Ruminations on SST Driving Habits
Jan 28, 2012, 01:55 PM
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Ruminations on SST Driving Habits
Over the last couple years we've heard from all different folks, in all different locales, with all different driving habits/characteristics. There are some noticeable similarities with those who do and don't experience problems. I am one of those who (knock on wood) have not ever had an serious problems. The worst problem I had was self induced; in 40* weather I floored it from a dead stop and caused one of the tranny lines going to my secondary cooler to start leaking. But like I said, this was self induced, and self rectified.
This thread is for everyone who wants to know what driving habits have shown a causality with known problems. This does not take into consideration physical defects (i.e. 09's with leaking filter housing and/or bad temp sensors) due to early technological generations. There seems to be a prevailing internet misconception that the SST breaks "just 'cause"
The mass majority of reported problems have been with completely stock cars being driven like they're a Prius (i.e. trying to conserve gas). They all have similarly report problems of slipping clutches, stuck in odd/even gearing, and bucking.
The car's with the apparent least reported problems: tuned and bolted; of course the noticeable exception to this are those tooooned by shops with virtually 0 experience with the SST or any DCT's.
The key to strength, longevity, and generally all around good characteristics seem to be 3 fold:
1) Temperature: The SST's major Achilles heal is temperature control. It has a difficult time maintaining optimal operating temps (generally thought to be 150-190* F, or 65-90* C). This can have two different implications-
2) Airflow: the SST seems to use expected airflow for most of it's calculations. This comes into play for everything from torque management to coasting, all related to clutch pressure and rev matching. Thankfully a while back there was a patch created to bypass the airflow tables related to torque management (
). But other's still come into play, most notably for non-boost operations, such as decelerating and coasting. If you ever look at the stock MAP tables relative to Load (actual g/s) for a tuned/modified car, there are striking differences. These differences have commonly caused the affliction affectionately know as "bucking". It seems that the TCU is making educated guesses for clutch pressures and rev-matching based on expected airflow values (a means of determining Load). Logically if the actual values are significantly different, there are drive-ability issues. I can't prove any of this, but it has shown a direct causality that is undeniable.
The simplest means of rectifying this problem is creating a smooth VE table and re-scaling your MAF (as the ECU switches back and forth between the two when calculating Load) to make expected airflow significantly closer to actual. However, there are 2 things to be prepared for: 1) you will need to re-do your fuel (it uses these same tables for AFR calculations), and 2) anytime you make significant changes to boost or MIVEC you will need to re-tweak the VE and MAF tables (which makes complete sense as boost and MIVEC control the volume the air entering the cylinders).
3) Tuning: Easily the most important aspect of this whole thing for modified cars. In fact all the airflow aspects are managed via tuning, as well as timing, shifting characteristics, etc. The key thing to remember here is EXPERIENCE SPEAKS VOLUMES! This is NOT an area to cheap out on by going to the local muscle car tuner. This has been a problem repeated here countless times, always with the same tragic results. Bad tuning (i.e. leaving stock values in some tables when modifying others) can cause any number of problems from slipping clutches at WOT (right into the rev-limiter) to bent valves (due to extreme timing changes). The most commonly reported problem (when logging) is shift knock.
TL;DR:The key things to take away are get the car into healthy operating temps, and invest in a good tune from an accredited SST-aficionado
This thread is for everyone who wants to know what driving habits have shown a causality with known problems. This does not take into consideration physical defects (i.e. 09's with leaking filter housing and/or bad temp sensors) due to early technological generations. There seems to be a prevailing internet misconception that the SST breaks "just 'cause"
The mass majority of reported problems have been with completely stock cars being driven like they're a Prius (i.e. trying to conserve gas). They all have similarly report problems of slipping clutches, stuck in odd/even gearing, and bucking.
The car's with the apparent least reported problems: tuned and bolted; of course the noticeable exception to this are those tooooned by shops with virtually 0 experience with the SST or any DCT's.
The key to strength, longevity, and generally all around good characteristics seem to be 3 fold:
1) Temperature: The SST's major Achilles heal is temperature control. It has a difficult time maintaining optimal operating temps (generally thought to be 150-190* F, or 65-90* C). This can have two different implications-
Stock: for those who drive around with the specific intention of saving gas, you may be hurting your car. The clutches intentionally slip themselves when cold, in an attempt to generate additional heat. So if day in day out you putz around looking slick, this is not the car for you. The car never generates enough heat, and after 20k miles of constantly slipping, the clutches seem give out. Little do they realize that if they just got on the throttle a bit before cruising, they would be helping their tranny (against the general idea of MOST American cars, understandable why a number of drivers incorrectly think they are "being nice" to the car).
