ish9

Hey guys, how is it going? I've got a 92 SC300 with a 5 speed that has been equipped with an Adaptronic ecu. The wiring is in its final stages. I know somewhat of the limits of the manual transmission in these vehicles. Read through many threads about that topic. My tuner plans on using boost by gear to taper the boost through the gears in an attempt to prolong the life of the transmission. I see a few auto transmissions for sale at a decent price and don't mind loosing the thrill of the manual. The factory ecu's are drive train specific, what is needed to swap the transmission using an aftermarket one?

I did a google search and a search through the forums and found nothing on this topic. Bare with me if I overlooked a thread. Any and all advice is highly appreciated.

Ali SC3

iTrader: (10)

the stock manual w58 has some limits.. but it can handle more than a stock auto can.
you can get a gte auto that will hold more, but you might as well just invest in a better manual transmission that will hold even more.
you can also build up the auto transmissions to hold big power, but in stock form even the gte auto's are ok at best.

with a standalone ecu, you can run an auto if the standalone supports it.
the only auto trans the stock ecu supports is the stock auto, which is fine for stock power but if you are turbo you will be on borrowed time and should just stick with the w58.

what is your setup like, are you going turbo? you normally hear people going to manuals to hold more power, not the other way around.
I would not swap out a stock manual trans for anything less than a built auto trans if it had to be automatic.

ish9

Thanks for the quick reply. I think I'll end up building an auto, solely for the cost compared to upgrading to the r154 or similar manuals.

gerrb

iTrader: (34)

A TT Auto Trans that is properly built will cost you at least $3k . Anybody who says rebuild them and do not install a 2nd gear billet sprag and better clutches are telling you stories and better run away from them. A properly built auto like one built from ATF Speed for which I got three of them will let you hold more power up to around 850rwhp / 750ft.lbs. just because its next weak link will be its input shaft. It aint billet.

So that would not be any cheaper than a stock R154 that can actually hold 750rwhp with the exception that its problem will be spewing fluid at the different seals due to the pressure. Depending really on your power goal and use of the car , then you make your decision. Like a car that will always be at the drag strip will be far better having a TH400 for strength and power .

It will be nice if you can let us know what the purpose of the car is and your power goal is. There are a lot of other factors to consider. Like as Ali said , going automatic ,you got to make sure your aftermarket ECU could support it.

ish9

Plan on using the car as a weekend car/short commute to school. Want to keep it around 400-500hp reliably. Wont be at the track much if any. Car has the stock motor, head gasket, stock intake manifold with a Borg Warner 67 mm turbo, FID 1000cc injectors, AEM 320 fuel pump, and adaptronic ecu.

gerrb

iTrader: (34)

then go for the TT Auto Trans and add 2 or 3 oil coolers if truly you want an automatic trans. It will hold the power if you are just a weekend and school warrior. The W58 wont hold long beyond 400rwhp/350 ft.lbs. . You will be on borrowed times. Depending on its condition and give way anytime. You might have to piggy your adaptronic ecu to the stock TT ECU after you have done the NA-T TT ECU of Ali on this forum just to control the TT auto trans. I doubt your adaptronic ecu supports the TT auto trans.

did you say you have a tuner ? may i ask who here in GA ? what was his suggestion about transmission ?

Ali SC3

iTrader: (10)

yeah I just googled the adaptronic ecu it seems like you have to piggyback with the stock ecu to control the trans, that is pretty weak sauce.
I would go for a r154 swap or t56 swap and forget about the automatic.

the r154 can be done for similar to what a built auto will cost, more or less depending on the part you use.
a tt auto can be had for a lot less but you will have to add all the wiring for it also which you need to get from a gte harness or wire from scratch = $$
check out the AR5 trans swap thread, you can get a newer version r154 and use bolt on parts to fit it in an SC.
since you are already manual, you wont need the extras like pedals and whatnot it will be just a straight trans swap.

ish9

Yea I found the same results on my google search. I'll look over the r154 swap threads to see whats all involved. It's not worth all the wiring thats needed.

My tuner is Steve Pullzone, he worked on my Subaru in the past and is helping me with this build.