Cars are really hard to work on anymore

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The throttling back is usually only while in 1st gear and while shifting . Much less driveline stress and no noticeable loss in performance.

On what cars is this happening during acceleration? I know some cars during downshifts are applying brakes by sensor (Mazda) to reduce driveline stress and increase braking performance but only when stopping. Haven't heard of this technology during take off.

 

[aczlan]

On what cars is this happening during acceleration? I know some cars during downshifts are applying brakes by sensor (Mazda) to reduce driveline stress and increase braking performance but only when stopping. Haven't heard of this technology during take off.

Dodge Challenger:

Hesitation when shifting (up to 2005). The engine computer lowers torque when shifting to preserve transmission life, but a service bulletin covers shift hesitation during wide-open throttle on early (2005) SRT-8 cars. When the gas pedal is floored, the engine RPM may go beyond the redline before the shift from first to second is made, so there’s a “short hard bump” as the shift begins, especially when the pedal is floored from about 15 mph. The problem has been solved with new software, and only applied to cars built before July 25, 2005. There is also reportedly a computer upgrade that fixes intermittent engine RPM limiting and ineffectual A/C in early (pre-2006?) Hemis.

Volvo 850:

To enable clean starts from rest the torque in first gear has been limited to 191 lb/ft to eliminate wheelspin and get the power transferred directly onto the road in addition to keeping stresses on the transmission to a minimum.

Evo X:

http://www.autocar.co.uk/car-review/mitsubishi/evo/first-drives/mitsubishi-evo-x-fq-330-gsr-sst][/url]
Perhaps most significant, however, is that the torque limiter, which allowed only 50 per cent of twist in first gear on early FQ-300 models, has gone

Just to name a few

Aaron Z

 

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Dodge Challenger:

Volvo 850:

Evo X:

Just to name a few

Aaron Z

Thanks Aaron. I stand enlightened but sad. The first example is a true computer generated torque limitation. Th other two seem like built in torque control. No loss in performance? Hard sell for a guy using 3000 rpm stall speeds or launching from a 6000 rpm stick shift. Overdrives although saving fuel, seem to have weakened transmissions. Imagine having to computer generate torque lessoning as a result. A 426 hemi in a 68 Road Runner never had to contend with such. Of course it got 11 miles to the gallon but gas back then was measured in cents.

 

[aczlan]

Thanks Aaron. I stand enlightened but sad. The first example is a true computer generated torque limitation. Th other two seem like built in torque control. No loss in performance? Hard sell for a guy using 3000 rpm stall speeds or launching from a 6000 rpm stick shift. Overdrives although saving fuel, seem to have weakened transmissions. Imagine having to computer generate torque lessoning as a result. A 426 hemi in a 68 Road Runner never had to contend with such. Of course it got 11 miles to the gallon but gas back then was measured in cents.

I would bet that most any modern car where the ECU controls the engine (electronic throttle) and transmission (to control shift points, etc) the ECO also limits the torque when shifting or in first gear. If you overbuild your transmission and know how to drive, it is not needed but it lets the OEMs cheap out a little on the transmission specs because it is protected by the ECM.
Some others:
VW: How do tuners get around the dsg torque limit - VW GTI Forum / VW Rabbit Forum / VW R32 Forum / VW Golf Forum - Golfmkv.com
A4 Corvette: http://forums.corvetteforum.com/c5-scan-and-tune/3203659-what-is-torque-limiting.html
Dodge trucks: 68RFE and adding power - DieselRam.com

Aaron Z

 

[Bird]

Overdrives although saving fuel, seem to have weakened transmissions.

I don't remember exactly when the manufacturers started making the automatics with overdrive, but the early ones did have a considerable amount of trouble and a lot of people didn't want them. In fact, when I was in charge of fleet management, one year I had sent the specs to the new, and very young, head of the equipment services department for them to send out for bids for new police sedans. And without talking to me, that idiot changed the specs to require 3-speed (non-overdrive) transmissions, and the purchasing department sent out for bids. I promptly started getting phone calls because neither Ford, Chrysler, nor General Motors made automatic transmissions anymore without overdrive.:laughing: And I can remember when we received new Ford sedans, and each one had a sticker on the dash to shift out of overdrive below 40 mph and in pursuits.

Fortunately, transmissions have gotten better.:laughing: How many people ever turn off the overdrive in their car now?

