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CRASH BOX SEQUENTIALS ARE THE OPPOSITE OF SMOOTH
This seems to be all the rage in hard core Time Attack and even some W2W race cars with V8 power - sequential transmissions! I have many friends / customers with these, know vendors who build and sell them, and we have even purchased a few. But they aren't as slick as what you'd think...
After watching countless videos and hearing the tales of woe, I'm not happy with how any of these things shift. NONE of the aftermarket "sequentials" are very smooth for "flat" shifting, as these are all just crash boxes. Meaning: they don't have synchros.
Some of the Rallycross sequential trans setups (Sadev) have been tweaked and tuned and dialed in for relatively smooth shifting, but it took a LOT of engineering time, very expensive pressure sensitive shifters, and a lot of time. And these all still required frequent rebuilds and replacement parts.
Sure, technically they can be "stronger" as they would have straight cut gears (see a G-Force 5-speed manual with similar gears), vs the helical cut gears on a synchronized box. But the faster shifting (via air or mechanical shifting) puts more stress on the gears to get that "fast shift".
These crash box sequentials also all need a foot activated clutch pedal to be used (see above left), as least to get moving from a standing stop - they are really just "crash box" manuals with a sequential shifter. They shift fairly violently and they all break - a lot.
THE SMOOTH SHIFTING SEQUENTIAL - OEM DCTS!
There is an alternative, based on the OEM style DCT. What makes the OEM Dual Clutch Sequential Transmissions (DCT or PDK) so good is the fact that they still shift smoothly (with two internal clutches / gear stacks that are pre-engaged using logic) and you never need a clutch to get going. So they can have launch control and smooth upshifts and downshifts, drive like a cushy automatic, AND rip up and down through gears perfectly on track.
These are typically created by BIG companies with BILLIONS of dollars of research, then paired with a BIG automaker and even more engineering and testing time. Getrag and Tremec that team up with BMW or Ford / GM. This isn't some backwoods circle track supplier or small European bespoke transmission builder's output. The key here is BILLIONS OF DOLLARS. And the results are... *chefs kiss* ...so choice!
I have been lucky enough to drive many OEM DCT equipped cars on track, starting in the mid 2000s. like our 2008 EVO X MR (above left), BMWs, Porsches, GT500 (below), GTR, and the Corvette C8 (above right), among others. Driving all of these on track is a JOY and they are SO EASY to push hard. Every shift is fast, butter smooth, and you don't have to worry about over-revs or other tuning problems. Billions of dollars and top tier engineering produced this...
It sort of angers me that not ALL sports cars come with DCTs, but there are some downsides - namely weight, cost, and complexity. There are horror stories of P-cars with problematic DCTs that have $30K rebuild costs.
BMW DCT SWAPS
The BMW DCT aftermarket has much more robust coverage, with aftermarket clutch upgrades, cooling, and even hacked TCMs (transmission control modules) and swaps.
There are just some added systems that need to be swapped along with the box itself - the shifter, the cooler, and hydraulic lines. Then an adapter to mate it up to whatever engine, then the electronics and tuning.
Yes, while some of these BMW DCT boxes can be swapped from OEM applications, not many folks have made this work well for V8 powered race cars (ie: smoothly driving street car + reliable track box with perfect rev matched up and down shifts), and the ones that do usually SUCK for street use almost as much as the crash box sequentials.
It's a real challenge to make these work with aftermarket EFI in drivetrain swapped setups (non-native BMW engines). There is this HTG gearbox copntroller shown above, but I have heard nothing but horror stories. There is one EFI system to date that has native control of the BMW DCT - and that is the MaxxECU system. The tech is too new on these swaps for me to comment further.
The mechanical and hydraulic adaptation is relatively straightforward and there are a number of suppliers for these "hard parts". Its the electronics that are the real challenge. This is a tricky subject we have looked at intensely, and there appears to be no perfect answer - and the power levels of modern LS V8s can overwhelm the BMW DCT. There are Facebook groups dedicated to this swap, of course, and we badly would like to do one. Just looking for the right project to do this on!
We are also working with Tremec engineering to TRY to get their 7 speed GT500 DCT but that has been 3 years now with no answer as to when or even if this will become available for aftermarket use. The TCM and ECM interface is VERY tricky.
We will update this thread if or when we move forward with a DCT swap. It is high on the list of WANT but low on the list of NEED.
