A340 how strong ?

[EvilJack]

my A340 is out of a jzz30 and is good for 300rwhp anymore and i'd have to look at upgradeing to heavy duty clutches and rebuild

[takai]

Yeah, Southo has just had to rebuild his for reference.
Pity that the R154 doesnt fit in neatly.

[mrshin]

I've got a 7MGTE one, presumably from a Supra originally (It was removed from an MA61 that the 7M died in)

[YelloRolla]

The strength of the modified 'box is adequately supported by both the Supercrown and 1JZ-747.
1JZ-747 has run in the 10's with the A340 (MX83 Cressy). Both gearboxes have been modified by MV Automatics I believe.

[MS-75]

Hi mate.

There are probably some small differences between the boxes. (I can't be sure on the box in your crown, but the following is quite likely)

The Crown one may have slightly smaller diameter clutch drum and bigger volume accumulator piston voids. This means it'll hold slightly less torque (and hence power) and will also have softer, longer changes.

The long changes are the biggest problem if you put some power through the box as it will slip for longer, putting more heat into the fluid and box.

The supra parts can all be changed straight into the box however.
(we discovered all this when we pulled the cressida box I had in the 'supercrown' out once I'd nuked it well and truly)

While you have the motor out though, putting a supra box in would be a good idea.
The best thing you can do is fit a big trans cooler and put some small fans on it. A trans temp indicator is also cheap insurance as you can see when you're overdoing it.

As for the trans I'm using, it's from a 7M cressida originally, but has the supra parts changed over, extra clutches, upgraded friction materials, valve-body modifications and is manually shifted. Compared to the mods required for a ford trans of GM trans to hold 700+hp, it is pretty close to stock and hasn't even hinted at letting go.

It's currently copping over 900ft/lbs at the (stock!) input shaft and has coped fine with pushing the heavy crown to 10.4@136! It's also looking likely it will see me into the 9's early in the new year. The boxes are cheap and plentiful, and if you do lash out and have one built up, my experience has been they are the best value big HP trans going around.

Cheers
Sean

[ProjectSleeper]

After just having mine re-built, my Cressida runs sooo much better, (I have only gone subtle compared to MS-75 and IJZ-747) - but the difference is still very remarkable under hard accelleration..

Previously, mine would flare out on gear changes soo much that it would hit the rev limiter and then change after what felt to be about half a second. After spending $2500 on it, it's fantastic, under light load / gentle driving etc - it runs almost exactly the same as standard and is super smooth, but once you get up it, the thing is very solid and defined in it's changes... Best of both worlds...