Ask MF: Auto Transmission Power Handling

Sections: Ask MotoringFile | R53 (Coupe) Oct 30th, 2007 17 Comments

Motoringfile Reader Clayton writes in with a great question concerning the Aisin automatic transmission.

I have a 2006 MCSA and I am considering adding some serious power to it, but I am worried that the transmission wont be able to handle the power. do you know of any company out there making after market parts to stengthen it?

As far as we know, there aren’t any companies that build any kind of kits to make that transmission stronger. It was never intended to be in any high power, high performance application.

That being said, I have seen many a MCSa out in the wild with reduction pulleys, upgraded intake systems and performance exhaust installed. After speaking with the owners, not only do they love the new power, they haven’t experienced any issues as far as the transmission goes. I have found some fairly high horsepower numbers (200+) on the boards and no trouble with the transmission either.

I wasn’t able to find any numbers on max power, but I’m sure one of the fine Motoringfile readers might have some further insight on this. Before you comment, please remember we are here to help, not criticize our fellow MINI owners who choose the auto transmission.

Written By: DB

17 Comments

Mark (Texas) Oct 30th, 2007 Link

I know that with the older CVT, I was warned by a MINI Speed Shop that they would not put in the old original JCW kit in my base MINI, as the trans would not stand up to it. But have not heard of any issues with the Aisin auto. My son used to race against a lot of rice burners with the same/similar Aisin auto trans in heavily modded (including nitros) cars. Some of the racers would push up the HP/Torque in their cars to the point where a heavy-footed take-off would snap an axle, but never any trans issues at the track.

Melis Oct 30th, 2007 Link

I didn’t see the MINIUSA Accessories Guy (German guy, I forgot his name) testing out the R56 MCS JCW Engine Kit for the Automatic while I was at Prestige MINI. He wasn’t testing out his tricked out Red/Red MCS with the JCW Aero Kit.

I really didn’t see anything. ;-)

Ian C. Oct 30th, 2007 Link

I’m shocked that you don’t warn that if the transmission does fail, it’s basically guaranteed that there’s no warranty, if the engine has been modified.

Mark (Texas) Oct 30th, 2007 Link

Iâ€™m shocked that you donâ€™t warn that if the transmission does fail, itâ€™s basically guaranteed that thereâ€™s no warranty, if the engine has been modified.

Good point …unless the mods are done by the dealer, ie. JCW Intake, JCW Exhaust, etc.

Victor Oct 30th, 2007 Link

if there is no automatic control software change with the power application the transmission with have phantom shifts all over the place. Also the torque converter will be overloaded and lockups could be very unsmooth.

Jahpaul Oct 30th, 2007 Link

Any word of when the jcw kit for the auto will be ready ?

GregW Oct 30th, 2007 Link

See my comment on previous posting about used Minis. The old CVT transmission is expensive to replace if it fails under normal use let alone being subject to extra strain of a modified engine output. Any car that has aftermarket modifications will be disqualified from the manufacturers warranty.

Gabe Oct 30th, 2007 Link

Any word of when the jcw kit for the auto will be ready ?

Well judging by the fact that I’ve sat in one already at an “undisclosed location”, it has to be fairly close.

Mark (Texas) Oct 30th, 2007 Link

See my comment on previous posting about used Minis. The old CVT transmission is expensive to replace if it fails under normal use let alone being subject to extra strain of a modified engine output.

…very true GregW, (which is why I’m trading for a Clubman before my ’04s warranty is up), but the person posing the question has the newer Aisin 6 speed auto slush-box, not the CVT.

BrewSwapGuy Oct 30th, 2007 Link

Any transmission failure does not automatically scrub the warranty if your car is modded. If the mod causes the failure it is. But the transmission could fail for other reasons.

I have a 2005 MCSa with a 15% reduction pulley, Alta intake and Larini exhaust and I’ve had zero issues. The car now feels “right” when it comes to power and acceleration. Still though, every now and then the computer gets confused and switches gears at the wrong times. Causes an annoyance and that’s about it.

Not sure what else the reader had in mind when he says “serious” power. I certainly wouldn’t call what I did serious.

Diosdado Oct 30th, 2007 Link

Torque specs here – http://www.ricardo.com/engineeringservices/transmission.aspx?page=productsalreadybenchmarked

See this thread on NAM – http://www.northamericanmotoring.com/forums/showthread.php?t=118367

CooperS33 Oct 30th, 2007 Link

Wow!! What an honor to have my question posted on Motoringfile! thanks Gabe! And thanks to all who have responded!

BrewSwapGuy Oct 30th, 2007 Link

Clayton, you already have a pulley and a Larini exhaust don’t you?

Gabe Oct 30th, 2007 Link

Wow!! What an honor to have my question posted on Motoringfile! thanks Gabe! And thanks to all who have responded!

Actually it was DB but you’re welcome :)

CooperS33 Oct 30th, 2007 Link

Nom just a Invidia 3″ and I was about to do the pulley. I just asked about the transmission cause i’m thinking ahead.

Ron Nov 1st, 2007 Link

Speaking of warranties, remember that MINI would have to prove that your upgrades caused the transmission to fail. They couldn’t arbitrarily blame it on your modifications.

And as I remember, the JCW kit was available for automatics in Europe. I don’t think they got a special transmission, so I think it’s safe to assume that upgrading your auto to JCW specs is safe.

John Connor Nov 6th, 2007 Link

I got a 15% pully on mine. Was one of the first ones ever put in (was fun with the guy up in Maryland who did it). It’s been, what, a couple of years now. Have never had a problem, Mini is running beautiful. (I think I put it on with about 3000 miles, it now has 27,000 miles)

John

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