Modified: for those who are fully bolted, tuned, and maybe a different turbo, the temp problems are on the other end of the scale. They generally have no problems getting up to operating temps (2 miles of boost is better than 10 miles of gas 
). The issue is with shedding off excess heat (+200* F, or + 95* C) when driving spirited for long stretches of time (track driving, not DD); IIRC around 230* F it starts to slip really bad. Thankfully there are several different options, depending on how extreme your upper temperature range is. Anything from removing the fog lights and installing a Spal fan, all the way to a deep/baffled/billet oil pans and secondary pumps/coolers.
The most efficient means seems to be shedding excess heat, rather than preventing heat build-up. This means go and drive your car!! It is not designed to be a gas sipping commuter, your car is begging for more right foot action. Get everything up into the healthy temp range, your car will tell you if you are starting to push it's limits; but conversely it won't tell you that you are too far below the optimal temp range...until it's too late.). The issue is with shedding off excess heat (+200* F, or + 95* C) when driving spirited for long stretches of time (track driving, not DD); IIRC around 230* F it starts to slip really bad. Thankfully there are several different options, depending on how extreme your upper temperature range is. Anything from removing the fog lights and installing a Spal fan, all the way to a deep/baffled/billet oil pans and secondary pumps/coolers.2) Airflow: the SST seems to use expected airflow for most of it's calculations. This comes into play for everything from torque management to coasting, all related to clutch pressure and rev matching. Thankfully a while back there was a patch created to bypass the airflow tables related to torque management (
). But other's still come into play, most notably for non-boost operations, such as decelerating and coasting. If you ever look at the stock MAP tables relative to Load (actual g/s) for a tuned/modified car, there are striking differences. These differences have commonly caused the affliction affectionately know as "bucking". It seems that the TCU is making educated guesses for clutch pressures and rev-matching based on expected airflow values (a means of determining Load). Logically if the actual values are significantly different, there are drive-ability issues. I can't prove any of this, but it has shown a direct causality that is undeniable. The simplest means of rectifying this problem is creating a smooth VE table and re-scaling your MAF (as the ECU switches back and forth between the two when calculating Load) to make expected airflow significantly closer to actual. However, there are 2 things to be prepared for: 1) you will need to re-do your fuel (it uses these same tables for AFR calculations), and 2) anytime you make significant changes to boost or MIVEC you will need to re-tweak the VE and MAF tables (which makes complete sense as boost and MIVEC control the volume the air entering the cylinders).
3) Tuning: Easily the most important aspect of this whole thing for modified cars. In fact all the airflow aspects are managed via tuning, as well as timing, shifting characteristics, etc. The key thing to remember here is EXPERIENCE SPEAKS VOLUMES! This is NOT an area to cheap out on by going to the local muscle car tuner. This has been a problem repeated here countless times, always with the same tragic results. Bad tuning (i.e. leaving stock values in some tables when modifying others) can cause any number of problems from slipping clutches at WOT (right into the rev-limiter) to bent valves (due to extreme timing changes). The most commonly reported problem (when logging) is shift knock.
TL;DR:The key things to take away are get the car into healthy operating temps, and invest in a good tune from an accredited SST-aficionado
Last edited by sstevojr; Feb 6, 2012 at 12:52 PM.
Jan 28, 2012, 03:41 PM
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Interesting analysis, but I take issue with your assumption that driving the car using light throttle will damage the transmission. I'm not sure how you came to this conclusion because I don't know which forums and threads you gathered information from, but I suspect your research is incomplete.
You seem to jump to the conclusion that consistent "fuel economy" driving damages the transmission simply because some people reported in a thread that their SST broke and they said they only drive it like a little old lady. It is dangerous to draw this conclusion because, shockingly, people lie in forum posts. Without neing sure of the whole truth, the poster's input must be taken with a grain of salt.
Here is an example where your theory might fall apart: Highway driving at 60mph in sixth gear requires very little throttle, so by your reasoning this behavior would cause the transmission to fall out of its optimal temperature range and begin to slip the clutches. Anyone who has a long commute to work could be subjected to premature clutch wear.
