[KYPHONII]

I'm looking for details and spec on the Automatic in the Jimny particularly 2015.
Make extra
Cheers

[Gwagensteve]

That’s pretty open ended.

It’s a unique auto shared with the 660cc Kei versions. 4 speed (overdrive 4th) with lockup torque converter. I think programming only permits converter lock in 4th

Peak torque capacity is ~100Nm.

Gear ratios can be found via google.

It’s linkage (not cable) shifted.
They are a very compact automatic but run hot.

[KYPHONII]

I found a reference to the
Aisin Warner TW-40LS (TW-40E, TW-40LE)
4-speed RWD

[Gwagensteve]

Yes, that’d be it. What was the reason for your query?

[vet 180]

Gwagensteve wrote:

That’s pretty open ended.

It’s a unique auto shared with the 660cc Kei versions. 4 speed (overdrive 4th) with lockup torque converter. I think programming only permits converter lock in 4th

Peak torque capacity is ~100Nm.

Gear ratios can be found via google.

It’s linkage (not cable) shifted.
They are a very compact automatic but run hot.

I find that very hard to believe considering the stock Jimny engine in 2015 produces 110nm......

I know you have a very big prejudice against the Jimny auto, but I really doubt Suzuki I talked a trans that is rated 10nm lower than the stock engine that mated it to.

On top of that it doesn’t seem Suzuki changed the Auto on the new model Jimny and that happens to 130mn.




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[Gwagensteve]

Don’t get your knickers in a knot- it’s very common for manufacturers to choose an auto with a lower torque capacity than the engine’s peak output. At its most dramatic, the late Bentley Arnage puts near 1000nm into a gearbox rated for ~600. Even my gwagen used an auto that was on its torque ceiling at 180Nm. There are relatively few automatic transmission designs out there and when you’re taking about a very small RWD low-torque application, there’s basically one.

The killer is when the auto is on or past its torque ceiling and then due to driver error (larger tyres without gearing, overuse of high range) it is left to generate lots of heat. That won’t happen in a bentley but it does happen on a Jimny.

I’m not prejudiced at all about the Jimny auto. Prejudice implies judgment without knowledge or experience. I have both- the Jimny auto needs to be treated with care.

There are some changes with the new Jimny. I believe the converter lock regime is different to improve economy and reduce heat.

[vet 180]

Gwagensteve wrote:

Don’t get your knickers in a knot- it’s very common for manufacturers to choose an auto with a lower torque capacity than the engine’s peak output. At its most dramatic, the late Bentley Arnage puts near 1000nm into a gearbox rated for ~600. Even my gwagen used an auto that was on its torque ceiling at 180Nm. There are relatively few automatic transmission designs out there and when you’re taking about a very small RWD low-torque application, there’s basically one.

The killer is when the auto is on or past its torque ceiling and then due to driver error (larger tyres without gearing, overuse of high range) it is left to generate lots of heat. That won’t happen in a bentley but it does happen on a Jimny.

I’m not prejudiced at all about the Jimny auto. Prejudice implies judgment without knowledge or experience. I have both- the Jimny auto needs to be treated with care.

There are some changes with the new Jimny. I believe the converter lock regime is different to improve economy and reduce heat.

Knickers aren’t in a knot I just don’t believe it. Despite you previous comment, it is not common practice for OEM’s to put underrated transmissions mated to higher engine outputs.

I am not aware of the Bentley you mentioned but I suspect that the trans started at a 600nm rated trans and Bentley made mods to the clutch packs, valve body etc to handle the power. I also suspect the same is true for the Jimny trans, maybe in its original form mated to the 600cc it was rated at 100mn but I am sure Suzuki made modifications for the M13 and then again for the K15 to increase the torque rating.

Your Gwagen runs an AW4 right? Plenty of them around rated to much higher than 180nm.

Out of interest what is the source for the claimed 100nm rating for the transmission?

