new design with second generation control systems.

It also fits in the same space and (at least in the Corvette application) weighs 8lbs less. The housing and input/output shafts will be different in the pickup application but the internals will be the same. Programming, shift algorithms and other fine tuning will vary by model and make.

I drove the 8-speed on GM's Milford Road Course at speeds over 100mph and with no restrictions. Summed up, it's the next best thing to a Porsche dual-clutch PDK. I was very impressed and have high hopes for its performance in the K2 platform.

I can see the quicker and firmer shift abilities of this transmission helping towing/hauling confidence. The wider ratio of gears will mean even quicker acceleration and better fuel economy. I think the most noticeable feature, however, is that you'll notice the transmission less. Partial throttle shifts are butter smooth and never hesitate.

Some quick notes:

• No shift slop, as we've sometimes experienced with the current 6-speed
• Very well tuned rev-matching on downshift
• A wider range of shift feel than the 6-speed. Ranges from very smooth to harsh, depending on throttle
• Built to handle up to 650 lb-ft of torque. Seems very mod-resistant.
• Quicker CPU/processor and a handful of new sensors to measure almost every rotating shaft at any given time
• 6.23msec between sensor measurements/adjustments
• Added 1mpg to Corvette highway fuel economy

Want to see and hear how it shifts? Watch this video of me riding with a GM engineer.

I hope this is useful to someone.

[chevyguy45]

Wow thanks Zane. I know the 6 speed in my 09 silverado and 2014 are some sloppy shifters. I cant wait to see how this is in the trucks. Any idea on when the trucks will be available for testing?

[newdude]

Dude how do I get your job or something close to it?

[Roidz]

Cool, good to hear!

 

 

Sent from my iPod touch using Tapatalk

[Daryl LBZ]

I bet having a quicker CPU/Processor is what will mainly contribute to smoother operation. The transmissions now seem to not be able to figure out how to act sometimes which makes me think the computers are slow to process everything.

[seamus2154]

One of my biggest complaints in my 2014 LTZ is the 6 speed trans shifting. Also how it needs so much throttle to downshift. Shifting is terrible.

[00Silverado4x4]

I bet having a quicker CPU/Processor is what will mainly contribute to smoother operation. The transmissions now seem to not be able to figure out how to act sometimes which makes me think the computers are slow to process everything.

I personally think it's not the speed of the processor rather the programming for maximum mpg's causing issues. You need to burn fuel to accelerate and the computer doesn't know what to do to use fuel to accelerate but not burn fuel to keep mpg's up. I think it's computer conflict personally. I drove a couple of the newer trucks (4spd & 6spd). I understand the 6 speed is a learning trans but my experience with it was not pleasent. I had to practicly floor it just to go from 15mph to 25mph.

[Daryl LBZ]

I personally think it's not the speed of the processor rather the programming for maximum mpg's causing issues. You need to burn fuel to accelerate and the computer doesn't know what to do to use fuel to accelerate but not burn fuel to keep mpg's up. I think it's computer conflict personally. I drove a couple of the newer trucks (4spd & 6spd). I understand the 6 speed is a learning trans but my experience with it was not pleasent. I had to practicly floor it just to go from 15mph to 25mph.

That's a good point too. I wonder if it's a little of both the programming, and slow computers?

[PMattras]

Here is a story on the Silverado 8-Speed transmission.

 

http://www.offroadxtreme.com/news/details-new-8-speed-auto-trans-2015-chevy-silverado-1500/?utm_source=rss&utm_medium=rss&utm_campaign=details-new-8-speed-auto-trans-2015-chevy-silverado-1500

[fondupot]

Dangit....and I was perfectly content with my 14 and its 6 speed trans......

[Sluggo]

Was talking to my nephew last weekend about the 6-speeds. He works on developing the algorithms for transmissions at GM though mostly for new, yet to be released designs like the 8-speed and beyond. Apparently there are a herd of engineers working on the various algorithms each a small part of the whole system. One for gear ratios, one for shift points, one for AFM, one for fuel economy... Basically, lots of heads not always talking to each other. All these algorithms are developed by computer simulation and those raw numbers drive the final design, sloppy shifts, slow shifts, excessive downshifts be damned. It's all about the simulated results...real world not so much. He doesn't work on the trucks, but there are many similarities among the vehicle lines so I'm sure he knows what he's talking about. When I commented on the 1-2 shifts and how you often didn't know if it would be crisp or slushy he said "Yep, I know what that is." Obviously, GM knows about a lot of the issues spoken of here, but doesn't think they are real issues because the simulation says it's OK.

 

Hopefully, a lot of these problems in the older design 6-speed don't show up in the 8-speeds, but I wouldn't hold out a lot of hope until someone drives one in an actual truck. That and I don't want to be tempted to buy a '15 when I just got a '14.

[j-ten-ner]

I'm wondering if they finally managed to put a drain plug on the pan...

 

so long

j-ten-ner

[Daryl LBZ]

I'm wondering if they finally managed to put a drain plug on the pan...

 

so long

j-ten-ner

Doubt it. If anything they probably made it harder for the people who change their own fluids.

[kstruckcountry]

Like I've said before, you have to drop the pan to change the filter anyhow, so who needs a plug? I guess in the "simulation" no one spilled transmission fluid all over.

[Sluggo]

Like I've said before, you have to drop the pan to change the filter anyhow, so who needs a plug? I guess in the "simulation" no one spilled transmission fluid all over.

 

I think it's safe to say that nobody working on the simulations, or most of the other parts, would ever think about changing the trans fluid themselves unless you could plug a keyboard in and do it that way. And it would add $0.75 to the BOM,