There is also another flaw to your theory. Both Mitsubishi and Getrag performed extensive testing on these transmissions. This testing usually involves extensive use of low speed driving. This is done so they can tune the TCU to get proper shifts as well as to measure clutch wear. It would seem logical that excessive clutch wear would have shown up in these tests. After all, Mitsubishi doesn't want to spend alot of money replacing clutches before the 5/60 warranty is up.
It would be improper to conclude that slow driving contributes to SST failure based on the data you have presented. I understand why you made the statements that you did, I just believe that there are too many unknowns involved to make this conclusion. However, I do agree with you that proper ECU/TCU tuning and transmission cooling are essential to extending SST life when engine power is increased. This has been proven extensively by both computer science and general physics.
I don't intend for this post to demean you, or to be insulting to the effort that you applied to your research. My issue is only with the conclusions to which you have arrived. If you have more insight into your opinion, please post.
You seem to jump to the conclusion that consistent "fuel economy" driving damages the transmission simply because some people reported in a thread that their SST broke and they said they only drive it like a little old lady. It is dangerous to draw this conclusion because, shockingly, people lie in forum posts. Without neing sure of the whole truth, the poster's input must be taken with a grain of salt.
Here is an example where your theory might fall apart: Highway driving at 60mph in sixth gear requires very little throttle, so by your reasoning this behavior would cause the transmission to fall out of its optimal temperature range and begin to slip the clutches. Anyone who has a long commute to work could be subjected to premature clutch wear.
There is also another flaw to your theory. Both Mitsubishi and Getrag performed extensive testing on these transmissions. This testing usually involves extensive use of low speed driving. This is done so they can tune the TCU to get proper shifts as well as to measure clutch wear. It would seem logical that excessive clutch wear would have shown up in these tests. After all, Mitsubishi doesn't want to spend alot of money replacing clutches before the 5/60 warranty is up.
It would be improper to conclude that slow driving contributes to SST failure based on the data you have presented. I understand why you made the statements that you did, I just believe that there are too many unknowns involved to make this conclusion. However, I do agree with you that proper ECU/TCU tuning and transmission cooling are essential to extending SST life when engine power is increased. This has been proven extensively by both computer science and general physics.
I don't intend for this post to demean you, or to be insulting to the effort that you applied to your research. My issue is only with the conclusions to which you have arrived. If you have more insight into your opinion, please post.
Last edited by jkennedy293; Jan 28, 2012 at 04:02 PM.
Jan 28, 2012, 05:00 PM
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You took one small aspect of what I said an applied it as an absolute. I did not say:
What I said was:
This in no way infers that cruising on the freeway damages your car, that's obvious absurd (not sure why you would think that).
Cruising in 6th gear means you are staying in gear, there is no slipping to happen. BUT always putz around in town doing short drives in auto/normal as the ONLY means of driving is not ideal for this transmission. Being in 6th at 35mph has undue wear and tear:
I used the recurring reports as a basis to go and test with my own car. Give it try, let me know how your tranny drives when constantly short shift to stay out of boost w/o allowing the car to warm up. The car starts to drive extremely poorly. No conclusions made from "internet liars", I've been testing everything I said day in and day out for the last 4 months.
The key point of the Temp section is the need to get the car up to temp. It doesn't even slightly hint that cruising on the freeway will damage the car.
Highway driving at 60mph in sixth gear requires very little throttle, so by your reasoning this behavior would cause the transmission to fall out of its optimal temperature range and begin to slip the clutches.
So if day in day out you putz around looking slick, this is not the car for you.
Cruising in 6th gear means you are staying in gear, there is no slipping to happen. BUT always putz around in town doing short drives in auto/normal as the ONLY means of driving is not ideal for this transmission. Being in 6th at 35mph has undue wear and tear:
The car never generates enough heat, and after 20k miles of constantly slipping, the clutches give out.
You seem to jump to the conclusion that consistent "fuel economy" driving damages the transmission simply because some people reported in a thread that their SST broke and they said they only drive it like a little old lady.
The key point of the Temp section is the need to get the car up to temp. It doesn't even slightly hint that cruising on the freeway will damage the car.
Last edited by sstevojr; Jan 28, 2012 at 05:12 PM.