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[Gwagensteve]

Here: https://en.m.wikipedia.org/wiki/ZF_6HP_transmission

And here: https://www.aisin-aw.co.jp/en/products/ ... up/at.html

So 114.5 Nm for the current TW40 transmission.

The gwagen used the smallest Mercedes auto available- shared with the 190e as it turns out. Hydraulic 4 speed with a 180Nm torque ceiling behind an engine that made 180Nm.

Expect to see more of this happening- small transmissions are lighter and less power consumptive. Modern engine management can torque limit to prevent damage.

It’s all about use and application.

The opposite problem was when Suzuki put a trimatic behind a g16a and created a dull, laggy, doughy car because the auto was too big and absorbed too much power.

[vet 180]

Gwagensteve wrote:

Here: https://en.m.wikipedia.org/wiki/ZF_6HP_transmission

And here: https://www.aisin-aw.co.jp/en/products/ ... up/at.html

So 114.5 Nm for the current TW40 transmission.

The gwagen used the smallest Mercedes auto available- shared with the 190e as it turns out. Hydraulic 4 speed with a 180Nm torque ceiling behind an engine that made 180Nm.

Expect to see more of this happening- small transmissions are lighter and less power consumptive. Modern engine management can torque limit to prevent damage.

It’s all about use and application.

The opposite problem was when Suzuki put a trimatic behind a g16a and created a dull, laggy, doughy car because the auto was too big and absorbed too much power.

Ok that makes a lot more sense. The 114.5nm spec would be what’s behind the Jimny for the past 10+ years. A 110nm engine and a 114nm trans. That’s a 14% increase on what was previously mentioned and makes perfect sense. In the new Jimny they most likely did some small mods to get it rated to 13nm exactly.

I agree with everything mentioned in this post and tbh is one of the reasons the Jimny trans is actually a decent unit imo, crap for after market support and engine conversions. But good in factory spec.

Transmission tech development and correct specing over the past 10 years has had a huge effect of emissions and fuel consumption.




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[Gwagensteve]

Where is the evidence suzuki trick the auto up?
The current version of the auto is not identical to that used earlier. The 100Nm came from Rodney at wholesale automatics when Greg approached him about improving the g series variant to live behind a 1.6. (To which the answer was no, it’s already beyond it’s ceiling)

I see you understand what’s going on but I don’t think you’ve grasped that it is common practice to run autos above their torque ceiling. This will be done for lots of engineering reasons, much like the way an LS V8 in a corvette will run a light transmission and a tiny air filter but the same engine in a Silverado will run a very heavy transmission and huge radiator and air filter. A corvette can’t hold the engine at peak torque for more than a few seconds, a Silverado might do it all day. Using a corvette transmission in a Silverado would see it fail quickly

Nobody is putting a 6HP in a truck with 1000nm, but in a Bentley that reaches the speed limit in 5 seconds it won’t get hot enough to be a problem even though the auto is being “overloaded” Same with a Jimny... except when it’s over GVM and on 30’s and in highe range on the beach.

[vet 180]

Gwagensteve wrote:

Where is the evidence suzuki trick the auto up?
The current version of the auto is not identical to that used earlier. The 100Nm came from Rodney at wholesale automatics when Greg approached him about improving the g series variant to live behind a 1.6. (To which the answer was no, it’s already beyond it’s ceiling)

I see you understand what’s going on but I don’t think you’ve grasped that it is common practice to run autos above their torque ceiling. This will be done for lots of engineering reasons, much like the way an LS V8 in a corvette will run a light transmission and a tiny air filter but the same engine in a Silverado will run a very heavy transmission and huge radiator and air filter. A corvette can’t hold the engine at peak torque for more than a few seconds, a Silverado might do it all day. Using a corvette transmission in a Silverado would see it fail quickly

Nobody is putting a 6HP in a truck with 1000nm, but in a Bentley that reaches the speed limit in 5 seconds it won’t get hot enough to be a problem even though the auto is being “overloaded” Same with a Jimny... except when it’s over GVM and on 30’s and in highe range on the beach.

