Summary

A common issue with installing an 8HP behind engines with high idle speeds is the compatibility of the torque converter. At raised idle speeds typical of engines with aggressive cams, the car push against the brake pedal when pulled into gear. This can also cause stalling due to the load on the engine. In this webinar we will discuss the Clutch Sleep strategy and see how this can help in this situation.

00:00 Hey team, Andre from High Performance Academy and welcome along to another one of our webinars.
00:04 Now, slightly different with this webinar, it is being pre recorded, we're making the most of this Volvo with the ZF8HP swap while we have access to it, so unlike our usual webinars, we will not be able to take questions live.
00:19 However, of course as usual, if you've got questions after this webinar's aired, then feel free to ask those questions in the forum and I'll be happy to answer them there.
00:27 Alright, I'll give you a really brief background on the ZF8HP, we've already got an introduction to the ZF8HP in our webinar archives, if you want more information, go there.
00:39 Essentially it is a modern 8 speed automatic transmission that has become very very popular for transmission swaps.
00:47 In my opinion it kind of bridges the gap between the best elements of a sequential dog engagement gearbox and the best elements of a modern automatic transmission.
00:57 So, that is why it's becoming, so popular.
01:00 However, of course with these swaps comes the requirement to control them properly and interface with the engine control unit as well.
01:09 One of the most popular transmission control units or TCUs for the ZF8HP swap is the turbo Lamec and that's what we're going to be basing our webinar on today.
01:20 Now, there's a lot that goes into this, they are incredibly complicated transmission, we can't hope to do justice to every possible parameter, every possible control strategy within one webinar.
01:32 The reality as well that a lot of people will never really need to dive too deep into the 8HP and turbo Lamec TCU calibration.
01:41 It's very dependent on the specific application and what you're trying to do.
01:46 However, there is one common trend that I think a lot of people are going to stumble with and that is the compatibility of the torque converter with the engine that you're now swapping the 8HP behind.
02:00 So, let's just dive into what I mean by this and why it's a problem.
02:04 What we've got is a torque converter which is still effectively like a conventional automatic transmission torque converter, there's not a lot that has changed in that aspect of the design, it's got a lock up clutch inside of it like most modern automatic transmissions as well.
02:20 Essentially the design of the torque converter, it's kind of a fluid coupling between the engine and the transmission.
02:26 The idea behind this is that when we're sitting at our normal idle speed, there is no transmission of rotation or torque into the transmission.
02:35 Essentially the engine's obviously spinning, part of the torque converter or the torque converter at engine idle speed, but that isn't resulting in rotation of the transmission.
02:45 In a nutshell what this means is that we can sit there and drive with our foot off the brake and the car is going to potentially just creep forward very slightly, just like you'd expect with any factory automatic transmission equipped vehicle.
02:58 The problem here though is that the design of the torque converter, the internals of it are also designed around the engine that that particular torque converter is going to go behind.
03:09 And if we're talking about a big old lazy V8 or maybe petrol or diesel for that matter, then it wouldn't be uncommon with a modern big capacity V8 for it to want to idle at maybe 500, 550 RPM when it's up to operating temperature.
03:26 We put that same transmission now behind, in this case a 2.3 litre Volvo four cylinder turbo engine, definitely not a very modern one, should have mentioned the car, this is a 1992 Volvo 230 SE Estate.
03:40 And with the modifications to this engine, typically it's going to want to idle somewhere close to about 850 to 950 RPM.
03:49 So, why does this matter? Well, the problem here is that at that elevated idle speed of 850 to 950 RPM, we're already starting to get that fluid coupling inside of the torque converter and we are then forcing the transmission to rotate.
04:03 So, what this means is the car wants to drive forward and this creates two problems.
04:09 First of all, if we are at our natural idle speed with the transmission in neutral or park, when we pull it into gear there's going to be an instant load on the engine and what that's going to result in is that the idle speed will be pulled down.
04:23 At best this is going to be awkward, uncomfortable, it's not going to feel or sound very nice and at worst we're going to end up with our idle speed hunting and potentially the engine stalling.
04:32 So, let's actually just jump straight into the Tuner Pro software and we'll see exactly that.
