Manual conversions and TCL musings

This is mainly a brain dump thread, just putting out some thoughts I'd had recently, everything that follows is my perception on the situation and may not be factual.

The bits I'm not 100% sure on will be in italic. Take it with a pinch of salt people :)

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There's one thing thats been puzzling me for a while and thats how PFL Auto VR-4s converted to manual tend to have the TCL spaz out and cut power to the engine when least desired.

Case and point of this is me building the TCL switcher for Atik because he's spun out on roundabouts due to this.

The TCL is designed to reduce power being applied to the wheels when it thinks the wheels are slipping, it does this by pulling back on the throttle by means of a vacuum when it detects slippage. It determines slippage by checking each individual wheel speed and comparing it against the accelerometer, the vehicle speed sensor on the gearbox and what the auto box is currently doing.

The reason for the TCL spazzing out in a manual conversion is there is no feedback from the (missing) autobox as the car is tricked into thinking the auto gearbox is in neutral.

Feedback that can be determined from the auto box is what gear its currently in and what the torque converter is up to.

My thoughts are thus, would we be able to keep TCL in converted cars if we perform one or all of the following;

1. Wire up a series of switches in the manual gearbox shift gate to feed back what gear the car is currently in (and as such, get a nice readout on auto-dashboards what gear the car is presently in)
2. Wire up a switch to the clutch to provide some level of feedback to what the torque converter may be up to

Also, when doing a auto to manual conversion, if you replace the auto gearbox ECU with a manual gearbox ECU at the same time, do you still have problems with TCL?

I'm not sure which bits the tcl system monitors, but the gear selected should be easy enough to display. I think the problem is more likely to be the lack of input shaft and output shaft speed sensors though, which would be a whole lot more tricky to replicate.

Ah-ha, it monitors the input and output shaft speeds, but at which point does it monitor input though?

Before (engine rpm) or after (auto box shaft input) the Torque Converter?

I'm guessing that it'll be after the TC, which isn't too hard to simulate I guess, we could do the following;

• Input Shaft Sensor - Take feed from crank (engine rpm) sensor, and permanently wire the signal from the TC to read as if the TC is locked
• Output Shaft Sensor - Use the vehicle speed sensor as it should be immediately after the gearbox anyway

I think you are assuming too much there bud!

The input shaft suggestion might work, but the output shaft of the gearbox is not appropriately named. The output shaft sesnor is not on the same shaft as the speedo, there is at least the final drive ratio between.

Well, how does the output shaft relate to the speedo shaft? Is it a locked gear ratio or something?

I don't know. I think the issue will be where the auto box sensors measure speed. The box is not as easy to look at and work out which bit does what. A manual gearbox, sure, no problems, but an auto has magic cylinders that change gear when the ATF says abracadabra!

If you want to have a look at a stripped autobox and see if you can fathom it all out, feel free to come and have a gander. I've got a box in bits in the garage at the moment.

Output shaft speed sensor takes its readings from this here:

http://ozvr4.com/forums/showthread.p...l=1#post167850

And, here's the workshop manual for the F4A51 automatic transmission too, which is very similar.

http://www.mivec.co.nz/tech/F4A4x_AT_Manual.pdf

Quote:

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Originally Posted by eyeballprawn

Output shaft speed sensor takes its readings from this here:

http://ozvr4.com/forums/showthread.p...l=1#post167850

And, here's the workshop manual for the F4A51 automatic transmission too, which is very similar.

http://www.mivec.co.nz/tech/F4A4x_AT_Manual.pdf

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I look at those and I just go :dizzy2: I'll read them tomorrow and see what I turn up, thanks Dylan!