No evidence just an assumption based on the wording of the aisin site saying it’s used for 600cc lei cars to 1.3L. I just assume it hasn’t been updated for a while.

Having worked a little with the OEM’s on product testing in the OEM world it’s just not how it works, doesn’t matter if it is over the rated power for a few mili seconds or 100 seconds if it exceeds maximum input torque it can not be used. What happens in situations where there is no other gearbox option is they will de-tune the engine. I.e. mid 2000’s Mercedes CL65. Problem is if it exceeds torque rating then clutches are slipping, pre-mature wear is produced and warranty claims start to happen. It becomes a PR nightmare with lawsuits etc. if an OEM deliberately and knowingly mates an under rated transmission to a higher powered engines.

Now having driven the Bentley you mentioned (the one I drove was a 4 speed though) and have also driven a 2013 Mulsanne I know how torquey those engines can be so the previous comment peaked my interest. But as I assumed Wikipedia doesn’t tell the full story, the transmission might have started its life out as a 600mn rated trans but in the application of the Bentley it was modified and rated at 1000nm:

However, the biggest progress is not the engine but the gearbox. Bentley finally said good-bye to the outdated GM 4-speed automatic and replaced it with a ZF 6-speed automatic. This is the first time the ZF unit (first born in BMW 7-series and since then used in many luxury saloons and grand tourers) fitted to an engine so torquey. It requires strengthened internal clutches to handle the 1000Nm of torque. The shift quality of the 6-speed unit is far smoother than the GM unit, and the extra ratios reduces the power fluctuation further. Moreover, in swift driving the ZF unit locks up its torque converter to deliver instant response, so that the laggy feel of the old transmission is completely eliminated

Source:
https://www.autozine.org/Archive/Bentle ... rnage.html

Regarding you corvette analogy, I actually work with GM and the corvette ZR6 trans is actually rated higher than the Silverado/Sierra. The radiators are also surprisingly large, but when they are not it is more to do with the body shape and airflow into the radiator not requiring as large a unit that engine load. Air filters an any truck or off-road capable vehicle will always be larger as they can travel on dirt roads and expect more dirt ingress, a corvette can simply not drive in the roads that would swallow the same amount of dirt and therefore does not require a larger filter. Once again it is not about engine load or sustained torque or certain rpm from the engine.

I can’t speak of old mate Rodney’s expertise, but can say there are many other factors to consider there that would affect his opinion, one that springs to mind is he is there to run a business and it might have not been profitable to invest time and energy into developing a low volume transmission that he sees no repeat business from. It also seems irrelevant as you are appear to be referring to an older spec version anyway.

I also can’t speak on behalf of your experience, but my gut tells me there is more to this also as the automatic used in the Jimny is one of the more reliable units out there in terms of warranty claims. If you want an example of a trans that has many issues with warranty claims Jeep and dodge have the worst record I have worked with and GM used to get a lot of complaints but not a whole lot of actual warranty work.


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[KYPHONII]

I have a JEEP XJ with a AW4 auto transmission.
It’s a 4 litre and lots of torque and a few HP.
Given that there where millions produced around the world and thousands of them abused with out issue. Seems you can put about 800 hp through one with out modification as they do in the turbo Toyota Soarer. Safe to say that Asian Warner don’t make crap.


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[KYPHONII]

Automatics hate heat and around town stop start traffic generate the most heat with normal average operation,
Off-road low range generated the lest.
Qualify this statement by saying that abusing the converter stall will boil oil in a few minutes.


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[KYPHONII]

Are we sure that 4 th gear is a over drive.
3000 rpm at 100 kph


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[KYPHONII]

I’m interested in what capacity the transmission has to tow a trailer.
I’m looking to build a aluminium trailer.
I have mounted a temperature sensor on the transmission housing and one on the engine block.
The results so far are that the transmission is predominantly heated by the engine. I have not had any temp above 95 from the transmission. That was a 2 hour trip on dirt loaded up and with a speed around 50 kph, probable the speed most likely to generate heat.


