Torque Converter Lock-up mods any BTDT
- Thread starter SUMOTOY
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Cruiser Jimmy
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Just thought you guys might like a view from across the pond.
as you guys will know our "wheelin" is very different to yours- having spent some time playing in Moab i know just how different- what would scare me is fine for you guys and vice versa.
A huge amount of my descents are at 40-45degrees on mud with very very little grip. You need 2 things, engine braking as much as possible and the ability to accelerate to get wheel speed to match ground speed (a very very good skill to learn when your sliding towards a 20ft dropoff with no winch line!). I run a lot of descents by left foot cadence braking- ie i accelerate and brake at the same time and modulate speed like that.
With stock gearing the engine will rev until 1900rpm before the stall point of the TC is reached (mine is a diesel- petrols probably have different stall points). The stall point is that point at which the TC will prevent the engine from revving if you are stood on the brakes. In my rig with 34" tyres and stock gearing i can easily do 8-9mph which is far far too fast. hence the left foot braking.
however even below stall point the engine will still provide some engine braking. The basics of the TC mean that this has to be case- the gearbox is effectively trying to force fluid past a slower moving obstruction.
[for those that dont understand TCs very well just think of it this way- put 2 fans opposite each other and switch one on full- the air coming from one will turn the blades of the other. this is exactly what happens in a TC but instaed of using air it uses fluid in a pressurised enviroment. The engine drives one "fan2 that forces fluid past nother "fan" attached to the gearbox and thus forces the fan of the gearbox to rotate in sympathy. When you engage TC lockup its like gluing the front of one fan to the other and turning the switch on- both fans will turn the same speed no matter what happens]
A manual TC lockup switch that forced lockup even in low 1st would be a godsend for me- even at idle as long as you are moving then you aren't going to stall the truck as its no different from running in low first with the clutch in. You might find that the truck still wants to go too fast but you can still hold the truck against the brakes even at idle with the TC locked up- i wouldn't do it for long but it is possible (i have a Gm 4L80e with manual valve body but an electric (but manually controlled) lockup for my competition rig).
i will be looking into this very soon possibly using an extreme valve body from rodney (would be nice if it firms shifts up too and thus reduces wear on the g'box- FWIW hard shifts are a good sign in an auto- it means the clutch bands are nice and effective- sloppy changes mean lots of wear often)
HTH
Jim
as you guys will know our "wheelin" is very different to yours- having spent some time playing in Moab i know just how different- what would scare me is fine for you guys and vice versa.
A huge amount of my descents are at 40-45degrees on mud with very very little grip. You need 2 things, engine braking as much as possible and the ability to accelerate to get wheel speed to match ground speed (a very very good skill to learn when your sliding towards a 20ft dropoff with no winch line!). I run a lot of descents by left foot cadence braking- ie i accelerate and brake at the same time and modulate speed like that.
With stock gearing the engine will rev until 1900rpm before the stall point of the TC is reached (mine is a diesel- petrols probably have different stall points). The stall point is that point at which the TC will prevent the engine from revving if you are stood on the brakes. In my rig with 34" tyres and stock gearing i can easily do 8-9mph which is far far too fast. hence the left foot braking.
however even below stall point the engine will still provide some engine braking. The basics of the TC mean that this has to be case- the gearbox is effectively trying to force fluid past a slower moving obstruction.
