SLK/R171: RennTech transmission upgrade
Thread Starter
Newbie
Joined: Jul 2016
Posts: 3
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2006 SLK 350
RennTech transmission upgrade
I've been autocrossing my 2006 SLK350 for the last 5 years, it has an automatic trans that is painfully slow to engage when downshifting under heavy acceleration. I am considering the Renntech transmission upgrade but don't want to spend the money and have the same problem. Anyone have experience with this?
Newbie
Joined: Dec 2014
Posts: 6
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From: Lake Tahoe NV
1999 ML320, 2007 SLK280 Amg Package, 2012 C3004matic, and 1975 BMW2002Ti
"Downshifting under heavy acceleration"?
That's a bit of an oxymoron isn't it?
I can see downshifting during de-celeration, and UPshifting during acceleration, but not downshifting under heavy acceleration. Sure that's what you mean?
That's a bit of an oxymoron isn't it?
I can see downshifting during de-celeration, and UPshifting during acceleration, but not downshifting under heavy acceleration. Sure that's what you mean?
Thread Starter
Newbie
Joined: Jul 2016
Posts: 3
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2006 SLK 350
If you are cruising and you push the gas pedal to the floor to accelerate, the transmission will downshift to give you faster acceleration. My engine revs quickly but there is quite a pause before there is any forward acceleration.
Newbie
Joined: Dec 2014
Posts: 6
Likes: 0
From: Lake Tahoe NV
1999 ML320, 2007 SLK280 Amg Package, 2012 C3004matic, and 1975 BMW2002Ti
Oh, so you mean auto downshift. If your's seems slow are you using the S or sport selection? This mode increases response of downshifts when WOT. The other option is to manually select gear, especially when auto crossing, which is the preferred method. A transmission mod seems a costly solution for a small improvement in performance, IMHO.
Former Vendor of MBWorld
Joined: Jun 2016
Posts: 416
Likes: 25
From: Carrollton Texas
clk and e coupe
We do allot of transmissions. So you are having a delay on downshifts. Is it on all gears?
You may have an issue, hard at this point to diagnose online. But i dont think you need a renntech trans to fix it.
How long have you had the car, have you serviced the trans? Is this a new problem. Have you had anyone reset the shift adapts?
You may have an issue, hard at this point to diagnose online. But i dont think you need a renntech trans to fix it.
How long have you had the car, have you serviced the trans? Is this a new problem. Have you had anyone reset the shift adapts?
Thread Starter
Newbie
Joined: Jul 2016
Posts: 3
Likes: 0
2006 SLK 350
It has always been this way, since the car was new. Just not a great transmission I guess. I recently learned how to reset the adaptive shifting and that has helped with shifting in general. But it has not corrected this delay before the transmission engages when I floor it.
