[Marck]

Has anyone had a converter lockup fitted to the new grand vitara ? Or can it be done ?

Thanks
Marc

[Gwagensteve]

Well they have lockup standard, so I assume you mean adding a manual switch to aid engine braking?

You'll need to get some solid advice from a trans specialist. Some lockup solenoids won't take large torque loads in low gears, and a broken solenoid will be very expensive to fix.

[Gwagensteve]

Can you tell me more about the context you want to use the manual lockup control in?

[Marck]

Where I think I have the need for it is at highway speed with 245 AT's and racks and all the bolt ons at 100km an hour the slightest incline you either have to shed speed or it will unlock and soon after change down. And rev its ass off. People seem to use a lock up when towing so I thought it might help a little.

The GV is only used when going off road but the last trip to Fraser was a little painful on the highway.

I suppose I am just trying to get the best of both worlds.

[Gwagensteve]

There shouldn't be more than about 150rpm of converter slip at highway speeds. It sounds like it's kicking down- often unlocking alone isn't that easy to detect.

Welcome to the world of aerodynamic drag!

Manually locking the converter will cause a range of potential weirdness and is likely to worsen fuel economy. I'm on my phone at the moment so a more detailed reply isn't easy. I'll see if I have a chance to type something more detailed later.

[Gwagensteve]

In short, the auto can't shift with the converter locked. In an ideal world the shift will be inhibited. In reality though, the transmission might try to shift, or throw a code and go into limp.

[Marck]

Ok interesting so what I'm trying to do is possible it might just not be safe / worth it

[Marck]

Just out of interest I spoke with wholesale automatics today about this and they said a Torqe converter lock up will help with my problems.

I just need to find out which transmission it has in it to get a price. I am away for work but when I get home I will find out.

Somthing of interest he said is a couple of the autos used in the NGV are a Toyota transmission from the hilux and Prado.

[Gwagensteve]

Firstly, your auto already has a converter lock. You're talking about adding a manual override that you control manually.
No, it's not a Toyota automatic. It's likely to be an Aisin-Warner auto which might be mechanically similar to any number of automatics.

The manufacturer will try and keep the converter locked as long as possible for economy. Keeping the converter locked when the computer is trying to unlock it will increase fuel consumption and lug the motor. Keeping the converter locked to inhibit a shift when the computer is trying to call a downshift is counterproductive for performance and economy.

Steve.

[J--A--C--K]

Dose it have an over drive switch, my Pajero and old Subaru had the same symptoms you described and a simple flick of the over drive button disengaging it at the bottom of a hill or befor an over take seemed to have it sorted, obviously revs still increased but it wasn't and big of a down Shift or give that feeling of the engine spinning faster than the movement your gaining , if that makes sense.

[Gwagensteve]

I think that's the opposite- the op is trying to hold it in OD/locked.

[jdk81]

Manually locking the converter to hold OD, and labouring the engine won't help fuel economy.

I don't understand why having it drop down a gear as designers intended is such a problem.
Is there some obnoxious aftermarket muffler in place?

[Gwagensteve]

Additionally, as I said earlier, it's likely the lockup solenoid isn't designed for high torque input. Additionally OD might not be strong enough to hold with large throttle openings.

[ZUZUKI]

Often, the solenoid is not the limiting factor in torque load - the friction surfaces within the convertor are only designed to act in light throttle openings, ie at cruise, to improve efficiency / reduce heat of the auto fluid, by eliminating torque convertor slip when driving conditions don't require torque multiplication via the convertor.
When those driving conditions change (eg. going up a hill) the soleniod is instructed to release pressure to the friction linings within the convertor, to allow some slip & torque multiplication to occur, to help the engine cope with the load.
If the engine load continues / or increases (hill gets steeper / longer & RPM falls) then a down shift should occur, to keep the engine in it's effective operating parameters - which for the 2.7 V6 is higher than you might think.

A V6 design, especially of relatively small capacity (like the H family 2.0 / 2.5 / 2.7litres) is not that great at producing low RPM torque - the stroke is just too short & acts on the crank in an odd fashion. But it does allow relatively high RPM. High RPM though, is not that flash for fuel economy.
So, the compromise is lowish RPM at cruise, which is right at the bottom of the effective torque curve. This means that there is very little 'reserve torque' available when the engine is asked to work harder (hill, wind, weight, drag etc) so an early down change increases RPM to put the engine into a higher point of the torque curve.
My H25A is a slug below 2500RPM, but at 4000RPM there is little other than deep sand or a steep hill that will slow it down.
Early H25A peek torque is 208Nm @ 3500RPM, with power of 106Kw @ 6,200RPM - but at which point torque has dropped to about 165Nm. This means you have a 'torque rise' of 40+Nm from 6200RPM back to 3500RPM - this is a trucking engine power measure of older times, when fuel economy was not that important, but it means that the H2.7 you have is going to be 'happiest' in an RPM range from 3+ to 6k RPM.
These days, we have gotten used to engines operating at lower RPM (for fuel economy reasons) than most of them are really happy to run at - they sound 'busy' at 3500+RPM, so we don't go there & they drink more fuel when they do.
If you increase the base load on the engine - by running larger tyres, increasing wind resistance (bullbar, roofrack, wider M/T tyres etc), while also increasing weight - then you have even less RPM margin before the engine wants to be at higher RPM, & therefore higher torque, to cope.