04:37 So, what I'm going to do is I'm just going to change my mode into mode three here.
04:41 And this is a manual mode where the clutch slip strategy we're going to look at isn't being used.
04:47 What we can see, I've just circled our engine RPM and we can see in neutral here, our gear target we can see is zero.
04:54 We can see that we're idling at 850 RPM, the Haltech ECU's just doing its job.
04:59 So, what I'm going to do now, I've got my foot hard on the brake and we can see that is being circled here as well, our foot brake is in position one, we'll come back to just circling our RPM.
05:09 And now I'm just going to pull the transmission into first gear.
05:14 So, we'll do that.
05:16 And we can see straight away our RPM, it didn't die, but it dropped all the way down to about 600 RPM, we'll just go back to neutral and do that one more time.
05:23 So, we see that flare as well when we come back to neutral.
05:26 Basically, the ECU is accommodating this with the drive by wire throttle settings for our idle speed control.
05:32 So, we're back in neutral, back at our 850 RPM target idle, we'll pull it into drive again, done that now.
05:38 Down to 400 RPM and you start to see that RPM bounce around.
05:41 So, that's the first problem, but the bigger problem which I can't really demonstrate here is that if you are stationary with your foot on the brake, depending on the specifics of your engine, the specifics of your idle speed, you can find that the car really needs quite a lot of brake force applied, otherwise it just wants to drive forward and that's quite disconcerting.
06:01 Particularly if you give the car to someone who's not sort of used to driving this sort of modified vehicle, could easily result in a nose to tail in traffic.
06:10 So, obviously we don't want that.
06:12 How do we get around that? Well, that comes down to this clutch sleep strategy.
06:17 And this is something that is not documented on Turbolamex's website.
06:21 And I think it's probably fair to say in my limited experience with the Turbolamex software, so far, probably somewhere in the region of about 90% of the functions and the settings are not documented.
06:33 What is documented is going to be enough for you to get by if you've got a basic installation, but if you want to go beyond that, then there's a lot that is not really documented and it takes a while to get your head around this.
06:45 I'll be the first to admit, I haven't done this alone.
06:48 A huge shout out to Andrew Astley from 8 Speed in Australia.
06:53 He's been an absolute massive game changer with support on this.
06:56 As well as Greg from Turbolamex in the US.
07:00 Alright, so what is this clutch sleep strategy and how does it work? Well, to start with, let's actually look at how it works without the clutch sleep strategy active.
07:08 So, I'm still in my manual mode here which doesn't use clutch sleep.
07:13 And what we're going to do is just come across to our clutch pressure dashboard.
07:16 And what we can see is that at the moment clutch 1A and clutch 2B are both at their maximum value of 250.
07:23 Again at the moment I've got my foot on the brake here.
07:26 So, what I'm going to do is just pull the transmission there into gear and what we can see is now clutch 3E has also ramped up to 250, it's maximum.
07:36 And the 8HP needs three clutches engaged in order to be in a gear and by varying which of the clutches are engaged at any particular time, that is how it can change gear.
07:47 So, this is the problem at the moment, just having our three clutches fully engaged.
07:51 Let's go back into neutral and we'll go back into our program one mode which is our cruising around automatic mode where we want nice smooth shifting and we want basically, the car to act like a late model BMW fitted with one of these transmissions.
08:07 OK, so let's have a look at the settings that are available and we want to start by going into transmission calibration here, we can obviously open and close that menu.
08:14 And we're going to come down here to our clutch sleep strategy, it's spelled slipped here, I've been told that it is clutch sleep, but take that as you want, we'll open that up.
08:26 So, what we want to do for a start is look at our clutch enable slip strategy.
08:31 So, we double click on this parameter here, you can see that that is set and by default this will not be set.
08:37 Obviously, this enables the strategy in the first place.
08:40 Now, interesting as well, we can control which modes this clutch slip strategy is functional in.
08:47 So, we've got here our P1 through to P8 mode and of course we'll just have a quick look here at P3 which is the manual mode I've just been showing you, we can see obviously I have that disabled in the manual mode.
09:01 P1 which is what we're in at the moment, there we go, we've got that set.