 

[3930dave]

I would bet that most any modern car where the ECU controls the engine (electronic throttle) and transmission (to control shift points, etc) the ECO also limits the torque when shifting or in first gear. If you overbuild your transmission and know how to drive, it is not needed but it lets the OEMs cheap out a little on the transmission specs because it is protected by the ECM.
Some others:
VW: How do tuners get around the dsg torque limit - VW GTI Forum / VW Rabbit Forum / VW R32 Forum / VW Golf Forum - Golfmkv.com
A4 Corvette: http://forums.corvetteforum.com/c5-scan-and-tune/3203659-what-is-torque-limiting.html
Dodge trucks: 68RFE and adding power - DieselRam.com

Aaron Z

Done right, today, dialing back the engine a bit, to save a trani is not noticeable to most consumers. In general, it is a design/marketing tradeoff that works fairly well. Knowing about this is important, esp. before you slap a (performance, stays-in-while-driving) tuner into a car - some of how they get "improved" performance can be from reducing or eliminating the softening of the engine output - fine if you were budgeting for a performance trani anyway, but an expensive lesson if not.

The glass half full way of looking at this is there are still plenty of times that the full engine output is available.

Not just shifting...... I know GM trucks will dial back power based on steering wheel angle - if you are doing a slow turn in a parking lot, you don't need 400hp. Takes out the fun for a 17 y/o out with Dad's new truck, trying to lay down doughnuts.

I'm mostly OK with the above tradeoffs. That said, I would pay extra money for a physically tougher transmission when signing on the dotted line, but myself and the other TBN'er types that would do this appear to be in the minority, as car companies see it.

There are a number of things driving the mechanical volume and weight of trani's down - modern platform design typically does not give the designers much room to work with (P/U's still being the exception).

Rgds, D.

 

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I would bet that most any modern car where the ECU controls the engine (electronic throttle) and transmission (to control shift points, etc) the ECO also limits the torque when shifting or in first gear. If you overbuild your transmission and know how to drive, it is not needed but it lets the OEMs cheap out a little on the transmission specs because it is protected by the ECM.
Some others:
VW: How do tuners get around the dsg torque limit - VW GTI Forum / VW Rabbit Forum / VW R32 Forum / VW Golf Forum - Golfmkv.com
A4 Corvette: http://forums.corvetteforum.com/c5-scan-and-tune/3203659-what-is-torque-limiting.html
Dodge trucks: 68RFE and adding power - DieselRam.com

Aaron Z

Its not the ECU so much that controls shift points as much as the transmission control unit itself. The tcu certainly gets feed back from the ecu and this all gets transferred with the use of solenoids and sensors. . I'm not sure "cheapened" is the correct word to use when more money has gone into todays tranny technology than ever before. With todays legislative edicts that manufacturers must follow, you can no longer build a simple, sturdy 3 spd transmission in todays world and it woudln't matter if the car had only 180 hp.. Perhaps "tipping point" is a better description that balances (what Dave 3930 alludes to) price points, vehicle sustainability, manufacturer reputation and the performance people are clamoring for. To the original op, in every do it yourselfers tool box today, a set of metric gear wrenches is just about mandatory.

 

[aczlan]

Its not the ECU so much that controls shift points as much as the transmission control unit itself. The tcu certainly gets feed back from the ecu and this all gets transferred with the use of solenoids and sensors.

Sorry, I should have said PCM, not ECU.

Aaron Z

 

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Sorry, I should have said PCM, not ECU.

Aaron Z

No "sorries" needed Aaron. I suppose today there needs to be a delineation if indeed things are being separately controlled but many times and in many circles a pcm and ecu were talked about as one in the same. Mopar has a performance pcm for OBD 1 vehicles that does absolutely nothing to the tranny shift points but is advertised as such. As a "Performance Power control Module" you would indeed think it alters shift points. Snappy throttle response is tricky today. Yesteryear, if one wanted to control launch torque, you'd just plop in a cam with a higher duration and balance that off with a steeper gear set. Who cared about vacuum. If you had enough to stop, that's all that was needed.
Today you need to have everything including gas mileage. With all the added crap that people's vocations need to contend with today from teaching to engineering, I barely function in todays world. I'm still wrapping my head around a computer controlling wot launch.

 

[buickanddeere]

Full power shift tend to break the tires loose. Looks, sound and feels cool but........There is a risk of loss of control when the tires break loose on a shift. Also the 1/4 mile time may improve when the tires stay in full contact and the chassis/suspension does not have to absorb a shock load. Backing off the engine torque a little during the shift isn't all bad. Makes for simple reliable and smooth shifts from one clutch pack to another.