Jan 28, 2012, 06:34 PM
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Yes, you did say:
but you also said:
Which seems like a bold claim that you cannot back up with a single fact. I will admit my scenario was a bit out there, so i apologize for that.
This a problem in every transmission, it is not exclusive to the SST. Also, this is not the same as "drive around with the specific intention of saving gas." The two can be mutually exclusive.
I'm interested to know how you are able to drive your car for so long without it warming up as mine is completely warmed up before I get two miles down the road. Yes, short shifting below boost does cause stumbling, but it isn't because of temperature, its because the engine RPM in the higher gear is too low.
So I assume you broke down the transmission to measure clutch wear before and after your testing.
Look, your second post clarified, greatly, the points you expressed in your first post. And if it was included, I wouldn't have said anything.
I do agree with you never get the car above 40mph you shouldn't own it. I just have a problem with you painting with a broad brush by saying that driving the car gently will cause damage to the transmission.
If you look at the transmissions on the stock cars that were replaced, almost all of them have been low mileage units. I have not seen any that broke with more than 30,000 miles. This seems to indicate a production problem, and these transmissions probably would have broke regardless of how they were driven. Now, I haven't seen every post, so if you have some insight please share. I would be interested to know about these other cars.
Once again, nothing against you. I just don't like misinformation floating around on the forums.
So if day in day out you putz around looking slick, this is not the car for you.
but you also said:
for those who drive around with the specific intention of saving gas, you are hurting your car.
BUT always putz around in town doing short drives in auto/normal as the ONLY means of driving is not ideal for this transmission. Being in 6th at 35mph has undue wear and tear:
I used the recurring reports as a basis to go and test with my own car. Give it try, let me know how your tranny drives when constantly short shift to stay out of boost w/o allowing the car to warm up.
I've been testing everything I said day in and day out for the last 4 months.
Look, your second post clarified, greatly, the points you expressed in your first post. And if it was included, I wouldn't have said anything.
I do agree with you never get the car above 40mph you shouldn't own it. I just have a problem with you painting with a broad brush by saying that driving the car gently will cause damage to the transmission.
If you look at the transmissions on the stock cars that were replaced, almost all of them have been low mileage units. I have not seen any that broke with more than 30,000 miles. This seems to indicate a production problem, and these transmissions probably would have broke regardless of how they were driven. Now, I haven't seen every post, so if you have some insight please share. I would be interested to know about these other cars.
Once again, nothing against you. I just don't like misinformation floating around on the forums.
Last edited by jkennedy293; Jan 28, 2012 at 06:37 PM.
Jan 29, 2012, 12:13 AM
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Logging the SST temp separately is a real eye-opener.
Rich
Jan 29, 2012, 12:28 AM
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I'm deffinitely paying more attention to my SST from now on!! But not to get too off topic. When I go in to get my tune from english racing, what question should I ask as pertaining to my "stock tables" and the tables they may be modifying. I just want to make sure I'm understanding what it is I'm actualy paying for. Besides I'm up for any education on good tuning. PM me if you have something for me.
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Jan 29, 2012, 01:05 AM
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I'm not sure of what "Prius" everyone is talking about, but where I'm from, we have mountains and they try to pass me up hill all the time.
I shift at 2.5`3.5 in the drone. Always Manual-Normal! Auto-Sport is faster than me in SCCA Solo by a few tenths on a 60sec run.
The only worry I have about my transmission is the fluff on the nets about how soft the SST is and equaly, how soft MitsUS is treating them for warranty. I'm not a fan of being dicked.
Do I drive better than a Prius for MPG? Yes
Do I hoon it? Of Course
Do I have issues with my SST? No
Do I feel lucky? Yes
Am I scared ****less for when it all goes pear shaped? Fuq. Yes.
I shift at 2.5`3.5 in the drone. Always Manual-Normal! Auto-Sport is faster than me in SCCA Solo by a few tenths on a 60sec run.
The only worry I have about my transmission is the fluff on the nets about how soft the SST is and equaly, how soft MitsUS is treating them for warranty. I'm not a fan of being dicked.
Do I drive better than a Prius for MPG? Yes
Do I hoon it? Of Course
Do I have issues with my SST? No
Do I feel lucky? Yes
Am I scared ****less for when it all goes pear shaped? Fuq. Yes.
Last edited by GAbOS; Jan 29, 2012 at 01:11 AM.
