No Lift Shift Discussion

[ShelGame]

I'd like to have some discussion about how to do a No-Lift-Shift system using our stock ECU's.

Now that I have the spark cut working, the next upgrade I'd like to do is a NLS. But, it will require adding some hardware to the car to implement. For example, it could be done with a clutch switch. The later cars had a clutch switch to sense if the clutch had been pressed as a cancel mechanism for the cruise control. That could be added to the earlier cars and used as the main sensor for the NLS system.

Or, a sensor or switch could be added to the shifter itself, shifter cable, or shift mechanism on the trans. This would have the advantage of not needing the clutch at all to shift.

Of course, with synchros on every gear, NLS will be tough on our transmissions, I think.

[roachjuice]

I think adding like a clutch pedal switch would work out just fine. Work kinda like a brake light switch. If it moves a 1/4 inch it will trigger whatever it's hooked up to.

[ShelGame]

I think adding like a clutch pedal switch would work out just fine. Work kinda like a brake light switch. If it moves a 1/4 inch it will trigger whatever it's hooked up to.

Ture, but if it was on the shifter, you might not need to clutch at all...

[zin]

But unless you have a "crash box", I don't think it would work so good... How's it work on the SRTs?

Mike

[Irocelectric93]

I don't have one but the SRT guys love em. I don't even know how they wire up but you can get the boost box which you can use for WOT shifting, 2 step launch, and control boost by gear i believe. I'm sure someone will chime in with the info.

[forcedfedmopar]

I have a N2MB and love using it. works well and is easy to use

[ShelGame]

I have a N2MB and love using it. works well and is easy to use

How does it work? What does it use for an input? Clutch switch?

[DOHCRT]

The traction control Cindy sells uses a clutch switch.

[moparman76_69]

WOT box uses a clutch switch.

[shackwrrr]

The neon WOT box is pretty simple, there is no rev limit per se for wot shifting, just the ms that the spark it cut and a TPS arming threshold.

[Vigo]

There is no way to do a no lift shift without using the clutch. The only way that would be possible would be if your synchro was strong enough to overcome whatever power your motor makes at redline and slow it down by 2000+rpm at full power (it may be able to do this a handful of times, but i doubt it), OR the synchro would have to accelerate the entire car to make up the rpm difference (acting as the main clutch).

So i think talk of no clutch no lift shift is misguided or based on some misunderstanding.

Having said that, USING the clutch, no lift shift would not be any harder on synchros than a normal high-rpm shift.

[forcedfedmopar]

Yes, it uses a clutch switch for activation. (i added one to my GLH at the clutch arm on the trans) It uses TPS for input and cuts spark. Very easy to set up. took about 2 hours (4 beers) to install

[wowzer]

the only kind i have ever used was tied into the clutch switch. it's nice to be able to stomp the pedal to the floor at the tree and leave it there until the finish line.

[Force Fed Mopar]

Brake-switch style clutch would be best I think, as roachjuice suggested.

[GLHNSLHT2]

Uhh already have a No lift shift. 2 step rev limiter is engaged by the clutch switch which is one of those spring loaded door hinges so it moves with the arm but the switch is adjustable. The only problem is it seems to cut too much power so it ever so slightly bogs on each shift. I can shift smoother without it on. Also doesn't let you heel and toe downshift above the 2 step rev limit which sucks when you need 4500-5000rpms to match the next lower gear.

[Force Fed Mopar]

NLS and a clutch-activated rev limiter are 2 different animals...

[ShelGame]

Sorry, I'm more used to NLS with straight cut dog-drive gearboxes. I wasn't sure how it would work with Synchros. With a race gearbox, you only have to cut power for a fraction of a second to unload the gears and allow the dogs to re-engage.

So, clutch switch it is. I think it can actually work very simply - when the switch is 'on', engage the rotating spark cut. I may add some logic to turn it off by a timer instead of just waiting for the switch to go 'off'. Might make for faster recovery. Eventually, it might also be necessary to specify a different spark cut fraction and maybe even set timing much like antilag. It might also be possible to do it simply with timing, not cutting spark at all. We just have to unload the gears enough to allow them to move.

[Vigo]

Well if you are using the clutch than no lift shift is just a 2step with anti-lag. It probably could be done with just timing and the stock rev limiter if you didnt care that the engine is 2000+ rpm above the tranny when you let the clutch out (i wouldnt care). You just want to keep the turbo spinning and the engine from blowing up with the throttle plate open and no load. But is the rpm limiter spark cut? If it's fuel cut you'd want to avoid that and set the NLS function to spark cut, and if you cut enough events you could use that as your anti lag and clutched-in rev limiter at once.

Also im not really seeing how it wouldnt let you heel and toe if you are double clutching because the clutch comes out in the rev part of a rev-matched double clutched downshift. Now if you arent double clutching (serious racecar driving, synchros be damned) then yeah i could see how that could be annoying.

[bakes]

Rob what about using the park input with a brake switch use on the clucth pedal and the SDS set to about 20mph

[ShelGame]

Rob what about using the park input with a brake switch use on the clucth pedal and the SDS set to about 20mph

Yeah, it would have to go in the P/N input. It's all that's open on a manual car.

I thought about it some more, though. What if instead of just engaging the 2-step, it was a set rev DROP. When you shift, the RPM needs to drop a pretty consistent amount for each gear. I don't know exactly what that is - 1500-2000rpm or so I'd think.

