Tell me about your DTT Smart Controller...

[zman]

For those of you that have the DTT Smart Controller, I would like to get more information about what it is supposed to do, how well it does it, and whether you like it. The DTT website is a little vague on what it does and how it works, so I'd like to get some perspective from the guys that already have it. I think there have been changes to the newer versions, so let me know how old yours is as well.



I already have the DTT VB and TC, but I'd like to see SOME engine braking as I'm slowing. I don't have an exhaust brake nor do I plan to buy one - hoping the Smart Controller will help. Thanks for your input!



Steve

 

[gsmith1]

I had the smartcontroller installed this past July. I also had the TC and VB installed at the same time. I believe all these componets are designed to work together, but I have noticed a reduction in the free wheeling characteristics of the factory setup. Now there is a definete "grab" that helps slow down the vehicle as it is stopping or slowing down.



The smartcontroller comes on at about 25 mph and will lockup the TC at about 32 MPH if the overdrive is off. Lockup in OD seems to be at about 40 MPH. The shift points were also changed. Final shift is at 50 MPH.



The unit has event lights that will tell you when the unit is on, when the TC is locked and when the last shift into OD has occurred. I like this to tell me what is going on with the transmission.



The installation was done with a switch to allow manual turning of the unit or or off. I just leave it on all the time.



I did find that occaisionally the unit seem to leave the transmission in OD too long before down shifting out of OD and into 3rd when pulling my 5er up hills. This did not happen all the time. This made a difference in transmission temps. I prefer to control that by simply turning OD off and then back on again myself, instead of leaving it to the smartcontroller.



Overall, I believe the unit's purpose is to best manage the lockup and shifting of the transmiussion to increase the life of the transmission. Time will tell if it makes a difference in that regard, but I am satisfied with the unit thus far.



I hope this helps your decision.

 

[SlyBones]

The short answer is YES, the smartcontroller ( SC ) will help do what you want.



It has several main features. One is second gear lockup capability ( requires a VB that has been appropriately modified ), and the lockup control feature for engine/exhaust braking.



-- Second gear lockup. Has a switch mounted near transmission that senses when the lever is moved to the manual second gear position. There is also an adjustment for this. Mine is set to 20MPH. When the lever is moved to manual second, and the speed is above 20MPH lockup is forced. When below 20MPH lockup is removed. When the lever is not in manual second, the SC has no effect on 2nd.



-- I believe that manual second, is the only place where lockup is forced. Otherwise lockup occurs when the PCM tells the transmission to locup. Once locup does occur, the SC HOLDS lockup so you have the engine/exhaust braking feature you desire.



-- There is an adjustable speed for what speed the SC does finally release lockup. It just cant hold it till you come to a complete stop. Like on a manual transmission, you have to push in the clutch sometime. Currently mine is a 30MPH.



-- I am a little fuzzy about this part but I will give it my best. Lets say you are traveling 70mph in OD. You let off the throttle and you have a mystery switch that is holding lockup. My impression is that the transmission will hold lockup and stay in OD until lockup is finally released. What does this mean. Well at 70 the rpms are high enough that you get some engine braking effect. But by the time you slow to 40 the rpms are low enough that you have little engine braking effect. What would be nice is if you lockup out the OD button, get the transmission to shift into 3rd, lockup again. This would raise the rpms up, and continue to allow for engine braking that is usefull.



-- The SC does this for you. You have an adjustable setting for what speed the controller does the 4->3 downshift for you.



-- As a side note this also controls what speed the transmission is allowed to shift into OD. With the SC turned off, and at light throttle like driving in town, my PCM will shift from 3rd to 4th at 30-35MPH. Lockup does not occur to 48mph. Dont be confused the actual shift into OD can occur sooner than when lockup occurs. At least on my 97 anyways. In onder to keep the transmission in third driving in town, I always had to use the OD button. With the SC enabled the transmission stays in 3rd until the set speed is reached. Then shifts into 4th. Then into lockup according to the PCM signals. I am not required to use the OD lockout button to stay in 3rd driving in town.



-- When I do manually use the OD lockout button the transmission stays in 3rd. The normal OD lockout works like it always did. Justnow w/o the use of the OD button, the SC controls the 3-4 and 4-3 shifts according to the user adjustable speed, when it and the od button are enabled.

 

[zman]

another question...

Thanks for the replies, guys. Does the SC provide 3rd to 2nd downshift with lockup, or does it only control lockup from 3 to 4 and 4 to 3, with additional lockup for 2nd only if you manually shift to 2nd? Thanks!



Steve

 

[jwdeeming]

Re: another question...

Originally posted by zman

Thanks for the replies, guys. Does the SC provide 3rd to 2nd downshift with lockup, or does it only control lockup from 3 to 4 and 4 to 3, with additional lockup for 2nd only if you manually shift to 2nd? Thanks!



Steve

SC does 4 to 3 automatically for you. From 3 to 2 you must do manually. SlyBones described it all pretty well. Mine is adjusted to shift down from 4 to 3 at 60mph which works well for me. You can change that if you want - I think originally it was set to 55mph.

 

[RADdodge]

I’m easily confused and when folks refer to 4th gear as opposed to OD, I sometimes get the feeling I’m driving a 5-speed auto! I have a Pacbrake, DTT modified auto and the Smartcontroller. When I take my foot off the pedal at 70 mph heading into a long off ramp, I get two downshifts and freewheeling at about 26 mph. That tells me the transmission is shifting down to 2nd, doesn’t it?