Jan 29, 2012, 02:59 AM
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Jan 29, 2012, 09:37 AM
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You got it backwards, the SST is inefficient at getting up to temp.
You can't use the coolant temp gauge as a means if determining if the tranny is up to temp. The gauge isn't even accurate for engine temps, let alone the tranny which it receives 0 inputs from.
You can continue to dispute all you like, it's always easier to poke holes than prove something new.
No reason to be a jerk about it. Let me guess, you were in debate class in high schools, and learned the old trick of "pick one minor aspect as a basis for refuting the entire statement".
Like I said, go out and log SST temps and clutch slippage. See the results for your self.
I'm interested to know how you are able to drive your car for so long without it warming up as mine is completely warmed up before I get two miles down the road.
You can continue to dispute all you like, it's always easier to poke holes than prove something new.
So I assume you broke down the transmission to measure clutch wear before and after your testing.
Like I said, go out and log SST temps and clutch slippage. See the results for your self.
Last edited by sstevojr; Jan 29, 2012 at 09:48 AM.
Jan 29, 2012, 09:49 AM
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For logging...
SST Temp is quite odd. It takes a long time to warm up. It sheds heat well when moving... unless you're really giving it heaps.
Track driving is therefore an issue - it builds up heat, which then sticks around all day. A cooldown lap won't do much at all, and parking it up does nothing.
I stuck a temp-switched fan on my stock cooler. Will see how the old SST fares with that...
Rich
PS. sstevojr has a point about granny driving, but IMHO there are only two specific risk areas...
1. Endless AUTO mode gearshifts in stop/go traffic
2. TCU riding the odd clutch in 1st in crawling stop/go traffic
Code:
code] <DataListItem DataLog="N" Color="" Display="SST Transmission Temp" LogReference="SST_TM_Temp" RequestID="CAN28-0" Eval="x-50" Unit="Deg F" MetricEval="x-50" MetricUnit="Deg C" ResponseBytes="1" GaugeMin="0" GaugeMax="1000" ChartMin="0" ChartMax="1000" ScalingFactor="1" Notes="" Priority="1" Visible="False" />
Track driving is therefore an issue - it builds up heat, which then sticks around all day. A cooldown lap won't do much at all, and parking it up does nothing.
I stuck a temp-switched fan on my stock cooler. Will see how the old SST fares with that...
Rich
PS. sstevojr has a point about granny driving, but IMHO there are only two specific risk areas...
1. Endless AUTO mode gearshifts in stop/go traffic
2. TCU riding the odd clutch in 1st in crawling stop/go traffic
Jan 29, 2012, 09:50 AM
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I'm not sure of what "Prius" everyone is talking about, but where I'm from, we have mountains and they try to pass me up hill all the time.
I shift at 2.5`3.5 in the drone. Always Manual-Normal! Auto-Sport is faster than me in SCCA Solo by a few tenths on a 60sec run.
The only worry I have about my transmission is the fluff on the nets about how soft the SST is and equaly, how soft MitsUS is treating them for warranty. I'm not a fan of being dicked.
Do I drive better than a Prius for MPG? Yes
Do I hoon it? Of Course
Do I have issues with my SST? No
Do I feel lucky? Yes
Am I scared ****less for when it all goes pear shaped? Fuq. Yes.
I shift at 2.5`3.5 in the drone. Always Manual-Normal! Auto-Sport is faster than me in SCCA Solo by a few tenths on a 60sec run.
The only worry I have about my transmission is the fluff on the nets about how soft the SST is and equaly, how soft MitsUS is treating them for warranty. I'm not a fan of being dicked.
Do I drive better than a Prius for MPG? Yes
Do I hoon it? Of Course
Do I have issues with my SST? No
Do I feel lucky? Yes
Am I scared ****less for when it all goes pear shaped? Fuq. Yes.
Jan 29, 2012, 09:54 AM
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Sorry about the logging formatting! I am pecking this out on an iPod, in a hotel room near Paddington Station. 
. Damn Apple and their cut&paste afterthought.....
. Damn Apple and their cut&paste afterthought.....
Jan 29, 2012, 10:14 AM
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1. Endless AUTO mode gearshifts in stop/go traffic
2. TCU riding the odd clutch in 1st in crawling stop/go traffic
2. TCU riding the odd clutch in 1st in crawling stop/go traffic