Auto gearbox modification

[Apache]

As a follow on from the thread in 'General'

I have roughed out a prototype design with a bit more elegance than a simple switch. I will post the diagram for critique later, but for now what happens is as follows.

Two momentary pushbuttons control 'lock' and 'unlock'. 'lockup' is input via a set/reset latch to a relay which switches the solenoid between either the ECU output or 12v, giving manual or ECU control of lockup.

Using the latch means its not possible to start the car in 'lockup'

The 'reset' portion of the latch is fed via a 3 input OR gate, the inputs of which are 'unlock' pushbutton, the 'brake on' signal and (the clever bit) also the 1st and 2nd gear active lines. This means lockup will automatically disengage when the box changes down to 1st or 2nd gear. It will also disengage when braking, which is a useful safety feature if you need to brake hard and forget you're in lockup!

So, to sum up. Manual lockup will be available in 3rd and OD. It will automatically cancel when the box shifts down to 2nd or 1st, or if you brake.

As this is in development, comments are welcome. The design will befairly flexible, but I am erring on the side of safety / reliability. I dont want to trash the gearbox!

[CaptainBeaky]

Sounds good to me

[KERRSURF]

Sounds good so far, when will prototype be on truck.

pics required!

[Apache]

Done the switch mod today, seems to work fine. Had a bit of a blonde moment working to the pinouts for a different ECU... DOH!

The basic 'failsafe' circuitry is firming up nicely in my head - just need the time to get the bits and build one. I want to design the circuitry so full modification to manual control of shift points is an easy next step, and circuitry to display what gear you're actually in on a wee alphanumeric display on the dash.

Manual control will probably take longer because there are more ways to trash the box you need to avoid!

[BUSHWHACKER]

Where's my Knight rider scanner?

[Apache]

Do you still want one of them Vince?!

[BUSHWHACKER]

Do you still want one of them Vince?!

[whisper] Yes please. [whisper]

[Apache]

Hehe, its back on the list then!

The 'new' job (not that new now - been there a year!) has reminded me I know how to do that stuff - after years and years of not having the chance

[Apache]

Now the roads are quiet, I've just been for a drive to get the feel of the manual lockup switch. Accellerating as normal and then selecting lockup seems fine. You can slow to about 45mph / 1500rpm on a flat road and cruise at that. Accelleration back to 60mph obviously takes longer, but in the sort of traffic I envisage this being useful, that wont matter. Taking your foot off the gas at 60 allows a small measure of engine braking - also useful in A road traffic.

It does seem to hold on to the gears longer rather than downshifting, and I'm not sure why that is yet, but releasing lockup allows a normal (and smooth) downshift.

I still think for normal operation an automatic release of lock when in 1st or 2nd would be worthwhile.

[The Lovely Boyo]

I still think for normal operation an automatic release of lock when in 1st or 2nd would be worthwhile.

I would have thought it would need to be essential. With a locked TC you would have 'solid' drive between the engine and the road - that would be interesting when coming to a halt lol

There's an American company doing these things. One of their features is to allow a 'snow' start - selects and holds 2nd only, apparently can have its uses in muddy conditions too.

Have a go at figuring that out and I'll buy one off you.

[BUSHWHACKER]

There's an American company doing these things. One of their features is to allow a 'snow' start - selects and holds 2nd only, apparently can have its uses in muddy conditions too.

We can do that anyway, just select 2 with the lever.

[Apache]

Andy, it looks like full manual control should be fairly simple, so selecting and holding 2nd should also be easy (but you have that on the stick?)

I'm planning on using the 1st and 2nd gear signals logically OR'd (along with brake light signal) to deselect lockup, so lock when stopping wont happen. On the version I'm planning, lock will only happen in 3rd or OD, but no reason why I cant make it available in 2nd too.

[Apache]

OK, after a wee drive around this morning, it seems I can select lockup at any point, but at this point, the box 'seems' to change up to top, whatever speed I am doing, and slowing down doesn't 'seem' to elicit down-changes.

I say 'seem' because its hard to tell. I need to build something to display what gear the box is selecting to be sure, but are there any autobox experts out there who might know why the box would change up when selecting lockup?

I have a theory that the ECU might be processing it as "ok, there's lockup - we MUST be in 3rd gear" and selecting 3rd.

[The Lovely Boyo]

Originally Posted by The Lovely Boyo

There's an American company doing these things. One of their features is to allow a 'snow' start - selects and holds 2nd only, apparently can have its uses in muddy conditions too.

We can do that anyway, just select 2 with the lever.

Hi Vince,

If you put an auto tranny to 2nd, it'll start off in 1st, change into 2nd and thats all. No 3rd or overdrive.

But it won't pull off in second.

For someone who has the ability to do an V8 engine swap to the standard you have, I'm quite surprised at you, old chap.

Splasher been causing you some sleep deprivation????????

[TonyN]

I would have thought it would need to be essential. With a locked TC you would have 'solid' drive between the engine and the road - that would be interesting when coming to a halt lol

"Apache...The only man to stall a Auto"