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[Gwagensteve]

4th gear ratio is 0.696, so yes, it’s an overdrive.
Temp rise is totally connected to converter slip. The hottest my AW-4 runs is on fast dirt. I’ve seen surprisingly high temps on a Jimny auto (correctly geared, 26” tyres) when on a long climb with the converter unlocked, ~80km/h

The correct place to read trans temp is on the line to the cooler. This is a reflection of how hot the fluid is in the gearbox. I don’t know where you’re reading that 95 from. Engine load will translate to trans temp pretty faithfully but it’s converter slip that adds heat. Towing will unlock the converter more frequently due to increased drag.

Greg has managed to get his Jimny auto to run cool with 2x 250x250mm PWR trans coolers, one in front of the radiator, one with its own thermo. It now runs equivalent temps to an AW-4 in the same service.

Aisin Warner do not make “crap” - but in the Jimny the auto has no headroom. It’s on (or already past) it’s design limit. That’s not Aisin Warner’s fault, it’s mostly down to some engineering compromises Suzuki made, keeping the same auto for the 660 and 1.3 litre models. (An AW-4 is not on its design limit in an XJ and it’s massively under its design limit in a vitara, which is why they run cool and they handle heaps of abuse. My AW-4 has been remarkable in my car.

I don’t have time to work through Vet-180’s comments now, but it’s not a warranty issue. The transmissions are degraded by excessive heat and this is a relatively slow process. They last out the warranty period, only to fail at 100k+ in the hands of a second owner who’s put 30’s on it, loaded it up and is running down the highway with the converter unlocked in blissful ignorance the trans is at 120 degrees. In comparison, an AW-4 doesn’t just outlast the warranty period, it outlasts the vitara it was built with and will likely outlast the Sierra it’s swapped into next. That’s the difference when something is engineered with headroom.

[KYPHONII]

As i understand it the fluid leaves the converter and travels to the cooler.
The transmission picks up fluid from the pan and puts it through the clutches, valves and bearings.
For that reason I have moved away from temps on cooling lines to temps of fluid going in to the transmission from the pan.
My temp gauge is on the Pan on the Suzuki and on the cooling line out on the Jeep, (20 years old).

That brings me to the position of a cooler, before the radiator, after the radiator or inplace of the radiator.

With regard the overdrive in 4th.
Over drives in manuals where problematic due to not transferring torque straight through a gearbox but the auto don't necessarily do that so i'm interested in why the overdrive in auto's is seen as a issue.

[Gwagensteve]

Overdrive isn’t an issue, it’s the converter lock. In order to improve fuel economy and minimise heat with a relatively loose torque converter (to provide crisp acceleration with a low torque engine) manufacturers started using lockup torque converters in the 1980’s. If cruise load (and therefore throttle position) exceeds factory parameters, the engine will start to bog if the converter remains locked, so it unlocks, revs increase due to converter slip and the trans gets cooking.

As to your temperature measurements- transmissions fail because the fluid degrades due to heat. To know how much you’re degrading the fluid it makes sense to measure the fluid temperature at its hottest. If you’re seeing 95 in the pan the fluid going to the cooler is very hot. Synthetic trans fluid can withstand higher temperatures. It doesn’t really matter how you read the temperature, but if you’re measuring it somewhere other than where people normally do, you’ll need to take that into account in relation to cooler efficiency etc.

We do not need to heat our trans fluid in Australia to achieve proper shifting, so there is no reason to only ever cool the auto to the temperature of the bottom tank of the radiator. You won’t hurt it by “overcooling” - run the cooler in front of the radiator. Run at least a 200x200 quality cooler like PWR.

If you’re regularly towing consider lower axle or transfer ratios to raise cruise RPM to get the converter to lock. Certainly don’t make things worse with larger diameter tyres without gearing correction or roof load.

