All Things Chev

[FNQGU]

Yeah, I've got no complaints in the torque department either. I'm just about to pull the trigger on the 4L85E install. Out of interest, I was just reading how you can get a custom job done on the 4L80 & 85 to make them six speed too! Used in a lot of US muscle cars and racers by the looks of it.

Got to sort out some sound proofing and some interior stuff first, then get the diffs protected before taking a look at getting the slush box fitted up and sorting my low range for more rock crawling slow work.

[the evil twin]

Hiya BenK,

Whoever does the install for you ask them about a few things like;
Will they fit the optional harness so you can have "Power" and "Economy" modes
Transmission Cooler placement and
Fan switching (Thermo/Manual/Both).

Also the 4L8x trannies will not lock up the TCC in 1st gear so if you are doing serious low range crawling (which I take it you are from the post) then as you mention, you will def need to suss out a few options like a Manual Lock Up or crawler ratios so you can get away with using second or whatever.

I was reading those articles about the "Pseudo 6 speed" 4L's as well. It kinda made my head hurt a bit and I couldn't understand exactly what they are doing but is seems to involve higher pressure valve bodies and hard lock ups of the TCC.
Might be well worth exploring later.
I toyed with the idea of a 6L to get that awesomely low 1st gear and 2 overdriven ratios but they are a physically much bigger unit and the 4L took enough modding to fit so I said bugger it

I was going to wait a few months before I dick with my Tranny proggies but my fingers are itching to play with the TCC lock up settings in 2nd and 3rd.
That is because Brunnies default settings are with TCC lock up only in 4th.
The down side is you have to be careful as the Yanks reckon if you use TCC to much for engine braking in the low gears the 2nd and 3rd overrun clutches can burn out.
They are talking about seriously more HP and Torque in waaaay heavier trucks than we are tho so I am will ing to give it a go when I get my Tranny Instrumentation sorted out

[FNQGU]

They don't fit the Power / Economy functions and said it would be extra if you really want it, but that it had very little if any benefits in real life driving.

Fan switching can also be done, and sounds like a good idea, along with a Tranny Fluid Temp gauge.

They did offer a choice of three different ECM's though. The install comes with the standard GM unit but there were two other far more complex modules that can be ordered and fitted if wanted. Cost goes up to about 2 grand for the system from Wholesale Automatics, and it was 1700 for the other one. Not sure I need to get fancy with this though so will probably just stick with the simpler GM version and use their software to tune it up to how I want it.

The Transmission Cooler unit gets mounted up in front of the radiator. Hopefully there is room, it looks pretty jammed to me.

To be honest with you, I am still trying to understand how the Torque Converter Clutch lockup works and how it would be advantageous in gears other than 4th for that overdrive economy. If I fit a reduction gear in the transfer case, and then select First or Second Low, it should cover my 'go-real-slow' needs wouldn't it? Are you referring to the ability to hold it in any gear you want for differing driving conditions?

[the evil twin]

Going "uphill" is no problem, its the down that may worry you

The 4L trannies "freewheel" in 1/2/3 and in 4th when the TCC isn't engaged and the TPS is 0.
In my vehicle with teh default proggy when you lift the foot it coasts IE you can be doing 80 K's or going down hill and pull the shifter back to 3rd, 2nd or 1st and there is absolutely no engine braking.
The truck keeps coasting along, very disconcerting initially.

The 4L's don't have a gear "hold" setup either so if you select, say 3rd it will shift 1,2 and 3 but not go into 4
In a Tranny that will Hold a gear that is the only gear it will use.
Sooo if you are in say 3rd and going down a hill and lift the foot the TPS goes to 0, the RPM's drop to idleish and the vehicle just goes quicker due to good old gravity

That is why I want to proggy the TCC to softly lock up in 2nd and 3rd

[FNQGU]

Sh!t, didn't realise that. I tend to rely quite heavily on engine braking as I am sure we all do. I'm going to try and go for a drive in a vehicle fitted up with the 4L85 in the next few days so i'll suss out the whole setup.

Have you got a temp gauge fitted? I take it that if you want the option of running the fan in manual mode, that you must have a gauge to give you the heads up on when it is time to flick it on?

[the evil twin]

Sh!t, didn't realise that. I tend to rely quite heavily on engine braking as I am sure we all do. I'm going to try and go for a drive in a vehicle fitted up with the 4L85 in the next few days so i'll suss out the whole setup.

Have you got a temp gauge fitted? I take it that if you want the option of running the fan in manual mode, that you must have a gauge to give you the heads up on when it is time to flick it on?

1st gear is no different to any other Auto regards engine braking.
2nd and 3rd are different "out of the box" but only due to the programming as the TCC operation is left up to the user to set up.
The reason for that is the yanks are looking at normal use as being fanging along the road and when you want to slow down you use the brake.
Sooo... they want to let the engine idle at 0 TPS to save fuel.
If you ask the installer they will proggy it for your requirements.

Still researching the various options for temp monitoring and auto switching of the Cooler Fan.
Brunnies are adamant that for 4WD use and light towing the 4L85 with it's larger pump will absolutely eat anything we throw at it.
The Yanks are using more power coupled to 3 to maybe 4 times the loads we are.
Anyway, will probably go with a Watchdog solution or similar with temp readout, fan switchig and overtemp alarm.
Mainly because I cant be stuffed cobbling together my own setup between now and the Simmo trip.

[T-roy86]

My 2004 3ltr Gu blew up and im looking at putting another engine in. Was looking at 4.2 but its hard and expensive because mine is auto any recommendations on chev engines and a rough price ill be looking at to get 1 fitted. Also im from s.a if anyone knows people who do this kind of work here. Thanks

[Gecko17]

@ ET... is there much difference between the 4L80E and 4L85E?

[the evil twin]

@ ET... is there much difference between the 4L80E and 4L85E?

4L80
Input Torque 440 Ft/Lbs
Output Torque 885 Ft/Lbs
Vehicle GVM 8,000 Lbs
4 Pinion Gearsets

4L85
Input Torque 480 Ft/Lbs
Output Torque 885 Ft/Lbs
Vehicle GVM 16,000 Lbs
Towing capacity 22,000 Lbs
5 Pinion gearsets

NB specs vary by minor amounts depending on year of manuf and phase of the moon, the above are sort of an average that I found when researching.

I bought the '85 for two reasons.
Firstly it was a brand new crate tranny and secondly I will probably be looking at significantly heavier towing in 4 to 5 years or so

[FNQGU]

Am waiting to speak to Wholesale Automatics again tomorrow, but I do like the sound of the manual TCC switch as an addition, plus a temp gauge. Was out for a drive today in the forestry tracks and coming back home from any direction into Cairns involves coming down a winding range. Found myself sitting in 3rd for most of it with the odd touch on the brakes. I reckon being able to hold gears going downhill with an Auto would be how I'd want to drive it.

Gecko - have you played with the programming on yours yet?

@ T-roy86 - mate, if a 4.2 is too expensive, then sit down for the pricing on a new chev. If you want to go for a crate TD version, then allow $35K installed, if you go to Brunswick in Perth. I haven't heard of anyone in SA, but there could be someone doing it. Wholesale Automatics will sell you an upgraded Valve Body for your Auto that they reckon will handle the Chev no worries. I think price is around $850, so factor that in as well. Brunswick will do reco motors a whole lot cheaper, and also if the engine is non-turbo'd it will be cheaper again. Have a chat to them about your options if you are interested. Also ring around for insurance BEFORE you do it so you know what you are in for. Most here found Shannon's the cheapest.