Thinking about a PCS TCU

Iain_B · New Member Joined: Aug 21, 2006 Posts: 12

Hi, I'm currently fitting a 4L80E into my Jaguar XJ-S V12. I'm looking at using a TCU instead of the stock system so I can get a transmission that meets my needs, both as an every driving car - home to work with maximum ecconomy, then have a setting for the occasional bit of track work/high speed fun driving. I'll also be fitting the TCU to a friend car once I get the program sorted out.

I have a few questions:

1. I want to modify the stock torque convertor to around 2500-2800 RPM stall to improve the acceleration, but in normal driving this is about 40 kph in first gear, can I set the TCU to lock up the torque convertor quickly in all gears so I don't end up reving high when crawling along at 30kph? Will this wear out the torque convertor lock-up clutch quickly, and should I be fitting an uprated clutch when they modify the torque convertor.

2. In manual mode, can set it to lock up the torque convertor in all gears, I assume it would need to drop out of lock up to change gears each time? I would like to be able to chug along in 3rd gear at 60kph, torque converor locked up and pulling about 1500rpm. I would also like some engine braking like in a manual car, could it be programmed to hold it in lock-up until I reach a certain road speed regardless of which gear it is in?

3. I would like a "sport/normal setting in which I used the paddle shifter in sport, and be a normal auto otherwise. Can I also have an option to lock out first gear when crawling along in traffic?

Look forward to the answer and I will be placing my order soon - I assume you will ship to Australia

Thanks

Iain Burgess
Brisbane -Australia

jballenger · Posted: Mon Aug 21, 2006 4:21 pm Post subject:

1. The 4L80E will not allow lockup in 1st gear. This is prevented by the mechanical & hydraulic systems in the transmission, not our electronics. Other than first gear you can have the converter lockup at any point you wish. You can have one table that controls lockup in all gears or, if you choose, you can have a table for lockup parameters in each gear so that you can dictate behavior for each gear independantly. Yes, using the converter more will wear it out more

2. You can keep the converter locked for shift events or have it unlock during shift events; this is a personal preference that affects transmission and drivetrain longevity. You can force the converter to hold lockup until a certain speed regardless of gear, yes. The 4L80E may not be the best choice if you want engine braking as this transmission only offers engine braking in 4th gear when the lever is in the OD position. To get engine braking in 3rd, 2nd, 1st you actually have to move the manual lever position. On some newer transmissions, engine braking is electronically selectable.

3. You can pair paddle shifting with our calibration B which can be your sport mode. If you want to pair this with paddle shifting you just don't shift down into 1st gear. We do offer a snow mode setting that provides 1st gear lockout.

Yes, we do ship to Australia. We have a dealer in New Zealand who may be able to better serve you (lower shipping costs), Dave Roche autoprosolutions@yahoo.com.au .
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James Ballenger
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Iain_B · New Member Joined: Aug 21, 2006 Posts: 12

Hi, I've bought the TCU - it's on the way over from from Dave Roche soon.

The 4L80E is one of the few transmissions that will fit a V12 both from a power handling capability and due to the transmission tunnel. It also was a cheap buy, as they Jaugar wrecker has quite a few of them - apparently they don't break and my local ones have never sold one unless the person bought the engine as well for a complete drivetrain swap.

Next step is the torque convertor. SInce I have to run an adaptor plate - the TC legs must be spaced as well as the centre. Whilst it's in the shop, I was going to get tehm to take it up to 2500rpm stall.

Any comments on a higher stall torque convertor? I've spoken to a few torque convertor places and they seem to think it is not a good idea for a everyday car? Say that it would be diffiuclt to drive, and irritating. Has anyone got a high stall TC in their daily driver, and if so, what stall have you found to be workable.

Regards

Iain

jballenger · Posted: Wed Sep 20, 2006 1:47 pm Post subject:

There are a lot of people building up 4L80Es to be strong and reliable here in the US. There is also a slightly stronger variant, the 4L85E in some newer applications.

As far as the stall converter, this is certainly an issue of gas mileage and whether or not you mind revving the engine out all the time before you get some forward motion when the converter is unlocked. In general, I would say that 2500rpm is well within acceptable limits. Many new vehicles like the Lexus IS 300 and Nissan 350z come with conveters in the 2800-3200 rpm range from the factory.
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James Ballenger
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