[for those that dont understand TCs very well just think of it this way- put 2 fans opposite each other and switch one on full- the air coming from one will turn the blades of the other. this is exactly what happens in a TC but instaed of using air it uses fluid in a pressurised enviroment. The engine drives one "fan2 that forces fluid past nother "fan" attached to the gearbox and thus forces the fan of the gearbox to rotate in sympathy. When you engage TC lockup its like gluing the front of one fan to the other and turning the switch on- both fans will turn the same speed no matter what happens]
A manual TC lockup switch that forced lockup even in low 1st would be a godsend for me- even at idle as long as you are moving then you aren't going to stall the truck as its no different from running in low first with the clutch in. You might find that the truck still wants to go too fast but you can still hold the truck against the brakes even at idle with the TC locked up- i wouldn't do it for long but it is possible (i have a Gm 4L80e with manual valve body but an electric (but manually controlled) lockup for my competition rig).
i will be looking into this very soon possibly using an extreme valve body from rodney (would be nice if it firms shifts up too and thus reduces wear on the g'box- FWIW hard shifts are a good sign in an auto- it means the clutch bands are nice and effective- sloppy changes mean lots of wear often)
HTH
Jim
- Thread starter
- #44
Jim,
Keep us posted on the results, I would agree that the benefits are much higher than any 'keyboard wheeling' objection/senario and pretty pictures posted in this thread. I have directly emailed the guy that did the mod to the 40 in the link above, and have received a response from him already. I don't have his permission to quote yet, but he uses it for crawling, uphill and downhills alike. His paraphrased summary: Don't even think of knocking the mod until you tried it.
I also appreciate your 'fan to fan' reference on how a torque converter works, I tend to see it as a powered fan driving an unpowered fan. And the roles reversed when gravity drives the gears to rotate faster than the engine (=TC overrun).
I see no reason to build a 'stronger' TC referenced above, in fact, this mod is less strain on the torque converter, trans, and clutchpacks during wheeling, in my understanding of how a torqrue converter works.
I've read nothing here that detracts from trying the mod, and so far in my research, math, FSM reference, and experience on the trail, I see no reason not to. It would also directly help those trying to claim downhill axle gearing 'gains'. The charges of my "lack of experiences" without any knowledge of them, seems weak and tangential. Lucky for me I guess, I have had direct contact with a hardcore toyota wheeler that has BTDT, something missing from all the negative posts on this thread.
Cheers
Scott J
94 FZJ80 Supercharged
When do you think this will be completed on your truck?
- Thread starter
- #46
Wouldn't it make more sense to have someone that either changed gears, or regularly crawls with his 80 do it first? That said Rick, my interest in the mod and my design for the mod revolves around the fact that I drive a supercharged truck, and modifying the locking on the torque converter is also beneficial for on-the-road boosted trucks too. I don't care to do it for low speed crawling, because that's not where the mod will give me the most benefit. YModMV
I only started this thread because of (IMO) blatant ignorance to TC operation put forth in the 'gearing' thread over a week ago. That actually turned 'on' me personally, I'm an arrogant nitwit. Hey sure, I'm good with that charge... I regularly do mods to my vehicles, all of them, including my 80. Some I share, some I don't. I do them for me, I don't sell anything here. I don't believe in a forum pecking order, and I don't believe an 80 is an exception to the experience I have in automotive modifications and my research of them.
I asked in post 1 if there was any BTDT. The answer appears to be 'maybe 1' on the 80 forum, and someone else 'looked at it' but doesn't understand how a torque converter works.
I claim this mod works, is less expensive than installing a set of gears, benefits crawling and on road boosted trucks, gives more 'claimed' downhill gains to axle gearing changes, and is less stressful on trans and brakes in downhill wheeling. I proposed this, and spent a lot of time doing more research, cuz my experience, understanding and my FSM tells me I have this dead nuts on. Even emailed a guy that did the mod to his toyota truck, with every other conceivable wheeling mod already on his truck. And the guy plays on the rocks where most of the pundits here play....
I chuckle at the challenge that I just haven't done enough. I don't claim to regularly go rock crawling with my 80. I haven't changed gears to equalize tire size, then claimed it was better in downhill descents. I run both my summer and winter tires at the stock tire size and weight. I will modify my TC lockup because my *experience* and *understanding* of torque converter operation in the 80 makes me think I should. The mod should benefit me in daily driving and towing my trailer.
