Rebuilt Gearbox

[NeedmorePower]

My question is this who has taken there gearbox to preston automotives and once the job was done you could hear and feel a donk with most gear changes?

I asked them whats with that and they said it will go away after the gear box has run in after 1000km or so?

I've spoken to my mates and they say its not normal.

Any feed back will be great.

Edited 23/06/06 06:10 AM by Adam

[Adam]

If your referring to the hard shifts at low speeds I'll tell you that it won't go away one little bit.

If I could change 1 thing about my ute it would be the hard shifts. Even with edit they can't be smoothed out enough at low speeds, it's fine when I'm on the gas though.

[G6ET8U]

Ask Adam or Mr Turbo they are both running Preston prepped auto's...

Jack

Edited 23/06/06 06:11 AM by Adam

[NeedmorePower]

For example I'm in 3 gear and the auto shifts down into 2nd "cruzin speed" you will hear and feel a 'donk' as it kicks down.

When I tool the car for a spin I came back straight away and told him the 'donk' doesn't feel right. They said its the thrust bearing, once that wears in it will stop. Apart from that the tranny feels strong.

Now I've cleared that issue can anyone comment on the 'donk'?

Edited 23/06/06 06:16 AM by Adam

[turbotom]

I've had my gearbox overhauled (not by Prestons, though... but typically same mods - kevlar bands, grooved clutch plates, S5 solenoid, oil pump overhaul etc etc ) . When I had the Unichip, the changes under light load were not pleasant.

Great under hard acceleration, but TOO jerky and clunky under light load.

Driving in the normal Drive mode (adaptive mode) after a while it got better, but was not as smooth as I'd like. Was still clunky at times.

It was a matter of modifying my driving technique to get the best response.

When I retuned with EDIT, I asked HPF to soften the shifts on my everyday tune:

soften the adaptve mode, but retain the quick shifts for performance mode.

They did a good job. I'm pretty happy with my everyday map. The adaptive mode has settled with my style of driving and is as good as the stock box.

Rob did say though, NOT to do any full throttle runs in that mode.

Full throttle runs are only done in Performance or SSS mode.

I'm keen on making the performance shifts a touch quicker still. It's the only mod I need doing to my everyday tune ( 270 rwkw) when I come to big vic weekend 2

If you've only just had the box done, drive around gently in the adaptive mode and see if there is any improvement. It takes quite a few km to learn to adapt.

Bottom line though, if you don't want slippage, the line pressures have to be high and clutch plates need to be pressed hard. The result is hard, noisy, and jerky shifts. It's one of those compromises that have to be made. Getting the exact balance isn't easy, and it will depend on your driving requirements and style.

tom

[Adam]

For example I'm in 3 gear and the auto shifts down into 2nd "cruzin speed" you will hear and feel a 'donk' as it kicks down.

When I tool the car for a spin I came back straight away and told him the 'donk' doesn't feel right. They said its the thrust bearing, once that wears in it will stop. Apart from that the tranny feels strong.

Now I've cleared that issue can anyone comment on the 'donk'?

←

Yep, that 'donk' is normal.

Mine did the same thing and I heard it less and less as I put more km's on it.

I still hear it occassionally now and then, and that's after 30,000km's.

[xrdreaming]

It really is horses for courses mate, the catch 22 in the whole setup is that the auto needs to shift firm and fast in order to last with high torque and power outputs. You can have nice smooth soft shifts and the box may need a rebuild every 6 to 12 months or have a firmer shift but get a longer life out of the auto.

The donk is standard fair with the Ion 4 speed once "Shift kitted". The thrust bearing noise and the raesbestos bands squeking will lessen with time though.

The edit can help with low speed shifts as Adam has said, though it will always be there.

[NeedmorePower]

thanks guys for your comments they have been reassuring

[jordak]

Out of interest I have a stock auto (with cooler) and an electronic shift kit.

This allows me to maintain the smooth factory shifts for putting around as well as the option of super firm shifts with a flick of a switch for when I'm giving it some.

Is it possible to strengthen the auto and maintain smooth shifts and rely on the shift kit to firm up the shifts when required?

[Headsex]

As well as changing shift feel between the 3 different modes (Adp, Perf, and Sequential), Us tuners are also able to change the shift at high or low driveshaft speeds...

Confused? Let me explain..

Each shift sequence ramps between 2 rows of tables.. ones for low driveshaft rpm (crusing around), and ones for high driveshaft rpm (heaps of pedal).

So If the car shifts at low rpm (low driveshaft speed), you can maintain factory shift feel.

However, when your hooning, the auto will change gears later on in the rpm range(high driveshaft speed), you can make it change harder.

I have tuned alot of cars this way.. and the customers love it.. They dont need to change to Perf mode to get harder shifts, they just boot it

Danny.

Edited 27/06/06 03:01 AM by Headsex