Newer auto transmissions

[Gary Allan]

Originally Posted By: SteveSRT8
Originally Posted By: Gary Allan
Quote:
Mercedes has had infinitely variable lockup for over a decade. Works in any gear but first and reverse.


Is that ala Chrysler method of transitioning?


Wish I knew what you mean.



Look up ^

Quote:
Partial lockup began in 2nd gear, with progressively more lockup applied in 3rd and 4th (which of course ended in 100% lock).


..or some variant of the above? I would expect the Teutonic's to come up with a single t-c with 25 individual fans that were interactive (driving each other) and then sequentially being locked to one another until there was only one rotating mass ..then that too would be locked up.

That is, "something wonderful"

 

[CBR.worm]

Originally Posted By: Gary Allan
Quote:
Partial lockup began in 2nd gear, with progressively more lockup applied in 3rd and 4th (which of course ended in 100% lock).


Never quite saw that as a reliable process. I can't imagine (I'd never pull that one out of my behind in a million years) a "slipping clutch" being used as a virtual variable gear. Too much fine management and too much wear. It would, naturally, provide those velvety smooth shifts that we all pounded our fist on the engineer's desks for ..but ..hey, they're getting paid the big bucks. Simple 6 or 8 range transmissions should have managed well enough, or so I would have thought.

I do admit that my son's 96 Caravan has totally invisible shifts for the most part. I just don't see it as an issue one way or the other. What's it for, providing a better platform for putting on makeup on the way to work?


I don't think it's a major issue, just a novelty that they could shift so smoothly. Not so much today, but in 1989 it was unique in that it didn't feel or work like a typical automatic. Also that they adapted - today we expect that.

The flip side was that no one knew how to work on them and many were getting rebuilt or replaced for software/solenoid/wiring or sensor problems.

 

[SteveSRT8]

Sorry, Gary, you lost me!

But the fact is that the trans can go from 5% to full lockup in 2nd through 5th. It's not progressive, it can go any amount in any gear as the computer sees fit.

But the trans is known for durability and longevity in the most demanding conditions. With minor modifications it is even used in the S65 twin turbo V-12 with over 700 foot pounds of torque.

 

[Gary Allan]

Quote:
Sorry, Gary, you lost me!


Would you ever use your foot with a slipping clutch to regulate your engine to road speed ratio? I find it such an odd way to accomplish this task. I mean, it obviously works, but I'd never EVER go in that direction except for the self glorification of saying that I got it to work.

That's all.

 

[XS650]

Originally Posted By: Gary Allan
They've already sorta done that, haven't they? I mean, don't some transmissions use the lock up converter as intermediate (effective) gear changes? Turns a 4 speed into an 8 range trans??



No, I haven't even heard a car company slimeball marketeer claim that.

 

[rslifkin]

I agree with Gary there. I'd rather have a variable ratio torque converter achieved via moving the vanes, etc (like a variable turbo), than slipping a clutch.

 

[OVERKILL]

Originally Posted By: Gary Allan
They've already sorta done that, haven't they? I mean, don't some transmissions use the lock up converter as intermediate (effective) gear changes? Turns a 4 speed into an 8 range trans??



Yes, I know Ford has been using this technique for years. The 4R100 does it, as does the 5R110. Don't know what other transmissions they build that use it but I imagine all the newer truck ones do.

 

[Gary Allan]

I was sure someone described a Ford engaging lock up between gears .. 1st unlocked/1st locked/2nd unlocked/2nd locked/etc..etc.

I found it complicated, but it would manage smaller steps for the engine to swing rpms under lighter throttle acceleration. All it would require is proper gear spacing and determining a stall speed that would sensibly fit in between them ..a few more points for a ground enabling signal

I've never experienced it, myself. I've got a simple 904 with a lock up. In most lighter throttle situations, my tach never moves until lock up. You just hear the trans shift.


Oh, and I'm all for glorification in engineering feats and marvels. It's just more appreciated when the complexity doesn't compromise durability or result in net losses economically if the thing requires repair.

 

[SteveSRT8]

no added complexity, the clutch is already there. The trick is the variability. The design is incredibly durable and reliable in high torque apps. I had one in an E55.

Many TC lock ups are on/off only. But lots of mfgrs are using variable lock now. It's not a parlor trick, it's a genuine advance of technology.

If you don't like slipping clutches then you don't like automatics!

 

[Gary Allan]

As I conceded, it obviously works. I wouldn't call co-engagement the same thing. In most automatics it's a necessary evil. It's the principle wear factor in every trans out there. Shifting is the one thing that separates an automatic from a simple hydraulic power transmission device.

..but just because it's employed and designed by the big boyz that make the big bucks ..that in itself doesn't make it a 'good thing'. We can assemble a laundry list of design folly that would fill volumes. If the variable lock up torque converter were instead the A4LD trans ..or whatever, we obviously would be treating them like the bad joke that they were, instead of proclaiming them as ingenious.