I would also discourage anyone from doing *any* mod to the operation of the stock Torque Converter if they don't understand how it works. Just because the truck can take the abuse, doesn't mean it has to?
Scott J
94 FZJ80 Supercharged
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How about a simple answer to my question with out the soap box. Are you or are you not doing this mod?
- Thread starter
- #48
Pardon my immediate reluctance to see your interest in this mod as genuine? I will be modifying the conditions under which I get torque converter lockup for the obvious on-road benefits to my boosted truck. You will need to challenge someone else to do it for the obvious off-road benefits.
Cheers
Scott J
94 FZJ80 Supercharged
Find out if it can apply to my A440 and I'll test it everywhere
All I'm doing is asking a simple question. I'm not challenging anyone. If you didn't follow through, it wouldn't be the first time you start with some theoretical idea and do nothing with it.
I honestly don't know enough about this topic to have an opinion one way or another. That's why I'm following this thread.
As I've said, I don't fully understand how a TC works (though I get the basics now at least
).How do these 8 stages work? The TC's that I've seen torn apart have splines that engage when the TC is locked, forcing the engine and tranny to spin at the same speed. I'm not sure how that could be partially locked up.
Maybe you could provide a breakdown of the 8 different stages?
I'm getting the feeling here that completely locked isn't going to be ideal, but completely unlocked won't either. Maybe one of the intermediary settings would be perfect, or maybe the ability to adjust on the fly which setting was being used (IE: fully locked for the scary downhill sliders on mud, fully unlocked when you're about to climb a big rock at slow speed and want as much slip as possible, something in between for everything else).
right to stop you guys arguin
Wildsmith has already done this mod and i will be doing it soon enough as well (well as soon as i get a XMAS bonus- i'm having TC lockup probs anyway and can't be arse to find the real problem!).
This is not a substitute for fixing your gearing- if you're running bigger tyres then your truck will benefit from re-gearing either of the diffs or the transfer box.
A fully lockable TC will only help on the highway (and only if yours doesn't work right - like mine- in all other situation it will already lock up) or off tarmac in certain situations- it will improve engine breaking massively- i CAN explain why if needs be but it will take a while. It will also helpin towing i guess as it will reduce heat build up and allow you to accelerate faster- although if you have big loads the lockup will remove the torque multiplication whihc is a bit like shooting yourself in the foot!
Dont get hung up on the 8 stages guys (i have to say that i was NOT aware that 80s had a variabe pressure solenoid in the locking control system- its very very rare and a little pointless). For those that want to know how a TC lockup works here goes:
The TC is a big doughnut shaped thing with lots of fins in it in a variety of ways- there is a pump (driven by the engine), the turbine which connects to the gearbox and in the middle is the stator. the pump causes the turbine to rotate, but because of the stator and the fluid movement there is not 100% efficiency (although there is torque multiplication near the stall point- that is the engine produce 200lb/ft but the gearbox feels 440lb/ft).
Normally the pump and the turbine are entirely disconnected apart from the flow of fluid
What a lockup does is lock the two together so that they are solidly locked together. It does this with 2 plates that face each other. Under certain conditions the ECU will decide to lockup the transmission- it forces pressurised fluid against one plate which closes with the other plate,friction occurs and the plates are held together. The same as clutch in a manual car (sorry- stick shift)
in a landcruiser the lockup works exactly as above but the control works like this:
ECU takes a variety of inputs such as Fluid temp, Speed, Throttle input, line pressure and a couple of other things and when these all solve a certain equation the ECU sends a signal to a lockup solenoid- this solenoid closes and fluid is pressurised through the valve body and thus locks up the torque converter.
Technically you can have as little or as much line pressure going to the lockup plates as you like- more pressure equals less slip on the lockup plates. i was under the impression that the A442F (fitted to most post 93 cruisers) didn't have variable lockup- i've never seen it mentioned before or in the FSM but i'm happy to be proven wrong.