Your 4 options are:
1) Do nothing & let the car & it's computers cope with load as best they can - even if you don't like the way it sounds.
2) Run a town / touring set of tyres that are slightly smaller than the factory size - to compensate for the extra weight & wind resistance you have. then run the 245s only when necessary & then live with 1).
3) Reduce weight & wind resistance as best you can, then add back on only when necessary & then live with 1).
4) Deepen the gear ratios in the diffs / transfer case - not sure what options you have with a NGV, but likely to be limited or non-existant & expensive, especially when considered to 1).
IMO, the worst 'solution' to your perceived problem, is the one you are considering - trying to force the torque convertor / transmission / engine do something they are not happy doing - it will end in tears down the track somewhere.

Rgs, Michael

[Marck]

Thanks Steve / Michael

Alright this is all good info. One of my concerns is that running the engine at 4K it was going to be unhappy. If the 2.7 is "happy" up there and it has no real impact apart from fule economy and my problem is just me worrying about the level of loud high revving engine noise I will just leav it be and get used to it working hard when running uphill.

Or buy a blows hat and do 90 in the right hand lane.



So what is the "correct" use for a converter lock up?

[Gwagensteve]

If you mean a manual, driver operated lockup control, there isn't really one. Patrol owners have been fitting them for years because they don't have enough gearing, to "cheat" some engine braking. It's no substitute for the right gearing though. My own car runs an auto and off road I rarely ever need to select 1st for descents. It's too slow, but I have lots of gearing.

[ZUZUKI]

The engine will be happy enough a 4000rpm - with a proviso.
Suzuki never engineered the car & specifically cooling system, to cope with the engine running at 4000rpm for long periods of time.
If you have restricted airflow into the radiator, buy putting bullbar / winch / driving lights in the way, loaded up the car with additional weight / drag, then spend lots of time at 4000rpm, the cooling system just won't cope - the occasional (shortish) hill is ok, but with a long drag, monitor temp guage & like you say, be prepared to lower road speed - in a lower gear.

Some transmissions (like the AW4) had a 'power' button / mode & a O/D (over drive) button - to allow some driver control.
The power button would hold lower gears longer & prevent torque convertor lock up. This was to keep the engine in a higher rpm range & for it to be more responsive - ie, you didn't have to wait for a T/C lock up release, or down shift to access higher power & torque.
The O/D button will prevent shift into 4th / over driven gear, so back to 1:1 3rd gear. This was to put the transmission into it's strongest drive configuration for heavy load, like towing. At 1:1, the whole auto geartrain is locked into to engine speed - no load on the planetary gearsets & the only Auto Trans Fluid heat source is the torque convertor, which would go into lock up down hill or coasting on the flat.

A torque convertor lock up switch, manually controlled by the driver, has some benefit in assisting engine retardation to slow the vehicle on steep descents. The torque convertor friction surfaces are under less load (only partially 'supporting' the vehicle weight, as the engine braking is also partially / primarily supporting the vehicle weight, at engine idle torque) than compared to the load imposed by fully pulling the vehicle weight under higher torque load (if the t/c lock up is used to prevent t/c slip & down shift). Those friction surfaces are then transmitting all the drive (no torque convertor torque multiplication occurring) at a 'lugging' engine torque (1800-2500rpm = about 80% of peak torque).

Rgs, Michael

[fordem]

ZUZUKI wrote:

Suzuki never engineered the car & specifically cooling system, to cope with the engine running at 4000rpm for long periods of time.

I don't know where you get this idea from, but I'm pretty certain that I am not the only person who has done this or, does this on a regular basis with NO ill effects - all it takes to run a GV at 4000 rpm for a long period of time is a decent interstate run - Miami to Tampa on the I75 takes me between four & five hours, at an average of 85 mph, and I've been led to believe that it's not difficult to cover some pretty good distances in a single day in Australia.

Quote:

Some transmissions (like the AW4) had a 'power' button / mode & a O/D (over drive) button - to allow some driver control.
The power button would hold lower gears longer & prevent torque convertor lock up. This was to keep the engine in a higher rpm range & for it to be more responsive - ie, you didn't have to wait for a T/C lock up release, or down shift to access higher power & torque.
The O/D button will prevent shift into 4th / over driven gear, so back to 1:1 3rd gear. This was to put the transmission into it's strongest drive configuration for heavy load, like towing. At 1:1, the whole auto geartrain is locked into to engine speed - no load on the planetary gearsets & the only Auto Trans Fluid heat source is the torque convertor, which would go into lock up down hill or coasting on the flat.

Whether or not an AW4 has the "power/normal" mode is dependent on the implementation, not all manufacturers use it, the only AW4 equipped vehicle I've driven that had it was a Suzuki (a 2000 GV), and on that, power mode does not prevent the torque converter from locking, also, in my experience, with OD disabled, the TCC on the AW4 will lockup with the vehicle under cruise conditions - it does NOT have to be coasting or going downhill - I've even seen it lock going uphill, depending on the gradient and how far open the throttle is.