[KYPHONII]

I’ll be staying with 215/75r15 wheels
No roof load / drag
Trailer weight of about 600 kg gross
The fluid shows no sign of burning and the 95 degree would more reflect the engine / radiator.
I have another temp sensor that I’ll put on outlet to Guage the difference.


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[Gwagensteve]

215/75 is already 50mm over standard.
600kg is a very heavy trailer for a Jimny.

I sincerely hope your bottom radiator tank runs well under 95 degrees. Rest assured the temperature you’re seeing is from the transmission. Normal operating temperature is circa 85 degrees measured at the line to the cooler. I’d be guessing, but I’d suggest you’re up around 105 in the line to the cooler.

Transmission oil won’t show visible burning until it’s way too late.

Steve.

[KYPHONII]

I’ve mounted 4 temp sensory on the transmission.
One one the pan
One on the fluid out
One on fluid in
One on engine for reference
Will see how it goes


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[KYPHONII]

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[Gwagensteve]

Cool. Please publish your findings. They’ll be very useful for Jimny owners.

[KYPHONII]

First run, cool NQ evening about 24 degrees, ac on, 12 kilometre run up to the local lookout, Mt Stuart,
All temps started at about 80
Pushed it a little , 40 to 70 kph. Empty standard Jimny.
Engine temp moved up to about 90
Transmission pan temp peaked at 100
Return line peaked at 98
Fluid out of the box / converter peaked at 105
The out put temp quickly responds to less load, there is a short section of flat and a slight decline before the last short steep section, the transmission fluid temp out of the converter dropped 5 degrees in the short easy section.
First observation would be that the heat builds up through the converter about 6 to 8 degrees so extra cooling of the return would be my first move.


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[KYPHONII]

The cooler the fluid is in the pan the better able to control the converter heat generation.
The return fluid cooled to radiator temp quite well but the transmission body takes quite a bit longer to respond to a drop in temp. Overheat the entire body and component, that would take quite a while to cool down if it got very hot.
Letting the gearbox heat up over long high temp exposure would be very hard to control.


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[fordem]

KYPHONII wrote:

First run, cool NQ evening about 24 degrees, ac on, 12 kilometre run up to the local lookout, Mt Stuart,
All temps started at about 80

Are you mixing temperature units? Shouldn't all temperatures have started at ambient 24 degrees?

[vet 180]

fordem wrote:

KYPHONII wrote:

First run, cool NQ evening about 24 degrees, ac on, 12 kilometre run up to the local lookout, Mt Stuart,
All temps started at about 80

Are you mixing temperature units? Shouldn't all temperatures have started at ambient 24 degrees?

I read it as he started at 80deg due to driven normal roads until he got to his mountain climb where he pushed the trans hard


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[KYPHONII]

fordem wrote:

KYPHONII wrote:

First run, cool NQ evening about 24 degrees, ac on, 12 kilometre run up to the local lookout, Mt Stuart,
All temps started at about 80

Are you mixing temperature units? Shouldn't all temperatures have started at ambient 24 degrees?

the 80 degrees was operating temp from normal city driving, the engine operating temp had stabilised the transmission due to the transmission standard cooling setup.


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[Gwagensteve]

It doesn’t matter how you rationalise the number, you’re only getting 7 degrees of delta across your cooler. That’s a problem. Your number is exactly the same as the number I said you’d be getting under those circumstances. It’s not in itself all that worrying, what’s worrying is that if you add (any) load be it by tyre diameter, vehicle payload or towed load, engine temp will increase as will trans fluid temp, so your delta won’t improve.

[KYPHONII]

Gwagensteve wrote:

It doesn’t matter how you rationalise the number, you’re only getting 7 degrees of delta across your cooler. That’s a problem. Your number is exactly the same as the number I said you’d be getting under those circumstances. It’s not in itself all that worrying, what’s worrying is that if you add (any) load be it by tyre diameter, vehicle payload or towed load, engine temp will increase as will trans fluid temp, so your delta won’t improve.

We will see.
There won’t be speculation, that’s a bonus.


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