im looking at getting a resonably big cam fitted into my ef and its suggested that i run a histall but i have also been told that i will run into problems doing that with these gearboxes can somebody please explain the problems i will have and how to fix these problems ( I Dont Want A Manual )

High stall converter in Falcons can cause the ECU to go into limp home mode. From what I can make out you should be alright if you don't go higher than 2500 stall and you're not doing anything strange with the driveline like running lower ratio diff than std with an ECU that's not programmed for it (as this will exacerbate the problem of ECU seeing too low a roadspeed for given rpm).

You need to also fit a transmission cooler.

You can get a 2500 stall Dominator with lockup - ie. specifically for I6 Falcon. They're available thru vpwmailorder.com.au for somewhere between 6 and 7 hundred bucks.

how will i got if im changing from stock 3.23 diff gears to 3.45 diff gears and a 2,500 stall will the change of the diff gears muck anything up

running a higher number diff ratio will make your roadspeed slower than what is shown on the speedo,, how the ecu is to know this however is beyond me?



-mitch

Get the correct speedo gear and should be OK... worse case scenario, get an ECU that came on a car with 3.45's (EF XR6?)

As a matter of fact if you change from 3.23 to 3.45 and want to run a high stall you'd be better leaving the speedo gear alone and mentally compensating for the innacuracy (or fitting a signal conditioner for the speedo reading) - ie. if you fit the 3.45 diff and then the correct speedo gear then the ECU will be seeing lower road speed for any given rpm - this will be worsened by a high stall converter and the ECU may drop into limp mode. If you leave the speedo gear alone then the ECU will THINK the car is going faster than it is (it's speed vs rpm figures will still look right) so there's more room to handle the high stall converter slippage.

Downside is that the speed limiter will still cut in at 180 indicated - so in real world figures it'll be somewhat lower.

The best way to do a diff ratio change in an Auto Falcon is to also fit not only the correct speedo gear but also an ECU from a car with that ratio - ie. for 3.45 you'd be after an XR6 ECU.

To be honest I don't think you'd suffer too bad at all by leaving the 3.23 speedo cog as 3.23 to 3.45 isn't much of a change. That raises another point - I went from 3.08 to 3.45 and noticed precisely f**k all difference - so it's honestly questionable whether going to 3.45 is at all worth your while.

If I were you I'd try putting in a 2500 stall converter and see how that goes with no other changes - then perhaps look at a diff ratio change after that - but more like 3.23 to 3.7 - in which case you'll be wanting to watch the whole limp mode issue - ie. may need to run an XR6 ECU and 3.45 speedo cog and cop the speedo indication error.

I know this all seems confusing but just step back and look at it in simplest terms:
1. Lower diff ratio means more revs for any speed.
2. Auto ECU is programmed to expect certain speed at certain revs.
3. The speed the ECU sees is what you see on the speedo - ie. from the speedo sender (VSS) - which ACTUALLY is just reading the drive shaft speed - ie. BEFORE it reaches the diff.
4. Too much discrepancy between revs and speed according to the ECU program looks like a fault to the ECU.

The ECU sees the same signal as the speedo - where they branch or whether the speedo takes it's reading in series with the ECU I don't know.

so.. sorry for my dumbness will all this mean that if i get a 2,500 stall and 3.45 diff gears if i change my speedo gear that i will be ok

Nope - what I've said is that:
1. You should try just the 2500 stall converter first.
2. If you fit 3.45 diff you should NOT change the speedo gear (just mentally compensate for the inaccuracy - which will be only small as 3.23 to 3.45 is small change).
3. The change from 3.23 to 3.45 is simply not worth it IMO - I went from 3.08 to 3.45 and noticed virtually no difference - so 3.23 to 3.45 will be no difference at all IMO (as far as how it makes the car feel).

From what i remember of the wiring diagrams for EF/EL the VSS goes to the cluster. The cluster then passess this on to the ECU (i6) or TCM (V8)....

There you go - in order to condition the speedo signal you'd need to use two modules - one before and one after the cluster.

In that case it'd be better to run the accurate speedo gear and then condition the signal to the ECU to offset the limp mode issue.

the main reason i was going to go 3.45's was so i could convert to lsd and i figured if im changing all the parts i way aswell change my ratio

could you please pm me or post the link to show exactly where the hi stall converter can be found because i cant find it.

Thanks

Argh! - they've changed their site since I saw those torque converters - now they don't list any Dominator stuff at all. All I can suggest is try to track down someone who sells Dominator converters. I think there's at least one place here in Australia that can costom make converters too.

Give JMM a call.