13-speed-transmission

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Stan Weiss
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13-speed-transmission

Post by Stan Weiss » Fri Feb 23, 2018 6:46 pm

At what point would a CVT be better?

http://www.autoguide.com/auto-news/2018 ... ssion.html

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Re: 13-speed-transmission

Post by exhaustgases » Fri Feb 23, 2018 7:24 pm

Advanced Engine Tech ?

CVT will never be a better choice. A CVT is in constant slippage mode, it does not have high torque capacity. Unlike having materials that are designed to lock together and minimize slippage a CVT has constantly moving cone shaped pulleys that the whole function is to press and slip a metal clad belt between them. They may work in grandma cars just fine, but in a truck for towing heavy loads, or in a performance application, just a bad choice.
In some cases where the belt breaks it can mess the case up and pretty much makes them a disposable unit. I will never buy a vehicle with one.

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Re: 13-speed-transmission

Post by pdq67 » Fri Feb 23, 2018 8:03 pm

Maybe it's just a case where, "mine is bigger than yours!!!"..

I sometimes think that some guys drive great big 1-ton 4x4's all jacked up to compensate for having one too small!!

He, He!!

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Re: 13-speed-transmission

Post by Kenova » Sat Feb 24, 2018 10:18 am

A CVT is great for snowmobiles. Cars? Not so much.

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Re: 13-speed-transmission

Post by gunt » Sat Feb 24, 2018 1:37 pm

Like anything they can be made to handle the tq required , I think Renault F1 developed them and when they were out testing , no one knew about it but the engine was at the one peek bhp rpm at all times the note never changed , a lot of phone calls Bernie was onsite quick enough and they were told what ever they were testing it would be banned . the engine at its most efficient and the box doing all the work .
Some set up like that is in the Fendt tractors and they are famous for it they have licensed the patient to other companies , for town buses i think

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Re: 13-speed-transmission

Post by Stan Weiss » Sat Feb 24, 2018 3:16 pm

It would have been interesting what the results would have been with someone with that R&D budget working on it for racing.

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Re: 13-speed-transmission

Post by peejay » Sat Feb 24, 2018 3:18 pm

CVTs are like anything else. When they are good they are very good, but when they are bad they are horrid.

Subaru/Nissan seem to have figured out how to make a CVT kick ass.

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Re: 13-speed-transmission

Post by pdq67 » Sat Feb 24, 2018 8:16 pm

I thought I read someplace that gigantic earth moving equipment slow rpm torque converters have been filled with, "metal shot", instead of oil.

It was the centrifugal force at low speed that threw the shot out so that the converter locked.

Don't know if this is real or not.

Anybody else hear about this??

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Re: 13-speed-transmission

Post by Truckedup » Sun Feb 25, 2018 8:17 am

pdq67 wrote:
Fri Feb 23, 2018 8:03 pm
Maybe it's just a case where, "mine is bigger than yours!!!"..

I sometimes think that some guys drive great big 1-ton 4x4's all jacked up to compensate for having one too small!!

He, He!!

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Yes, it's the same as having a 500 HP street car... :wink:
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Re: 13-speed-transmission

Post by Brian P » Sun Feb 25, 2018 4:46 pm

The neat thing about planetary gear-sets is that (with suitable design) the number of possible drive ratios goes up exponentially with the number of clutches and gear-sets. The GM/Ford 10-speed has 4 planetary gear-sets and 6 clutches. The ZF/Mopar 8-speed has 4 planetary gear-sets and 5 clutches, the front-drive 9-speed has 6 clutches. The old school 3 speed automatics generally had 2 planetary gear-sets and 4 clutches (a band counts as a clutch). So, the new transmissions are more complicated ... but not in proportion to the number of available ratios.

So, it probably wouldn't be too much of a stretch to go from 10 speeds to 13. But, the law of diminishing returns also applies.

The big efficiency-improver was the ability to lock up the torque converter early (requires short-ratio low gears) and then keep it locked, even through gear shifts, without causing driveability issues, particularly in the higher gears. That requires closely-spaced gears. The other big efficiency-improver, now that the torque converter can stay locked, is to get the cruise revs down. That requires tall cruising gears. Add all this up and you want lots of closely-spaced ratio choices with a big range between 1st and top.