09:04 You've got a lot of control and flexibility over when and where the clutch slip strategy comes into play.
09:10 You might be thinking to yourself well why am I not using this in every mode? Well, P3 I've set this up and all of this totally comes down to total user preference here.
09:19 You can do what you want and make this drive how you personally want it to.
09:25 I've set up the P3 mode as a manual mode where we're going to be shifting manually with a sequential shifter, a DCT shifter and it also has a virtual clutch pedal.
09:36 So, that's how we can get away with this.
09:37 In P3 mode we're actually going to be using a clutch, the virtual clutch or clutch emulator to basically make this seem like you're driving a conventional manual sequential gearbox.
09:47 And I can tell you it actually does fool you quite nicely after you've been driving for a while, so that's how we're using P3 mode, but of course we don't care about that at the moment.
09:57 So, what we want to do is start by looking at our minimum clutch pressure here, we've got neutral, we've got drive and then we've got add pressure with our foot brake off, so let's open these three parameters and we'll explain what's going on here.
10:10 Just move these around, so we can see what we've got in each of them.
10:13 I'm not really too sure here why we have a difference between neutral and drive.
10:18 Obviously, in neutral we don't have a gear and gauge, so it's really not that relevant.
10:22 But basically I've got both of these set to a value of 10.
10:26 Despite that we actually can see that clutch 2B here which is the one that we're actually controlling is sitting at 14, so we've got a little bit of a discrepancy there which I cannot explain, but the principles of what I'm going to show you remain.
10:41 Now, what I'm going to do is pull the car into first gear.
10:45 And what we can see is clutch 3E ramped all the way up, we'll just go back to neutral and show that again, so we start at zero, clutch 3E then ramps quickly up to 250, its maximum value.
10:56 But we can see that clutch 2B remains at 14 here.
11:00 So, remembering again, the 8HP needs three of these clutches fully engaged at any point to be in a gear.
11:07 So, we've got this parameter here which is add pressure foot brake off and it does exactly what it says on the tin.
11:13 So, when I take my foot off the brake it should jump up by 19 to of course a value of 33, we'll watch that happen, there we go, does what we expect.
11:22 Now, what you can't tell easily from here is that now the car is actually starting to move, I'm on a dyno, so we can't really demonstrate that, but let's just put my foot back on the brake here and we'll come back to our main dash.
11:34 And what we want to do here is look at, we've got our engine RPM here, of course, we've already seen, we've got then our input RPM into the transmission and then we've got our output RPM from the transmission.
11:47 So, of course if our output RPM is greater than zero, then we have got drive.
11:51 And just as an added bonus we can see that our foot brake is here.
11:55 So, right now, just take note of what happens when I get my foot off the brake here.
11:59 Go to zero, straight away we see our output RPM jump up.
12:03 I'm not touching the throttle, I'm not touching the brake and we're sitting at an output RPM of 250, obviously this means that we have some slip internal.
12:11 So, I'll put my foot back on the brake.
12:13 Now, slip can sound a little bit of a scary term here, but of course we do need slip for this to happen.
12:20 At this point we don't have a lot of torque going through the gearbox, so there's not a whole lot of danger here, we've got a multi plate wet clutch, so it is surrounded in the automatic transmission fluid which does a great job of cleaning and cooling the clutches, so we don't have necessarily any damage being done.
12:38 We also need to understand that on every shift there is going to be some level of slip.
12:41 So, that slip itself is not critical.
12:44 Now, what we're trying to do here is tune this particular, or a combination between our brake off add pressure value and our minimum clutch pressure value here so, that when we get off the brake, what we want to do is just have the car start to creep forward.
13:00 What we're trying to do here is replicate a DCT gearbox, basically the way a DCT gearbox works for those who have driven them, when we come to a stop with our foot on the brake, when we get off the brake, the car's just going to gently start creeping and then as we add throttle, it adds clutch pressure and we get a nice smooth take up.
13:19 Now, there are a couple of other parameters, well actually before we get into those, so, let's just show that in action.
13:24 So, again we've got our value of 19 here, let's just bring this down to a value of 10 and we'll flash that change in.