So, when the ECU senses the clutch is in, it goes into the rotating sparkcut+pre-set timing mode (like launch control) until the RPM drops a specified amount. Say, 2krpm or whatever. That rev drop would be user-calibrated. That should work better (faster) than just looking at the switch on/off status. Of course, it could also have a user-set delay added. IE, after the RPM has dropped the set amount, then wait xx milliseconds to stop the rev limiter.

[ATaylorRacing]

My wrench on the SRT4 swears by the NLS on the N2MB box....says what breaks the input shafts on higher hp SRT4 is when the engine revs drop and then get hammered back in at each shift. Keeping the revs at a higher rpm with the NLS option creates a lot less stress on the input shaft since there is not as much difference in rpm drops at the shifts. As far as the launch holding feature of the N2MB box....I LOVE IT! The 95 Neon that I drag is a bit modded and was very consistant until we removed the power steering. The extra hp made it hard to launch without tire spin and using the box setting at 3500-3700 brought all the consistancy back. This car don't have much torque and I use regular 185/65/14 tires with....FORTY ONE psi and hook! I go around the water box, if possible, then do a single dry hop at about 5000 with smoke pouring off the tires. Using the box also made the car launch harder and run a little quicker. I used to have my clutch pedal near the friction point when waiting on the tree, but using the clutch switch that is normally used when starting the car, the clutch pedal is now dropped when all the way to the floor...it hits harder at the launch and picked up .10 in the 60' and about .25 in the 1/4. All the guys in the United Manual Transmission Racers series that finish at the top of the points use some sort of launch limiter, while a very few use the no lift feature.

[ShelGame]

My wrench on the SRT4 swears by the NLS on the N2MB box....says what breaks the input shafts on higher hp SRT4 is when the engine revs drop and then get hammered back in at each shift. Keeping the revs at a higher rpm with the NLS option creates a lot less stress on the input shaft since there is not as much difference in rpm drops at the shifts. As far as the launch holding feature of the N2MB box....I LOVE IT! The 95 Neon that I drag is a bit modded and was very consistant until we removed the power steering. The extra hp made it hard to launch without tire spin and using the box setting at 3500-3700 brought all the consistancy back. This car don't have much torque and I use regular 185/65/14 tires with....FORTY ONE psi and hook! I go around the water box, if possible, then do a single dry hop at about 5000 with smoke pouring off the tires. Using the box also made the car launch harder and run a little quicker. I used to have my clutch pedal near the friction point when waiting on the tree, but using the clutch switch that is normally used when starting the car, the clutch pedal is now dropped when all the way to the floor...it hits harder at the launch and picked up .10 in the 60' and about .25 in the 1/4. All the guys in the United Manual Transmission Racers series that finish at the top of the points use some sort of launch limiter, while a very few use the no lift feature.

Go read the latest in the T/SMEC thread. We have launch control in the SMEC now. Just polishing up one last added feature tonight. As soon as I'm happy with that, it will get ported over to the SBEC; and I've already started looking at how to do it in the TIII and the '95 Neon. NLS is just the next step. But, I agree, Launch control is much more important...

[shackwrrr]

My wrench on the SRT4 swears by the NLS on the N2MB box....says what breaks the input shafts on higher hp SRT4 is when the engine revs drop and then get hammered back in at each shift. Keeping the revs at a higher rpm with the NLS option creates a lot less stress on the input shaft since there is not as much difference in rpm drops at the shifts. As far as the launch holding feature of the N2MB box....I LOVE IT! The 95 Neon that I drag is a bit modded and was very consistant until we removed the power steering. The extra hp made it hard to launch without tire spin and using the box setting at 3500-3700 brought all the consistancy back. This car don't have much torque and I use regular 185/65/14 tires with....FORTY ONE psi and hook! I go around the water box, if possible, then do a single dry hop at about 5000 with smoke pouring off the tires. Using the box also made the car launch harder and run a little quicker. I used to have my clutch pedal near the friction point when waiting on the tree, but using the clutch switch that is normally used when starting the car, the clutch pedal is now dropped when all the way to the floor...it hits harder at the launch and picked up .10 in the 60' and about .25 in the 1/4. All the guys in the United Manual Transmission Racers series that finish at the top of the points use some sort of launch limiter, while a very few use the no lift feature.

Thats where I learned about the feature was that N2MB box I sold you. I think the cut all spark for x amount of ms when clutch is pressed is better.

Im not sure how the revolving spark cut would act and if it could act fast enough. The N2mb is cutting all spark for 25-550ms, If you cut spark for longer or waited for the clutch to be engaged again I think the RPM would drop too fast.

[Vigo]

I think if you cut enough spark events you will have the anti-lag functionality AND drop rpms. I dont think it's crucial to drop any certain amount of rpm. The clutch will happily drag the motor down by whatever rpm it needs to. Even 2000rpm is not that big a drop and i dont think it would be hard on parts or anything. So i wouldnt spend too much effort trying to hit a certain RPM drop. I think the main thing is keeping the boost up with no load which is just anti-lag with enough skipped sparks or retard that it doesnt gain rpm and maybe loses some.

Angelo, interesting info on the neon. If it dropped .25 where does that leave it? Just my curiosity as i have a 95 sohc 5spd!

[Force Fed Mopar]

From what I've been told, the WOT boxes on the SRT's just holds the revs at whatever rpm you push the clutch in at.

[bakes]

What i like to see is the WOT NLS drop from a set point (say 1000rpm) from the current Rpm at the time of activation untill the clutch switch is released