Pro's and con's of a mystery switch

[snowracer69]

Am considering putting in a mystery switch for t/c lockup. Would be used only when on the dyno or racing, which isn't too often for either.



I know it's hard on the transmission, but what exactly is it hard on? Can my DTT handle it? I know Rhonda is running one, and I'm at about the same power as she is, and she's in the 12's now!



What do I risk if I flip a switch on the shift into second and let her shift locked-to-locked down the track? (That is what is happening, right?)



Thanks, Josh

 

[MD500E]

The only problem i encountered was forgetting to turn the switch off and coming to a stop! It can't be a good thing when the engine and drive-line feels as if it is going to buck out of its mounts and hit the road in pieces Other than my stupidity, I really like having the switch. I have a 3 way switch; locked, unlocked, and stock mode. Also beware of breaking input/output shaft when using lockup while drag racing. Do you have the billet shafts?

 

[snowracer69]

No, unfortunately I made the mistake of not going billet from the start Live and learn, and it will be fixed, someday... .



What I was thinking, since I can't really/don't want to launch in 4x4 is that when racing in 2wd, once I hit 2nd I hit the switch and that would give me back some of what I lost by not launching 4x4. Do you think that the switch, when in 2wd, would be harder on the shafts then launching in 4x4 would be w/o the shafts?



Thinking out loud again...



Josh

 

[Stefan Kondolay]

Josh,



I dont have your file in front of me so i dont know if you have a billet input shaft or not or even which upgrade you did. Here is what a guy needs to consider if wanting to add a mystery switch.



We have been charting this stuff as a lot of our customers run high horse power trucks that they dyno,race and drive daily. Since you mentioned Rhonda, lets use her, to do what she does she has a billet input shaft, she has a billet out put shaft as she snapped the factory one like a twig. Rhonda has the DTT system ie)the full transmission including the specialty shafts . She started out only wanting reliability, and to tow her horses. Ask her where the horses are.



Josh , a lot of guys may tell you to lock it up in 2nd and let it shift on through the gears. The factory oem system has a huge amount of overlap between 2nd and 3rd. Some guys may tell you that is not true but a pressure gauge will tell you the exact opposite.



So put a gauge on your truck and decide for yourself how you want to proceed. Only you can decide where to draw the line.



The first pressure you will see is the energize pressure, the 2nd pressure you will see is when 2nd and 3rd are on at the exact same time and the 3rd is your actual 3rd gear apply pressure.



If you add a mystery switch and shift locked to locked there is no forgiveness. In fluid coupling the converter will absorbe some of the shock . In lockup, which means you are 1 to 1, there is no slippage, so no protection.



Most guys think that breaking the input shaft is about hp, it is not about power it is more about shock. That is why we originally designed these shafts for the RV guys, for exhaust brake application because they do shift locked to locked. The hp guys that started drag racing their trucks started adding mystery switches for that little extra et.



As far as using a mystery switch for dynos, thats not a big deal , you dont need to add a billet input shaft solely for that because you are already are in 4th gear and just lay hammer down.



Bill told Rhonda before she added the mystery switch she would gain 3 tenths by locking it up in 3rd gear and she had to make the decision if the shafts were worth the gain. She added the shafts and gained 3 tenths.



As for the 2 wheel drive launches,









Ask Rhonda how long that lasted

 

[snowracer69]

Stefan, just the guy I wanted to hear from...



89% t/c, valve body (not sure exactly which one, but Fred at Desert Diesel put my transmission together, and he said it's cranked up pretty high?), update kit. No billet anywhere.



So tell me, in your professional opinion, is it a bad idea for me to do it? From your post, I'm assuming it is and I'm better off just sitting on my hands for a while longer till I can have the full billet stuff put in (when I do it this time, there's no dickin' around... if you make it, and it's billet, it's going in my transmission!).



The reason this comes about is that Denis' pickup is acting up (something with the map sensor) and there's a 6. 0 furd around home who's talking a lot of crap w/ a chip and injectors. Since I don't wanna launch in 4x4, I was trying to think of another way to make sure I have an edge on him if it comes down to me racing him... if not, well, I think we can swap the M3's into Denis' picukp in about 45 minutes and I'll just let him beat him in 4x4.



Josh

 

[Cummins4Life]

ooooooh Good topic. Oo.

 

[propuller]

Stefan,

The last time i was on a dyno i tried to make a run in 4th with the converter locked via the mystery switch & it kept down shifting into 3rd. I talked to Nate & he said that he can put his truck in 4th lock the converter & mash the throttle at any rpm & it will not drop out of 4th. My question is how can i keep my trans in 4th gear lock the converter & be able to floor it at 1200 rpm & get it to stay there so i can get some decent dyno numbers for a change. Runnin in 3rd gear locked just doesnt cut it. By the way it never down shifts if im in 3rd i can floor it at 1000 rpm & it will stay there.



Kurt

 

[ECappleman]

Originally posted by MD500E

The only problem i encountered was forgetting to turn the switch off and coming to a stop! It can't be a good thing when the engine and drive-line feels as if it is going to buck out of its mounts and hit the road in pieces Other than my stupidity, I really like having the switch. I have a 3 way switch; locked, unlocked, and stock mode. Also beware of breaking input/output shaft when using lockup while drag racing. Do you have the billet shafts?

If your having that problem it would be easy enough to solve with a small circuit that will disable your switch when you hit the brake pedal. It would only take a couple of relays to make it work.

 

[Joe G.]

If you are towing you really DON'T want the TCC to unlock when you press the brake pedal. Then you have the problem of locking it back up again which can get kind of hairy on a steep crooked place. I have a push button on the floor to do that quickly if I want to or if I have forgotten to unlock before a stop.

 

[MCummings]

I snapped an OE input shaft on a locked 2-3 shift at 1/4 throttle on the street.



If you are bound on locking it up, lock it up just into 3rd gear. A Locked 2-3 shift is very harsh, and shocks the drivetrain very hard.



The 2-3 shift feels like a manual truck when the driver stays on the fuel, lets the mtotor rev on up, and then dumps the clutch into the next gear.



Merrick

 

[jimk]

mystery switch

I like my switch because of the TPS switch acts up. I just use the switch when that happens. A lot easer on my attitude, at least I can keep the converter locked up instead of revving up going down high way. Jimk

 

[kaptn]

OK now I am confused. What does the voltage regulator do that I installed with my DTT transmission? It fools the computer to do what? I thought it was a fancy mystery switch.

 

[snowracer69]

95% sure the voltage regulator makes it so the computer doesn't see the high valvebody and line pressures that your DTT transmission is putting out.



Josh

 

[kaptn]

Thank you. Snowracer

 

[powerwagon440]

so is there a kit for this from DTT or what? iv got the full blown setup from them and if it will give me 3 tenths then lets do it!!!

 

[snowracer69]

No, no kit... . it's a pretty simple install w/ just running a wire, and preferably a diode in line, from the PCM to a switch that you ground.



Will post a link soon as I get it from Luke to a page w/ wiring instructions for it... it's easy, and no I haven't done it yet as I don't have billet.



Josh

 

[snowracer69]

TST's install instructions



There ya go

 

[BillGotthelf]

I have one switch to make sure TC is locked and another switch to make sure TC doesn't lock.