A little switch that either locks or unlocks the TC is all thats needed- nothing fancy as it will just work against you.
You guys will konw crawling more than me (having only done 100 or so trips that need rock crawling skills) BUT at low speed to get maximum control you want an unlock TC and you raise the revs to stall point with your right foot and control your speed with your left. That way you get maximum torque low down ass well as ultimate control.
Wildsmith has already done this mod and i will be doing it soon enough as well (well as soon as i get a XMAS bonus- i'm having TC lockup probs anyway and can't be arse to find the real problem!).
This is not a substitute for fixing your gearing- if you're running bigger tyres then your truck will benefit from re-gearing either of the diffs or the transfer box.
A fully lockable TC will only help on the highway (and only if yours doesn't work right - like mine- in all other situation it will already lock up) or off tarmac in certain situations- it will improve engine breaking massively- i CAN explain why if needs be but it will take a while. It will also helpin towing i guess as it will reduce heat build up and allow you to accelerate faster- although if you have big loads the lockup will remove the torque multiplication whihc is a bit like shooting yourself in the foot!
Dont get hung up on the 8 stages guys (i have to say that i was NOT aware that 80s had a variabe pressure solenoid in the locking control system- its very very rare and a little pointless). For those that want to know how a TC lockup works here goes:
The TC is a big doughnut shaped thing with lots of fins in it in a variety of ways- there is a pump (driven by the engine), the turbine which connects to the gearbox and in the middle is the stator. the pump causes the turbine to rotate, but because of the stator and the fluid movement there is not 100% efficiency (although there is torque multiplication near the stall point- that is the engine produce 200lb/ft but the gearbox feels 440lb/ft).
Normally the pump and the turbine are entirely disconnected apart from the flow of fluid
What a lockup does is lock the two together so that they are solidly locked together. It does this with 2 plates that face each other. Under certain conditions the ECU will decide to lockup the transmission- it forces pressurised fluid against one plate which closes with the other plate,friction occurs and the plates are held together. The same as clutch in a manual car (sorry- stick shift)
in a landcruiser the lockup works exactly as above but the control works like this:
ECU takes a variety of inputs such as Fluid temp, Speed, Throttle input, line pressure and a couple of other things and when these all solve a certain equation the ECU sends a signal to a lockup solenoid- this solenoid closes and fluid is pressurised through the valve body and thus locks up the torque converter.
Technically you can have as little or as much line pressure going to the lockup plates as you like- more pressure equals less slip on the lockup plates. i was under the impression that the A442F (fitted to most post 93 cruisers) didn't have variable lockup- i've never seen it mentioned before or in the FSM but i'm happy to be proven wrong.
A little switch that either locks or unlocks the TC is all thats needed- nothing fancy as it will just work against you.
You guys will konw crawling more than me (having only done 100 or so trips that need rock crawling skills) BUT at low speed to get maximum control you want an unlock TC and you raise the revs to stall point with your right foot and control your speed with your left. That way you get maximum torque low down ass well as ultimate control.
I don't disagree. The TC lockup mod would only work in certain situations, gearing works for (or against
) you all the time.Thanks for the explanation. That makes a lot of sense.
As for the 8 stages, it seems to me that they would be the key for those who aren't as adept at the dual foot braking. Using partial lockup would allow you to avoid stalling the engine at low RPMs, but still maintain the benefits of the engine braking.
- Thread starter
- #54
Exactly what makes me want to be selfish Rick. Even you must admit, "it wouldn't be the first time with some theoretical idea" and put up a reference modification. After recently living thru the gearing thread, I was tempted to just keep this as a mod for myself, I have a few of those on my truck too.
Pugwash, glad to see this is catching on and you see the benefits... We need more 'n'. As soon as I get permission and more feedback to my questions from meerabus, I will post some of his thoughts here. I will say he noted he uses it all the time crawling and wheeling, not just downhills.
