Shift Kits Auto Box

[Chids34]

Hi, I have recently bought a stage 3 shift kit for my auto r34, I will probably get a medium stall converter. Is there anything else I am going to need besides a rebuild to the box also how will a shift kit affect gear changes and the way the car drives, stage 3 is the firmest you can get I think and I've heard that they can be pretty wild, as its going in a street car would it be to much, can I still just put the car into 'D' and go grab some Thai noodles on a Friday? WILL IT STILL BE STREETABLE?

Thanks J

[Ben C34]

Ask the trans place that's doing it? They will know how hard it will shift. Stage 3 doesn't mean much .

Get a bigger trans cooler.

[LTHLRB]

Shift kits are just kits that put higher amounts of pressure through your valve body making the vehicle shift more "positive" so to speak. The shifting will be harsh when cruising, kind of like a kick in the pants and it might even let off a little churp. Your stall converter size should be coming in when your power comes in, so lets say your cars power band is from 3 - 7500. Your converter would need to be 2800 - 3200 or thereabouts.

It would still be streetable, but will chew more juice because of a stall converter. You are still able to drive the car in D unless you have a semi manualised or a fully manualised valve body, then you'll need to manually shift from 1 2 3 D or whatever pattern your car has.

As Ben stated, a decent sized trans cooler is a MUST when it comes to stall converters and stuff.

[Chids34]

Hmm thanks, as to bens comment Ive worked with auto boxes before so Im building it myself, but mainly 727 torqueflytes and 904 boxes out of valiants and dodges so old school. Just out of curiosity what happens if I don't upgrade the converter, say because I wanted to use less fuel. As a street car I'm not going to be stalling it up, so is it necessary. Also the shift kit goes into the existing valvebody if I'm right, so If I have a normal valvebody (the r34 has the triptronic or whatever its called where it has the sideline so you can choose gears semi manually) it should be able to be used in the same way? Ill definately be adding a trans cooler anyhow.

[Ben C34]

That's right, there's no need to upgrade the converter if you don't want to.

Where are you getting the shift kit from?

You realise the r34 trans is different to the R33 trans?

[Ben C34]

Also as the factory trans computer is staying in place shifts are still reasonably nice at light throttle due to the trans computer reducing line pressure. It's only when you go full manual and run full pressure the whole time that shifts become very harsh all the time.

[Kinkstaah]

Is there any info anywhere as to how much the standard computer modulates line pressure? Does it go for "X" PSI or does changing the valve body result in it working in a "percentage?"

eg, at 'low' load does it go for "50%" of line pressure, or a set PSI?. I am kind of assuming it does a percentage, otherwise upgrading a valve body would do literally nothing if the standard computer would control exactly how much pressure to shift with

What you want though, is an aftermarket TCM for your transmission. Hopefully I will be able to see what the difference is running a big shift kit on the standard computer to one with a tuned TCM.

In all aspects though, a big shift kit is usually just fine for the driver, passengers may complain, though. This is the case with almost any modified car mind you..

[Ben C34]

From what I understand it does it by pulsing a solenoid to bleed off pressure.

It doesn't monitor what the actual pressure is, so its just a set duty cycle thing.

You can add add larger resistor into the solenoid wiring so it bleeds less pressure off by not allowing the solenoid to open fully. At full throttle it's full line pressure so it just adds pressure for part throttle stuff. I did it as I run an rb2530 so make more torque with less throttle openings than the stock trans ecu would be expecting.

Edited August 27, 2014 by Ben C34

[Chids34]

To Ben, yeah I realise the transmissions are different, its a kit made by Paul Keeas Transmission, I think he is based over east, thanks for the info guys helps alot Ill be installing the kit soon