Thanks for reading my rant!
This seems to be all the rage in hard core Time Attack and even some W2W race cars with V8 power - sequential transmissions! I have many friends / customers with these, know vendors who build and sell them, and we have even purchased a few. But they aren't as slick as what you'd think...
After watching countless videos and hearing the tales of woe, I'm not happy with how any of these things shift. NONE of the aftermarket "sequentials" are very smooth for "flat" shifting, as these are all just crash boxes. Meaning: they don't have synchros.
Some of the Rallycross sequential trans setups (Sadev) have been tweaked and tuned and dialed in for relatively smooth shifting, but it took a LOT of engineering time, very expensive pressure sensitive shifters, and a lot of time. And these all still required frequent rebuilds and replacement parts.
Sure, technically they can be "stronger" as they would have straight cut gears (see a G-Force 5-speed manual with similar gears), vs the helical cut gears on a synchronized box. But the faster shifting (via air or mechanical shifting) puts more stress on the gears to get that "fast shift".
These crash box sequentials also all need a foot activated clutch pedal to be used (see above left), as least to get moving from a standing stop - they are really just "crash box" manuals with a sequential shifter. They shift fairly violently and they all break - a lot.
THE SMOOTH SHIFTING SEQUENTIAL - OEM DCTS!
There is an alternative, based on the OEM style DCT. What makes the OEM Dual Clutch Sequential Transmissions (DCT or PDK) so good is the fact that they still shift smoothly (with two internal clutches / gear stacks that are pre-engaged using logic) and you never need a clutch to get going. So they can have launch control and smooth upshifts and downshifts, drive like a cushy automatic, AND rip up and down through gears perfectly on track.
These are typically created by BIG companies with BILLIONS of dollars of research, then paired with a BIG automaker and even more engineering and testing time. Getrag and Tremec that team up with BMW or Ford / GM. This isn't some backwoods circle track supplier or small European bespoke transmission builder's output. The key here is BILLIONS OF DOLLARS. And the results are... *chefs kiss* ...so choice!
I have been lucky enough to drive many OEM DCT equipped cars on track, starting in the mid 2000s. like our 2008 EVO X MR (above left), BMWs, Porsches, GT500 (below), GTR, and the Corvette C8 (above right), among others. Driving all of these on track is a JOY and they are SO EASY to push hard. Every shift is fast, butter smooth, and you don't have to worry about over-revs or other tuning problems. Billions of dollars and top tier engineering produced this...
It sort of angers me that not ALL sports cars come with DCTs, but there are some downsides - namely weight, cost, and complexity. There are horror stories of P-cars with problematic DCTs that have $30K rebuild costs.
BMW DCT SWAPS
The BMW DCT aftermarket has much more robust coverage, with aftermarket clutch upgrades, cooling, and even hacked TCMs (transmission control modules) and swaps.
There are just some added systems that need to be swapped along with the box itself - the shifter, the cooler, and hydraulic lines. Then an adapter to mate it up to whatever engine, then the electronics and tuning.
Yes, while some of these BMW DCT boxes can be swapped from OEM applications, not many folks have made this work well for V8 powered race cars (ie: smoothly driving street car + reliable track box with perfect rev matched up and down shifts), and the ones that do usually SUCK for street use almost as much as the crash box sequentials.
It's a real challenge to make these work with aftermarket EFI in drivetrain swapped setups (non-native BMW engines). There is this HTG gearbox copntroller shown above, but I have heard nothing but horror stories. There is one EFI system to date that has native control of the BMW DCT - and that is the MaxxECU system. The tech is too new on these swaps for me to comment further.
The mechanical and hydraulic adaptation is relatively straightforward and there are a number of suppliers for these "hard parts". Its the electronics that are the real challenge. This is a tricky subject we have looked at intensely, and there appears to be no perfect answer - and the power levels of modern LS V8s can overwhelm the BMW DCT. There are Facebook groups dedicated to this swap, of course, and we badly would like to do one. Just looking for the right project to do this on!
We are also working with Tremec engineering to TRY to get their 7 speed GT500 DCT but that has been 3 years now with no answer as to when or even if this will become available for aftermarket use. The TCM and ECM interface is VERY tricky.
We will update this thread if or when we move forward with a DCT swap. It is high on the list of WANT but low on the list of NEED.
Thanks for reading my rant!