supposedly there was an option for the mr2 spyders sometime between 1999 and 2003 for a semiauto tranny - no clutch just two paddles, one to shift up and one to shift down. i dont know what engine it was behind or how strong it is or even if that type of tranny would be viable for trail use. just kinda throwing this out there. could end up being one of the exotic swaps like a lexus v8 or it could be the stupidest idea in the history of wheelin'.

I don't know how that works, but I do have semi-automatic tranny experience.

The CAT 7155 is a 16 speed semiautomatic tranny. It uses air-actuated shifter and clutch mechanisms. While the DEEEEEEP underdrive of the low gears would be awesome off road (4 mph top speed in 1st gear), the clutches would wear out quickly. The clutch determines how hard to apply itself based on the input from the crankshaft... 700 rps means no clutch, 1200 means engage quickly. If you are negotiating an obstacle, the clutch would not apply enough force to get up until about 1100 rpm, but you would then lurch forward, losing traction in the process.

I believe the unit you are talking about is more like an automatic tranny, with changes to the valve body... This would allow the unit to only engage the gear selected, until you input another gear. Same thing as running an auto in L1, but when you shift to L2, it will never go back into L1 without your input. Just like an auto, you would have to keep an eye on the fluid, as your input may require more slip from the torque convertor, and more shearing of the fluid.

While mr2's are rear wheel drive, they are also rear engine. You would have to do a full engine swap into bed of your truck to get it to work... <img src="/forums/images/graemlins/shiner.gif" alt="" /> then you would have to deal with the IRS and fun stuff like that...


Josh

didnt think about it being rear engine...that would kind of negate the point of having a truck, wouldnt it? like i said didnt know much about it but it sounded kinda neat.

The transmission used in that application was a plain old slush-box... the only difference being that you can force the thing to upshift. With most automatic transmissions, you can force a downshift(by moving the gear selecter lever to a lower gear), but you can't force it to upshift or hold a gear. The system used in the MR2 allows the driver to control what gear the transmission is in. However, the ECU won't let the driver run the engine over redline or stop in a gear higher than first.

There are cars out there that have a true manual transmission that will shift/engage the clutch itself, but I've never heard of one in a car in a car costing less than $100,000. Aston Martin, Ferarri, and Lamborghini offer vehicles with automatic shifting manuals.

In other words, there probably wouldn't be much benefit other than being able to make the trasmission hold a gear for crawling... but you can do that anyway by putting the gear selector into the first gear position. (would you want to crawl in any other gear?)

Maybe, just for fun would be fun to convert a Mr2 to an off road vehicle, kind of the Porsche 911 Paris Dakkar winner in the early 80's... <img src="/forums/images/graemlins/cheers.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" />

There's an MR2 all jacked up on huge swampers somewhere in the less populated area of my state. I've never seen it myself so i'dunno what the deal is with the running gear..

Might be able to get some pics sometime.

The MR2 used a front wheel drive Corolla drivetrain swapped to the rear of the vehicle. Fun car though.

Not completely related to the original question but manual valve bodies have been available for just about every domestic automagic since the dawn of time. Many serious street/strip cars run autos with manual valve bodies and a Hurst or B&M ratchet shifter. The shifter is pulled down into the ratchet mode and the subsequent gears are obtained by slamming the shifter forward once for every gear. The streetable shifters also have a full manual mode where you simply select the gear you want by physicaly moving the handle to the appropriate gate.

A more off-road friendly shifter would be something like this one from Art Carr. By simply changing the valve body ($150-$500 depending on the application) and having one of these shifters, you can enjoy total manual control over the shifting of an automatic tranny. Having compression braking going down a steep hill is just one of the pluses one can enjoy with an automagic. Around my neck of the woods, blasting through a mud hole without having to worry about the tranny shifting into too tall a gear is pretty handy.

Now I haven`t heard of any aftermarket valve bodies for Toyota autos but in this day and age you can get an adapter to mate anything to anything so if that is truly what you want you can have your cake and eat it too.

Toughguy <img src="/forums/images/graemlins/smile.gif" alt="" />

My wifes 04 Solara V-6 has what is called a "Sport Shift" automatic. When in drive you move the shifter to the left and the you can shift it like a stick shift and hold it in gear as long as you like. It is great in the mountains!!!!! <img src="/forums/images/graemlins/lol.gif" alt="" />