13:31 Now, we're sitting here still in first gear and if we look at our output RPM here, I'll just take my foot off the brake, you can see it's much much slower to get moving but it actually did start moving after a little bit.
13:45 So, we'll take that back to, well let's just make it a little bit more aggressive, let's take that to 25, we'll flash that in.
13:52 Now, looking at our output RPM versus our foot brake position, off the brake, straight away jumped up.
13:58 Now, I could even feel that that was quite harsh on the dyno.
14:00 If we're on the road, that's probably as I get off the brake there, we've got a load of the car sitting stationary on the road, that's probably almost certainly going to pull the RPM down.
14:10 So, I can't tell you what this value needs to be, but as a case of just playing around here with the value and setting it to something where you get the desired result and the car just starts creeping forward, we don't want that RPM to be pulled down and we don't want the car to jerk forward.
14:27 At the same time, we don't want to just sit there completely stationary, slipping the clutches internally.
14:32 OK, so there's a little bit more to it than that.
14:35 We also need to consider the range of RPM over which this works.
14:39 Basically, the RPM range at which the clutch will become fully engaged.
14:44 And we can have a look at our minimum RPM limit activation.
14:49 And we'll also open up our disable engine RPM parameter.
14:55 So, basically here, let's start with our minimum RPM limit activation.
14:58 If you hover over this it will give you a little description, it says below this turbine speed threshold clutch slip strategy will be reactivated.
15:05 So, essentially what this means is that when the engine RPM is below 1300 RPM, our clutch slip strategy, clutch slip strategy is going to be active.
15:15 And we want to make sure that we've got a range between our target idle speed and this value here.
15:21 And that's sort of the range over which that clutch slip or clutch slip strategy will sort of be phased out.
15:28 So, here we've got an engine that's idling hot at 850 RPM, but we need to remember we're also cold, this will be idling closer to about 1000 RPM and it gives us a range over which the clutch slip will be active.
15:41 And if we've got this set too tight to our idle speed, we're going to get a very aggressive take up of our clutches.
15:48 And the other problem we're going to have here is that when we come back to idle, if we've got this set too close to our idle speed, the clutches will still be locked and that'll drag our idle speed down and create stalling.
16:00 And then we've also got our disable engine RPM parameter as well, essentially the same thing there and I've got those set to the same value.
16:09 So, by adjusting a combination of our add pressure foot brake off as well as our minimum RPM limit activation as well as our disable engine RPM, we can get the sort of feel of this take up to be very much like DCT.
16:26 That's the basics of the clutch slip strategy, but there is one more aspect to this which is easy to overlook and I know it's easy to overlook because I did exactly that.
16:36 Let's close down our transmission cowl here.
16:39 And what we're going to do is come up to our RPM limit and to our lock up settings.
16:46 So, what we want to do here is have a look at our lock up on RPM versus TPS and we also want to have a look at our selector, gear swap, lock up on RPM map.
16:58 OK, so this controls the torque converter clutch lock up and it works in conjunction with our program selector which I won't go over again in any detail, but we can see in our program selector we've got our eight program modes and we have our lock up settings here for each of those modes.
17:17 So, for example here in mode one which is where we're at, I should have actually made this live, so we can see where we're at if at any particular point, we are in lock up mode zero, we can see that lock up mode zero for gear one, and gear two actually which is the one we're in, is map two and we can see that yes, in fact we are sitting in map two.
17:39 So, the default values here from memory were somewhere around about 800 RPM.
17:44 So, this is going to be problematic because it's going to keep our torque converter locked really at or below our target idle speed.
17:53 So, it's important to make sure that the values we've got in here are sort of reflecting the new idle speed for whatever engine we've got this behind and make sure, that we can have our torque converter unlocked around that idle speed and transition off idle.
18:10 And by adjusting each of these parameters individually we can get the desired results, get our transmission essentially working just like a DCT, getting around that problem with the relationship between our torque converter and the engine maybe not being quite where they should be.
18:26 There you go, simple enough process there, simple enough strategy.
18:31 But again it's not documented, so without understanding how this works, it's very difficult to get the most out of it.
18:37 As I mentioned, obviously if you've got further questions, please ask those in the forum and I'll be happy to answer them there.