The Chrysler 6-speed in my van is not quite there ... it still unlocks the torque converter more than would be ideal (5th and 6th are too far apart). Just one more available ratio, slotted in between current 5th and current 6th, would be enough to do it. The 9-speed has that extra ratio plus a couple more.

As for that 10-speed ... watch this, and pay attention to the revs. No slippy slushbox here. https://www.youtube.com/watch?v=FrFnrcpBj5k

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Re: 13-speed-transmission

Post by peejay » Sun Feb 25, 2018 7:22 pm

My trans guy said that the Ford 10 speed has different gear ratios for certain gears depending on if it's upshifting or downshifting, or what position the transfer cases is in, or something like that. So technically more than 10 gears...

Without clicking that YouTube link, I bet it's the video of the automatic ZL1 ripping around the Nurburgring, with the driver not touching the shifter once. I love how the powertrain controller rev matches the downshifts automatically.

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Re: 13-speed-transmission

Post by exhaustgases » Sun Feb 25, 2018 8:19 pm

pdq67 wrote:
Sat Feb 24, 2018 8:16 pm
I thought I read someplace that gigantic earth moving equipment slow rpm torque converters have been filled with, "metal shot", instead of oil.

It was the centrifugal force at low speed that threw the shot out so that the converter locked.

Don't know if this is real or not.

Anybody else hear about this??

pdq67
I saw a D7 powershift transmission torque converter that had a nickel size steel shim that mistakenly ended up in the tc it destroyed the aluminum stator and peened the heck out of the rest of the inside. So you won't ever find any kind of loose metal purposely put in a torque converter, that is if you want it to last longer than an hour or so.

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Re: 13-speed-transmission

Post by Brian P » Sun Feb 25, 2018 8:46 pm

peejay wrote:
Sun Feb 25, 2018 7:22 pm
My trans guy said that the Ford 10 speed has different gear ratios for certain gears depending on if it's upshifting or downshifting, or what position the transfer cases is in, or something like that. So technically more than 10 gears...
The Ford/GM 10-speed doesn't do that but the aforementioned Chrysler 62TE 6-speed does, and there is at least one other Chrysler transmission (545RFE) that does that, and there might be others. The Chrysler 62TE is basically a 4-speed gearset followed by a 2-speed splitter-box so theoretically 8 combinations - except two of them work out to be the same ratio and two of them are pretty close. There are two different "4th" gear ratios that are about 10% apart - one used when upshifting, the other under kickdown-downshift conditions.
peejay wrote:
Sun Feb 25, 2018 7:22 pm
Without clicking that YouTube link, I bet it's the video of the automatic ZL1 ripping around the Nurburgring, with the driver not touching the shifter once. I love how the powertrain controller rev matches the downshifts automatically.
Busted ... that's exactly it.

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Re: 13-speed-transmission

Post by pdq67 » Wed Feb 28, 2018 10:30 pm

exhaustgases wrote:
Sun Feb 25, 2018 8:19 pm
pdq67 wrote:
Sat Feb 24, 2018 8:16 pm
I thought I read someplace that gigantic earth moving equipment slow rpm torque converters have been filled with, "metal shot", instead of oil.

It was the centrifugal force at low speed that threw the shot out so that the converter locked.

Don't know if this is real or not.

Anybody else hear about this??

pdq67
I saw a D7 powershift transmission torque converter that had a nickel size steel shim that mistakenly ended up in the tc it destroyed the aluminum stator and peened the heck out of the rest of the inside. So you won't ever find any kind of loose metal purposely put in a torque converter, that is if you want it to last longer than an hour or so.
If I read it right, the fine shot took the place of the oil used to drive it. All slow rpm and way high torque here if not mistaken. I figure more like a fluid coupling instead of a torque converter.

I know, off topic, but my old '48 Dodge 5 pass coupe had a, "Hi-Drive", in it. it was a fluid coupling with a C&PP and 3-speed stick behind it. I used the clutch to drop it in 1st gear and didn't use it again until I had to start from a dead stop again.. I( had to watch the rpm's so that the stick's gears would mesh ok shifting it was all IF I remember correctly, it's been years and years..

pdq67

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