BTW, the auto downshifts with the sound of the Cummins working against the Pacbrake and DTT transmission is very cool.

 

[SlyBones]

RADodge,

working down from 70, at what speed is the first downshift and what speed is the second downshift. About how many rpm increase is each shift.

 

[RADdodge]

SlyBones - I would have to guess and don't want to give you inaccurate info. I know it kicks out around 26 - 28 mph. I would go out and drive it, but I've been laid up with a broken leg (unfortunately it's the go pedal leg) and won't be driving for a month or so yet (I hope it's not longer!). I would suggest you call DTT or post your question on their web site. Better to get the answer from the horse’s mouth so to speak.



http://www.dieseltrans.com/

1-866-504-4002

 

[SlyBones]

RADodge,



I was only curious about your apparent 2 downshifts. I dont know how to answer your question related to it. I was only curious about it. I dont really need an answer. -- I get one downshift from OD to 3rd. then kicks out at 30mph. The kick out is adjustable. You can have 30 if you want, and I could have 26 want. The downshift is adjustable. I do adjust the downshift differently for towing versus empty. Otherwise I leave the other 3 settings alone. They way DTT set them for my truck.



Wish you well for the speedy recovery!!

 

[RADdodge]

Thanks

Opps! Sorry for the misreading of your post. I do get two down shifts from OD, one from 3rd.

 

[zman]

need more input...

Thanks again for the replies. It sounds like RADdodge is experiencing a 3 --> 2 downshift with lockup, but SlyBones isn't. Anyone else out there care to chime in on this?



Hey Lsfarm (Greg Long), don't you have one of these on your truck???



Thanks!



Steve

 

[Strick-9]

zman,



Slybones has it correct. While slowing down with the DTT smart controller, you first experience a locked 4-3 downshift. The next event is the smart controller turning itself off at 25-35 mph which unlocks the converter. You can feel the torque converter unlock and that is what RADdodge is calling his second downshift.



Hope that helps clear it up.

-Chris

 

[GLASMITHS]

Downshift of DTT Controller

Just returned from a trip with the RV in tow, and can tell you the correct way it does. MINE. The SC will make the 4-3 at the selected speed. It disengages the TC at the selected speed, usually 28mph (factory set). IF before that speed you manually downshift to 2nd, the TC will remain locked and you can have engine braking to the selected speed or 18mph (recommended), then and only then does the TC unlock.



So by anology, you can go from 70 in O/D (4th) to 2nd and 18mph locked - lots of braking



My only problem with it is the fact that I can't use the GV in 2nd with the SC on. It causes a no drive condition? So if you gear down to 2nd you cain't gear split out, unless you turn the SC off.

 

[SlyBones]

Thats true you can get the downshift to second if you do it manually. I believe Chris and I were referring to what happens automatically with no manual moving of any levers or pressing any OD buttons.



And I would point out about that capitol IF in there, that I believe that 2nd gear lockup is forced when ever the lever is in manual second and the vehicle speed is above the 2nd gear kick out speed. Meaning even if the SC kicked it out of lockup in 3rd at 28mph ( in your case ) and then you moved the lever manual second afterwards, it would lock back up again and give braking down to the 2nd gear kick out speed.

 

[GLASMITHS]

SlyBones

You are probably correct on the 2nd gear lock-up. I have found that the best speed to downshift to 2nd is 35mph. It's really not worth the effort since it will be to 18 real fast. But, at 35mph coming into a rest area the PAC Brake is really hollering, and EVERYBODY looks

 

[RichB59]

Is it safe

to run down hill with shift lever in second position. I recently went down a 9% grade coming out of death valley into Cal. on rt190. I t's a tough downhill with loads of curves so you have to go slow. I got the brakes kind of hot before I got to the bottom. I let smart cont. do it's job but I think it would be better to get into second gear manually? Thanks in advance.



Ricb B

 

[GLASMITHS]

RichB59

Do you have an E Brake?



That is the most important thing for me, this PAC Brake and the SC will bring it down fast. I have been down up to about 8% and never had to use service brakes. That is with up to 26K pushing.



I'm not sure that I would go down into 2nd without an EBrake. I'm not THAT experienced travelling in the mountains. Maybe a poential of overspeeding

 

[RADdodge]

Apology

SlyBones and everyone else- Sorry for saying that I experienced two down shifts with the Smartcontroller. I swear, that’s how I remembered it. My wife took it out this weekend so we could go fuel up. Only one downshift to third. If it ever shifts to second on it’s own, I’ll be the first to speak up. I apologize for the misinformation I conveyed. (If I were a betting man, I would have bet on this one – wrong!) Sorry about that.

 

[GLASMITHS]

RADdodge

No sweat - I messed up also.



I had never shifted to 2nd after the TC unlocks in 3rd (28 mph).



So tried it yeasterday, it will relock and continue braking until 18 mph - that is where mine is set. But it will relock. Didn't know that It just gets better

 

[Greg Boardman-RIP]

If I downshift to second after it comes out of third,locked. I have to blip the throttle to get it to lock up again. If i downshift at 40 mph it will drop into second locked. I have done this a hundred times and it works great. I would suggest though to try and match the rpms of the motor/trans to help lessen the blow.