I have already designed a test box to see how the A442F Trans brain works the TC lock in DD, and will be installing it this week. I have already built the circuit to override the trans brain. That said, my testing and application will be specific to a boosted truck, which will be different than a non boosted truck because some of the Trans input parameters are modified by boost (throttle position changes specifically).
My understanding too, is that the 343 (95>) trans ECU's don't use the same inputs/outputs as the 442, and it is a more comprehensive software matrixed ECU.
My installation goal and modification is targeted for DD and for Towing my tandem axle car trailer. The benefits to offroad are not my interest, nor goal. I've also read several places that Rodney claims both the 343 and the 442 require his valve body to get this mod to work in first gear. Easy enough to test I guess, but a first gear lockup overpressure failsafe in that stock TC circuit sounds very typical 'Mr. T'.
I had hoped to jump right to the Sumotoy TC Lockup Mod assuming folks know how a Torque Converter works. I will leave that part for pugwash and others to work on... I will say that most electronic lockup torque converters use a complicated matrix to get the ideal ramp of torque multiplier to the stock engine, trans gears and rpm lockup. Most electronic lockup TC's with trans ecu's are staged on-off solenoid activation via load to make a specifically plotted load based ramp up/down > lockup, and it appears the 80 is no exception.
Tempting as it is to just lockup the TC with a push-on, push-off switch, I want to get an idea of what Mr. T designed into the programming first.
Cheers
Scott J
94 FZJ80 Supercharged
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I don't think there is a Trans ECU in the 95+ trucks as it is integrated into the main engine ECU. But I believe that I have read that someone plugged in a 93 tranny into a 95+ truck without issue.
If you need someone to test it in an NA truck....
Why have 8 lockup settings and only use 2 of them?
Seems a positional switch would be the way to go, so you can manually control the lockup depending on the situation.
A simply on/off switch probably would be where to start though.
- Thread starter
- #57
Backing up here.... I just went thru and edited my posts above to clear up some confusion here. I agree with Jim that the torque converter solenoid in the 442 and 343 transmissions are off/on (locked/unlocked) gate, I am speaking to the input matricies the Trans ECU uses to trigger that signal. That is where testing the conditions under which lock is enabled/disabled would prove helpful. The main focus I have with a boosted truck for the 442 is the Throttle Position Sensor. This will also be different to the 343 transmission as I understand load uses the MAF signal as well.
A boosted truck will have less TPS angle for a given load. I don't have a non-boosted truck, but I suppose I could bypass the boost pressure to get those numbers. Could prove an interesting comparo on the same truck.
HTH
Scott J
94 FZJ80 Supercharged
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So what you are saying now is that the TC is either completely locked or completely open? No partial/variable lockup?
Just trying to be clear here since that is different than what I took you to be saying earlier.
I'd be real surprised if your truck didn't also use the AFM to calculate load.
- Thread starter
- #60
Fixing your diff gearing is primarily to correct the effective gear ratio back to stock of larger tires. This mod *can* be a good substitute for 'just' diff gearing for the weekend warrior that changes wheels/tires to go wheeling. It can maximize the potential stock truck offroad behaviors, especially downhills.pugwash said:
Landtank said:
For the Trans ECU solenoid control, Vehicle Speed and Throttle Position Sensor are the only *load* inputs to the A442F according to the FSM. Transmission fluid pressure is partial to the shift points (and possibly to first gear activation of TC lockup), but that's not a function of the ECU, that's a function of the valve body in the transmission.
I can believe that. And if so, it would support that the function of the transmissions (4 solenoids on/off gate control) is the same. No surprise, but that doesn't mean that the inputs to control the 4 solenoids are the same, nor the software matrix.
I believe I cleared up the 2 posts where I might have given you that wrong impression. All 4 solenoids in the A442F transmission are on/off gates, including lockup. I was speaking to the conditions on the input side of the TCM, not the output side.
HTH
Scott J
94 FZJ80 Supercharged
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